Golf V 2005 4motion TDI 2.0 103kW BKD getting hydrolocked with coolant.

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
I'm new on the forum so hello everyone. I have a 2005 Golf V 4x4 drive (4motion) with a 2.0 TDI BKD engine (PD). I bought it 2 years ago and I had no issues until a couple of months ago I noticed gradual coolant loss. Now that I think about it the loss may have been there from the start, just very slow. I normally do short trips. I noticed the coolant loss on those rare occasions when I drove for more than 10 minutes. I initially thought this is probably a head gasket seal, or warped/cracked head. I had a similar issue on another car so I was on the lookout for bubbles in the reservoir. Nope, there were no bubbles. I had to use the car so I continued to drive it until I also started having very strange starting issue.
The starting issue would only happen if the car was left off overnight or longer. Basically I would hear the starter turn the motor somewhat and then get to a sudden stop. Waiting a minute and trying again would eventually start the car. Sometimes I had to try few times. I would see lots smoke in the exhaust after starting. Once the engine got to the temperature the smoke was gone and it drove fine. I suspected the starter and replaced it. It didn't make any difference. The starting problem and coolant loss got progressively worse. Eventually once the starter stopped I would have to turn the engine manually a bit to get it going. To do that I would put the car in first gear and push it slightly until I felt engine give a bit of resistance. Then attempting to start would succeed (again sometimes after few tries).
I started researching the problem and I came to a conclusion that this may be an EGR cooler leak that sends coolant via the EGR valve into intake and cylinders. I thought that when the engine was hot the coolant would evaporate and don't cause much issues (I was always topping up with red coolant, never water), but once the engine was stopped it condensed in the inlet manifold and on startup whichever cylinder would try to get air first would get a gulp of coolant and get hydrolocked in the process.
So I replaced the EGR cooler, but in the process I found no sticky gunk in the old one, just what looked like dry soot. Same in the EGR valve and pipe connecting the two. If EGR cooler was the source of the leak I thought the pipe, the cooler and the valve would all be full of gunk.
However, when I removed the inlet manifold I poured half a liter of coolant from it, and the inside walls were covered in sticky black gunk :( I also removed the rocker cover and removed glow plugs in hope of sticking an endoscope camera into cylinders to assess their status. No luck the camera was about a millimetre too thick :( However, when I turned the engine by hand coolant shot from the first cylinder's glow plug hole. The remaining cylinders were dry. Also the ends of the glow plugs looked dry in cylinders 2,3 and 4, while number 1 was covered in something that looked like dense oil? Based on the above I started thinking I probably have a broken head gasket seal, a cracked head, or a cracked engine. I also drained oil from the engine and I found about a tablespoon of coolant in it.
Now, I think if I had a cracked engine block I would also have oil in coolant unless the crack was where there is no oil pressure. Also, I would expect a lot more coolant in oil if this was indeed a cracked engine block. On the other hand if this was a cracked head or a broken seal I would expect bubbles in the coolant tank.
I refilled the coolant to the brim, I pumped squeezing the hoses to remove air and I left the engine with glow plugs removed overnight and coolant cap open. The coolant level didn't go down. Also there was no coolant in the cylinder in the morning. I put everything back together with exception of replacing the coolant cap (I left the reservoir open), connecting the anti-shudder valve and EGR valve as I wanted to take the EGR out of the picture. And I run the engine until it heated to temperature. Some bubbles occurred which suggests my previous air draining attempts were not fully successful, but once air was pushed out there were no bubbles. I left the car overnight. No issue starting it in the morning, also coolant didn't go down.
I left the anti-shudder valve off because I believe the way it works closing in the moment the engine is switched off creates significant vacuum in the intake manifold and the cylinder that happens to be attempting to pull air so it might have contributed to sucking the coolant into the cylinder through some breakage in the seal.
So now, I'm a bit puzzled. I know that starting and coolant loss issues were caused by the coolant hydro locking the first cylinder (maybe others too - perhaps I just managed to look at when the coolant was in the 1st cylinder by chance). The valves are not sealing completely (I could hear the air squeezing past when I turned the engine by hand with glow plugs in place) so the coolant could slowly escape through them allowing me to eventually start the engine. This suggests a coolant leak into the cylinder somehow, but I can't understand how is it possible that high pressure gases do not leak the other way too causing bubbles? Surely no matter the coolant pressure the combustion gasses are under hundreds time more pressure. Does anyone have any ideas? Is there any coolant supply to the pump-injectors in the BKD engine? (I have bosh injectors). Can coolant be leaking through into the first cylinder from anywhere else?
Since I replaced the EGR cooler I failed to replicate the issue, but I still have the EGR valve, the anti shudder valve and the coolant tank cap disconnected/removed and the car's front is lifted up by half a meter so the car is angled (I don't know if this matters. I worked on the car through the weekend so all my testing was with the front wheels up in the air.).
Also, I'm reluctant to close the coolant tank cap to avoid pressure build up as perhaps this is what causes the leak to activate. Can anyone think of any issue driving without it? I need to use the car until I get a new head gasket and I have time to remove the head. Additionally, I was told by a garage a head has to be planned after it has been removed. Is this true? Can I simply remove the head and replace it without doing anything (possibly replace the gasket), or is the head likely to warp when I release the bolts making proper reassembly impossible?
Sorry about the length of this post and the number of questions, but I don't know where to turn to deal with this. Various mechanics have quoted me thousands for various repairs while it is uncertain what is broken while my fiancee tries to convince me it's time to buy a new (used) car, but I'm still hoping this can be repaired cost effectively. I ended up doing the investigation and EGR cooler replacement myself. I also have a surface grinder so I could probably plan the head if necessary, but I would prefer to avoid it if possible.
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
Welcome to the forum!

FIRST AND FOREMOST!!! Stop trying to start your engine with coolant inside cylinder 1. Running it with coolant will bend your rods and mess things up. If you are hearing cylinder 1 leaking compression, it could be some blow by or it could be the valves are already bent. Once it runs, does it idle OK?

There is not coolant going to the injectors. In the head, coolant passages run near the injectors but there is not express cooling for the injectors. The cooling of the injectors is probably done by the diesel and the oil around them.

I think you've got a bad head gasket, that would explain why you've got so much coolant going into your cylinders. How many miles are on your car?

I just did a head gasket on my 2006 Jetta TDI 1.9 BRM engine, which I believe is somewhat similar to your engine. It is NOT difficult to do but it is involved and time consuming. It took me about three days all in all, making sure to follow steps and take pictures and do some research. You won't really need any special tools other than the tools to keep the crankshaft and camshaft locked in place. What is your level of experience working on cars? If you were able to do the EGR cooler, you are probably able to do this, just make sure and double check your work, and make sure you are being careful with the tensioner on the timing belt, it is somewhat simple and yet complicated and if you remove the stud to avoid removing the engine mount, remember to make sure you are not messing up the threads getting it out.

If you are going to do this all, I would recommend doing a camshaft service (on the BRM, camshafts get worn out) replacing the cam, lifters, cam bearings, etc... timing service and the head gasket itself. No real tutorials or diys on head gasket procedure but the way I did it was to remove the head with the turbo, intake manifold and exhaust manifold still on but I removed the camshaft and other items.

LAST! Get a second opinion.... Diesels are waaaaaaaaaay more common where you are and there surely is a TDI guru from this forum near where you live. Go to them and get a second opinion so as to save you time and money in the long run.

Best of luck!
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
Thank you maxtdi.
I think you're right with the cracked head diagnosis. I left the car in the normal state (everything put together and not lifted up anymore) and after 2 days of sitting I removed the glow plug from cylinder 1. When I turned the engine by hand I got few tablespoons of coolant from the glow plug hole shoot out. So it is still leaking even when everything is off.
Regarding my experience I've done lots of what I consider simple repairs on other cars in the past. Replacing alternators, starter motors, timing belts, water pump on a Peugeot, cleaning injectors etc. I also have an old diesel tractor I've been working on, but it has a Russian air cooled diesel engine so no coolant issues there :) The EGR cooler was really difficult to get to as this is a 4 wheel drive car and there is no access at all from the bottom - the front drive obstructs everything, but I managed to replace it during one full day. I also repaired few old lathes, a milling machine, a hydraulic surface grinder. So as long as I have the right info I hope I should be able to replace the head. I'm also waiting for the timing locking kit to arrive before I start.
I also can live with the car being unavailable for few weekdays so I've found out my current head gasket is a two hole one, I ordered a replacement and I plan to pull that head off, clean it real well and see what state it is in.
Regarding other items like camshafts, lifters, cam bearings etc, would wear be visible? Would I be able to assess it with some measuring tools like a surface plate, engineer's straight edge, an indicator on a stand etc, a set of hole gauges and a micrometer? Regarding timing service I'm also researching how this should be done properly for this engine, If you know about any materials I would be grateful for links or mentions of them.
Also, and this is probably the most important question for me, are there any materials ideally with drawings of the internals in the head showing all components? I already found the self study programme 316 from VW that shows and describes many parts in the head, but it doesn't contain a complete drawing. So far I have been looking for pictures taken by others dismantling their cylinder heads to see what I'm likely to encounter.
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
Since you have an AWD car, space is bound to be extremely limited. I found that you can do most of the work from above the car but it helps to be able to reach from underneath since there are a few bolts that are more accessible that way. The most difficult part for me was to remove the bolts that held things on the right side of the engine if you are facing the car, the part where the turbo is, there are four pesky bolts that hold things like the oil feed line, the pipe that sends hot air into the intake, etc... Those were a big pain to take off because the bolt heads are towards the firewall.

The turbo plugs into the return line with two o-rings so that will lift off straight up.

The clamp on the exhaust manifold from the turbo was a nightmare to pry off because it was stuck on there pretty good. Once you see it, you will know what I mean.

If you are methodical and follow instructions you can do this very easily. It just takes time.

Some people recommend removing the passenger side axle to get more space underneath the car, to get to where the turbo is.

To save some on costs you could possibly purchase a good used head, making sure to check it is straight. A machine shop can do this for you. Or you can have yours worked on. It is up to you.

The camshaft replacement procedure and parts is outlined by chittychittybangbang on his TDI forum. Follow it and read it at least twice to get everything cleared up.

I'm no BKD engine expert so I am not sure that the camshaft service needs to be done on it. The BRM eats camshafts for lunch. This is a common occurrence. For the added cost and peace of mind, replacing the camshaft is not too much trouble. Once you start removing parts from the head you will definitely notice wear if there is any. You will need to get new head bolts, new cam bolts, etc. The head bolts are not reusable but the other ones you need are available reusable, which are much cheaper.

YOU WILL NEED a set of triple square spline bits, get as good quality as you can on those because you will encounter many of those bolts and don't want to strip them... They come in sizes M8-M12? Without these you cannot do the work.

If you want to know a lot more technical information, you can talk to Franko6, he knows his stuff very well, but I'm not sure how much he knows on the BKD engine. You can reach out to him, he's extremely helpful and knowledgeable.

Best of luck!
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
So I pulled the head, but I haven't found any breaks in the engine block, the gasket or the head itself. I'm attaching photos in hope someone can perhaps recognise some issue with the gasket as this is the only thing I can think of.
I haven't checked head for warp yet though.
This is the closeup of the cylinder affected

This is the top side of the gasket:

And this is the bottom:

This is the only used head gasket I saw so I don't really have a comparison how "good" should look like. Does this look like it could leak?
Also the layers of the gasket itself can be easily separated by hand (other than being held by rivets). Is that normal?
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
Good job on getting your head off!
Did you find any excessive wear on the camshaft or lifters? It is all much easier to check once the camshaft comes off. Please double check because I'm not sure the BKD does or does not eat its camshafts like the BRM does.

The gasket is three metal plates riveted together, yes, they might seem flimsy and easy to separate but that's how they are. i don't see any unusual signs of wear or tear on your gasket but once you get the head tested to be true and maybe even hot tanked as well, you should be able to spot why you were getting coolant inside cylinder 1. How does the block look? Take pictures of the area on the block around cylinder 1, there might be some clues there too.

Don't forget to do your timing belt as well, including pulleys and water pump, that will ensure you will get many more years out of your car!

Good work!
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
Thanks.
I think cams look good. I also couldn't feel any unevenness etc. This is how they look:

Regarding the engine block the first photo is at TDC.

The second shows cylinder walls. Unevenness seen towards on the front of cylinder wall is oil, the metal looks the same all round:

Coming back to the head. I removed the valves and cleaned it as much as possible myself. I'm not planning to give it to a shop to work on because I have a hobby metalworking workshop and hopefully I'll be able to measure and surface grind it myself. One thing I can't do is hot tanking unfortunately. This is the head on the surface plate with one of straight edges I used to measure it. It came up as only being about 0.03~5mm out of flat. (under 2 thou in inches). The manual gives a limit of 0.1mm (almost 4 thou) as acceptable. I'm not sure what to think about it. The leaking cylinder is on the bottom.

I'll surface grind the head so it is hopefully no more than around 0.01~2 mm out of flat and cleaned up nicely. Then I'm planning to clean the engine with a brass brush and I hope the leak goes away. Good point on the timing belt. I have order a kit on Monday.
Another thing I'm not sure about is what looks like pitting on the surface of the head in the first(leaking) cylinder. Other cylinders don't have that. There are no pits where the seal is. Only inside the cylinder. I'm not sure if the pits are a reason for concern. Should I be worried about them? I only plan to grind a thou or two and they look deeper so it is unlikely I'll remove them.
Im also planning to grind valve seats as I could hear air leaking a lot when turning the engine before disassembling.
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
Great work on doing all of this!
Your TDI will probably run better than new when you are done with all the work!

I see the pitting you are talking about, not sure whether or not it makes a difference. The best thing to do so there are no surprises later is to have your head pressure tested so as to make sure there are no leaks. This is a fairly common and easy practice that any reputable machine shop should be able to do. That will ensure you don't have any leaks you can't see.

Lastly, don't forget to use new bolts for the head. The bolts for the cam caps and rockers are available as a reusable, more affordable option for the BRM, not sure for the BKD engine.

As far as the cams go, they look to be in good shape. I am sure a new set of cams would be somewhat expensive, especially OEM ones. I would still talk to Frank, see if he recommends changing the cams, or maybe he can even do a performance regrind for you for a bit more power.

Awesome work!
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
Thanks :)
I think I may have found the reason for the leak. I measured the head with a micron dial indicator and I found unevenness I missed with the straight edge. I found about 80 microns tall bump near the edge of the cylinder. Although it is less than the maximum given by the manual I think it may be the reason for the leak as it is right on the edge.
Tomorrow I'll grind the head flat. I'm also getting new head screws. Hopefully I'm going nearer the end of this repair :)
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
Don't forget to change your oil and maybe your coolant as well because both can get easily contaminated when the head is off. You want both the head surface and the block surface to be extra clean so some junk might fall into the coolant passages or the oil passages so it makes sense to either be extremely careful or change both out. Not terribly hard to do.

The BRM has a pump attached to the camshaft that pumps diesel and creates a vacuum. When removing it, it creates an air bubble in the fuel system which is then bled with either a vacuum pump or with a VAGCOM running the fuel pump. When restarting your engine, if you disconnected any fuel lines you will have to purge the air as well. Not hard to do.

Lastly, when I had my head off and the turbo and everything else apart, I was able to clean everything of the black gunk you get. You will see it everywhere. It is a good time to clean the intake of this, maybe the EGR as well if access is good. Engines run OK with this black junk inside the intake but I like things clean. It's up to you.

Don't forget to pressure test the head, just in case. If you assemble everything and not get it pressure tested and then it leaks, you'll have wasted all this time and effort.

Great work and thanks for posting pictures and documenting your work! I'm sure it will help others in the future.
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
I'm definitely changing both. It is a pity I've wasted one oil change when I swapped the EGR cooler. I thought the issue was gone and I replaced the oil. Unfortunately the issue was still ongoing and some coolant must have ended up in the oil as it is a little bit "milky". I drained it carefully into a clean container, but can't really reuse it due to "milkyness". I'll be getting new oil and coolant.

Regarding pressure testing. It is difficult for me to get to the nearest largish town while my car is in pieces so I'm considering rigging something up to do the test myself. However normally there isn't much pressure in the coolant passages so the head is probably not designed to withstand much coolant pressure. The last thing I want is to break it while pressure testing. Do you or anyone know what pressure they use for testing? I'was thinking of using no more than 10~15psi?

The BKD engine is the same with the diesel and vacuum pump at the end of the inlet camshaft. Normally when I start the ignition I can hear some electric motor running for few seconds. I always assumed that was the fuel pump in the tank. Perhaps I can use that for priming.

I did clean up the gunk from the intake manifold when I was replacing the EGR cooler. However now that I have the turbo out I'm also considering cleaning that once I'm done with the head. The engine was burning coolant for a while and I had some coolant in oil. The turbo can't be happy after such treatment. It looks pretty gummed up where it connects to the exhaust. I found a thread online where a guy cleaned up his turbo inside and some people were saying that unless you do that in a proper clean room it is likely to be worse after such cleaning. Do you or anyone have any advice on that? It is not broken now, so I could just leave it as is, but if it breaks few months from now due to all of the gunk in it I'm really not looking forward to having to remove it again. I'm not sure what is the best option here.

I decided I need to remeasure everything before grinding just in case due to different results on the surface plate and when mounted on the surface grinder. Better to waste time measuring than mess up a good head. I'll take few pictures of my measuring setup then. Hopefully it helps someone.
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
New coolant and oil will just lengthen the life of your engine.
Sucks about the cost but there's very few cheap things on our TDIs.

I am sure the coolant system in our cars runs at pressure, it is a closed system that has to withstand the pressure from the pump and expansion and contraction. If you can rig up a pressure tester, you'd be grand. You can also try doing the opposite, running a vacuum in the coolant passages and seeing if the vacuum keeps. Just an idea.

If you have access to a vagcom the purging of the system is very easy, if not you can just suck some diesel through one of the lines in the filter assembly in the engine bay.

If you are careful and don't use anything too harsh on your turbo, I don't see why you can't clean some of the more obvious junk. Opening it and cleaning it that way is more complicated and you might want to replace some of the inner seals, so you are essentially opening another can of worms. I would try and clean as best as you can without opening it up.

Good luck with your continuing project!
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
I'll probably clean the turbo from the outside. I don't want this repair to take an entire month :) It has already been two weeks.
Regarding my measuring setup I managed to get best results so far with a surface plate and a dial indicator on a stand. I had to take off 0.2mm to level the whole head during grinding. The measurement was pretty close.

And this is my 70 year old hydraulic actuated surface grinder at work.

On this photo the high spots are clearly visible as those areas are ground first.

This is the head after grinding is done, but before full cleanup. Slight surface ridges in reflections in the photo are not visible with naked eye, nor can be felt with a hand. They must be in ten of nanometers range as I read somewhere human hand can detect nano-wrinkles 13nm deep and I can't feel those so I don't think they will be an issue.

Regarding grinding the head, this is the first time I ground aluminium. Common knowledge is that one should use a carbide wheel and coolant to do that. Unfortunately I only had alumina wheels which I use for various tool steels and I use no coolant. That alumina wheel used was getting packed with aluminium dust and started rubbing after not even one full pass until I read somewhere online someone successfully used a paraffin candle on aluminium to prevent that. I didn't have a candle handy so I can't verify that it works, but I had homemade grease containing 50% beeswax, 40% neatsfoot oil, and 10% potassium liquid soap (used as bullet lube for black powder shooting). I tried that and the difference was huge. I had to keep applying the grease with my hands after every pass of the wheel, but I could finish the whole head without having to stop and dress the wheel (this removes any packed up aluminium and trues the wheel). I think this bit of info could be very useful to anyone who plans to grind a cylinder head on an old surface grinder.

Also, I definitely wouldn't recommend anyone to do this job on a manual grinder. I had to use 0.01mm (4 tenths of a thou in inches) deep "roughing" passes and half of that finishing pass, with 7mm feed (275 thou), and about 6 m/s table speed (18 ft/s). The whole operation including dressing the wheel few times before I came up with the grease trick took about 2.5h.

Next steps will be grinding/lapping the valves and cleanup.
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
I've been reading up on valve lapping and I'm finding differing opinions. Some people say it is fine to lap valve seats only by hand, others talk about using a drill, and others talk that lapping is for very old engines only and if the seat was cut properly in the first place it doesn't need lapping.

My valves leak air. I could hear it very well before I pulled the head and compressed the cylinders. Do you think I should lap them to remove that leak or just check the seat contact with prussian blue (maybe test if acetone would leak past them) and if it is concentric and contacts in lets say 80% just call it good?

I found this in SSP_316 (A VW doc about the BKD engine):
Valve seat rings should not be reworked, otherwise the swirl effect of the intake air, and thereby
the mixture formation, would be affected considerably. Only grinding in to match surfaces is
permissible.
To me this " grinding in to match surfaces" that is permissible sounds like conventional lapping. Am I correct with this?
 
Last edited:

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
'Only grinding in to match surfaces is
permissible' to me means that you can only grind the valve itself, and maybe a little bit off material off the ring if needed.

The man to talk to is Frank about the valves. You can call him long distance, he will surely point you in the right direction. You can reach him at +1 417-232-4634

Great work on grinding the head! Even with old tools you can accomplish a lot if you know how to do it!!!!! I am sad to say here in the US, many of the machine shops have bad reputations for not doing work correctly. I'm sure with your skills you'd be able to get a fantastic job here, just saying.

Last few steps to go! Amazing job!
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
Great, I'll give him a ring when I get stuck again :)

I like those old metalworking machines. They are built to last, but that also means they weight a lot. That grinder weights 1.3 tons (2800 pounds). Putting it inside my workshop was challenging, but well worth it.

Regarding valves I found this yesterday night:


Which made me think it is ok to lap them. I did two valves so far. The first one manually, the second one with a drill.Normal coarse valve grinding paste is 100-150 micron grains I believe. I used a 50 micron generic corundum paste to get rid of some minor pitting as I didn't want to remove too much material. Then I used a 5-8 micron paste as the finishing one. I lapped with the coarse paste only until the entire circumference of the mating surface showed uninterrupted grey line. The width of the line is quite narrow. Perhaps a mm or so (40 thou). I read it is easy to mess this up by removing too much material. If the gray line starts growing in width, but there are spots that still don't show contact it is not good. Thankfully my valves are not that bad.

Same with fine lapping. When I started I could almost immediately see the surface looks different where it was lapped with the fine paste. The difference is tiny scratches made by the coarse paste are gone. They are really tiny. I could barely see them with naked eye. I would probably recommend some sort of magnification for anyone wishing to do that. Once the scratches are gone around the whole circumference I cleaned up all traces of the paste and wiped everything dry (the valve stem was lubricated with oil). I put the head on two blocks of wood in the same orientation as it sits in the engine (valves down). I held the valve being tested pressed into its seat with one finger in the middle and with the other hand I sprayed quite a bit of WD40 into the relevant intake or exhaust port that leads to that valve. I then observed the valve seal for any leakage while it is pressed into its seat.I read the conventional way is to install the valve spring and retainers for this test, but I didn't want to install and uninstall the springs too many times if it can be avoided. So I tried this and It appears to have worked fine.

Interestingly even when I stopped pressing on the valves it took WD40 a good 20 seconds before it made its way around the seal a tiny bit. This wasn't a drop, more like a bit of a weep around entire circumference of the seat. Now, this means the newly lapped valves are liquid tights, are they gas tight? We'll find out after I do the rest and assemble everything.

I'll take some photos when doing the remaining ones.

Edit: One more thing, a blue 4/6mm pneumatic tubing with a 5mm drill rod inside works much better than the suction cup (for holding the stem of the valve). Then the other side of the tubing can be chucked into a cordless drill and rotated slowly in both directions to lap. The drill rod is there to avoid the knotting of the tube.
 
Last edited:

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
I've finished lapping the valves. Interestingly almost all exhaust valves were pretty good while almost all intake valves didn't have proper circular contact. I'll add some photos showing valve lapping in another post as I haven't got time to upload the photos now. I noticed that there are not that many examples of good and bad valves how they look like during lapping so hopefully this will be useful.
I've also came up with a method to install valve springs I haven't seen described anywhere so I recorded this video to demonstrate it.
https://youtu.be/gqdyoBk1K5o
 

prblue

Well-known member
Joined
Oct 11, 2019
Location
Poland
TDI
Golf V 2005 4motion 2.0 TDI BKD 103kW
I finally put the car back together yesterday. Interestingly the most time was spent on few things:
- Almost a full hour aligning the new timing belt. I would set everything up turn the engine few revolutions and the locking pins wouldn't go in or the tensioner would be at wrong tension. Those locking pins have to be right to a tenth of a mm to go in effortlessly. Eventually I concentrated on the tensioner first. Once I got that to stop moving I think tweaked the cam position. If I was doing that again that one tip would've saved me 80% of the time. Also to anyone having to turn the engine by hand, the best way I found is to lift one wheel. Take the wheel off, put the car in 6th gear (it's a 7 speed gearbox) so the wheel-crank ratio is almost 1 to 1 and turn it with a very long wrench with socket on the large central bolt. Whatever you do-do not turn the engine by the camshaft bolt. I torqued the bolt when assembling to the right spec and later I tried to turn the engine by it when setting pump-injector screws. It was fine initially until I was very lucky to notice I'm seriously over-torquing that bolt. I managed not to strip the thread, but I don't trust that bolt and I'll be replacing it.
- Ages trying to get the catalytic converter attached to the turbo. I wish I found out sooner there is a way to detach the cat from where it is held by removing a single bolt. Then it could be manipulated easily as it is flexibly attached to the rest of the exhaust.
- Finally the worst of all to install. This bolt attaching the turbo to the engine block behind the turbo oil return line.

- Removing air from the fuel passages in the cylinder head. I have a vacuum pump and a valve so I can set the pressure. I connected it to the return line from the head as per the manual and it took 3l of diesel being pumped through the head before the fuel coming out was completely free of bubbles (this was at less that 5% normal pressure which makes bubbles substantially bigger). Then it still took 8 or 9, 10 second cranks to start the car for the first time.
However, I'm pleased to say that the car is running fine. No smoke in exhaust once it warms up. No leak so far.
Here are some valve grinding photos I mentioned before.
First photo. I saw some videos and articles showing how to test surfaces with non drying prussian blue and in almost all of them people seem to be using way too much blue. I've been using this method for checking flatness before so I'm used to using as little as possible. This photo shows the absolute most blue that one should use IMO.
Here is an example of how most intake valves were badly matching the seat surface. This is before any grinding in my 170k km engine.

Another bad intake valve pre grinding:

Same valve after coarse grinding. Better but not ideal yet:

After fine grinding. This to me is "good enough". There is some slight overgrinding visible and no doubt it would be better to have the seat recut, but for this car for me this is good enough.
Valve after grinding is done showing good matching of surfaces.
A valve and a seat showing good surfaces.

A valve after coarse grinding showing how I think it should look. Please bear in mind that I have no prior experience grinding valves, but metalworking has been my hobby for years and I lapped/ground other things. I was using the coarse compound only until I saw the grey ground line across entire circumference of the valve. Even thou blue was still showing non contacting spots I switched to fine compound at this stage.
This is how a valve looks after fine grinding is done before cleanup.
As mentioned before this is the first time I did something like this on a car engine so I may've made some mistakes, but I hope this will help someone. I was looking for photos online before I did this task and I found no closeups showing the grinding/lapping process. I hope I'm not going to discover in few thousand km the valves are burned because I did it wrong. I tested each valve for leaks with acetone and I washed everything very carefully before reassembly so hopefully it is all good.
After first starting the engine I let it idle about an hour. Then on next day it again idled for an hour before I took it for a ride that included a bit of motorway driving. My elm327 scan tool detected no issues.
 

mextdi

Veteran Member
Joined
Dec 16, 2013
Location
Saint Paul, Minnesota
TDI
2006 Jetta TDI 1.9, 2012 Passat TDI SE DSG, Previous 2014 Beetle TDi, 2012 Golf TDi DSG
Great job! I am really happy for you!
Excellent work overall and thanks for the tips and tons of pictures!

Make sure and check fluids a few more times, just to make sure you are not getting any contamination. I'd recommend changing the oil filter after 500 miles or so just to get things out of the system. Did you also remember to 'burp' or bleed your cooling system? When cold, you unscrew the reservoir for the coolant and let the engine warm up to running temperature, when the thermostat opens, the level goes up and down and gets rid of air bubbles. Then add coolant accordingly.

Good job!
 
Top