Upgraded Alum Main Coolant Tube Leaking

[Corvetteboy6988]

Hello all, I purchased my first Porsche, a 2005 Cayenne Turbo in Sep. has 44000 miles and mechanically is in great shape, no issues. With the help of this forum I budgeted to replace the coolant pipes with the upgraded alumn ones after purchase. I called around for pricing, went to a local ex porsche dealer who still has their master tech, and got them replaced.

This was done proactively as the original plastic pipes were not leaking.

About 500 miles later, lost a good chunk of coolant, out the bellhousing weep holes, the very thing i was trying to avoid.

Dealer said pressure tested and leaking where main coolant pipe enters the block. The after market pipes orings appeared flat instead of round after removal, I sent the pipe back to the manufacturer, and they indicated the orings where softer than they should have been. So, plan was to replace with OE porsche pipe and orings so did that. All other pipes where fine, even the main couple at back distribution bank.

500 or so miles later, small drip or 2 out the bellhousing, andc the smell of coolant. Back at the dealer currently, and leaking again at the main pipe and the double orings where it enters the block, not as bad this time.

The tech cleaned the mating surface in the thermostat housing good, but he mentioned it was a bit rough and pitted from corrosion and thinks that's the cause for the leak.

Any ideas, what else can we try, is there something we might be doing wrong. Everyone is saying this is the first tune this had happened. Ive read other posts of pine hole leaks due to bad castings, or loose clamps, etc. But not this.

Should we use rtv or an anerobic gasket maker on the mating surface?

The current plan is to fine polish the mating surface in the housing to eliminate the pits, I just don't want to remove too much material so using very fine grit wet sandpaper like 2000 or 3000, then we are gonna try the Hamburg Technic pipe from ECS tunning. I got the Porsche lube as well to use sparingly. That will happen this Monday.

Also, why would it pass the pressure test once the job is done, then last for a while, then leak?

Ive attached some pics.

Looks like they damaged the right top side of the opening a bit by prying to remove the old pipes, but its way outside the oring area.

I love this truck, but ive hardly even been able to enjoy it, and regretting being proactive but know in my heart it was the right thing to do.

Sorry for the long post, but need done help.

Btw, the dealer suggested possibly needing to replace the top of the block to correct this, wow.

 

[lewisweller]

10 hours ago, Corvetteboy6988 said:

Hello all, I purchased my first Porsche, a 2005 Cayenne Turbo in Sep. has 44000 miles and mechanically is in great shape, no issues. With the help of this forum I budgeted to replace the coolant pipes with the upgraded alumn ones after purchase. I called around for pricing, went to a local ex porsche dealer who still has their master tech, and got them replaced.

This was done proactively as the original plastic pipes were not leaking.

About 500 miles later, lost a good chunk of coolant, out the bellhousing weep holes, the very thing i was trying to avoid.

Dealer said pressure tested and leaking where main coolant pipe enters the block. The after market pipes orings appeared flat instead of round after removal, I sent the pipe back to the manufacturer, and they indicated the orings where softer than they should have been. So, plan was to replace with OE porsche pipe and orings so did that. All other pipes where fine, even the main couple at back distribution bank.

500 or so miles later, small drip or 2 out the bellhousing, andc the smell of coolant. Back at the dealer currently, and leaking again at the main pipe and the double orings where it enters the block, not as bad this time.

The tech cleaned the mating surface in the thermostat housing good, but he mentioned it was a bit rough and pitted from corrosion and thinks that's the cause for the leak.

Any ideas, what else can we try, is there something we might be doing wrong. Everyone is saying this is the first tune this had happened. Ive read other posts of pine hole leaks due to bad castings, or loose clamps, etc. But not this.

Should we use rtv or an anerobic gasket maker on the mating surface?

The current plan is to fine polish the mating surface in the housing to eliminate the pits, I just don't want to remove too much material so using very fine grit wet sandpaper like 2000 or 3000, then we are gonna try the Hamburg Technic pipe from ECS tunning. I got the Porsche lube as well to use sparingly. That will happen this Monday.

Also, why would it pass the pressure test once the job is done, then last for a while, then leak?

Ive attached some pics.

Looks like they damaged the right top side of the opening a bit by prying to remove the old pipes, but its way outside the oring area.

I love this truck, but ive hardly even been able to enjoy it, and regretting being proactive but know in my heart it was the right thing to do.

Sorry for the long post, but need done help.

Btw, the dealer suggested possibly needing to replace the top of the block to correct this, wow.

 

Wow bad luck my friend. 

Without trying to be too negative one of the problems if coolant leaks and drains via the bell housing is the torque convertor seal will started to leak transmission fluid. An engine out job is the Fix. Ask me how I know and ask me how many 1000,s I spent on my 06 ctt before giving up and selling it on before I had even more repairs. (The major ones ....Head gaskets, alternator, battery x3, power steering rack end seal leaked all fluid whilst cornering, kessy module, torque convertor seal all in one year). Read all my posts if you want to get depressed. 

 

Unless you have a lot of money and a spare car to use whilst this is in the garage frequently, I would get this coolant pipe fixed and sell it on.

 

If the surfaces are pitted the oring won't seal. If you remove material you will need thicker orings possibly.

Use this RTV silicon to seal the gap between aluminum parts but don't get it on the oring. 

Suggest you remove and reinstall all those new pipes and orings whilst it is all apart again. 

 

https://www.permatex.com/products/gasketing/ultra-series-gasket-makers/permatex-ultra-grey-rigid-high-torque-rtv-silicone-gasket-maker-2/

Edited December 3, 2017 by lewisweller

[Corvetteboy6988]

Thanks lewisweller, I have seen some of your posts. Fortunately the dealer gives me a loaner car, but still it's not fun to keep going through this. 

I keep rinsing with hot water from my garage house the top of the motor till i see it run out the bellhousing the 2 times now that out leaked. It sounds like its when the coolant sits in there, keeps running down and building up, heats and dries forming crusties that destroys the torque pump seal, I hope.

What happened with the head gaskets on yours, what symptoms did you have, and what caused it? I thought head gaskets failing on these was rare?

So where should i put the rtv? I was gonna use "the right stuff" but ill compare to your suggestion, still wasnt sure where to put, cause i did see you don't want it on the orings.

[lewisweller]

32 minutes ago, Corvetteboy6988 said:

Thanks lewisweller, I have seen some of your posts. Fortunately the dealer gives me a loaner car, but still it's not fun to keep going through this. 

I keep rinsing with hot water from my garage house the top of the motor till i see it run out the bellhousing the 2 times now that out leaked. It sounds like its when the coolant sits in there, keeps running down and building up, heats and dries forming crusties that destroys the torque pump seal, I hope.

What happened with the head gaskets on yours, what symptoms did you have, and what caused it? I thought head gaskets failing on these was rare?

So where should i put the rtv? I was gonna use "the right stuff" but ill compare to your suggestion, still wasnt sure where to put, cause i did see you don't want it on the orings.

Yeah bit tricky to get a nice bead around the pipes to block orifice recess area. I think on the pipe only put small amount of Vaseline on the oring so it slides in easy and a wide bead of smeared RTV silicon behind  the oring on the pipe itself. Slide the pipe in all the way and then pack the RTV into the gap between pipe and orifice. This maybe be more difficult than it seems access wise. 

I did think maybe the flat face inside the orifice could be smeared with RTV before inserting the pipe but not sure it that will work well or not. 

 

I remember on mine under the manifold one of the pipes had a hard resin type sealer on it, which worked but wasn't the oem type approach and would never come apart again I doubt. 

 

Head gaskets symptoms loss of coolant and overheating at idle, if you rev the engine it will cool down to normal and the cycle repeats. 

Was blown between cyclinder 2-3. 

Torque seal, yes exactly how it happens dry crusty then seal is deteriorated and leaks.

 

Good luck.