Loosing his cool!!!!

[Scott Stephen]

My friend has an annoying problem with his 1989 740, 2316cc carb.

When topping up the coolant expansion tank to the max, after a couple of days of normal driving the coolant level drops quickly and the rate of loss starts to slow down as it reaches the minimum mark. The cap seems to be fine and the seal appears to be in good condition. There are no visible signs of leaks from all the usual places around the engine bay. Any ideas?????

[Scott Stephen]

Looking at this one logically perhaps the cap is actually at fault since the further the coolant level is away from it the less it tends to leak. There is however no visible signs of leakage in the vicinity of the expansion tank.

I certainly hope that the problem couldnt be related to anything more major!!!
Are these engines recognised for internal leaking or cylinder head gasket failure???

The car is running smoothly. It has been known for cars to maintain perfect compression with blown head gaskets near a coolant passageway and come to think of it the old girl does sometimes chuck out a lot of white smoke(So does my 940 however), but if the gasket is blown the car would lose coolant at a constant rate no matter where the coolant level is.

[Paul Wildsmith]

Is it an automatic with an oil cooler running through the radiator? These internal cooling pipes fracture - auto oil goes into cooling water, and water into gearbox. Expensive.

[Scott Stephen]

Sorry, it's a manual

[sheerwater]

Hi,
Easy one this I think!! Check your hoses. Running through the problem. Water expands when hot. This pressurises the system and exapands hot hoses. Filling when hot fills a larger volume due to expanded hoses. Hoses retract when cool and water seeps out overflow or the water expands on start up and leaks out before the hoses expand. Thus the settling down to one level every time. Worth noting levels when hot or cold. When is it being filled ...hot or cold. Hope this gives one solution. Cheers Nige

[Scott Stephen]

Cheers Nige, I'll give it a go and see what i can come up with. It will probably be a case of removing each hose one at a time and carefully inspecting them.

Thanks.

[sheerwater]

Hi again,
I had a hose similar to this problem. Basically its the bigger hoses although the small ones could be at fault but they wouldnt hold much excess water. Because the rubber is a sandwich the inner rubber deteriorates allowing the outer rubber to balloon and tear away from the reinforcing web. I had a near miss once on the continent. Id been belting it for hours at above the uk legal limit. Stopped for petrol and opened the bonnet to find a bulging hose about the size of a tennis ball!!!. When it cooled it settled back down. Its easy to feel for softer spots on the hoses but they are items that have improved over the years so we tend to forget about them. Hope you have luck. Chers Nige