Have had my q7 for 10 years now and I love it... only reason I have so few posts on this forum is because I really have had so few problems..... Fast forward and I ended up developing a massive oil & coolant leak from what I assume is the oil cooler gasket. Tore everything apart, and I found a 4-5" pool of oil/coolant sitting in the engine valley (see pic!). While I have this apart, I wanted to run my plan by some more experienced folks to get some opinions on whether I am doing too much or not enough.... the car is a 2014 with 165k


1: replace oil cooler - based on the appearance of it and the fact it was sitting in that liquid leaking for an undetermined amount of time, I'd feel better replacing this. What is the deal with aftermarket vs. oem? The price difference is steep -- ($100 vs. $900)... are there reasonable aftermarket brands?

2: remove egr cooler - I already have the Malone stage 2 tune installed and def system removed and purchased the egr delete from darkside

3: replace coolant shut off valve -- this thing was sitting in the pool as well and looks to be a good candidate for replacement considering its made of plastic

4: cp4 pump -- here's where I get indecisive... reading about potential cp4 failures and staring at the pump right in front of me.... I'm leaning towards keeping it an installing the whitbread disaster kit, but open to suggestions.


That's where I'm at... opinions welcome... I'd like to keep this car for as long as possible!

 

Do what 99% of most people do here! Do NOT troubleshoot!
Replace all perfectly working parts with more expensive equal working parts!
You're done!

 

​​​​​​​I like to think there is somewhere in between doing nothing and taking this approach, but thanks for the warning.

 

Replace coolant hoses, gaskets, and thermoplastic coolant fittings that you can access while you're in there. None are very expensive, and it would be a huge frustration to have to go back in for something like that.

You don't need to go with OEM, but I do recommend using a seller like FCP Euro or ECS Tuning, as you're less likely to have an issue with their parts, and they'll support you if you do have problems. I wrote up a parts list a while back on the "main thread" for this topic that includes part numbers, approximate prices (for the time), etc. Replacing the HPFP really comes down to your own peace of mind. If you feel comfortable letting it be, then let it be. If you consistently use a lubricity additive with your fuel, you probably have nothing to worry about. But, installing a control loop shouldn't be too challenging and will add a layer of protection if you do have trouble. I have opened up my TDI's valley twice now, and I didn't touch the fuel pump either time, so now you have me worried! LOL

 

Just searched around a bit on the Bosch HPFP part #. Rock-Auto has it for $830, FCP Euro is $955, or they also offer a remanufactured one for bit less also. NOTE: This is the pricing for the Bosch part # (they supply the CP4 HPFP), while the Audi part # boosts the asking price of this part significantly higher...eye watering in fact, lol. This is the Bosch part # for the Gen 2 TDI motor (HPFP mounted in rear of engine valley):
BOS-0445010692

So you've had the Q7 for 10 yrs and nary much trouble till now, and really this is all 'normal' stuff for this motor...@167k miles currently. Your intent is to keep driving it for significantly longer. The engine valley is empty to repair the oil cooler leak mess. If you've been using a fuel supplement for good while then I'd probably chance it with just doing the fuel bypass/protection filter kit, but do consider that the Bosch CP4 is not known for its' longevity as you consider your options, and the level of effort required to access it for R&R purposes, etc., given where it is located on this motor.

Not sure how much the 'protection kit' for if/when the current HPFP fails (they don't all 'grenade') costs, but I'd gauge that against buying/swapping out the HPFP if your goal is future longevity and not having to tear it down again like you are now. Definitely de-carbon the air intake you removed to access the engine valley. And like WES said, replace all the old hoses/anything plastic that is in the valley...especially those hoses that were sitting in the oil/coolant mixture, etc. You can definitely just throw it back together, but that invites future cascading failures in the engine valley...not the greatest fun to fix on this car, given the labor effort required.

Unrelated: Great idea to check condition of your Crankshaft Pulley/Harmonic Balancer on these TDIs, as they do eventually fail due to delamination/separation of the rubber insulator from the central mounting ring, etc. Took one off our '15 TDI that was just about to fall off the car on its' own. This is more common when your car lives in the snow/rust belt areas, but they all eventually will fatigue, crack, delaminate...roll off the car when least expected, etc.

 

Thanks for the advice... appreciated. My worries about the HPFP mainly stem from late night browsing/reading about them. I will say, I did not know about the lubricity issue with these pumps and I have not used any additive since I've owned the car (purchased used in 2016 w/ 50k miles). So, either my pump has survived the diesel fuel quite well around here, or it's about the grenade itself.

 

Good stuff, thank you.... pretty much confirms what I was thinking...with exception of the HPFP I'm still on the fence between swapping it out, and letting it ride w/ the protection kit (which is $400). Just purchased my oven cleaner to de-carbon the intake... and I will say while I don't necessarily want to tear down to the valley again, it wasn't all that bad.... most of my diesel work to this point has been on my Ford 6.0, so this was a welcome change of size.

And thanks for the heads up on the crankshaft pulley... we are in the rust belt in PA, and ours delaminated a few years ago so I have already replaced that. Thankfully it happened as my wife was pulling into the driveway!

 

All this info is extremely insightful. I am about to take my 200 4 Q7 TDI down into the valley. I have a EGR valve that is “stuck open“ and continue to get a check engine light. I also noticed recently that the coolant level was low. I plan to do the EGR delete and add a Malone programming. I will replace all the gaskets as well. I can turn a wrench but am not a mechanic. How long should I anticipate this process taking me. I heard one person on YouTube say that they had spent eight hours on the project. Other suggestions about what I might do to keep the vehicle running is appreciated. Some of the acronyms do you leave me puzzled. If using them, please add a more detailed description of the part.

 

That was 2014 Q7 TDI

 

Not a mechanic, first time in the valley... and, if you're going all the way down to the bottom (e.g., taking out the EGR cooler and the oil cooler) along with cleaning the intake manifold, I'd anticipate 12-18 hours. it is very doable work, but messy and time consuming! Just take your time, one step at a time.

This is the primary / granddaddy thread for the valley coolant leaks. I think that we have other helpful threads linked in here as well, so you can gather a lot of information before you take it on (including part numbers, videos, photos, etc.).