Technical Guys need a hand, mystery coolant leek

[mzhussein]

ok, ive had a rad change on stilo 1.8, at a good mechanic, very reputable.
but it was still loosing coolant, so they checked it over and had it presurised for an hour, and they found no leak, they then tested the cap and found that faulty, so they ordered me one up. but the car has been in and out of the garage and looke dover many many times int he last 2 weeks, but it is still loosing coolant!!

after driving fastish (legal speeds), steam will come out of the bonnet, not allot just whisps, open the bonet and there is water in the under tray, it is loosing about half the header tanks worth of water in an hours driving, the mechanics are happy to keep lookign over it (at no charge) but they keep drawing blanks, i realy would appreciate some advice as to where to look for a leak.

also when i remoe the cap after about an hours driving, there is NO pressure in the system, so its not pressurising, hasnt oveheated, cos im keeping an eye on it.

thanks,

mzhussien

 

[ROWENA]

Hi MZ is your water pump working ??? could be its lost its vanes/sheered off inside, hope not but it sounds like the water itn't moving inside your coolant system overheating and allowing steam to blow out of the cap.
you didn't say what your temp guage is reading is it normal as water boils at 100 c and the pressure in the coolant system keeps it liquid at temps over 100 c, no pressure = steam at normal engine temps

Karl

 

[mzhussein]

temp is reading normal, water pump was changed when i had timing belt done, not venting form the cap! its evaporating from inside engine bay. heaters are working, and rad gets hot.....

 

[Argonought]

Well it's a sealed system so it must be getting out somewhere.

Usually best to start with a really clean engine then, assuming you have anti-freeze, it should be obvious where it's leaking from.

 

[PNL]

Have a feel around the carpet area under the heater might be a leak on the heater matrix.. a little drip can add up to water loss over time..

 

[sixpotman]

Water pump seal? difficult to see because
it's protected with covers.

John

 

[mzhussein]

ok, i think it might be solved, i got it back just now, and he said that whilst he wa sunder the car, and a bottle in the car fell on the accel pedal, he had a ureka moment, as boiling coolant hit him in the face....there is a hose clip that was ever so slightly loose, and when revved the engine flexes a bit, causing the pipe to come out slightly from the hose, causing a lil leak....so he fixed it and pressure tested again all seems good, gonna take it for a test drive now, will post back....

p.s. i was also thinking water pump, cos its new-ish, can the seal go without the bearing going? cos when the bearign goes it whiiines.....

p.p.s, its not heater matrix...carpets are dry, and it was no small leak

 

[PNL]

All's well that ends well then and the fact he got a face full of coolant says he was in the right place at the right time..you might not have found it other wise..

RESULT..

 

[mzhussein]

exactly,hjave taken it for several 'Itallian style' test drives, and its alll gravy, just goin back on monday, cos he didnt have enough antifreeze to put proper % in (i think cos my car, which has a 9L system by the way!!, drank it all, then pissed it out lol), so he said to bring it by on mon and hell do it while-i-wait, so problam solved indeed!!