I have had a nightmare with my Audi A6 1.9 tdi. Please can someone shed some light where the mechanics cant seem to:
The car has always been reliable until recently the water thermostat clip disappeared, the t-stat fell out allowing the water to drain out instantly the warning light came on and I managed to pull over before the car got to the red line, probably got to about 120c.
When trying to start the car again the engine barely made any attempt and the battery sounded dead, I assume this means the engine partially seized due to the heat? Black smoke and a burning stench came out of the engine.
Car was taken to a garage and they replaced the t-stat and all the coolant, replaced the battery and it all started fine, they ran it for about 40 minutes checked pressure and all looked good.
Two days later the pressure light came again, all the coolant had disappeared with no obvious sign where it had gone. I replaced but by the time I got home (50 miles) it was all gone again. I sent it back to the garage who felt that the head gasket was probably gone.
One new head gasket later I have driven for three weeks doing about 100 miles a day. Went to scotland (600 miles) no problem however on the way back light comes on again, pull over and all coolant had gone, I (stupidly) refil with spare water once the enging cooled down, only to find a hose had disconnected from just behind the engine, RAC replaced and ran the car for 60 minutes to make sure no over pressure or signs of gasket failure.
Drove back from scotland, no problems. Drove for three weeks no problem. Drove to work fine, on way back on comes red light and again no coolant, this time the hose at the top of the radiator has come away.
It suggests to me that too much pressure is getting into the coolant system. Sent it back to the garage who traced it back to a defective pressure cap on the tank. This has now been replaced and my car returned to me yesterday.
After the drive to work, just to check I opened the bonnet to look at coolant level, the top hose is so hard you cannot squeeze it at all, after an hour I tried again and by this time it was slighty flexible so that I could see water shooting back into the reservoir tank.
The car does not overheat, it has new pressure cap, it has new head gasket, why the hell are the hoses blowing off and where is the pressure coming from?
Thank you for any help you can give and sorry for long post
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The garage can 'sniff 'the header tank for combustion fumes but as a DIY test run the can until hot and CAREFULLY undo the header tank cap and slowly release the pressure, refit the cat and continue driving for say 20 miles then check the pressure again, if the hoses are fully pressurised it implies the HG is leaking or the original overheat has cracked the head or the block. Regards Peter
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The radiator has a pressure release valve with this NON operating it will blow a hole in the radiator before it would blow of a correctly fitted hose.Seems to me whoever refited the system was in a rush and did not tighten the hoses properly so I would check the remaining hoses.
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