Coolant filler cap

[Best in Red]

Apologies if this has been discussed before, however search did not show up any results.

 

Have found it necessary to top up my coolant twice recently, works out I am loosing 1 litre every 1200 miles, no evidence of water leaks.

 

On close inspection of the blue filler cap there are signs of dried on coolant residue inside the cap but not within the o ring seal (hope that makes sense), basically what I mean is external to the cooling system.

 

Also there are dried on coolant splash marks inside the combined oil and coolant filler pocket.

 

Do the caps have a reputation for leaking?

 

Appreciate your comments

Edited April 3, 2018 by Best in Red
Photo added

[Tom]

That’s a lot of coolant to be leaking past a faulty filler cap.  Have you checked the rest of the system for leaks too, rads etc? 

[Buggyjam]

My car was leaking coolant and the cap was the culprit. It was using about a coke can full of coolant every few hundred miles. I had minor coolant residue inside rubber boot but not much.

 

 

Two inspections and two pressure checks no one could find the cause. In the end Porsche Belfast nailed it. They said the cap wasn’t leaking when checked normally but the pressure relief activation on it was faulty. Apparently only slight pressure in a certain direction on the cap when under pressure caused it to blow out coolant. Really tricky to spot as the cap looked normal otherwise and didn’t appear to leak on first check. When the car was on the ramps there was pink coolant residue down near the running gear below where the coolant housing drain would be.

 

 

Edited April 4, 2018 by Buggyjam

[Buggyjam]

Sorry forgot to clarify. It was more than a coke can every few hundred miles. It actually needed topping up twice in about 800. And it was more than a coke can, prob a good litre. 

 

Take your car for a drive and get it to temp so the coolant is under pressure. Then leave the engine running, open the coolant hatch and put light pressure on the cap. Try wiggling slightly or pressing gently down on it. Just be careful, perhaps wear gloves and long sleeves in case as the stuff is crazy hot. Failing that doesn’t mean it isn’t the cap but chuck it into someone. They’ll check the cap again properly, hoses, rads,  pump and pressure test etc.

[Best in Red]

Really appreciate your replies, picking up a replacement cap tomorrow so hopefully problem solved.

 

Cheers

 

Steve

[SpannerMan]

The two main culprits of coolant leak on these cars already mentioned, definitely check the rads and for the cost i'd recommend changing the coolant filler cap on a major service type frequency anyway.  

 

There are other areas to check, such as the coolant hoses running under the car - the joints have been known to corrode. 

 

 

[Best in Red]

Cap was definitely faulty and was not sealing properly.

 

Had the car on the ramps today, unfortunately I have a leaking front radiator hose so now looking to replace all four plus the two aluminium cross over pipes. Makes no sense to me replacing one at a time.

 

 

[Woodhouse]

On the 987 and 997 cars, the coolant hoses between the radiators and aluminium crossover pipes suffer from corrosion at the connection between the two.  The rubber hoses have quick release Henn couplings which push into the pipes and are retained by wire clips.  The steel Henn couplings corrode to the point where you can't seperate them from the crossover pipes so need to replace both.

 

All 987 and 997 cars will need hoses and crossover pipes replacing sooner or later.  The parts are around £200 but its a fiddly job which requires the front subframe dropping for access.  

 

I did mine last year and wrote up a fairly detailed procedure.  Let me know if you intend to DIY and I'll PM it to you.