Date: Fri, 9 Jul 1999 13:55:43 -0400 From: "Eric Law" <elawxnospamxnopsamecsxnospamx.com> Subject: Re: Boil over problem
George, I can think of two possibilities here: incorrect coolant mixture (not enough antifreeze), and a bad reservoir cap. Both would cause the coolant to boil at a lower-than-normal temperature. It never boils over when running, right? Sounds like the motor is very close to the boiling point of the coolant when running, and when you shut it off, the temp rises a little and it starts to boil. I'm inclined not to suspect a head gasket since if the head gasket were leaking into the coolant, it would bubble whenever the motor was running. It's also possible that you have a combined thermostat and temp-sensor/gauge problem. perhaps the 'stat is making the engine run hot, and the gauge is not properly indicating the condition. You could check this by using an accurate thermometer and measuring the temperature of the head near the thermostat housing. It should be 180-210 degrees F during normal warmed-up operation. Anything over about 220 would indicate a problem. Eric law George F. Johnson <gfjohn0751nopsamcomnospam> wrote in message news:19990709104323.19829.00004920nopsamq1.aol.com... > Robert Brown wrote: > > >Can you explain "boil over" in a bit more detail - i.e. is there a large > >surge in > >gases from the coolant when you remove the resevoir cap? In that case you may > >have > >exhaust gases being pressed into the coolant via a leaking head gasket or > >cracked > >head. A mechanic can analyse the coolant for traces of CO to confirm this. > > > >If your problem is due to the above, there is often a slight increase in > >coolant > >temperature (due to high temp of exhaust gases), and the radiator fan should > >start > >coming on sooner than you'd expect. Have you confirmed that your fan is > >starting > >up as it normally has done? A broken fan or thermostat switch is a common > >cause of > >cracked heads on the 8V (I have had bad fan -> cracked head on my 1983 99). > >Since > >you report _no_ increase in temp, then the problem can be due to something > >else > >instead. > > After turning off the engine, the coolant begins to rise in the reservoir. > Soon it begins to boil up through the hose and then overflows the reservoir. > Enough coolant will be expelled so that the reservoir is empty when the car > cools down. The cooling system seems to be functioning properly otherwise. > The fan will come on as usual and the gauge reads normal. Occasionally in very > hot weather the gauge has read on the high side but never has it gotten into > the red. The leaking head gasket/cracked head (I hope not) idea sounds like a > possibility. I will check it. Thanks for the info. In the meantime, any > other ideas are appreciated. > > > George F. Johnson
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