i have a 1987 TII (stock) the car stays pressurized after the engine cools down. i mean like the next day you grab the hose and its tight. open the cap to check how full the system is and it gushes out!? any ideas thanks also long drives it will act as if it has bad coolant seals could this be a T-stat?

 

Do the test for bad coolant seals. Its possible thats the problem, though I don't think so.

 

bad cap?

 

If you have a stant radiator cap then you need to throw it away and get an OEM cap.

 

My thought would be bad cap - if the coolant seals were bad, it seems like that much pressure would force water back into the combustion chamber. Any noticeable pressure in your coolant system should go into your overflow tank and eventually the ground, so you shouldn't be able to keep that much pressure in the system unless the overflow system wasn't working properly, like stuck cap, clogged line, etc.

At the same time, if the only thing that was wrong was the overflow, then the pressure should go back to normal whenever the temperature returns to ambient. Pressure and Heat are directly proportional, so if you fill up a closed system and heat it pressure goes up. When the temperature returns to original filling temperature, the pressure will too. So if it wasn't overflowing when you filled it, then it shouldn't overflow when you take the cap off, if the temperatures are the same.

Also, if the thermostat was bad, the temperature in the car would be high (on the gauge) and the upper radiator hose wouldn't be too hot to hold.

 

FYI, my coolant seals were blown, water jacket cracked, and even though there was no smoke from my exhaust, the combustion pressure would blow all the water out of my cooling system within about 10 minutes, unless I clamped the overflow with a pair of vicegrips, then it ran for an hour without getting hot.

 

yeah it's werid.. the over flow works.. sometimes it flows out the over flow and it over heats and add coolant lights up.. i add'd a new cap and this is where iam at. i started and ran it for awhile today iall go check in a few ( ok checked it and its still pressureized!! after like 6 hours!) i have never ran into something like this.. how is there pressure if its cold?!? is there blown seals? and iam just starting it for like 5-15 mins each time.. so the bubbles from the gas chamber push into the coolant system.. enough to keep it pressureiezed but not enough to escape pass the rad cap to the over flow? and after hours of shut down the system keeps this same pressure? if the seals were bad.. wouldnt after time the small air and water leak back into the chamber? ( i would think how bad the seals were.. right?) leaving no little/no pressure
its a cool night iam going for a drive iall let ya know it if spits out the over flow or stays pressuriezed

 

take the cap off and start the car. if water or big bubbles start coming out, you got a blown seal. have you tried bleeding the system to get all the air out, if any is there?

 

Keep in mind that water will come out as the car heats up though, too. If water comes out because of a coolant seal, it'll come out immediately as you start the car.

Oh, and like Karack says, if you have a blown coolant seal, you have another problem. In my case I had two cracked irons.