EMC2, how did you go about fixing this? I may try to fix mine as preventative maintenance with some JB Weld while also doing the plastic coolant pipe under the intake manifold as shown above.

 

Hi Loxxrider,

From what I could tell Porsche is using Loctite 638 for these parts on multiple models (very interesting read here in Porsche's response to NHTSA - http://www-odi.nhtsa.dot.gov/acms/cs...009-57948P.pdf), but I could not determine for certain if it also applied to earlier Cayenne's such as mine (2008), although the document references vehicles dating back as far as 2001 using this adhesive.

They cite inconsistent manual application of the adhesive (bead thickness) as one of the reasons for failure.

There is also an updated/improved formula of Loctite 638 since my car was manufactured 2008. I figured if the bond lasted 7 years I may as well use the same adhesive and just try and be very careful with getting very full coverage of the adhesive.

I also noticed that the fitting was still very snug before removing the old dried adhesive. This means explains why some people have complained about slow leaks before the sudden failure occurred. In my case there were no such warning leaks whatsoever. It just let go all at once during a downshift.

I considered the option of tapping into the housing and inserting a retaining screw. However there was really too little room to do this from above.

Thinking of some alternative options to at least eliminate a catastrophic failure (pipe blowing completely out of the fitting) I came up with a very simple fix.

I used 2 strands of 100lb stainless steel hanging wire (flexible) to create a tether securing the hose to the water distributor. I simply threaded the wire between the opening on the top of the hose clamp (refer to position X in the attached diagram) and through the cavity between the 2 mounting points on top of the distributor which are sealed from above (yellow shaded area) by another part.
I kept a very minimal amount of slack in the wire tethers to ensure they would not interfere with the assembly, but at the same time, if the adhesive ever fails in future the insert piece would not be able to move more than about 2mm. This should prevent a large and sudden coolant loss.



Of course I should emphasize that I have not been able to put the concept to test. I am simply stating what I have done to get some peace of mind and avoid the alternative of a $3500+ bill to have the engine dropped and the water distributor replaced.Hence to anyone who tries this option - it is entirely at your own risk.

Despite doing a lot of reading first, this job was still a real pain because you just have to be very slow and patient the first time around whilst you get the feel of how things fit together. Especially the HP pump. Although now that I have done it once, I really don't mind doing it again if I really have to as it would be a lot quicker the 2nd time around.

The tools that I would consider essential are as follows I'll list the exact ones I used for reference:

Milwaukee M12 inspection scope (note not the one I used in the original picture posted. That was a friends scope. What I like about the M12 is the excellent depth of field and the rotating screen.



Because of the very tight spaces, the following wrenches are really helpful:
Tekton Stubby ratcheting wrench 3/8



Tekton stubby metric wrench set



Lastly you should replace the hose that connects to this part which means removing a clamp which is even lower down in the engine bay and impossible to get off without one of these:

Craftsman remote hose clamp pliers



Pipe brush to clean inside the neck of the distributor and around the fitting. I also used emery paper to clean off the old adhesive.



I also used the recommended Loctite cleaner/degreaser:



Loctite 638 Adhesive:




Finally the Airlift UVIEW 55000 coolant filling tool. I cannot say enough good things about this product. I was unable to drain all the fluid from the radiator because the lowest hose fitting just would not budge. I eventually gave up, as I was really concerned I might damage the actual plastic connection. This tool is meant to be used on a completely drained system, but for this application it worked just as well. I poured several gallons of distilled water through the coolant reservoir to flush the water distributor before refitting the rubber hose. (note I left the adhesive to dry for a full 8 days before doing this - not necessary but I had to travel so it worked out well and at least ensured really good cure time) I then forced out as much of this water as possible with compressed air into the reservoir.
When it came time to fill up with new fluid the UVIEW showed that there were no leaks in the system, and then it pulled the new coolant into the system in no time at all with no issues.

 

Thank you so much for taking the time to write that. This will surely be very helpful to all who will inevitably have to do this job in the future. Great idea on the hose clap and wire. I think I may do something similar, but also slather the area where the fitting meets the water distributor in JB weld such that it is held in firmly and also seals against potential leaks.

The scope is just for inspecting to determine if that fitting is the issue right? Or do you need it to actually perform the job?

I have also posted a quick DIY on Rennlist for 957 thermostat and water pump service. I'll post it here as well.

 

You're most welcome
Regarding the inspection scope:
It was very useful in checking that the inside of the distributor neck was 100% clean before refitting.
It was also really useful in determining the location of bolts and other fittings. In particular as the HP pump plastic cam stopper tends to disintegrate upon removal you really should use a scope to ensure you thoroughly clean that area before inserting the new part. Im not sure an inspection mirror would give you enough visibility back there.

Here is an excellent write up on the HP pump removal:

http://dorkiphus.net/porsche/showthread.php?t=33572

 

Great information, thank you!

 

EMC2,

Great contribution to this thread! Two thumbs up!!

Interesting...very plausible and currently the leading theory of why some fail and others do not.

I like your "bush-fix" here.. As you said, it is a simple mechanism to prevent a catastrophic coolant failure in the future if the new sealant fails.

Great list! The only tool that I would add is a Coolant System Pressure tester to make sure your re-positioned fitting does not weep. Even though the UView system draws down a vacuum, the coolant system tester applies positive pressure exceeding over what the stock system uses for a through test before putting in expensive coolant.

I used the OTC 7991 Cooling System Pressure tester on my Cayenne and can recommend it.

 

Renaissance.Man,
Thanks for the info, that is a really good point. I see that Porsche also suggests this approach as a second test for leaks (i.e. after doing the initial vacuum test)

 

These are the parts I ordered for the job - note these apply to a 2008 Cayenne S, so please confirm fit for your specific model year.
I order many of my Porsche specific parts here, and it's also a great lookup resource:
http://www.jimellisporscheparts.com

95510632210 water hose (S bend hose)
95551240700 clip (hose clamp for upper connection into radiator)
I could not find the part number for the other hose clamp for the lower end of the hose which is slightly larger. ( just reused the original one for that connection)

These are needed for the HP Fuel pump:
1 Stopper high-pressure pump clutch . PLUG. 94810511400
1 o-ring 94811061500

 

After doing my thermostat, I still have a slow leak of coolant. I haven't identified the source yet, but I've got my money on this coolant distributor fitting. It is worthwhile to fix anyway for peace of mind.

Can you guys think of anywhere else there might be a leak that I should address while I'm in there? I plan to replace the coolant vent line, the plastic pipe that runs under the fuel rail, and perform some kind of fix on the coolant distributor fitting. For that, I have the idea in my head to just glob a bunch of JB-Weld around the outside of the fitting. Can you guys see a problem with doing that? Will I have sufficient access to cover the bottom side of the fitting-distributor interface and seal it?

I am going to buy some intake manifold gaskets, a coolant reservoir, and the two HP pump parts you've listed. I will also make sure to have the tools on hand that you mentioned. Is there anything else anyone would recommend for this job to ensure all aspects of the cooling system will be addressed? I will of course inspect for other leaks while I'm in there.

 

Just my 2c, but having worked back there, if you're going to go to the effort of removing the HPFP, I would suggest removing the fitting, cleaning, and applying adhesive from scratch. This should give you many more years of peace of mind.

Also, the rubber hose sits very close to the housing so it would be difficult to get the adhesive in there properly without removing the hose. To get the hose off you will probably need to cut it off and in the process you could further weaken the existing adhesive/bond of the insert. Which is why I would suggest full removal of the part.

I don't mean to sound negative, but just saying how I would look at it, being super cautious.
I would also suggest using the same adhesive (Loctite) again because at least it seems to hold up for 5 or 7 years (very rough approximation from what you see on the boards), and the formula was improved in the last few years also.

Hope you manage to find that remaining leak easily enough. Good luck.

 

Thanks for the reply. I will buy everything required for doing the job by removing the fitting then. I was hoping maybe removal of the HP pump wouldn't be necessary if there was a way for me to seal everything with the JB weld externally. I just hope the fitting isn't too hard to get out all the way. If it is, then I'll probably just have to try another method to ensure sealing.

Thanks!

 

are you guys sittin on the engine to reach down there?

 

Mostly kneeling in extreme discomfort

 

I just ordered all of the parts and tools required for this job. I will report back with my findings. I just need a day off to get it done. Should be interesting to see if the $15 USB borescope I ordered from China will arrive in time and get the job done!

 

so how far below the HPFP is this fitting? I've spent over an hour sticking my boroscope down the area but can't locate it. I see the O2 sensor...then see 2 coolant hoses but can't find the hose in question.