Please Help
 

As some of you know I Just bought this car 2 days ago.
https://www.rx7club.com/forum/showth...threadid=95102

I bought it assuming that the coolant seals were bad, but I want to just make 100% sure that they are before I spend 2k on a motor. Here are the symptoms.
1.The car over heated with the owner, he replaced the tstat, that didn't work.
2.His mechanic told him that there were bad coolant seals. He sold it to me 2 days ago.
3.My friend Robbie who owns an FD himself came over today. We burped the coolant system a little bit, added coolant and let it idle. It was fine and temp was perfect and there has never been any smoke.
4.We decided to drive it just to see if she would show any signs of overheating. We drove it for about a half an hour and the temp never budged, at stop lights or anywhere.
5.We get back to my house and as I am backing up the hill to my drive way, the coolant buzzer goes off and she began to slightly overheat.
6.The AST which is a 1.3 bar AST cap(which Robbie said could have a small link to the problem) was hissing like a snake and you could hear the coolant boiling and flowing right over to the overfill tank.
7.We are confused as to what it could be, here are the ideas that he came up with.
A.The AST cap is the wrong one and it is sending the coolant over to the overfill tank way too quickly.
B.Since the car was not driven much, and there is like algae down in the AST tank, the coolant system may have shit loads of air pockets, and or a blockage somewhere(this is what RIKKI suggested)
C.And last case and worse case scenario the coolant seals are bad. But the problem he has with this is that even if they are bad you should still be able to drive the car as long as the coolant stays topped off, unless the coolant seals are horrible. But if they were that bad and they leaked coolant that fast there should be shit loads of smoke coming out the exhaust, if not then where the hell is all of the coolant going? I AM SO SORRY ABOUT THE LONG POST, JUST WANT TO MAKE CERTAIN I AM NOT REPLACING A MOTOR FOR NO REASON.

into the over flow and on the ground due to the bad cap

Why don't you try replacing or eliminating your AST, flush your coolant system and install an electronic temp. gauge for a more accurate temp. reading.

It has a new SR Motorsports radiator. But I will get the new .9 AST cap(where is the best place?) and is there any other way to flush the coolant system other than going to a radiator shop? Cause I don't want to drive the car and have it overheat if the motor isn't bad. Thanks again for all of the support.

the drain for the motor is on the driver side of the motor on the the bottom in the middle. there is also a drain for the rad at the bottom it, its probably a plastic screw plug on yours

Bump, I don't know what I would do without the forum. Thank you guys sooo much for the help, especially RIKKI

So does anyone else think that there is a chance that it may be because the AST cap is a 1.3bar instead of the called for .9? Also there is a wierd noise when driving, like a quick squeal, does anyone think that it may be the water pump, or the belt too tight? I have to check all possibillities before putting in a new motor? Also one last thing, there is like algae type crap in the AST tank do you think that the coolant system has crap all through it, and is getting clogged up? I just can't figure out how all that coolant is leaking so fast and the hasn't smoked one bit. If the coolant was leaking that bad into the motor, or even a little bit, wouldn't there be smoke.?

^Bump^

I think some black stuff in the radiator is normal for FD.

Why don't you flush the radiator and get a stock AST cap (don't know what psi rating)? BTW, the squeal usually means the belt is a little loose.

Since you don't see white smoke being burnt off in the tail pipe and you aren't loosing coolant, your coolant seals are probably okay.

I would check the coolant hose too for blockage. Just get new hoses if they are old.

I am losing coolant, the coolant buzzer came on about 30 min after driving, right when I backed up the hill into my driveway. The coolant was coming out of the overflow tank, which would lead me to believe that it is the coolant seals. But what I don't get is why in the hell if the coolant seals are that bad and they just let that much coolant into the motor, why has there never been an ounce of smoke? I don't get it.

^Bump^

have you you tried a pressure test on the cooling system. do one check from the ast. do another from the water neck. your ast cap could be weak and not holding enough pressure. it is important you do this test. it can tell you alot and could lead to fixing your problem.otherwise we,re just guessing