1.9 PD Tandem pump, fuel in oil adventure

bogno

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Oct 2, 2019
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Wales
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VW Caddy 2005
Hello All. There are two parts to this post, a cautionary tale and an unfolding question.

Edited Update: I want to thank everyone that helped me with this, I am really humbled by you taking time to respond here.
If you are coming to this thread fresh there are now two (lockdown fever induced) videos that would do a good job of getting you up to speed: The first shows the two tank veg oil conversion we did on our 2005 1.9 Caddy van.
The second follows my investigations into what went wrong with the engine and can be found here.





First a quick intro: I enjoy a bit of hobby mechanics, and have been playing with our 1.9Tdi PD 2005 Caddy. It's been re-mapped (was before we acquired it at 47kmiles, so don't know the details, but when you put your food down it goes!).

At 140k, I decided it was time to dabble in running it on straight veg oil and began a two tank conversion. We produce a youtube channel, called Flowering Elbow, and thought it might be an interesting thing to share with our subscribers there… To cut a long story short, we recorded the conversion process, got the van up and running, did 500 miles (in two long trips).

Then we did a few short 1-2mile (diesel powered) trips, the last of which there was an audible bang on startup, but ran fine… Before a serious problem…

Starting on diesel, we noticed more smoke than normal. Should have stopped then, but my wife had urgent appointment. Drove very cautiously - basically idling through town, got to a hill, low power, engine suddenly increased noise, plume of smoke :( Luckily there was a place to pull over right there and I cut the engine quite quickly, after noise increase. We got toed and my wife never made her appointment :eek:

Upon Investigation: There was fuel (diesel) in the oil. Lots of it! When I drained the sump, there was about 12L of oil-diesel in there. So I guess hydrolocking may have been a thing? There was also about 1l filling the pipe from turbo to bottom of the intercooler.

My Theory: The lift pump for the new aux diesel tank was too high pressure. I was working from the assumption that the tandem pump would regulate pressure and send any unused fuel back along the return line. Of course the tandem pump may have just failed anyway... But I strongly suspect my lackadaisical testing of the new diesel pump and feed pressure causing tandem pump to blow seal between fuel and oil?

How bad is it?: Pulling the sump, I haven't found any debris, and the bottom of the connecting rods an crankshaft look ok (to my untrained eye). If a connecting rod was bent is there a way to tell by looking?
The turbo looks surprisingly ok? At least the turbine blades seem intact, if oily, and I can move it by hand without huge amounts of play – although, again, I don’t know how much play is unacceptable?



Looking behind the valve cover, I see quite a bit of wear on the cam shaft (I guess that’s expected when you lube it with half and half diesel-oil right:confused: The chamfer on the sides of the lobe peaks is worn and I can feel a burr there. I can’t see how worn the lifters are until I have the shaft out, so I don’t know if I have any holes in them yet…




And so, my questions to you: I think the tandem pump was the problem, but equally, fuel could be leaking round the unit injector O-rings (but maybe not in that quantity?) Either way I may as well have the unit injectors out and get them tested / new seals…

A new camshaft kit is £360, new tandem pump £240. I have the option of getting a new (to me) engine inc. tandem pump, camshaft turbo, and injectors that’s done 85k for £610… I don’t know what to do – try with new parts which should last longer assuming cylinders ect. are ok. Or just get the whole engine and then if injectors or some other bit is bad, I can replace…

What else should I be looking at with this? What other obvious components that might have failed due to oil dilution / over volume?

Thanks friends,
Bongo.
 
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Lightflyer1

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Do us all a favor and post smaller pics (800x600) so as not to blow the margins out on the pages. It makes reading the thread hard as you have to now scroll back and forth just to read it. You can post a clickable thumbnail with a small pic that when clicked on links to the larger high rez pic if needed. Good luck with your issue and welcome to tdiclub!
 

bogno

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Wales
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VW Caddy 2005
Hi Lightflyer,
You got it. I see that now I an looking at it... Will try and edit the post to correct it when I get back to my desktop.
Thanks for the welcome :)

A small update: I got a glow plug out and it seemed in surprisingly good condition. I half expected there to be a flow of oil out the plug hole...
 
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philngrayce

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I am far from an expert on the PD (or anything else), so take this with a large grain of salt. But I wouldn’t think too much lift pump would cause this. You will only get fuel in the cylinder when the injector is firing, and the bit of extra LP pressure shouldn't make a difference. Generally, I would blame this on an injector stuck open, allowing the fuel to flow constantly. Have you ruled that out?

Once the cause of the diluted oil is corrected, I might be tempted to bolt it all back together and just see how it runs.
 

Lightflyer1

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Looks like you may have some dreaded cam wear as well. That lobe that is up seems to have lost all of its bevel from around the edge up towards the top.
 

bogno

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Wales
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VW Caddy 2005
Hi Philngrayce. I thought that about thr lift pump too. :confused:
A unit injector stuck open is an interesting possibility. I didn't know that was a thing... I will have to have them out and sent off for testing. Anyone know how I might go about bench testing the tandem pump for oil to fuel leakage?

@Lightflyer well spotted, yes. I think a new cam shaft and lifters are in order. Just tossing whether it would be best to get a whole engine... ?
 

bogno

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Location
Wales
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VW Caddy 2005
Unit injectors out!

An update. I had the unit injectors out today. Not easy - they were in there tight! I ended up wrapping some webbing round them, tying it to a long leaver and using it to pull them out :D

Now I need some help interpreting what I am seeing:





The tips are quite blackened and crusty - a lot of which comes off with a firm wipe off with paper towel. Unusual looking for 140k miles?



Upon removal - there is a band of fuel between the small o-ring and the middle o-ring (does this indicate fuel leaking past?)



Once wiped down I can see quite a bit of wear along the body here, where the anodising has rubbed off. Significant :confused:

Does anyone know of anywhere good in the UK to get the injectors tested?

Assuming similar crud build up has occurred round the piston rings, now I have both the sump off and the injector ports open - what would be a good thing to squirt in there to try and break down/flush away that stuff? Would carb cleaner be a good option?



In other news I also had the throttle body and ERG off to look at (and as it turned out clean :p). As you can see, before the ERG valve entry, things are relatively clean. After ERG entry, things start to look like the bottom of a student oven...




From what I have read this is normal for this kind of milage, and I probably should have cleaned it out a while ago, can anyone confirm?
 

Vince Waldon

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How many psi was your add-on lift pump running?

The injectors are lubricated by engine oil (so there is a fuel/oil interface, per the two o-rings) but in general oil pressure >> fuel pressure, which is why a bit of oil leaks into the fuel normally and why the inside of the fuel tank eventually turns black.

I suppose a really strong lift pump would mean fuel pressure >> oil pressure and reverse the flow direction.

Just a theory. :)
 

Matt-98AHU

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Would not be the first time I've had a tandem pump spew fuel into the head and thus the rest of the engine.

The injectors I commonly see the bottom o ring compromised, but that won't fill the crankcase, though may be the primary cause of why you commonly see black soot in PD fuel filters and the rest of the fuel system.

The top o rings are exceptionally rare to see any failures from, and those are what seals the pressurized fuel from the rest of the head.

Also, the high pressure feed into the injectors is between the bottom red o ring and the middle o ring. The return side, which will be significantly lower pressure, is between the two black o rings. The pressure there is low enough to where it would be really strange to see fuel working past that upper o ring and into the head.

The tandem pump input shaft seal is what will generally cause the fuel contamination into the head. I've replaced more than a couple tandem pumps for this.
 

bogno

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@Vince Waldon, that's a really interesting thought thanks. It's going to sound stupid but I'm not actually sure what pressure the new lift pump was making. I will test and get back to you...
Matt, thanks for this, great info in regards to the unit injectors. I do suspect the tandem pump was the problem. If I take it apart on the bench, will I be able to spot 'by eye' if the shaft seal is gone? Is there another way to test it on the bench? Anything specific to look out for?

Matt, do the tips of the injectors look excessive to you? Any thoughts on what might be best to flush out the cylinder area with / what dissolves the black deposits but wont attack the alu head or cast iron cylinder?
Thanks for the replies guys, keep em coming :)
 

WrEkkED

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Toronto
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How long did you drive with the oil/fuel mixture? I put in a new tandem pump that from factory had a failed seal inside and within 2 days I had 10L in my oil but my oil light went off and I pulled over. I have 177,000km and my cam, turbo and injectors look nothing like that (all of which had a peak at after failure). I also still had good power. I can't speak to the other work you've done, but something else is probably causing your failures unless you ran for weeks like that.
 

bogno

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Hi Wrekked. Thanks for the info, really interesting. There was about 15L of oil/fuel mix - so way more diesel than fuel. No lights came on. I don't honestly know how long I was driving with it like that.

After pricing up just a few bits - good OE quality cam shaft kit and tandem pump, I was already spending more than a whole new engine. So I decided to go that rout in the end.

The new to me BLS engine has done 85k miles, was £550. I pulled the valve cover and had a look at the cam shaft which looks perfect. No leaks anywhere, nice and clean, came with the turbo that looks in good condition. A small amount of carbon build up round ERG & manifold, which I am cleaning up.
So yeah, I am quite hopeful ;)
 

WrEkkED

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The oil light only comes on when running higher rpms. Iirc it won't come on until 3000+ rpm.

good thing with diesel is that it has some lubricity. If this were in a gas engine I'm sure everything would be toast.

I wouldn't be suprised if the other issues were caused by BIO, but I know nothing about that. Hope the new engine serves you well!
 

bogno

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Thanks WrEkkED. I just thought I'd follow this up with the continuing adventure.

So I installed a new e-bay engine (85k miles). So far everything is working well :D
I tested it on just diesel before making the plunge and running the 2 tank veg oil conversion again - this time with a reasonable fuel lift pump for the aux diesel tank. Only done about 100 miles so far. Now with lockdown, it might be a while... :rolleyes:
 

bogno

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Ok so lockdown is getting to me - here's a video with animated diagrams and everything(!), of the initial two tank diesel to veg oil install. Its 22 mins, so might help with the Lockdown playlist ;)




And a few pics of the engine coming in and out for anyone who doesn't get geeky car related watch time:



 

philngrayce

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Wow, beautiful, the mechanical work and the video. It’s clear, funny, interesting, humble, well lit, and great simulations. I love the homemade hose clamps.

I’ve got a few questions: Why no heated tank and hose in hose line? Will your fuel always be liquid, even in the winter? Are you sure you want that diesel tank inside the vehicle? It’s never going to leak, and you won’t spill when you’re filling it?

Just what I needed to watch as we remain in lockdown here, thanks again. And it looks like you are in a lovely place to ride out the coronavirus. How are things in Wales?
 

bogno

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Wales
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VW Caddy 2005
Good morning Philngrayce. Damn, stop it :p Thank you so much for you kind and encouraging words about the conversion video, it really means a lot to me :D

To address you questions:
Why no heated tank and hose in hose line? Will your fuel always be liquid, even in the winter?
Good question. My reasoning was that in the coldest months of winter (which this year, here in Wales, has been very mild barely going below freezing) I could just add 20% or so diesel to keep things liquid. That would save on complexity and a long run of coolant hose. I also read tales of tank heaters (especially copper ones) tending to cause polymerisation, so thought I'd at least start without, and see how it goes, with the thought that I could always add later...

Are you sure you want that diesel tank inside the vehicle? It’s never going to leak, and you won’t spill when you’re filling it?
I actually ummed and arred about this for a good while and am still a little unsure. I didn't really want to loose my spare wheel, and without making a custom tank, it seemed like it was going to be tricky to fit one anywhere outside the van.
I ended up getting that tank because it fit in well in the cubby, was a little bigger than a lot of people get (33l), and was reasonably cheap (~ £50). It's reasonably thick walled, so I'm not too worried about leaks (except from the hose connections, which is a concern). I plan to continue the line of the wheel arch and cover over it in plywood, probably leaving a slit for fuel level to be easily seen. I didn't fancy messing with fuel sender gauges and pulling the dashboard to add a dial (at least not to begin with).

In terms of filling it up - it feels a little weird taking the pump nozzle inside the van at the filling station, and has redefined my notion of ‘mindful re-fueling’. I have only done it twice so far, and not a drop was spilled inside. I'm sure it's only a matter of time, but the ply lining is far from pristine :rolleyes:

In this part of Wales, I have countryside around and can't complain about being in lockdown really. I'm quite worried for my parents (my dad's asthmatic), but they are quite isolated on the farm here. I can't imagine sitting it out in a big city and really feel for my friends who are there now :(

How are things there in Connecticut?
Peace, Bongo
 

philngrayce

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Thanks for the response Bogno. I still think your interior is going to wind up smelling like diesel; please prove me wrong.

I don’t know if you’ve ever been here, but there are really two Connecticuts. Suburban CT is pretty much part of the New York City metropolitan area. That section is not doing well, with very high rates of coronavirus, overloaded hospitals and stressed services. The other CT, where we live, is quite rural. Logging and farming are still pretty big industries here, and there is a lot of open space. So we are fortunate to be in a good spot to ride this thing out, (so far). There are very few cases, stores and farm-stands remain well stocked and the mood is not bad. My daughter’s college term was switched to remote learning; it’s nice to have her home, but not for this reason, obviously. My Mom is healthy, but lonely as we are hesitant to visit and risk getting her sick.

That said, I grew up in and worked in New York City for 30 years, so I have many friends and connections to the city. Though I moved out to the country, I still love that city and it is very distressing to watch.Several friends are sick, and more will no doubt be. Most have or are recovering, but a few have passed. You can’t even have a funeral. This is a very strange time.

Thanks for asking. Be healthy and take care of yourself and especially your parents. Come visit Connecticut when it’s all over.
 

bogno

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Philngrayce, it's sobering to hear your account of it. NY sound bad from the news. Glad you get to at least enjoy the countryside where you are.

I think you may well be right in terms of the tank inside... We shall see, I will do my best ;)

Atm, I'm trying to get a reading on the fuel temperature, through the android app "torque". Any tips anyone? It just doesn't seem an option...

I know I want to be sending veg oil to the injectors about 120C, where veg oil viscosity is very close to regular diesel. It is (best case) leaving the heat exchanger about 80C... I know the tandem pump heats the fuel a lot, but without reading the fuel tep sensor, which is right by the tandem pump, on the fuel return line, its hard to know how much... It would be very interesting to see.

If it the temp reads lower than I like, I might consider some kind of heat exchanger between the fuel return and veg oil coming in...
 

philngrayce

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Back in the day, we used digital oil/water temp gauges like this one:

https://www.amazon.com/HOTSYSTEM-El...temperature+gauge&qid=1585744450&sr=8-1-fkmr0

It works well, and we thought it made the car look pretty cool, though I suspect you don’t want to clutter up your dash. The nice thing is you had a constant, easy to read display.


If you do decide you need a supplemental heater, I always liked the “Vegtherm” heaters. It’s electrical, so very easy to install. Also easy to turn off when you don’t need it.

https://plantdrive.com/collections/vegtherms-other-12v-heaters


As far as the android app goes, you’re way beyond my pay grade. But I’m sure the car knows the temperature, and I’m sure someone on here knows how to get it to tell you. If you don’t get a response soon, try posting the same question elsewhere on the forum. There are a lot of folks on here who know an awful lot about these cars, but they may not be monitoring the alternative fuels section.
 

bogno

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Wales
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Philngrayce, thank you for the links. The vegtherm heaters look good and I will have a good close look at them if I find the fuel is not reaching ~120C. First step is to monitor that.
I did look at those sensors, and they would probably do the job, but as you say, I'd rather not mess up the dash if I can afford not to, and I was thinking that brass (I think that's what they are) is not so good in contact with heated veg oil? There is a sensor there on the return line... I just need to work out how to access it through the data bus... Will have to get a post going elsewhere when I get time :)
Thanks again,
Bongo.
 

philngrayce

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My conversions always had a lot of brass. I used the Greasecar kits, which have copper tubing for the fuel lines and a copper heat exchanger in the tank. I know many folks said that the copper led to polymerization. It never bothered my systems, but the inside of the tank was pretty ugly. Would it have been just as ugly without the copper? I don’t know.

I have the fuel temperature sending unit sitting on my bench and it is fairly clean. Of course, it gets flushed every time you purge, then sits in a diesel bath so it should be okay.
 

WooK

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My Greasecar Kit didnt have any copper tubing at all and had PEX Pipe. I guess it was cheaper but I havent seen any poly on the PEX Pipe after 4 years. The inside of my tank as well as the copper heat exchanger has a honey coat but the PEX does not.

Bongo, i really enjoyed that video. Very and informative and entertaining. I hope everything gets worked out for you.
 

bogno

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Wales
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VW Caddy 2005
Wook. Thanks for your kind words on the video :D
That's really interesting to hear about the pex pipe condition vs the heat exchanger and tank... what was the tank made from?

I have been driving (but not much as on lockdown) with the new engine and the veg oil system (with some tweeks) so far so good.
 

philngrayce

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Wook is right about the pex tubing. My mistake; my kits did not have copper fuel lines. Only the heat exchanger inside the tank was copper. At one point, I changed the pex to aluminum tubing, figuring that it would heat the fuel better. It probably did, but not a noticeable difference. The pex works fine, is cheap and easy to work with.

Not to answer for him, but I believe all Greasecar tanks were aluminum.
 

philngrayce

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Another delightful, charming and informative video, even though I don’t really care that much about tandem pumps. Thanks. Or maybe I’m just a bit on the bored side and suffering from the lockdown, but I don’t think so.

Perhaps I’m showing my age, but since when do engines have a plastic cover over the main bearings? And isn’t that sweater you’re wearing a bit too nice for this kind of work?

But what I really want to know about is that cute young lady in the back seat of the tow truck? My wife never smiles like that when the car breaks down in some inconvenient location and has to be towed home.
 

bogno

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Wales
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VW Caddy 2005
Hey all,
A bit slow in updating here, but I had only been on a few short trips with the new engine on veg oil. Sadly I had the cause to travel across the country a few days ago, as my father-in-law was taken to hospital (not with covid, but equally deadly). I must admit, driving my wife to see her dying father was about as far from an ideal first proper test of the engine I can imagine - and yes I was terrified it would breakdown on the way and she would never forgive me.

As it was we got the call about an hour away from the hospital that he had passed, and we should turn back to avoid unnecessary potential virus contamination.

Anyway, to speak more to the point of this thread; before we set off I hooked up my laptop running vcds and took a log of the fluid temps - it was quite interesting...



The green is the speed in Km/h, and the others Oil, fuel and Coolant temps are in degrees C.
If you click on it you can see that fuel temp basically follows coolant temps, staying a few degrees below it. I guess this is what you'd expect considering the fuel is heated by the coolant in the heat exchanges, but I thought it might have been substantially further heated by the tandem pump - it seems not!

On this trip I switched to veg-oil almost straight away, as the van was already a bit warmed up, as soon as coolant is reading over 80C I switch... The coolant stays between 80 and 90C as the thermostat opens and closes...
At the end you can see the fuel temp decrease rapidly, and that's the switch back to diesel...

The loged trip was about 160 miles - mostly motorway. The way back was very similar.

@Philngrayce, thank you once again for your kind words. LOL The "cute young lady in the back seat of the tow truck" is indeed my wife, I can't explain it - seems it's her favourite way to travel? I am very lucky.

I want to test it further to determine if the high fuel temps result in any changes in injection timings. I have heard that it does and that it might reduce the time the veg oil has to combust - resulting in potentially un-burned fuel = polymerisation of the veg oil = bad... More testing needed. For now it runs.
 

bogno

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Wales
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VW Caddy 2005
An update on this project. So I have been back and forth from Dorset a few times to (~160miles). Have been driving on Veg after warming up on diesel. All good so far!
There was one 'forgetting to switch back to diesel at the end of a trip incident'. The van , struggled to start next time - but was a warm day and got going after about 15 seconds cranking...
Only other news is I edited a video of the TDI engine change - which you can check out here: https://youtu.be/Nh0o4uLVTdU
Peace, Bongo.
 
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