TDI Coolant Leak from Oil Cooler / EGR - Owner Repair Stories
 

We share/d a lot of information regarding this issue, needed parts, links, etc., on this thread: https://www.audiworld.com/forums/q7-...urvey-3035876/

I thought it might be informative for the "future us" to have a location where we can see visuals of other owners' experiences and repairs, so please post up your own photos, videos, tutorials, etc. for posterity's sake.

For me, I had a fairly significant leak in the "valley" of my 2014 Q7. Being just outside of the extended TDI warranty, I decided to research and tackle the repair myself. I ended up pulling apart the engine in early July 2022, ordered parts based on what I found, and put it back together a couple weeks later. Here are some visuals (WARNING: GRAPHIC CONTENT.) LOL:

All told, I'd estimate this job took me about 12-18 hours.

https://cimg3.ibsrv.net/gimg/www.aud...7d6456d8dd.jpg
Before starting, as a reference in case of mystery parts!
https://cimg4.ibsrv.net/gimg/www.aud...912ee02d94.jpg
With intake pipe removed, showing carbon buildup in the manifold. I cleaned all of this up in both the manifold and the pipe before reinstalling.
https://cimg6.ibsrv.net/gimg/www.aud...f643204d8f.jpg
Everything loosened up (wires, hoses, fuel lines, etc.) before removing the intake.
https://cimg8.ibsrv.net/gimg/www.aud...f760918a50.jpg
Intake removed. There was some carbon buildup in the heads, but it was extremely minor compared to the manifold.
https://cimg9.ibsrv.net/gimg/www.aud...b0fedc5035.jpg
EGR Removed; note the lake of mixed coolant and oil surrounding the oil cooler at the center of the frame.
https://cimg0.ibsrv.net/gimg/www.aud...b5818a4b86.jpg
Oil cooler removed; adapter plate (in the center of frame) still in place.
https://cimg3.ibsrv.net/gimg/www.aud...a6388fb3fb.jpg
Adapter plate removed and the lake is sucked out.
https://cimg4.ibsrv.net/gimg/www.aud...c9ca1ad121.jpg
Valley wiped up and ready for final cleaning.
https://cimg5.ibsrv.net/gimg/www.aud...d0bd5097f9.jpg
Final cleaning complete; view shows the front of the engine with both the thermostat/oil filter housing and water pump removed.
https://cimg6.ibsrv.net/gimg/www.aud...5f2249a1fa.jpg
Valley is ready for reinstallation!
https://cimg7.ibsrv.net/gimg/www.aud...37881840fe.jpg
Oil cooler, adapter plate, and EGR coolant bypass valve installed. Compare this to the fifth photo above (with the old oil cooler in the center of frame) to get an idea of how deep that lake was! I'd estimate more than a gallon of fluid pooled there.
https://cimg8.ibsrv.net/gimg/www.aud...a918df0638.jpg
EGR and intake reinstalled.
https://cimg9.ibsrv.net/gimg/www.aud...3c43bd4bf7.jpg
Fully reassembled and started.

Here is a first start video of my TDI:

I will be bringing in mine in a few months under the tdi warranty. I think it would also be helpful to have a comprehensive check list of everything to be addressed while in there whether covered or not. This looks like a good thread to cover. I think my service will be the engine out reseal


thank you.

Great work and thanks for the photos. I know the feeling after all that work and starting it for the first time after having so many connectors and pieces off the engine. Congrats. I hope I never need to do this job but will reference back if I do.

A comprehensive check list..... Hmm.... well, I think that other folks could probably add to this, and there are arguments about how deep one could really go to address "everything." I certainly won't claim to have done so, but I feel like I was reasonably thorough given my time constraints and budget.

#1: Take this opportunity to clean the carbon buildup from the intake and related components!
#2: Replace the rubber coolant hoses (three short lengths) that connect the oil cooler and EGR assemblies.
#3: Replace the EGR bypass valve and coolant adapter (the small black plastic unit that is to the right of the oil cooler in the photos).
#4: Reseal the oil cooler adapter plate and oil cooler. Both of these have complex, compound gaskets passing both oil and coolant, and both are subjected to constant vibration. Even if your leak is coming from one of the units in #3, you can bet that these gaskets aren't far behind.
#5: Replace any o-rings on coolant lines that you disassemble.

I think those are the must-dos.

Here are a couple optional items that are just much easier to do "while you're in there":

#6: Replace and/or reseal the oil filter housing and thermostat housing. New units include a new thermostat.
#7: Replace the water pump and bolts (if aluminum).

G'day I have a 2011 Q7 3.0 TDI and I presume I have the same problem . I was told at first that the valve cover was the cause of the oil leaking onto the alternator and had it fixed?
1 Did you replace the oil cooler or just clean it and new seals ?
2 The oil has been driping onto the alternator and now not charging and this was only 6 months old

Just had mine done. i was not going to tackle that myself. I thought about it but decided to let my local indie Mech do it.

I did replace the oil cooler, but I could have done the latter. Unfortunately, I was having a devil of a time finding part numbers for the gaskets alone, so I finally gave up in the interest of time and just replaced the part.

Interesting note about the alternator. I had an alternator failure last year (12/24/21, to be exact!), and boy, was it spectacular! When I pulled it apart, I also found that there was oil or *something* leaking down onto it from the front of the engine. It was my exploration of that source that led me to discover the "lake" in the valley, which was simply overflowing the front of the engine and dripping onto the alternator. I put a new alternator in at that time and put some aluminum flashing over the top of it to deflect the drip away from the sensitive bindings. This worked perfectly and the alternator remains in good condition (even though I didn't fix the leak until July).

I certainly thought about it, but I'm always a sucker for a good automotive project that's way over my pay grade! :D

That seemed like a lot of cranking on first start; did you bleed air out of the fuel system via VCDS prior?

I did not. I tried, but the software wouldn't open for me, and I couldn't figure out how to get it to work. I finally lost patience with it and just cycled the vehicle a few times, then lit it.

I eventually was able to get the software working again after uninstalling, downloading the newest version, then reinstalling that (rather than letting it update), but it wasn't something I could do from home due to internet limitations.

Well Gang....after 4 days of working on my Q7, cleaning the monumental mess in the "V" of the engine, changing out EGR and Oil Cooler seals, the Coolant Diverter Valve, and related hoses...., I finally buttoned everything back up. I actually had everything together on Tuesday but I was rushing to finish up as we only had my wife's car to drive. But something just told me to go back over and triple-check everything. To quote the Skipper on Gilligan's Island...."hurried work is worried work". Sure enough....I missed hooking the connector up to the EGR Cooler....and I also needed to re-route many of the hoses and wires - as it's a rats nest of crap on top of this motor! So last night I took my time and got everything back to proper location. I then cycled the lift pump to make sure there was fuel at the HPFP, and then after a long cranking time....it fired up! I had a fuel leak at the driver's side fuel rail, loosen and re-tighten...all good. I then changed the oil and took her for a test drive, all seamed well. After my 45 mile drive into work this morning, I popped the hood and looked around...all dry and tight - yay! Doing this job is NOT for the faint of heart!

100% true!

Congratulations! It really is a great feeling to see it running again *and* not leaking anything up there!

Mine is booked into the mechanics to get the work done and when it's fixed It will be getting sold . beatifull to drive but a real p.i.t.a to do anything on it when things go wrong learnt my lesson . Bought a Landcruiser

Landcruiser....yeah....very nice! An associate of mine has an older Land Cruiser and recently had to get one of the front hubs replaced, and it needed a radiator recently. No real major issues, and it has 384,000 miles on it. It shows it's age and miles but still runs like a top. I totally understand why you'd get one...

Thermostat/Oil Filter Housing
 

I'm right in the middle of this same job. (By the way, I had the same massive lake under the oil cooler. It's shocking how much liquid was sitting in that valley.) During disassembly I removed the oil filter housing because it makes it much easier to get the intake manifold out. (You may be able to do it with the housing in place but I'm not sure how.) I bought a new gasket set for the housing from idparts.com (great guys, in MA). The main gasket around the thermostat (attached to the housing) requires removal of the thermostat from the housing. I removed the two T20 Torx screws holding the thermostat in the housing and pulled the thermostat out. Unfortunately there are two wires going from the back of the thermostat to (what I assume is) a switch/housing which pulled out when I removed the thermostat. Now I believe I need to buy the entire housing/thermostat assembly (another $300+) because I see no possible way to reconnect those wires.

Is it possible to replace that seal without removing the thermostat, and if so, how can you do that without pulling those wires out with it? Since the seal kit it sold separately, I assume there's a way to replace the seal without destroying the housing. I just can't figure out exactly how.

Not that this helps now, but, yes, you can get the manifold out without removing the housing. I'm only imagining, but I think you're talking about a gen2 engine...? It's a little tricky because you don't have much forward movement available before you need to lift it up while coming forward and out.

That said, I pulled my thermostat/oil filter housing off afterward, and I ended up just replacing the full unit, which came with a new thermostat. The new unit *should* also come with a new gasket.

Thanks. I didn't want to put too much stress on the manifold trying to wrangle it out. My experience with 9-year-old plastic parts in hot parts of an engine tend to get pretty brittle and the gentler you can be during removal/installation the better. I've broken more than one over the years. :-)

what are the torque specs for the oil cooler bolts?

Or, what is a good source for service manual?

A few folks have posted links related to online service manuals for these vehicles on unrelated threads. I don't recall them off the top of my head.

Personally, I torque by feel for nearly everything except those items that are extremely sensitive to torque, such as heads, and the same was true for the parts involved in this repair, so I really don't know what the specs are. These were pretty low... WAG? 10 NM.

Here's a document I just found that may be of help to you:

https://static.nhtsa.gov/odi/tsbs/20...21466-9999.pdf

Thanks for the reply, when I did the oil filter/ thermostat housing and the waterpump the bolts were 9 nm torque, Im thinking these are probably around that also.

Thanks a lot for that link! A lot of great info there!,
Morguns1cam

Got started on this today! Wiring harness from hell! This is a freaking nightmare! I noticed you didnt unplug the glow plugs, was gonna ask if there was a trick to get them loose! Knocking off for today! Gonna have a bourbon or four! Back on it again tomorrow!😜

Definitely not for the faint of heart!!!! If you have any question of your mechanical skills you may want to pass on this one!!!
mine is a Q5, even less room than the Q7, I hope I dont have to pull the front of the car off ( again!) to get this done!

Well, perhaps it is a benefit that the Q5 doesn't have quite as much maw out front that you have to work over....? Just take it one step at a time. It'll get there!

I didn't unplug anything that didn't strictly require it, that's for sure. I don't recall the plugs being in the way at all. I think the most substantial things that was removed just to get them out of the way were the high pressure fuel lines. I would have preferred not to pull them, but there just wasn't any way to get the intake manifold off otherwise.

Thanks for the words of encouragement Wes! I shall continue on! ( its not like I have a choice!🤪)

Ok, long day in-the garage! Got the intake off finally , had to remove the drivers side fuel rail and related fuel lines to get the intake out! Then removed the EGR cooler and finally the oil cooler and base plate! Cleaned out the gunk! About 8 hrs worth today. Start cleaning out the carbon build up and start reassembly tomorrow!

Looks like Im on hold waiting for a new egr bypass valve ( hard part to find, some say this part doesnt fit a Q5) got one on order from FCP Euro but wont be here till Saturday, guess that gives me plenty of time for de- carbonizing every thing and a good clean up.

Attention to detail is key - this job is not for the faint of heart. I ordered all of my parts from our local VW dealer with no issues. So the bypass valve is scarce....?

When searching for the bypass valve on the Q5 tdi in doesnt even show up on most part houses, and different part houses call it by different names. When I referenced the VAG part number some says “ this part does not fit a 2014 Q5” once I got everything disassembled and had the part in my hand and confirmed the
VAG part number was indeed the correct part I was able to order it from FCP Euro ( OEM part). I dont have a VW/Audi dealer near me.

I think that part numbering / compatibility concerns are higher for VAG products than others I have experienced. I don't know why this is, but I always stick with this rule: If the part # is the same, it will work, regardless of what the vendor says.

COMPLETELY OFF TOPIC...... I am having an interesting experience right now with RockAuto.... I have a 2013 Subaru Forester, and I ordered some hood and hatch struts for it since they are both having a hard time doing their jobs anymore. The parts, which RockAuto have listed on their site as fitting my car, were all for the fourth generation Forester (2014-2018), simply because someone at their company inventoried the parts wrong. However, because I removed them from the packaging to prep the install (it was about -15F outside, so I didn't want to spend any more time out there installing than necessary), the company won't allow me to return, and they won't even communicate with me about their cataloging mistake. Idiots.

Finally all done! Received the coolant bypass valve last Thursday, had everything cleaned up by then, took about 8 hours to reassemble everything.
after double and triple checking all connectors and plugs, I held my breath and hit the starter button, she turned over for about 15 seconds and came to life!
Its amazing the thing was running as well as it was with all the carbon build up in the intake and throttle body! It seems more respondve and accellerates quicker and smoother!
If I had to do this again it would no doubt be quicker ( 3 days to disassemble and 8 hrs to reassemble) hopefully she will go another 100k or so ( currently at 185k)
thanks for all the works of encouragement and help!
Morguns1Cam

Greetings all! I looked around, and didn't find what I was looking for using the search. I have a '14 Q7 TDI Prestige with this oil cooler/egr cooler leak. Has anyone posted a list of gaskets/seals they used when doing this job? I'd like to order it all beforehand if possible, down to the orings for any coolant connections etc.

I'm an automotive teacher by trade. So, I'm well versed in mechanics and have full access to a shop. I just want to be efficient with my time.

I have a link to the thread with the parts list I used / recommend. The list itself is #21 of that thread, and I think this link will take you directly there:

https://www.audiworld.com/forums/q7-.../#post25776309

Unfortunately, I could not find some gasket part numbers, such as a gasket for the oil cooler.

Thanks. I found that list somewhere in my searching, but wasn't sure if your Q7 was the same engine gen as mine. I'll use that list and the parts diagrams to order what I can beforehand.

Oil cooler coolant leak update
 

Update: Took the Audi on a 300 mile roadtrip, interstate driving 75-80 mph, first highway drive since the repair, happy to report no coolant leak!
Glad to have this repair in the rearview!
Thanks for all the info and encouragement!

Thank you, Wes! Your list was VERY helpful.

Okay, Wes you're awesome for making this thread. I'll post a couple of pics later, showing any difference I found useful. I will say, there were a couple of part numbers I used that weren't listed.

I was able to find the gaskets for the top and bottom of the oil cooler adapter plate. So I did not need to replace either of the coolers. This was where mine was leaking, because once I got mine apart, I found RTV around those gaskets. Also...whoever had been in there previously had decided to just leave one of the intake bolts off. -.- Luckily I had some extra bolts that were the right size.

There are three part numbers for the adapter plate gaskets. Luckily they are all nearly identical except for the last character:
Engine Oil Cooler Gasket 059-117-070 This is the gasket between the engine and the adapter plate, except for a very small indexed round o-ring looking gasket.
Engine Oil Cooler Gasket 059-117-070A This is that small o-ring looking gasket.
Engine Oil Cooler Gasket 059-117-070B This is the gasket between the adapter plate and the cooler.

The total for those three was like $30. The small o-ring looking one is tricky. It has a notch/tab and there is a cutout on the adapter plate that they need to be matched to. The rest of the parts are listed by Wes and I used them all. I had some extras, which were ordered in case the new parts were somehow missing the gasket. Small investment to save a headache later.

Unfortunately, I didn't have time to clean all the intake like I wanted to. I spent about 10 hours removing, cleaning then reinstalling. If I had another ride to work that day, I would have left it apart and spent the next day cleaning the carbon buildup. I spent too long fiddling with removing the intake after it was loose before I realized I should pull off the fuel pressure sensor. After that it was cake. Having a shop 9 months of the year is a real luxury.