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I wouldn't vote HG... cylinder into coolant leak would result in at least an oily film in the coolant. It would blow combusted/semi combusted air into the coolant passage because of the pressure difference during the power stroke. It may not consume coolant, but you'd still be able to tell.

Well he said he wasn't losing any more coolant. I vote for thermostat. My grandmothers car did the same thing where it would be at operating temp and then randomly go to cold. Thermostat fixed it.

Back to this problem. When I did my clutch, it was at a friends garage. Final days were approaching and my heat still wasnt fixed. My buddy replaced the thermostat and all was good. Mind you, I already replaced the thermostat about 2 months prior with a new one and it didnt help. This time it was good. A few months later, I sprung a hole in the hose that connects the thermostate and the radiator. Luckily I pulled over in an auto zone and put the new hose back in. Filled what I needed and off I was, with heat! 2 months later, my gauge is taking 20-30 minutes to move off of cold and semi warm heat. When going up hills and riding out the gears, the gauge moves and heat is hotter but once I let off, it goes back down to cold and not much heat. Dont know what this could be..again. Is there a bleeder in the cooling system? How to get the air out? Maybe a flush?

have you tested the thermostats that you pulled out? if they are in fact failing there has to be a cause. are you buying some no name thermostats or what? maybe your getting a bad batch? what your describing sounds exactly like a stuck thermostat or one thats rated too cold. you want one thats rated for 180F. if you put it in a pot of water on the stove with a thermometer it should start to open +/- 5F of 180F and should be fully open by 200F at the highest. if they are failing you may have debris in the system clogging the spring mechanism in the thermos and id suggest a good flush. you can flush the system by removing the thermostat and running a hose into the fill neck with the lower rad hose disconnected and running the engine while cold. FYI you do not want to run cold water into a hot engine.

id also grab a new rad cap (13PSI) and pressure test the system if possible. cooling systems are fairly basic and if the thermostat, rad, and rad cap are good and there is no leaks or clogs the car should run at ideal temperatures. assuming your pump is functioning properly that is.

mikeinaus wrote:have you tested the thermostats that you pulled out? if they are in fact failing there has to be a cause. are you buying some no name thermostats or what? maybe your getting a bad batch? what your describing sounds exactly like a stuck thermostat or one thats rated too cold. you want one thats rated for 180F. if you put it in a pot of water on the stove with a thermometer it should start to open +/- 5F of 180F and should be fully open by 200F at the highest. if they are failing you may have debris in the system clogging the spring mechanism in the thermos and id suggest a good flush. you can flush the system by removing the thermostat and running a hose into the fill neck with the lower rad hose disconnected and running the engine while cold. FYI you do not want to run cold water into a hot engine.

id also grab a new rad cap (13PSI) and pressure test the system if possible. cooling systems are fairly basic and if the thermostat, rad, and rad cap are good and there is no leaks or clogs the car should run at ideal temperatures. assuming your pump is functioning properly that is.

thanks for the info. I just tested the original thermostat, the first replacement, and now the one i just pulled. All opened up just as they should. The one in their now is rated for 185 degrees.

Figured it was odd that it only did it in the winter, maybe because my engine is twice as warm to start off with in the summer where it didnt really matter. Now that I think of it, I got a new radiator cap and it didnt help. I just thought there was an air pocket or something? Ill hopefully do a flsuh sooner than later.

I jacked up the front of the car, opened the rad cap and lightly applied the throttle. Eventually the air bubbles started rising to the top, and alot of them. Lowered the car, refilled, and off I was, with heat and a normal operating temp gauge. Thanks everyone.

With the air situation I was actually wondering if you had a faulty head gasket. Glad you got it fixed. Cheers

OK finally got this problems figured out (knock on wood). When I got a hole in the initial radiator hose I got a new one at an auto zone. Well it was too big. I got the right one from advance auto and measured it to make sure. The old one that I put on and had the problems was 1 and 1/4 inch. The new one is 1 and 3/16 inches. As of about 2 months, no problems and heat has worked great. Thanks for all the help.

thats weird, i dont see how 1/16th of an inch on a rad hose would make a difference... was it clamped securely with hose clamps? im assuming it was sucking in air which was causing your problems?

mikeinaus wrote:thats weird, i dont see how 1/16th of an inch on a rad hose would make a difference... was it clamped securely with hose clamps? im assuming it was sucking in air which was causing your problems?

yes I had hose clamps on tighter than I would have normally gone but I kept getting a slow (real slow) leak out of where the thermostat housing meets the rad hose. I initially thought it was the housing so I took the rad hose clamp off the housing and coolant rushed out in between the inside house and the outside of the housing. I got another new one and measured it at the store to see if it was smaller and it was. Hopefully it stays normal, like it has been lately.