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[Deleted User]

Yesterday I left work for an appointment and had gone about two miles when I noticed my temp gauge getting abnormally high. I started for home to switch vehicles when the temp gauge went to normal. I ran about 20 miles with no more problems. I left the appointment and it went up again but then dropped down to normal. This morning on my way to work it did it again so I checked the radiator and it was very low. I filled the radiator and looked for leaks but couldn't find any. On the way home this evening the temp looked normal but as I pulled away from the last stop sign I saw I was leaving a water trail. I pulled into my drive and popped the hood and the overflow line from the radiator was pouring water out but the hoses were not excessively hot nor was the radiator or block. I think my radiator cap failed and is letting the water overflow at normal operating temperature. No sign of a blown head gasket at least no water in the oil. It could be cylinder pressure pushing the water out of the radiator. I'll replace the cap tomorrow and check it again. I'll fill the radiator and watch for bubbles coming out the neck. If the headgasket is blown I guess I'll do a complete rebuild. No need to go halfway if I have to pull the engine down.



Harry

Unknown

Maybe the thermostat is sticking closed now and then ?

[Deleted User]

Ron, that was my first thought, except the water isn't boiling back through the head. Usually when a thermostat sticks closed the water in the head will boil and you will hear an explosion of the boiled water and gasses back into the tank. If the thermostat is stuck open the car never heats right and you won't see the temperature stabilizing, it goes up and stays, it doesn't drop back down when the thermostat opens.I could have a badly blown headgasket that is pushing spent gasses into the radiator and forcing the water out the overflow. The gasses should bubble out through the neck though and come up through the water. When I lifted the release on the radiator cap there was no surge so I think the cap has failed but I can test it. The other thing that tells me the thermostat isn't stuck closed is the lower hose was not any hotter than the upper hose, if the valve is stuck closed the lower hose will usually be much hotter.



Harry

[Deleted User]

It seems my problem was the radiator cap. I put a new cap on, the old one was an Atlas S-9, and low and behold, no more overflow and the thermostat openned where it was supposed to. I filled the radiator to the max before I changed the cap there were no bubbles coming up, just before the thermostat openned the water expanded enough to dump quite a bit out of the neck. With the new cap on not a drop came out. I drove up town to test it and no problems coming or going. I'll keep an eye on the water level just to make sure it isn't going somewhere else but right now it looks good.

Thanks for the help and suggestions guys.

Harry

[Deleted User]

It looks like I jumped the gun on my problem, after doing fine yesterday the car overheated on the way to work this morning. I put a new 180 degree thermostat in this morning and no problems since then. It's strange that this thermostat went bad so fast. It wasn't in the car six months.



Harry

[Deleted User]

Well Heck, three trips with no heat problems whatsoever then this afternoon a short jaunt to the car was and the temp gauge was going too high. Plus there was a little overflow from the cap. Since it isn't likely the new themostat is bad I'm wondering if there is something floating up to the thermostat once in awhile and causing a restriction. I guess the next step is to flush the engine with the thermostat off and see what comes out.I would love to see a chunk of rubber or something come out. It does seem strange that in a year of pretty regular running this is the first overheating problem I have had. The other thing I'm thinking is maybe the lower hose is collapsing internally. Does any one have any ideas here?



Harry