Reply With QuoteThe top hose will be firm to the squeeze on a hot engine right after shut down. Don't see anything abnormal there. Good luck with the HG and hopefully it'll be just a replacement without any complications.
3 Grand Master
A sad day
for the first time in about seven years me and my 535 are more than a few metres apart.She is in the workshop with a suspected blown HG.Like the other poster i have no real signs of a blown HG,just a miss at start up and coolant loss,oli clean,coolant clean,no overheating,even after three days there is pressure in the cooling system,top hose firm to the squeeze immediately after shut down....
Major Contributor
The top hose will be firm to the squeeze on a hot engine right after shut down. Don't see anything abnormal there. Good luck with the HG and hopefully it'll be just a replacement without any complications.
2 Grand Master
It sounds a bit confusing, but he also said there is residual pressure after three days (???). Thats a looooong time to hold pressure.Originally Posted by Rus
Anyhow, I hope its an external leak.
Dave
10/90 Build 525im, 630,000+km, Eibach/Sachs, Engine Rebuild
*RIP Oskar the DOG*
3 Grand Master
3 Grand Master
the shop rang me today...they arent sure but its looking likely.The aux pump is leaking so thats one source for the coolant loss but their is a build up of pressue while running enough to bulge the radiator!
4 Grand Master
The system holding pressure for three days and leaking from anywhere are contraindicative. Also if there is enough pressure to bulge the radiator the cap is defective, this pressure should be relieved.
There is a simple chemical test to determine if combustion gasses are present in the coolant. I suggest having this done.
"The gas pedal wouldn't go to the floor if it weren't meant to be there"
3 Grand Master
i went about 100k miles on a bowed out radiator, i suspect that it got that way when my car blew a headgasket. i didn't know it was bowed out until it came out of the car and I saw that a good number of the crimps were on the verge of being straightened back out. i say that you should tell them you want to keep it as a spare when they replace it.
ps..i'm not saying to drive around with the thing gushing water if that is the case, but from the situation as I garner it from this board, people in NZ/aus pay a premium for parts. i was losing about 500ml of water per 6 months in my car, and i was driving it about 700-1000 miles a week at the time. the leak wasn't occuring from the radiator.
Last edited by ryan roopnarine; 03-20-2009 at 09:03 PM.
Grand Master
Have them start it up with the coolant cap off. Look for bubbles. Not good when you see them.
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Big, Big Time Poster
I had the same problem on my 525. The head was slightly warped causing a leak beween no1 and a coolant journal. The combustion gasses would only leak into the cooling system when the engine was under load, so there was no sign of problems at idle or without a load on the engine. The cooling system was under such high pressure that small leaks sprung up at the radiator and the water pump. The radiator cap was very slowly releasing pressure, but was not designed to accommodate this sort of problem. The cooling system would leak as the engine cooled. The leak would stop when the system pressure dropped a bit, but some considerable pressure would remain in the system indefinitely.
Solution was to skim the head and pop in a new hg. I did the value seals at the same time. It wasn't that big of a problem. Just looks a bit strange on first inspection.
3 Grand Master
i have been driving for weeks with it,It started as an occasional miss at start up,which became more frequent,then(i always have had a very slow coolant leak) the coolant top up became more frequent....I will ask them to do the combustion gas check.I dont know how else the system could get so pressurized.Howdo you check theexpansion tank lid pressure check?
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