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#1
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Hi All
I've a 1991 2.0 190E, Petrol, Man G/B 130K with a odd coolant problem. I'd been loosing coolant and found the seal had gone in the expansion tank cap, so changed this. Then found coolant on top of the engine under the injectors -traced to a leaking hose union, which I fixed but I was still loosing coolant at a rate of 0.5 litre every 500 miles. I took the car to a mercedes specialist and had a 36K service with a coolant flush, a new water pump and thermostat fitted. The tech pressure tested the coolant system and noticed a very slow drop in pressure which we put down to drips of coolant from the water pump. But the leak persisted so I rigged a plastic bottle up to the expansion tank overflow and drove my usual 500 mile journey at 80 mph with a couple of stops. At the end I found 0.5 lites of coolant in the bottle! So for some reason it seems the system is being over pressurised. The car runs brilliantly, temp sits at about 80, the oil level is fine with a good clear colour on the dip stick and the exhaust is clear. The expansion tank is a bit gungy with a sort of brown sticky residue in places and I noticed what looked like tiny aluminium particles when I flushed the tank - some sort of leak stopper maybe? The only other odd indication is the heater slowly cools off when travelling at speed, although this has improved since the coolant flush. My thoughts are a head gasket leak of some sort but I'm confused by the symptoms. Maybe there is a slight blockage somewhere causing the pressure to rise in the system? I would be grateful for your thoughts! Cheers Nick Dormor :-) |
#2
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You could test it by installing the pressure tester and running the engine then monitoring the pressure. It should not rise rapidly when you hit the throttle.
__________________
Benzmac: Donnie Drummonds ASE CERTIFIED MASTER AUTO TECHNICIAN MERCEDES SPECIALIST 11 YRS |
#3
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I'll have to give that a go.
I drove 550 miles yesterday in stop start traffic and I had nearly 1.5 litres of coolant in my bottle at the end of the journey, so maybe I'm loosing coolant each time I accelerate up to speed? As the heater goes cool at speed I'm almost convinced of a blockage resulting in a reduction of flow through the heater above 60 mph. At 30 mph I have to turn the controls right down as it gets very hot! |
#4
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Well the unfortunate fact is that the head gasket has gone!
My initial fears - financially - were correct! The heater problem was caused by a restriction in the heater matrix, which I fixed by flushing the system with some heavy duty radiatior cleaner. So I popped in to see the Merc Specialist in my town and we looked at the coolant hoses which happened to be rock solid - cause -head gasket over pressurising the system. I booked the car in for a head gasket and valve check then as I arrived home the return hose blew! At least it happened when I was at home. So hopefully I wont need any engine work for another 130,000 miles!!! Cheers! |
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