Re: heating problem
"Vassie" <email@example.com> wrote in message
> The radiator has been tested and I believe there is a head gasket leak.
> There is no evidence of oil on the dip-stick. Do I have to take the
> cylinder head out, or are there any quick fixes. The setup of the radiator
> without a main radiator cap is satisfactory according to the repair shop,
> he says the modification is fine. As explained, this heating problem has
> gradually increased over time.
Sounds like there may be a leaking head gasket like you thought. Check
for bubbles in the coolant with the engine running. The gasket fails between
a cylinder, often #2 (second from back) and the water passages, you won't
find water in the oil. This failure causes some coolant to be drawn into the
cylinder on the induction stroke and the cooling system to become over
pressurised as the fuel/air mixture is forced into the water passages during
compression. To test, first remove the radiator cap, take out all the spark
plugs and do a compression test. Coolant will overflow or shoot out of the
radiator filler neck when you get to the faulty cylinder. If you don't have
a compression tester, just try it with one plug fitted, the engine turns
over faster with the plugs out. That's how I found mine was faulty. Let's
know if you have to pull the head off, no quick fixes, just be thankful it's
a SI, makes it less complicated. BTW, the cap on the header tank on the
front of the engine is normally not a pressure cap, but the one on the tank
on the fender is.
71 SI XJ6, 85 SIII XJ6