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Help - Mystery Coolant Loss!!

8K views 15 replies 10 participants last post by  chrishendrix 
#1 ·
Hi

My 156 V6 is losing water but there is no sign of a leak??! Was worried it may be head gasket failure as there was a little 'mayonaise' around the filler cap so took the car to my local specialist where they carried out a 'sniffer' test and changed the oil and confirmed all was well. Whilst they had the car they also pressure tested the cooling system and checked under the carpets in case the heater was leaking into the footwells but couldn't find any problems or signs of the leak at all. In the end we hoped it was just an airlock in the system and that it had been cured by the pressure test. Unfortunately I have had the car back 3 weeks now and it is still using nearly 1/2 the coolant in the header tank each week (approx 150 miles). Does anyone have any ideas or advice )there are no drips under the car if i leave it running.)

Many thanks
 
#3 ·
mine does the same i have just changed my radiator not to cure this just the fins had crumbled away
still water disappearing usin the same as your v6 just keep an eye on your levels regularly dont by any means try rad sealers not good only use in an emergency
other engines drink water as well dont worry.
 
#5 ·
Not sure if its any help but my water level has been creeping down and i've just found the problem, back of the engine below the power steering fluid bottle there is a heater pipe with some kind of sensor looks like a brass t piece with the sensor coming off it and its that that is weeping coolant when the engine is hot. With the coolant weeping only slightly the coolant is boiling off instantly but leaving the remains of the antifreeze as a pink powder type coating, thats why I get no puddle, steam or any other signs like you would get from a bigger leak. Mine is a oil burner but would think the pipes for the cabin heater would be in the same place so maybe worth a look.
And 1 day i'll fix my leak lol
 
#6 ·
Have a good look around the engine bay for pink stains on the block/coolant pipes tell tale sign of modern coolant system leak, could also be an internal leak into the cylinder bore causing the water loss, try reving the engine with the expansion cap top off and see if the level rises or starts to bubble significantly, make a seal over the top with the palm of your hand and see if the pressure builds up quickly (over 4-5 seconds) just make sure not to burn your hand if the engines hot!! if it does then unfortunately its probably the head gasket.
 
#7 ·
Its funny u should mention this as am getting the same on my 147 lusso.

3 times i have topped up in the last 4 weeks....i to thought it could be an airlock of some sort after doing a water pressure test which was ok. The oil is fine, no grey sludge etc...and there is no signs of visable leaks...I have also been told that if the cap is not on tight or pressuring properly u can also lose ye coolant that way like the chap above said....Maybe its the faulty thermostat or iv got an air leak some where, but its pinpointing exactly where ?

At present my car has gone back to the garage where i got it from getting checked over....so hopefully they will suss it and ill update on here once i know....
 
#13 ·
Overtightening might distort the cap?

If you are in any doubt about the expansion tank cap, just get the engine up to operating temperature, lift the bonnet and look at the tank cap. DO NOT TOUCH OR REMOVE! Just look at it and listen carefully. If it is leaking you should see steam coming out. My cap developed a tiny crack in it and this was immediately obvious with the engine hot. If in doubt change it (when cold). Part cost is £5 from the main dealer. Unfortunately, in addition to my split cap I found my radiator was leaking :cry:
 
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