Im looking at an 86 N/A RX-7...the rad visibly is leaking, it bubbles/leaks from the top passenger side, but Im concerned that it may be more than a faulty rad. It stays down on the gauge fine until U start driving it hard. I have no intentions of droppin cash on a car with an engine that needs a re-build. He checked the water pump, hoses, thermostat is new...is the rad crack enough to do this or is there a coolant seal blown?...Any ideas?, thx for any help you guys can give.

 

sounds like a coolant seal caused by the car overheating from the crack in the rad you could pick up the car cheap then do a coolant seal temp fix as described on the rotary resurrection tech page the temp fix is said to last quite a while i heard about people driving their car for six month's to a year when they have done this fix
to be honest it all depends on how much you are getting the car for
to check the coolant seal simply take out the egi fuse in the main fuse box under the hood make sure the rad is full (bleed all the air out of it) leave the cap off and crank the engine over a bit if it looses mass amount of water it's the coolant seal

 

pressureize the coolant system with air and listen in the exhaust/intake manifolds for air leaks. do this with the car cold.

 

Pop off the radiator cap and crank the engine.
If you see colant being pushed out, the seals are bad.

 

Thx for the help, guys...Im gonna go look at it again tomm after I get off work, Im droppin 800 dollars on it...but for the job I have, I might as well be buying a new car LoL...If it IS the coolant seal, I dont really wanna tear it apart and rebuild it, I lack the money.
In either case, I hope its just the damn rad, I can find one of those for 45 bucks around here. I'll let U guys know what happened

 

Welp, I went and checked it out, it wasnt SHOOTING water from the rad, but it was damn sure building pressure awful fast. I wouldnt call it a fountain, but without using our hands to make pressure build it was bubbling out. It has no loss in power or anything to make think its losing compression,othing that would make me think coolant was getting anywhere it shouldnt. Maybe there is another explination (possibly cheaper?) that could make this thing overheat? At idle or a-to-b driving nothing happens, it gets hot, but not Overhheating hot...it doesnt do that til U try an drive it like Ur at Le Mans...maybe this is a good sign?

 

What does the inside of the radiator look like? I had an 88 that got hot while driving hard but was caused by a radiator with a lot of corosion inside of it. The corosion was causing the heat to not be pulled out of the collent very efficiently. I put a new radiator in it and now the temp never goes above 1/3 on the gauge. Just a thought you may consider.

 

i have a question...what if there is no thermostat and u crank it won't water shoot shoot out even if the seals are good or bad?

because on my car i had the thermostat on and cranked it nothing shot out and when i took off my themostat it threw it out..yet the rx7 place i took it to said my coolant seal is going..yet my car doesn't eat coolant unless it starts to ge 3/4ths of the way.

i also tried block weld and it didn't help for some reason...are u suppose to run block weld with a thermostat or with one off??

 

No