radiator problem..

[jarance]

Hi jarance... on E36 with expansion tanks integrated to the radiator (M43, M50, M52, not sure about M42 and M40), there is no HIGH or LOW mark, just one mark, the COLD mark. User manual says not to top up above the COLD mark, but I also think it is okay to exceed the COLD mark a little as our ambient temperature is already quite high, therefore there will be less expansion under normal usage (eg. water temperature will go from maybe 25-32C to 95C here, delta of 70C max versus maybe from 5-10C to 95C in Europe, that's a delta of 90C).

Anyway, mine dropped from a bit above the COLD mark to a bit below the COLD mark in one year and two months, and I haven't top up yet... I don't think there's a leak anyway.

LCP, you could be right... have not check or look at my expansion tank for sometime now. Use to carry about 5 liters of water in my boot. Nowadays, only carry about 1 litre for emergency case..

 

[irdanlz84]

Please do a pressure check on the expansion tank and the cooling system. Most workshop will removed the radiator and connect a handpump with a gauge. The will pump air and pressurise the expansion tank and the cooling system. If there is a leak, the pressure will drop indicating a leak somewhere.
However, based on my experience with an E36, the pressure test does not really can confirmed that there is NO leak in the cooling system. A very clear indication is when you have to top up the radiator expansion tank every week. This is very abnormal. If there is no leak, the level will remain the same whether you overfill or under fill. As long, the water level is within the HIGH and LOW mark, it is OK.

If you fill to HIGH mark and after a days of driving, the water level drop to "Middle", then there is a clear indication that there is a leak.

Leak can be attributted to many things. Some of the thing are:-
1. Expansion Tank (this one very classic)
2. Old rubber hoses (especially after 6 years in service). BTW there are about 6 water hoses.
3. Water jacket in the engine block have hairline crack. This can be caused by engine overheating and adding cool water to the engine when it is very hot. A work of caution is not to add any water for at least 2 hours to prevent engine block from warping.
4. Solenoid valve for hot water to AHU unit faulty or leaking.

As for me, my problem was old hoses. After changing the top up is less frequent. Finally found the solenoid valve was faulty. Did a bypass and now hardly top up at all. The last time I top up was 3 months ago and it is only 2 fingers.

hmmm.. if that is the case.. i'm still not safe yet.. have to closely monitor the coolant level for few days.. anyway thanks for the detail info bro..

 

[jarance]

LCP, you could be right... have not check or look at my expansion tank for sometime now. Use to carry about 5 liters of water in my boot. Nowadays, only carry about 1 litre for emergency case..

LCP, confirm you are right.

Extract from Bentley.. fill to about 50% when engine cold condition.

 

[irdanlz84]

LCP, confirm you are right.

Extract from Bentley.. fill to about 50% when engine cold condition.

With the cap off and on rite?

One more thing for all bros, after i went to the workshop, i realize that all this while, my car was running with broken o2 sensor, knock sensors, and my fuel pressure regulator was blocked... the previous owner disconnect the vacuum hose, and sealed the nozzle, basically the pressure of my injector rail cannot be regulate... now all are fixed plus decarb and injector cleaning.. the result is smooth engine, regain low rpm torque, and satisfied mid to high rpm torque... not to forget, better fuel consumption..

however, the burst of torque during high rpm from the old setup was more sensation and more umph than the current setup, even my friend who drove cooper s acknowledge that the jerk was more than his cooper s.. how could this be? i understand that knocking is multiple combustion in the cylinder instead of one complete combustion.. is this the cause of the sensational high rpm burst of torque? now that my knock sensors were replaced.. the knocking is gone already.. is that a correct assumption to be made bros? ( Sorry out of topic, really curious to know..hehe :wink: )