Porsche 996 Coolant Leak

[NickWallace]

I purchased a Porsche 911 Carrera 4 (2001) recently.

Has done just over 100k.

I had a mechanic (not a Porsche specialist, but very experienced) check it over before purchasing and he had it up on a ramp. All seemed okay.

After driving it less than a few hundred miles I have noticed a coolant leak. Not anything I can see dripping on the floor but simply the coolant levels are dropping.

I topped it up a week ago and just checked it again and I've had to put a good 1/2 litre in to reach maximum.

Does anybody have any ideas?

As a newbie to Porsche ownership it's causing me sleepless nights!


Cheers

Nick

[Chris Stott]

Have the rads been done in the last 50k?

[NickWallace]

Chris Stott said:

Have the rads been done in the last 50k?

Thanks for getting back to me.

I have checked through a mountain of paperwork that came with the car and there is no mention of the rads.

In late 2011 there is an invoice from an official Porsche garage - Supply & fit new water pump, gasket and Polyrib belt.

In 2014 a full inspection from a Porsche specialist states there were no coolant problems or leaks.


Cheers

Nick

[Cpt Stirling]

Maybe check the header tank for cracks - know weak point. Maybe an air lock in the system. Mine does a wierd thing; I'll top it up to the max level and after some use it'll drop to about the min level and then lose no more, it sort of finds it own level. I'm convinced it vents via the release valve on top of the plastic tank. No visible signs of a leak.

[tr7v8]

Check the header tank cap, in fact they aren't a fortune get a new one. There was a change in design & the part no. changed. I can't remember the numbers but they don't last for ever anyway.

[996Type]

Definitely check header tank, can hairline fracture and then only lose coolant under pressure, making it difficult to diagnose. It's possible to pressurise the system with an air cap which will show the leak under cold pressure.

Had a 996 and it didn't happen to me but did happen to 2 owners that I knew.

Also consider the evans waterless treatment when done, takes all the pressure out of the system I understand, the cyclic pressure / release is what causes the stress on the system which is removed by the waterless stuff.

[markyboy911]

I had a few in the years that I've owned my car;

Front rads - the usual suspect
Heater matrix behind the radio - The symptoms of the heater matrix were a very slight smell of coolant in the front cab.
Expansion reservoir - a very small crack
The coolant cap itself - the seal had become warped / degraded

HTH

[PurpleTurtle]

I had this with my 996 - fractured header tank.

Sadly the first of many warranty issues. Shortly after that was solved it needed a new rear main oil seal (another known issue) and a recon gearbox.

I ejected out of the car before warranty renewal, unfortunately fell out of love with it after all that.

[jkh112]

tr7v8 said:

Check the header tank cap, in fact they aren't a fortune get a new one. There was a change in design & the part no. changed. I can't remember the numbers but they don't last for ever anyway.

Try this first. The new cap ends in part number ...04 (at least it did when I changed mine a few years ago, it may be an even later revision by now).

[NickWallace]

Thanks for all the comments.

I bought a new tank cap. Tried it and used the car a few times with it fitted.

No signs of coolant level dropping! I don't use emoji's but if I did I would use the one with the mouth wide open!

Surely such a small thing cannot solve that problem. I'm keeping fingers crossed and touching all wood.

Have checked numerous times and there is no indication that the level is dropping at all!

I will personally be shocked but perhaps this was the problem.

Thanks

Nick

[Unbusy]

Happy days!
It would be mostly vapour under pressure escaping so yes, easy to drop the level. Nice advise from the guys here.
Had the similar problem on my Alfa recently. It uses pink coolant so finding the leak was easy. Plenty of staining around the thermostat. Just needed a hose moved slightly and tightened.
I love these cheap fixes!

[George Smiley]

Glad its fixed but if you ever have the issue again, get some rad dye and put that in. It will show where leaks are occurring by leaving a (removable) fluorescent colour.