brooklynkid

anyone have ideas or guesses on the nature of my coolant leak? All was well with 2004 996TT until yesterday, when i took it for a quick run to store. temp hit 200 and car smoking and leaking coolant and water. Turned off car and coolant kept pouring out under car. Water pump, expansion tank, or hoses?. Car got towed to mechanic. 36k on odo what you guys think?

Kevin

Typically you will have either one of two failures

1) You have 2 large coolant hoses from the engine that attach the engine to the car/body. These hoses are secured with "C" clips. If your car has been worked on, the clips could have been disturbed. It is a easy fix. I strongly recommend that you replace these two hoses with the updated 997 pieces. Also have them replace the clips with new. Install Genuine Porsche coolant.

2) The engine oil heat exchanger is water cooled. The connections for this console has fittings that are glued in with "green" loctite. These have been failing. You need a engine drop to fix this. There is a aftermarket kit that allows for you to weld these fittings in vs buying the new Porsche items.

If you have suffered this failure, it will be expensive.

brooklynkid

thanks for your input kevin, I had plugs, tranny, clutch work done recently. i hope its just the clips you mentioned. With regards to problem #2 can that be caused by not idiling car to lower temparture before shutt it down?

Kevin

Are you telling me that you don't cool down your engine before you shut the car off?

Heat loosens up the loctite sealant! When the car is running the coolant maintains the temp. However the engine oil temps remain over 210 degrees when you quickly do HOT shutdowns.

I have had customers tell me NO WAY are they idling down the engine. GO to page 60-61 in your owners manual.

When I program NEW tunes for customes I automatically raise the idle to increase the coolant pump speed. This is down to allow for more coolant flow AND oil flow to the turbochargers. The heat coming from the turbochargers is insane. What does damage is the short quick hot shut downs then the quick startup like after fueling.

PLEASE NOTE>>> With the new clutch I really do feel that the clip failed and the hose popped off. The passenger side fails more than the driver side.

One minute cool downs does alot of good! If you can't do that count to 30..

brooklynkid

thanks again kevin. typically I usually drive several minutes very easy before pulling into he garage to help car cool down and i do give it 30 sec before shut down. hopefully the clips just failed. should i be concerned of any contamination to the rest of the car from the coolant?

Macster

No experience with big coolant leaks with my 03 Turbo. Small "leak" -- cap.

Big leak experience with my 02 Boxster. Similar situation. I (on purpose) got the engine nice and warm with the idea of forcing the radiator fans to come on to check to make sure both came on at least on low speed.

Short version is when I got out of car to check fan operation I spotted a trail of coolant. At first it looked to be coming from passenger side radiator area, but that was just due to the slope of the driveway. On my way to back of car to check on the coolant level I spotted coolant just pouring to the ground from directly under the coolant tank.

At the dealer and the diagnosis was the coolant tank had split. Just around 225K miles on it. Piece of junk! Oh, passenger side radiator found to be not working at low speed. Problem was resistor. Tech replaced and fan works just fine again.

In the case of your Turbo my first guess would be the coolant tank. But as Kevin posted there are other possible sources for a big coolant leak. And I note there was some work done recently on the car which disturbed the items Kevin suspects. I always suspect the last thing touched too.

With a big leak it should be easy enough for the shop to determine the source so shop where you take it will should have no problem doing this.

Sincerely,

Macster.

brooklynkid

THX MAC,
I HOPE YOUR RIGHT. 200K ON YOUR BOXTER IS REALLY IMPRESSIVE

brooklynkid

well the mechanic found the problem. Kevin was closest. one of the hoses split from the heat exchange box. shouldnt have to sell my kidney to replace it!

Bryce

I have read the manual regarding cooling down the engine, and it says something to the effect of "you only need to do this after long or hard drives." When I drive to work or back, I never "cool" down the engine as it never really did much work. It can't hurt to do it, but it's really inconvenient to sit around for 2 minutes in the grocery store, then 2 more minutes once you drive 1 mile back home. Let's not get non-sensical.

Macster

Agree. Upon occasion I have let my Turbo idle for a few minutes after pulling into the driveway and have observed the oil pressure falling a bit from 2 bar to under 2 bar, call it 1.8 bar (just a needle width of so under the 2 bar mark).

This drop in oil pressure with no corresonding change in idle speed suggests the oil is getting thnner because it is getting hotter from an increase in engine heat as the car idles. Now one might argue this is the heat load flowing from the engine and the turbos but I note this occurs even when I arrange to when arriving at work and this after nearly 2 miles of easy going city driving after leaving the freeway I arrange to coast the last 2 blocks or so with the engine idling and the transmission in neutral. This allows plenty of air flow through radiators and because the engine is idling of course the coolant is being pump through the engine and of course oil too, so any heat load accumulated even in easy driving is disappated.

Idling may not run the turbos in boost mode by the exhaust gases still heat up the turbine end of the turbo, which is doing what one by idling the engine is seeking to avoid.

Now I would take a cool down lap (or two) if I tracked the car and possibly even let the engine idle with the A/C on (to run the radiator fans) and those few times I leave the freeway or highway after running at freeway/highway speeds and am unable to do a closed throttle coast down as I exit the freeway via the exist ramp followed by some easy driving before reaching where I'm going (oftetimes a gas station for fuel) I will let the engine idle maybe a minute or so before shutting off the engine prior to fueling. Allowing the engine (and turbos) to shed some of their accumulated heat load to the oil and coolant is is the lesser -- way lesser -- of the two evils: early engine shut down with a heat load build intact from hot/heavy runnng vs. prolonged idling which in this case helps remove the heat load build up rather than contribute to it.

Sincerely,

Macster.