Sudox_E

First, here's another thread I recently posted:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/running-hot-after-turbo-install-502023/

To sum it up, I've been running hot after my turbo install, but I've also notcied very high pressures in the coolant system. This was enough to cause coolant to go through the stock 13lb radiator cap, rip open a older radiator hose I hadnt replaced yet, and blow the gasket where the thermostat is.

My temps were past 3/4, but not into the red hot area

Basically everything is new on the car. Water pump, radiator, all of the hoses(now)

I saw in a previous post someone mentioning that there is the possiblity that exhaust gases could enter the coolant system through a bad water seal, and since this is the first time I have run the car on this engne rebuild for an extended period, should I be looking at the possibilty of a faulty rebuild, and that this is what is causing the extremely high coolant pressures? What exactly should I look for to find out if this is the case? I'll be working on the car tomorrow morning, and wanted some feedback before I started.

Also! Could 3/4 of the way on the temp guage or so be enough to cause such high pressures? I'm also thinking that my intercooler install did away with the stock radiator supports, and my custom job doesnt divert air towards to radiator the best. Maybe THIS is it? Sorry about the long-winded post. Thanks for the help

LongDuck

I read your other thread and was thinking all along that you had lost an engine seal and were leaking compression gases into the coolant system, but this would result in radiator overpressure and cap venting even with a dead-cold engine. Your description of overheating at 3/4 temp gauge isn't a good sign, either.

What's with your turbo install is that the engine seals aren't able to contain the additional intake pressure and are allowing part of the intake charge to make it past the seals into your coolant system. How much boost are you running? How many miles on this rebuild, and was it rebuilt to be a Turbo motor, or did you just take a standard 12a and throw a turbo on it?

(Turbo engines have lower compression rotors to help compensate for the additional pressurization that they'll experience under boost.)

In short, you need to fix your overheating problem really quickly or you're going to have even bigger problems down the road. Start there, and then get into what's causing the additional coolant pressure - the cap will allow venting at anything over about 10-12psi, so it's not a lot of pressure in the coolant to cause purging. Either way, that cap pressure won't be appreciably raised by the overheating - it just causes the purge to happen earlier, not increase pressure above 10-12psi that it normally runs. HTH,

Sudox_E

This motor is a freshly rebuilt and streetported 12a. I'm currently running about 8psi of boost. The thing I'm wondering, is that several other people are running similar boost levels on 12a's, without having this problem.

Tomorrow morning, I'm gonna first start the car cold, and check to see if there's overpressuring or bubbles in the radiator. After that, I'll drive around without boosting till the car heats up, check for overpressuring, and then drive around while boosting, and check for overpressuring again. At least if it happens while boosting and not boosting, I'll know it's not a turbo-related problem. Honestly, I hope youre wrong, and this isnt a problem with boost leaking past seals or anything, then I would just have a serious problem with my entire setup.

Anyways, is there anything else I should look for to check if it's a problem with the water seals?