My car won't start...

[pedroYUL]

I just priced every part I would change if that was my car. IDparts basket is returning $368.06 before tax:

- Cylinder Head Install Kit (A4 ALH)
- Camshaft Replacement Kit (ALH)
- Timing Belt [Continental] (A4 ALH)
- 4x Intake Valve (A3 AHU)(A4 ALH)
- 4x Valve Guide for 7mm Valves (AHU ALH BEW BRM BHW)
- Valve Stem Seal Set 7mm (AHU ALH BEW BRM)

Why would you change just 1 lifter, and not even the cam?

 

[tdihopeful]

Before I start purchasing repair parts I want to check piston protrusion as a way to rule out further damage as I don't have experience to know if the marks on the pistons are indication of impact that could cause other damage. Apparently the connecting rods can get bent from valve collisions? I may or may not have it in me to get that far into engine repair at least at this time. I don't have many tools, a car lift, "cherry picker" etc nor much $ or energy for such extensive work under such conditions.

I read Frank06's procedure for measuring Piston Protrusion and I understand what the effect is/procedure however I don't have things like dial indicator and am going to need to develop a modified procedure with substitutions for a few things.

Using a precision machined/cast piece of metal or glass as a flat surface place that on the top of the block and rotate the crankshaft through TDC on all pistons taking measurements with feeler gauge(s) between precisely flat surface and piston top in multiple locations on the piston particularly paying attention to measurements nearest to center of piston, average the measurements of each piston if it appears necessary. The pockets/relief for valves in piston should be flush with top of block I think is what I had read.

Basic question but an important one that I didn't see specifically referred to is wether the measurements should be with head gasket installed or without. I presume without. If anyone sees anything wrong with what I'm thinking let me know what would be an easier and more precise way to do this with minimal tools.

 

[csstevej]

It’s done without the head gasket, and in line with the piston wrist pin. Don’t use any readings from the front or rear of the piston , it wobbles and will mess you up , that’s why do it above the wrist pin on the piston.
You can get a cheap magnetic bass with a dial indicator .
Don’t need a cherry picker.
Need a good torque wrench and a good set of triple square bits 1/2” drive, a breaker bar would be good to for the final 90degree turn on the head bolts.

 

[tdihopeful]

IMG_20230518_150141179.jpg

Cam Lobe can be seen rounded off looking closely cam follower looks like a sink.

forums.tdiclub.com

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Severely rounded face of cam lobe.

forums.tdiclub.com

IMG_20230518_144549399.jpg

Piston 3 showing what I think to be marks from exhaust valve contact.

forums.tdiclub.com

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Piston 2 showing what I think to be marks from exhaust valve contact.

forums.tdiclub.com

Here are photos I took today of the damage that my car has. The marks on pistons are basically the same on all pistons. Evidence of exhaust valve contact I think. The first cylinder cam lobe is severely rounded and the accompanying cam follower is dished worn through in the center. None of the other cam lobes or followers look like that of exhaust on cylinder 1. I was working on taking measurements of piston protrusion but the battery was failing in my digital micrometers. Before the measurements became totally inaccurate I measured approximately 1mm protrusion on two out of four pistons. I know that dosen't say much and will get new battery for the digital calipers and try to take more accurate measurements. A question I have is does anyone know a set of measurement tolerance from the "deck" to top of piston BDC? I may be able to get more accurate measurements that way and I think those would give the same information as measurements at TDC.

 

[tdihopeful]

I estimate the indentations from exhaust valves to be approximately .002-.004 deep in the valve relief. I don't know if that is considered evidence of heavy contact or light contact.

 

[csstevej]

Use a dial indicator instead of calipers , in my opinion much more accurate.
Nice damage on the cam.

 

[tdihopeful]

What's your opinion on the cam lobe wear csstevej? It seems to me that amount of wear didn't happen in a 4-5 times of trying to start my car. If not, if that wear could only have happened over a longer period of time what would cause such a thing? The follower rotates freely. You've seen this type of cam damage before I guess?

 

[csstevej]

Yeah looking at the first picture you can see the lifter is dished out pretty good.
This has been a problem for quite awhile.

 

[csstevej]

Out of curiosity….What oil are you using?
Sometimes the lifter develops what they call is a “bow tie profile “ the top of the lifter looks just like a bow tie .
For some reason , maybe others will chime in , the lifter stops rotating or starts to wear and gets stuck in one position , once you break the hardness layer then it’s game on on wearing through…

 

[BobnOH]

Once you evaluate the lower end as good and decide to do the top, do it all. Internals like camshaft should show little to no signs of wear.
I'm lucky, my brother is a machinist. Much of the internals need machinist method and tools. You can do that stuff your ownself, but beware of cheap tools and be meticulous. Or maybe you know a machinist................

 

[tdihopeful]

I've developed a strategy for dealing with all the head rebuild points with minimal/diy tools. Watched a video where a guy uses a socket with a slot cut out of it a pry bar and a metal plate bolted to the cam journal caps to compress the valve springs for removal and installation. For removal of valve guides I saw a video where a guy taps threads into the old guides and use a metal plate a screw/bolt and nut to pull them out. My procedure for installation may be similar. I could use a longer bolt and (without cutting threads into the guide of course) along with a torque wrench to pull the guides into place with the torque wrench allowing me to get them seated without pulling them in too far with indication of when they bottom out. I haven't seen guides "pulled" into the head before but I'm quite certain it's doable and with satisfactory results. Either that or I'll take it to a local shop and ask for the valve guides to be seated with a hydraulic press with Guage. As far as install of the valves I understand the procedure and know to pay special attention to even compression of the retaining cap/application of even force to the valve assembly as to not bend the valve stem. I don't have any experience with lapping valves but understand that procedure as well and will watch a video or two on the process.

 

[tdihopeful]

I still will be determining if piston height is consistent with undamaged connecting rods and it appears in preliminary investigation that the pistons are at the bottom end of tolerances for a two hole gasket (that was installed) and will evaluate if a one hole would be appropriate instead.

 

[tdihopeful]

I wasn't planning on doing the valve springs or keepers. I figured Cam, Cam shaft seal, all exhaust valves, all cam followers, and perhaps all valve guides and clean all the carbon build up from the head. I will install a new timing belt and may do a new tensioner as when I removed the one that was on it, I didn't hold it back and it snapped back kinda hard. I don't know if that damaged it but I may do the tensioner because of that if recommend. Apparently when I bought the car it had a new timing belt recently. I've only put I think 20,000-30,000 on the car since I've had it. All the timing belt components look pretty new. I would like to not do all of those things and I don't expect or need 100,000 miles out of it at this point. I'll probably buy another ALH or PD Wagon in the future when I can afford. One that is in better frame and body condition that I would feel better about making really nice/spending money on.

 

[tdihopeful]

Valve stem seals of course.

 

[markdave]

you're going to be doing the timing belt. Hopefully it didn't move enough to let the pistons and valves make contact. Turning the engine over with the IP or cam bolts is no bueno.

Nox Vidmate VLC​

 

[tdihopeful]

MarkDave yeah I kinda figured out that turning the engine over from the IP is not good... Also not sure you read much of my post or even looked at the pictures... Pretty sure the valves and pistons did make contact. The pictures I posted I think illustrate that.

And moving on...

I started to order parts finally. Got the INA lifters on order. Going to see about a Febi camshaft separate. Then probably going to get the rest of the parts from one place. Going to do everything on the head including stem guides.

I'm sure to have a number of questions moving forward but for now only a couple.

One of those is concerning the head gasket. The gasket on the engine was a "2 hole" and when I measured piston protrusion it appears that what I've got is at the outside tolerance for a 2 hole. I would like to gather information/advice/consultation on the possibility of installation of a 1 hole gasket.

 

[tdihopeful]

And I remember my second current question and that is should I examine the head for true and level? If I find it needs resurfacing I would not consider a 1 hole gasket at all.

I did my best to relieve the head bolt tension slowly and in a pattern that would hopefully mitigate any possibility of warpage related to removal but don't know yet if it's totally true as far as surface goes.

 

[csstevej]

Resurfacing the head has nothing to do with what hole head gasket you use. It’s the piston protrusion a o e the block that determines which hole gasket you need.
If you don’t have a Bentley manual I suggest you get one as all the information you need is in there.

 

[tdihopeful]

I do have the Bentley Manual.

 

[tdihopeful]

That's where I read the head gasket tolerances. With the protrusion on my car the 2 hole is at the outside max tolerance (meaning basically the lowest allowable compression figure)

If I installed a 1 hole it would be at near highest compression.

Now I know that with gasoline higher compression basically equals higher performance. On diesels I don't know if the equation is similar.

I'd imagine slightly more torque and less nox emissions/a ever so slightly longer burn and more complete combustion.

If the head needs milling that does have to do with the head gasket used. I think what you were saying stevej is that the amount milled off the head in a professional resurfacing wouldn't usually need to be taken into account when choosing a head gasket thickness next to stock.

?

 

[AndyBees]

Keep us posted ....

 

[csstevej]

Milling the head has absolutely no effect on thickness of the head gasket used.
Only piston protrusion does.
If the head is milled down then the relationship of the valves in the head changes , I believe the valve seats are deeper in the head to provide the proper clearance and now the valve stems sit higher , which have to be ground down at the tips as they are now too long and will hit the pistons.
There’s a thread here ( recent ) where this is what happened to a member . The shop redid his head but didn’t adjust the valve height and when to start his car and destroyed several lifters in the process……he’s redoing his head again along with the valves.
There is a step by step process in the Bentley on all the heights and clearances that need to be followed when rebuilding a head that’s been milled.

 

[tdihopeful]

"If the head is milled down then the relationship of the valves in the head changes"

The relationship between the distance from the valve faces to the bottom surface of the head. Yeah.

That would also change the distance from the valve faces to the tops of the pistons.

So what you're saying is the custom procedure is to compensate milling the head by milling down the valve faces?

Why not use the head gasket to achieve the same clearance tolerances?

 

[AndyBees]

Why not use the head gasket to achieve the same clearance tolerances?

The proper way to off-set milling the head is to remove material off the the Valve Face and Valve Seat as csstevej stated. It has been a long time since I looked in the Bentley Manual, but if I remember correctly, there is a small tolerance that doesn't require modifying either the valve or seat.

Example: Several years ago, a friend of mine had a local shop to "cut" the head on his TDI engine. The cutter left rather large streaks in an arc from one end of the head to the other. The valves and seats were not modified. The head was installed but leaked almost immediately. There was no valve to piston contact. The head was removed and sent to a shop that used a "wet" milling process to clean-up the mess. Then the guy had the local shop to modify the valves and seats. I loaned him my Bentley Manual to follow the specifications. He also took material off the end of the valve stems which is not recommended, if I remember correctly.

I do not know how much, in total, was milled off the head. I do not know how much was cut off the valves and seats nor how much was removed from the valve stems.

I do know the head gasket thickness was not changed.

I do know the engine ran just fine and the vehicle is still on the road.

(Note: Seems I told this story recently in a different Thread. If I told it here, I apologize for being repetitive.)

You've been given good solid advice by experienced veteran members. I'm not sure what else they can offer.

The best way to improve performance is not thru increasing the compression by changing the head gasket thickness. An appropriate tune, bigger turbo (with appropriate tune), larger nozzles, 11mm IP head vs the 10mm, any combo of all, etc., is the best way to improve performance.

 

[J_dude]

Why not use the head gasket to achieve the same clearance tolerances?

Because that would change the compression...

 

[ts888]

you're going to be doing the timing belt. Hopefully it didn't move enough to let the pistons and valves make contact. Turning the engine over with the IP or cam bolts is no bueno.

Nox Vidmate VLC​

This post gives me deja vu.

Screenshot 2023-08-31 200457.jpg

• ts888
• Aug 31, 2023

 

[tdihopeful]

Andy I don't want to rebuild for performance. It just seemed if I was replacing the head gasket anyway and could get higher compression and still be within spec why not?

Basically just asking if slightly higher compression would have any advantage.

Maybe it wouldn't be a good idea for me to try getting away with a tolerance near the maximum compression spec though being that this is my first "Real" or "extensive" engine work.

I have no problem with using the same spec 2 hole that was installed.

 

[tdihopeful]

I'll just be very happy to have my car back in service if I can manage to get it all back together again and nothing is damaged further than it appears.

Probably the biggest concern for me is setting up/calibration of the ECU after all of the mechanical work that and the concern for if the (injectors, and turbo) are ok after sitting for months removed from the engine.

Maybe I'm wrong but it's my understanding that as long as I do all the repairs correctly the car should run but will need small adjustments to the injection map afterwards to run optimally?

 

[csstevej]

Are you sure that the two spec holed head gasket is the correct one?
Get a cheap dial indicator and magnetic base from harbor freight and set it up to read piston protrusion in line with the crank ( viewing eng from the front of the car ) at the 3:00 and 9:00 positions on each piston a couple of times, this takes the rocking out of the piston equation.
Then see what numbers you have and base the gasket off the hugest number…. They should all be close….. If one or more piston numbers are a lot lower than the others by I want to say .020” you have a bent rod…… the bend depends on how hard it hit .

 

[tdihopeful]

I attempted to check for bent rods about as best as I resonably could. I measured piston protrusion in two ways. Laid a stainless foot ruler across the pistons at mid along the block then inserted feeler gauges in gap between ruler and block.

I know people usually use a depth probe dial meter and measure the pistons at TDC. I figured why not measure them at BDC with my caliper depth gauge. Seemed to me that would provide at least a resonably accurate comparison of all cylinders with the measurement tools I have.

If that's not even a remotely accurate way to measure for evidence of bent rods let me know it.

I saw a slight difference between the pistons 1&4 compared to 2&3. 2+3 were approx 0.038" and 1+4 around 0.034" both respective pairs being very close maybe 0.003"difference. I think that's correct my feeler gauges are rusty and can't see the numbers well.

The results of caliper depth guage measurements of pistons at BDC we're basically 100mm for 2&3 and 99.9 for 1&4. My calipers don't have a battery so I guessed the mm fraction.

I've got most parts to partial rebuild the head now. Are the variation between the moving piston pairs a sign of rod or crank damage?

It seems to me it's ok.