Radiator cap pressure

[CROUCHY]

I just had a mechanic test whether my radiator was leaking with one of those manual air pumps. All seemed good but I have noticed that I tend to have to top up coolant frequently although have seen no leaks on the garage floor. he said that maybe I needed a radiator cap with a higher pressure at which it releases. He tested mine and it seemed to be 40 bar. Does this sound right? Maybe whoever makes the radiator caps have a higher pressure radiator cap for the Chimaera? Thanks.

[Bassfiend229hp]

40 bar? Are you sure? That's about 600 PSI - that's scarily high!

[CROUCHY]

Any idea what would be a normal pressure?!

[MADMAX2]

CROUCHY said:

I just had a mechanic test whether my radiator was leaking with one of those manual air pumps. All seemed good but I have noticed that I tend to have to top up coolant frequently although have seen no leaks on the garage floor. he said that maybe I needed a radiator cap with a higher pressure at which it releases. He tested mine and it seemed to be 40 bar. Does this sound right? Maybe whoever makes the radiator caps have a higher pressure radiator cap for the Chimaera? Thanks.

no need to have a higher pressure cap.. the blue cap you have does the job. if its faulty you would know believe me! are you topping up your expansion tank and checking after a while and it has gone down? if so its fine these cars do that what you need to do is check at the swirl pot you can do a check bleed test to make sure you have enough coolant in the system no airlocks etc.
if you are losing a lot of coolant then you need to check everywhere keep an eye on the oil cap filler for mayo (water in the oil but i doubt you have that. what is your normal operating temperature when cruising?

[CROUCHY]

Temperature when cruising about 70 I think, lower when I'm very fast

[MADMAX2]

CROUCHY said:

Temperature when cruising about 70 I think, lower when I'm very fast

thats spot on!


where are you topping it up?

[jamienshelly]

Hi, It has been mentioned before on other threads and I know from experience that if the cap has "blown Off" then they can and do become an issue. They are a VW part and the part number is on the chimaera pages site. Also the "mayo" on the oil filler cap can also be condensation, if its being used for short journeys and not getting hot etc. I have saved people a lot of money after they have been told that their head gaskets are shot by rip of merchants, and all it needed was a good run. If the rockers are covered then possibly but a little bit of emulsification on the cap then maybe not. (scare-mongering by car shows on tv).
A pressure test should be done to between 0.7 and 1 bar and dont forget to check the heater valve in open or "hot" position for leaks.

[macca]

13 years ago had a 450 and had to top up the coolant every week, never did find out from where it was leaking. Got back into the fold 6 months ago, done 1,500 miles with some very spirited driving and not had to put a drop of coolant in. Conclusion, they don't all leak as a matter of fact, so have a good look around.

[Bassfiend229hp]

macca said:

13 years ago had a 450 and had to top up the coolant every week, never did find out from where it was leaking. Got back into the fold 6 months ago, done 1,500 miles with some very spirited driving and not had to put a drop of coolant in. Conclusion, they don't all leak as a matter of fact, so have a good look around.

Mine loses fluids like an incontinent hemophiliac - no idea why or where from.

Doesn't seem to be smoking excessively and I can't see any obvious water leaks. Has always done so and - TBH - I've had cars that have used far more, just have to top her up every month or two (which I don't consider to be bad for a daily driver).

The expansion tank on these things does have a tendancy to find its own level - some seem to stay over half ful while some seem to settle at only an inch or so of water in the bottom. What's important is what's in the swirt pot - if the level in that is dropping badly then you need to top her up (and find out where she's losing water). If the swirl pot is staying full but it's just the expansion tank that is getting low (note - getting low, not running dry) then that's probably just "her level"...

Phil

[macca]

Bassfiend229hp said:

What's important is what's in the swirt pot - if the level in that is dropping badly then you need to top her up (and find out where she's losing water).

Phil

Agreed.
Thinking it through logically, if being topped up regularly then water is being released. Finding it's own level means the release is measured? That would point to the blue cap?

[CROUCHY]

I suspect that I may have been acting as a kind of "over anxious parent" as I have tended to fill the radiator pretty much to the top before any more than a short journey. Perhaps I haven't been leaving enough space for the pressure build up once she heats up?