All vehicles: Losing/blowing out coolant

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All vehicles: Losing/blowing out coolant

Post by Guest » 15 Nov 2002, 17:31

Courtesy of Alan Smith.
There are a myriad of causes for this problem (ie) cracked head, incorrect timing, blocked radiator, blown head gasket, partial blockage of the cooling system, collapsing hose due to age/deterioration on the intake side of the water pump.
Before assuming the worst, always check for air in the system. Air trapped in the system, particularly in the cylinder block or head region soon turns to steam. Steam in turn, develops high pressures quickly which will lift the radiator cap that has a pressure setting of 14.5 psi. This naturally causes coolant to discharge out of the system, leading to low coolant level & the potential for serious damage to the engine.
If there is doubt as to the presence of air in the system even after bleeding via the bleed nipples, a couple of things which have been tried & proven are: Fit a piece of hose to a plastic bottle which will fit neatly into the filler neck on the car. The hose needs to be around 18" long. The added pressure will sometimes force the air from the system. Another is to squeeze hoses with the bleed screws open & if they feel empty, keep squeezing until water is felt in them. This is a kind of pumping action & literally pumps air out of the system. Once the pipe feels full of water, nip off the nearest bleed nipple whilst the hose is held in a squeezed position.

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Post by rabenson » 17 Nov 2002, 17:43

My Wife was barreling up the autoroute in her BX19D (j-plate) to catch a ferry. she parked up at the port then, on returning to the car, found that there was a fair quantity of coolant dumped underneath.
Obviously concerned, she (after a suitable period) checked the coolant level and found it to be very low. Topped it up and was escorted to the front of the ferry by the port staff who had seen her working on her car. This meant that she was first off when arriving in England <img src=icon_smile.gif border=0 align=middle><img src=icon_smile.gif border=0 align=middle>
She set off back and kept a close eye on the temp gauge which stayed perfectly at normal. On arriving home rechecked coolant and found it normal too.
Strangely, on her BX, the cooling fan operates off the ignition switch ie stops when you turn off. All I can think is that the residual heat in the engine after the fast run had caused a bit of an overpressure when the fan stopped and dumped some of the coolant via the pressure cap overflow pipe. I note that later BX's fans are independent of the ignition switch. Car has been fine since.....

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Post by FFX-DM » 18 Nov 2002, 17:55

I don't suppose this applies in this case, but a lot of people stop the car at the ferry port, then notice the puddle underneath and start imagining all sorts of nasties, when actually, it's condensation from the AC. This can make quite a big puddle. Normally when you park the car you walk away and just don't notice it. I have lost count of the puzzled people I have seen scratching their heads and searching for leaks.

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Post by rabenson » 18 Nov 2002, 19:39

Would that it did apply... I'm sure that Lynn would love to have A/C in her aging BX but alas has to make do with opening the window.. ;-)

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Post by oilundernails » 31 Dec 2002, 04:42

I came across a tip (while trying to find hoover bags) for helping avoid airlocks in cooling systems.I havent tried it; but what you do is wedge open the thermostat with 2 half asprins,everything can circulate, then the asprins disolve.

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Post by tomsheppard » 02 Jan 2003, 18:49

Yes, I can confirm that one, Polo mints were used in one case because the dissolve rate was fairly slow but I suppose you'll get fewer headaches using aspirin