955 coolant consumption

[gravityalwswins]

My 955 turbo has consumed nearly 10L of coolant in the past 40 days. No apparent exterior leak (haven't opened up engine covers yet). White smoke exhaust upon cool-cold start up, tubes are done. Cooling system seems pressurized when I open reservoir cap. Apart from head gasket potential are there any other possibilities? Through intake somehow? Through turbos? Doesn't overheat. Help please

[wrinkledpants]

Check the coolant reservoir bottom for leaks on the seems.  Check the water pump for leaks.  And, get under the car and try to locate the coolant T fittings on the back of the motor.  You'll likely need a flashlight and mirror to check some of this stuff.  Aside from that, I'd take it in to have the system actually pressure tested.  My metal coolant tubes are leaking again, likely from install error.  So, it's not impossible for that to happen.

 

Does the exhaust smell sweet at all?  

[clarksongli]

10 liters is a lot. To answer your question the other source could be the oil cooler....and its steaming off during drives.

I'd start with the head gasket. Assuming no external leaks are found.

Pull the plugs after you come home and let it sit....then check the cylinders in the morning for fluid in the cylinders. ...and gain 10 liters is a lot so it should be visible. ...internally or externally.

[deilenberger]

Have the coolant pipes under the intake been done? That's the most common failure point for 955 V8's.  And 10 liters is an astounding amount of coolant to lose. I would have been concerned after 1 liter. Cooling systems do NOT CONSUME coolant. If they need "topping up" there is a leak. It's really that simple.

[gravityalwswins]

I understand that any engine shouldn't consume coolant. The dealership I purchased from had to replace the starter and when they went in to do so they verified the cooling tubes were done. A couple local (VW, audi, Mercedes) mechanics feel quit is unlikely the head gasket and more likely oil coolers, turbos or radiator. It was suggested that I test the coolant for exhaust gases but am unable to locate proper tool for 955. It also seems there is a great lack of head gasket experience on the forums.

[Pkscheldt]

I can tell you from experience that the head gaskets do "go" on these, as my 2003CTT's did. In my case we had the engine pulled for the repair. White smoke on start up and disappearing coolant was my only indicator. A little beyond my DIY.... Take it in and have the cooling system pressure tested, the test will be the least of your expense.

 

Best of luck to you!

[Stueysv8s]

I'm with you on this one. Mines using coolant , It was the t pipes at the rear of motor so changed them for stainless ones (valley pies already done)but now leak is rh side wheel. I'm suspecting expansion tank.

I'll follow your post and we maybe able to fix our cars.

Something for you to check, I had a 300z tiurbo that white smoked badly that was the turbo. Easy fix

[srfrdrew]

+1 check around the CET (coolant expansion tank) for residual coolant leak

[gravityalwswins]

dropped CTT off to dealer, thankfully the leak manifested in their parking lot so they would take me more seriously. I went on vacation for two weeks and in that time they pressure tested it and blew the expansion tank. They replaced the tank and have since sent it to Porsche Vancouver to get the main problem fixed as it seems beyond the scope of the small dealerships' abilities. I will update ASAP. In their trouble shooting they noticed it would only lose coolant when under boost and high rpm.

Edited October 24, 2014 by gravityalwswins

[srfrdrew]

Too bad, the CET replacement is really simple procedure IMHO.. You could save some good $ doing it yourself... and have the satisfaction of doing it yourself! (priceless)

[gravityalwswins]

I would totally do it myself if I were having to pay for dealership to do the work but as this problem existed upon purchase the dealer is so far standing up and behind their product. The only out of pocket expense I've had is the coolant. Granted that wasn't cheap but I will try to recupe that money as well in some way. I must give kudos to this dealership for not begging off  from the responsibility of standing behind what they sell. Many have and would just tell an owner that it's not the dealerships' problem. I've kept in constant contact with sales/service team expressing my concern over the coolant loss and made it clear they would have to be responsibe given how soon the problem manifested.

Edited October 24, 2014 by gravityalwswins

[gravityalwswins]

So an update since my CTT went to mechanics, first mechanic tore apart top end and said there was some improper work done on coolant tube upgrade and proceeded to correct and then send back to dealership and within the first day of me driving it again the same issue of extreme coolant consumption. So, back to dealership with a long face and extreme displeasure. They promise to get to the bottom of it as they just hired a 35 yr Porsche veteran. They dug deep and investigated the suspected head gaskets and, viola, obvious signs of gasket failure. So they have fixed everything properly, even some other issues they discovered. While the engine is out I want them to replace the tees in the coolant system that are susceptible to failure with a metal alternative. I have looked and have had no success in finding the actual measurements of the tees. I would like to source these out myself and bring them to the mech prior to reassembly. Has anyone actually measured these and recorded findings?

[srfrdrew]

Also, as long as the engine is out, make sure you have them replace the engine mounts.. Trust me..!