Blew a coolant hose

[roadsterdoc]

I have a 2001 996TT with 29K miles. Last night in 50 degree weather during highway driving I noticed a huge smoke cloud being illuminated by the headlights behind me. Moments later the instrument cluster flashed a "low coolant level" mesage and the temp guage warning light began blinking. Fortunately the upcoming exit had a parking lot with a grocery store (bought 4 gallons of distilled water to get home). The car did not overheat...guage never made it to 12 o'clock. The engine bay was covered with coolant. With a flashlight in hand, I was able to find the culprit. The 2" rubber coolant hose just forward of the rear engine mount had a big gash in it. Part number 996.106.501.74 (I love that Porsche puts the parts numbers on everything!). It looks like replacement will be fairly straightforward (yeah, right...who am I kidding). The local Porsche dealer ordered the hose overnight and I plan to replace it Friday night. I'll post the progress. I am so glad this was not a catastrophic failure. :thumbup:

BTW, is it common to blow a coolant hose like this? Seems a little strange to me. If it had 100K miles I wouldn't be so surprised.

Also, should I use standard coolant (ethylene glycol) 50/50 or does Porsche recommend something else?

Edited January 15, 2007 by roadsterdoc

[roadsterdoc]

OK, I've found seven other incidents where this same hose failed on a 996TT, GT2 or GT3. Two were on the same car, and two were on low mileage cars.

[roadsterdoc]

The hose replacement was simple. Remove airbox, remove C-clips and hose, reinstall. I went with Porsche coolant as recommended by the factory (could probably get away with one of the DEXCOOL products, but why chance it?).

I knew air pockets had developed throughout the system. To get all the bubbles out of the system I put the rear of the car up on jackstands, topped the resevoir and left the cap off and valve open overnight. The following morning, topped up the level and ran the engine (still on jackstands) to clear any more bubbles. Then drove around for 15 minutes and topped up again. Seems to be fine now, but I'll check it everytime the engine cools down for a few more days (or weeks, knowing me).

BTW, the blue coolant cap has been changed since 2001. The new one has a collar that extends below the center rubber/screen nub.

[RayGT3]

Based on the failure history of this hose, it might be worthwhile to replace with a Silicone hose instead of the rubber. These silicone hoses are pretty much bulletproof, standard issue on race cars. A bit more expensive, but worth the extra cost, never had one fail. If I have to change a hose for any reason I always go with the silicone replacement, if at all possible.

[roadsterdoc]

Based on the failure history of this hose, it might be worthwhile to replace with a Silicone hose instead of the rubber. These silicone hoses are pretty much bulletproof, standard issue on race cars. A bit more expensive, but worth the extra cost, never had one fail. If I have to change a hose for any reason I always go with the silicone replacement, if at all possible.

I agree 100%. I have used Samco on other vehicles. The problem is that nobody makes them for the 996TT (yet). :(

Edited January 27, 2007 by roadsterdoc

[wross996TT]

http://www.6speedonline.com/forums/showthr...highlight=samco

[roadsterdoc]

http://www.6speedonline.com/forums/showthr...highlight=samco

Thanks, but isn't that kit for the intercooler hoses?

[egbert]

test driving my car after an ECU change the other day, full boost in 3rd, brush the limiter and change to 4th, puff of smoke from the rear then full on plume of smoke.

clutch in and engine off immediately and roll 1/4 mile into a car park. I was so happy to see green coolant all over the back of the car rather than oil. :)

The guy fixing the car was out to me in 10 minutes with a replacement hose and fixed it in another 10 minutes so I was very lucky for it to happen then. The hose had a gash running pretty much the whole length of it, located under the MAF and coolant tank.

[mxdave74]

Thank heavens you didn't use Dexcool in the car. I've learned from my BMW, that it's best to stick with manufacturer or equivalent coolants (I actually use MBZ coolant in the Dinan because it's BMW equivalent and cheaper). I don't know that Porsche uses compsites in the radiator as BMW and MBZ do, but I'm guessing so?

Dexcool really isn't much good for anything and while I had a car with it from the factory, my experience is that you're better off with something else.

[pierre]

I have a 2001 996TT with 29K miles. Last night in 50 degree weather during highway driving I noticed a huge smoke cloud being illuminated by the headlights behind me. Moments later the instrument cluster flashed a "low coolant level" mesage and the temp guage warning light began blinking. [...]

The very same thing happened to me yesterday evening, just 1km before arriving home. Now going to check how much coolant I lost and if I can make it to my mechanics...

[Chuck Jones]

I blew the passenger's side hose too...but was stuck on the freeway after it blew most of the coolant out... so I had it flatbedded to the Porsche dealership...and got dinged $400 for what should be a relatively easy fix. None of your hoses fall under the warranty (CPO warranty) becasue they're considered as "wear items" like your brakes, fanbelts, bulbs, etc...so I ate the costs of repair and replacement.

Was your hose on the passenger's side? This seems to be a fairly common occurrence....next time I'll fix it myself.

[pierre]

Yes, passenger side. Will have the car flatbedded today or tomorrow morning to a Porsche specialist not too far from here. Since my car has "some" mileage, I stopped caring about warranty quite a while ago... ;) BTW, it's the first time in over 314'000 km that this happens, so I can't really talk about "common occurrence". ;)

Edited May 25, 2008 by pierre

[Chuck Jones]

PIERRE; It's rewarding to see a turbo with 314 kms on it.. I was going to say that it is a testament to the longevity of the engine, but I just saw that you rebuilt the whole engine and tranny at 217K kms....however. Still, to have it go for 217K kms is a fairly good testament to the longevity of the engines. I would agree that the radiator hose failure wouldn't be a "common occurrence" since you went almost 100K kms since the new engine....I see you're in Switzerland...so you must drive under a fairly good range of conditions..

Edited May 26, 2008 by Chuck Jones

[pierre]

Got my car back today. The leaking hose was looking exactly like yours on the above pic. All good now. B)

Special thanks to Röbi from Carlifting in Zurich for his friendliness, competence and flexibility! I highly recommend this guys...

@Chuck Jones: yes, I've been driving in all possible conditions: dry, wet, snowy, icy, from 40°C down to -20°C, etc... All good! Besides, we've seen quite a few track days, most of them on the Nordschleife. B)

[AndrewM]

Hi guys, I have had the exact same hose go in the exact same manner as the original poster here. The replacement will be here tomorrow and I intend to fit it mysefl after taking out the airbox.

have read the original posters guidance and its very helpful. Are there any likely pitfalls? The obvious one is a large amount of coolant loss in the process. Will it just pour out in the process? happily the car is nose forward on a steepish slope so the system wont drain entirely.

Anyone who has changed this or similar hoses have any tips?

Thanks in advance

Edited October 20, 2009 by AndrewM

[greenboxster]

The factory service manual states that you have to use the PIWIS to bleed the cooling system. I suppose you could replace the hose as a DIY and swing by the dealer for them to bleed you (so to speak).

[phillipj]

I suppose you could replace the hose as a DIY and swing by the dealer for them to bleed you (so to speak).

:clapping: :clapping: :clapping:

[AndrewM]

:D In fairness to my local dealership (In Northern Ireland) they were very helpful. Got the part for £24 and the guy selling it gave me advice on bleeding. Swapped the pipe around and topped up the system only for the hose to pop off and run more coolant out! Couldnt get the circlip to engage properly and 'click' onto the hose. Called the dealers and they checked out new clips for me. The guy spotted the problem on the computer when he was pricing a new clip.

It turns out that the two circlips (one each end) look identical but arent. One is slightly finer than the other. I had taken both off and put the clips back on the wrong ends. The tiniest difference in width was enough to prevent the clip engaging with the hose end.

Once swapped, they clicked neatly into place and refilled the system. All very simple and easy. Have bled it a couple of times in line with the advice I was given which was:-

1. park the car nose down on a slope (you could also jack the rear up).

2. Top up the header tank to max and replace the cap.

3. Open the ring pull bleed valve.

4. Start the car and run it to normal temperature with the bleed valve open.

5. Let the car sit for a few hours to cool right down.

6. Top up level.

7. Repeat.

8. Final piece of the process was to drive about 30 -40 minutes with the bleed valve open. Let it cool, top up and close the bleed valve.

I was advised to check that when warm the coolant pipes behind the front bumper in wheel arch were warm (they were). Told to keep an eye on the coolant level for a couple of weeks and top up when cold as required.

So far so good!

Edited October 23, 2009 by AndrewM