86 RX7 overheating, new owner, needs opinions!!!!

[KFunk1989]

This is my first experience with rotaries. I recently purchased an 86 RX7 from a guy who had been fiddling with it for the last few years, where it had been sitting in his shed. It has an overheating problem, and after getting the coolant flushed and thermostat replaced, it overheats even faster than when I bought it. After letting it idle for around 5 to 10 minutes, I drove it around the block and when I got back home, the temp gauge was at the top and I could hear a slight bubbling in the engine, and some coolant had backed up into the overflow resivour. Im thinking that I might need to replace the radiator, the water pump, or both. Any suggestions? Should I take these steps, or is my engine totally shot?

Thanks.

 

[pw~mp5]

My guess would be the water pump or a problem with the new thermostat. You can test the radiator by removing the upper and lower hoses and running water through the radiator with a garden hose.

 

[lil_red_wagon]

as long as you aren't burning coolant and water is circulating, you shouldn't need a new motor. I would check the radiator and the lines going to the heater core. also, check for leaks in all lines including the lines on the back of the throttle body. our rx7s are prone to thermal issues. the problem should be somewhere in there though.

 

[Mazmart]

Have a professional pressure test your cooling system. This will ensure that the integrity of sealing is sound. They will and should test your cap/s as well. If you have a bad cap or a cap of lower than spec rating it will boil your water early, which leads to bubbling into the overflow. This car is prone to air pockets in the cooling system when filling; be sure that the system was/is bled properly. The air can work itself out through heat cycles but it can cause lack of flow in the mean time and result in a less than optimum level in the system as well.

I hope that helps,

Paul.

 

[KFunk1989]

Thanks for the advice everyone, I'm taking it in to a local shop on Friday to see if they can get to the bottom of whats going on.

 

[Signal 2]

as long as you aren't burning coolant and water is circulating, you shouldn't need a new motor.

I agree with the pressure test and don't want to be an alarmist, but this isn't necessarily so. You don't have to be burning coolant to have a failed coolant seal.
It does sound like the coolant system is leaking somewhere. The overflow bottle may be overflowing because he's loosing vacuum during cool down. Coolant keeps going in but isn't drawn back out. If the pressure test doesn't reveal a bad cap or hose...there are no outward signs of leakage except at the overflow I'd move on for test of the coolant for hydrocarbons. Since you have fresh coolant it should be negative. You might also check the exhaust within a minute or two of cold start up for the appearance of steam or of coolant. The exhaust may also smell faintly sweet.