hey guys, ive got the running water noise behind the dash when i start my car (punto mk2 1.2 8v) in the mornings and i have noticed a bit of mayo build up under the oil cap does anyone know if this is leaning towards the HG? I havent experienced coolant loss and the car drives fine. mpg is a bit high at only 33mpg. anyone got a diagnosis? thanks. P.S i tried bleeding the system but i couldnt figure out what to do after taking the 2 valves off, there wasnt any air coming out just took em off and nothing happend which i assume means there wasnt an air lock?

Hi mate,

I wouldn't worry too much about the mayo yet (unless there is loads of it) as it can get a bit at this time of year due to condensation. Clean it off the cap and then see if it comes back at al. As you are loosing no coolant, it doesn't sound like any is leaking into the cylinders. Search in this section for "bleeding cooling system" as there are a few guides on how to do it properly. As there was nothing coming out of the pipes when you took the bleed screws out, im guessing you did it with the engine off. To bleed the system, you need the engine on.
If you still get mayo build up, then you can get the coolant sniff tested at a garage, will only take 15 mins, and will tell you if there are exhaust gasses in the coolant, indication a blown head gasket.

Hope that helps,
Alan

Yea i cleaned the mayo off and it came back again in a week (about half a cap full) i dont understand why as my car is running fine got it up to 87ish today no probs and acceleration is fine. After having a drive and leaving the car 2 stand for 10 mins i looked in the coolant expansion tank and i did notice a very slight bit of white foam by the side of the bottle but the coolant level still hadnt gone down. At first i thought this ment the HG was about to go but its bin like this for 2 months, can any1 tell me whats up or make any sence of whats wrong? thanks

is the header tank cap pressurizing fast? ie take it off with the engine running while warm (be careful) put it back on, if it builds up lots of pressure up in 5 minutes then i would say its HG

it sounds like maybe hg anyway, though

Right still same problem occuring but car is running fine! surely the headgasket woul have effected me by now? I tried taking the expansion cap off after driving around for 10 mins and when i took it off no coolant burst out but i got a release noise like you get when you open a fizzy drink bottle lid, (a very slight pressure release noise) also i noticed the coolant level was right to the top of the exp. tank (over max mark) but after letting it cool down it slowley went back down to 3/4 full. anyone explain this? cheers guys P.S also tried taking off bleed screws again and squeezing all the tubes, i noticed the pipe goin away from the expansion tank was very slightly warm but the one on the right going into radiator was much hotter is this how it should be? still getting mayo under cap 2. thanks

no1 got a clue?

Hi mate,

with the exception of the mayo and the gugling behind the dash, everything else sounds normal. The water in the cooliing system will expand when it gets hot. Hence the reason for having an expansion tank.
By the sounds of it the gurgling is an airlock in the cooling system, there is a technique to bleeding it properly and sometimes it can take 3 or 4 attempts to get it right.

hope that helps,
Alan