I have a 91 conv rx7 and for the past few months it overheats quickly when driving slow speeds. It can sit at idle with the ac on and the needle will never move. Whats confusing me is that the overheating is not consistant. Today I drove for 15 minutes with the ac on and nothing happend. I replaced the thermostat a few weeks ago and am hoping for some advice. Anyone ran into this issue before?

 

Did you replace it with an OEM thermostat? If you used something like a Stant brand then thats most likely your problem.

 

Autozone for me...I am sure they probably got the least expensive one available. Is there a particular thermostat that is better for the rx7?

Thanks for your reply! A simple thermostat would be an easy fix.

 

Sounds like a sticky thermostat or air bubble in the system.

Only Mazda OEM thermostats should be used. For some reason, all aftermarket thermostats for the RX-7 seem to suck.

 

The OEM thermostat is like $30 from mazda, so go order one and it will most likely fix your problem. Also while you are doing the thermostat, bleed the system properly.

 

ive got the same year and the same thing happened to me turned out it was my ac belt i had to cut it now its fine that could be the problem when u do drive dont have the ac full blast

 

thermostat tomorrow. I actually drove the car twice today and no overheating. Definately looks to be a sticky stat. I'm having a seperate issue with the car bogging down at high rpm...basically when i gun it. The engine light is coming on and i cant get full power. I'm still learning but it would seem to be some kind of mixture problem or maybe my cat conv. Fuel pump maybe?? Ill post this latest development on a new thread and hope for insight.

I wish I would of been using this forum a long time ago.

Thanks!

--Marc

 

This is handy for getting your air bubbles out:
http://www.sjdiscounttools.com/lis22150.html
Lisle 22150 - Spill-free radiator funnel kit

It's basically a glorified funnel. It is large and makes a good seal. So you fill it up with a quart of coolant, start your engine and wait for the air to stop bubbling out. Easy. A search through the forums will show some good comments about it. I got one myself. For now you can try the methods in the FAQ or repeatedly squeezing your hoses while the radiator cap is off and then adding coolant.

I'd also check your fan clutch. It should give some resistance when you try to turn the fan, as if it were full of taffy. It shouldn't be stuck or loose. A bad fan clutch will cause problems at a stop and slow speeds. But given that the problem comes and goes, I'd blame the thermostat or air bubbles. Probably the thermostat like what you figured.

 

Sounds like your oil metering pump may be bad. If it is, the ecu will go into limp mode when you hit 1/2 throttle, or maybe 3/4 throttle, i forget. Either way, you're going into limp mode, check to see what codes your ecu is throwing. 1300cc.com has a writeup about how to check codes.