My damn car has been running hot again.

It did this about a 2 weeks ago and spit out lots of coolant because the thermostat was stuck closed so I replaced it. It couldn't have stuck again????????? Also I flushed the radiator and added a little water wetter. It's been running fine untill after school today.

So I was just wondering if there's anyway to tell if the radiators bad. maybe some tests, or just looking at it??? I don't want to replace it if it won't do anything.

also, for testing if the fan is bad (the freewheeling)
, should it continuously spin after you hand spin it?
mine spins a couple times around after I spin it. is it bad????

 

I'm sure there's some kind of flow test you could run, but honestly, the car is over 10 years old, with 10 years of crud building up in that radiator. I'd replace it.

 

i think it may be the fan clutch, especially if it makes full revolutions when you hand spin it when it's hot. also check your water pump and if it's a turbo, the vacume lines that come off the valve that controls the waste gate. thats what was wrong with mine. you did use a mazda thermostat right?

 

Clutch fans rarely go out on rx7s so it could be it but probally not i would look into a super flush by prestone and if that doesnt help go with clutch fan first then look into a new radiator

 

i would drain all of that old crap outta your radiator man. thats what im doing to mine today. sounds like we are all having overheating problems. i know that should help a bit. is your fan shroud still there?

 

If the fan spins as freely as you suggest it's toast. That would be enough to cause a problem. However if the car is moving say at highway speeds and it's still running hot then it might be something else. I would do a flush of the rad and check the timing as well.

 

Yeah, if you didn't use a Mazda thermostat, GET ONE. I've seen parts store thermostats work good for a month then start overheating again - way not worth the hassle.

Dale

 

Also, check your belt tension. I had a problem a while back where my fan clutch was bad (overheating while stationary) as well as loose belts (overheating on the highway) It was a PITA to diagnose.

If the fan clutch goes freewheeling, it's toast. Sometimes you have to rotate it quite a bit before it starts to spin free, so spin it for a while.

Also, I agree with the above about using an OEM thermostat. Some (but not all) replacement thermostats can cause problems.

I doubt your rad is clogged. They generally fail by leaking, not clogging.

 

Rads often fail by clogging, mostly because the DPOs (Dumb Previous Owner) didn't change the coolant often.

Easy way to tell if it's clogged is if the thermostat has been replaced, and the car overheats at both highway speeds and low speed driving. The fan is not used in high speed driving, so no matter what conditon it is in it won't effect high speed airflow.

 

well what are the parts of the cooling system?

pump, radiator, themostan, jackets, hoses.

if the pump is bad there is no water flow and she will overheat almsot immediately. doesn;t sound like your problem

if it is the radiator it is prolly from clogging. you should try flushing it again. or replace it. if nothign else it will be a really good upgrade to hopefully a all aluminum raddy

if it is the thermostat replace ti with a mazda stat.

if it is the jackets you re screwed.

if it is the hoses you would see them spewing and you would replace them


my bet is on either a slowly dying water pump (least possible), clogged radiator, or stat if it is not a mazda unit

 

thanks for the help.

It was a bad fan. I replaced it with the fan from my other rx7 (its just waiting for me to rebuild) and I'll replace that with an electric.

today I had no problems though !!! It ran right at 1/4 up the temp gauge!!!! I'm sooooo happy I don't have to spend more money!!! for now anyway.

 

dont forget about the hoses how the lower hose has the spring in there, if it goes out, then the hose will collapse....just a thought, doesnt hurt to test it, its free. lol

 

Remove the fan and fan shroud - get the engine up to temp and shut it off.&nbsp CAREFULLY, run your hand over the radiator core to see if it's EVEN heat.&nbsp Be careful, you could burn yourself!&nbsp A badly clogged rad would have cool spots that would allow you to rest your hand on the rad core.


-Ted