alright so heres the problem everytime i drive my car with a load on it, it would overheat after about 15 mins of driving, i check the compression and pressure tested the car and everything checks out, replaced hoses and t stat(yes oem) fan is not slipping, the only weird symptom i got was when i put a presure tester on the car and started it the pressure build up pretty quick, i haven't replaced the radiator because the heat distribution on it seems to be pretty even...please help could it be my seals leaking outwards underload? i'm thinking of just getting a cheap radiator or rodding it out first, (the car doesn't boilover with the heater on but does get hot)

 

Replace your thermostat with an OEM thermostat,Good coolant 50/50 mix...also if you can give your rad and Heater core a Good flushing out.Without a properly operating cooling system,the engine is going to Likely be in Trouble..It sounds Like a STUCK thermostat to me,though.so I'd Try what I typed above and Good luck to you.OH..also replace your Fan belt.Just noticed.."under load"..that could be slipping too.

 

Heat distribution may seem even, but that doesn't mean the rods aren't restricted from corrosion. Be sure to check the clutch fan, belt tension and water pump. Overheating a rotary is a quick death.

 

i did overheat the car once driving it after i replaced all my hoses it boil over and i shut off the engine asap, but still compression is good and no weird smokes, plugs are still dry

 

see im having same problem, but i have replaced my radiator and im still having that exact same problem, but i installed an T-Stat from autozone which may be prob? but its frustrating as hell i feel ya bro.

 

I may have an explanation, at least for schctrg.

I got my engine rebuilt by a rotary engine specialist here in Ohio, Ken Carswell of Rotary Connection. He told me that my car is missing a part that goes between the lower part of the front bumper and the underside of the radiator. This piece is meant to direct cold air from the outside that travels through the grille into the radiator. Ken said that without this piece, I am likely to have problems with overheating in the summer. So, you may want to check to see if you have something like this on your car. If not, it's probably a problem that'll require a solution soon.

I am looking into purchasing such a piece or making something myself. I'll let you know what I come up with.

 

Your talking about the shroud that goes underneath the car that directs air into the radiator. If thats in place than I would look at how old the waterpump is and look for a bad impeler.

 

Whoa, whoa. schctrg, try the things listed in the FAQ first. Especially the OEM thermostat. If you want to check if that's the problem, just remove the thermostat and run without one for a little bit. If that solves the problem, leave the thermostat out and don't do any unnecessary driving until you get the OEM thermostat (I wouldn't worry too much about driving without a t-stat, but maybe someone else will say different). And, as always, don't do any hard driving unless your car is warmed up. www.rx7.com carries thermostats, as should any Mazda dealer.

Everybody hold off on the crazy and expensive suggestions until he does the basic stuff. schctrg: once you try the things in the FAQ, post again. That piece of plastic under the radiator is nice for the cooling system, but probably not major enough to move the temperature more than a little bit.

Here are a couple other things that are easy to check after you've done that:
Fan clutch: the fan should be difficult, but not impossible to turn when the car is off. If it's loose you may have a bad fan clutch.
belts: Push on the center of belts with your finger. A Haynes manual will tell you exactly where to push and how much they're supposed to give. But generally ~1/2" is good. Otherwise they must be tightened. I wouldn't go spending money on fan belts merely out of worry. Especially if you already change your worn out belts like you're supposed to.
flow: Feel the radiator, belts, etc. If it's a lot hotter in one spot than another, then coolant isn't flowing. For example, if only one side of your thermostat is hot, then your thermostat is stuck closed.

 

i aready did the T stat YES OEM, and no i'm not missing the bottom shroud, water pump isn't leaking or weeping.. theres a lot of presure in the upperhose anyways, so the t stat is opening

 

argh so out of ideas..

 

Have you done the bubble test?

http://www.rotaryresurrection.com/2n...l_failure.html

It is possible to have good compression yet still have a coolant seal failure. Your statement that 'the only weird symptom i got was when i put a presure tester on the car and started it the pressure build up pretty quick' sounds like a cooling seal failure.

Don't spend a dime until you do this free test. If the coolant seals are bad, nothing else will help.

Good Luck!

 

Have any of you with heating problems checked the fan clutch yet?

At operating temperatures and engine running, make sure the fan is pulling air. I had this happen to an FC once, and I was able to stop the fan with my finger while the car was running. Thats how shot that damn thing was.

Rat

 

The viscious clutch on the fans are known to wear out,like J-Rat stated.But I would really like to know how you perform a coolant pressure test,why did ya start the car? just pressurize the cooling system to 14lbs and let it sit awhile and if the pressure drops look for a leak externaly on the outside of engine,If there arent any,take the tester off put the cap back on and start it up and see if it smokes,know it's kind of hard to tell here in cincy cause it's cold.internal seal failures are usually on the inner seal if thats the case with the engine running compression pressure outweighs cooling system pressures and coolant isn't burnt its pusshed out of coolant passages by combustion gasses ie the rapid building of pressure with eng running,or get it warm/hot and pull resivior cap off with hose in resivior bottle and look for bubles and smell for exaust gasses.I guess your tester is diff than mine,I pump mine up and let it set.hope its not that inner coolant seal,hope its the fan clutch..lol and check out jackhild59s system test

 

the reason why i left the pressure tester on and started the car was to see if the gases are pushing outwards, because its holding presure and my plugs are dry not to mention fan is working.. so i guess i could just leave the cap on and see if any gasses are flowing into the bottle. i do not see any smokes out of the exaust, nor smell burnt coolant..

 

I see you checked all the cooling issues gut you didn't say anything about the O.M.P. If thats leaking or not working roperly It could be the cause. Check your lines first You should not see any oil on the front of the engine at all. If that aint it then all I can say is flush the cooling system real good to see what comes out.

 

If you have a very high mileage original engine your coolant passages might be clogged. (If that is even possible).

Run some sort of cleaner through the system as a last resort maybe?

 

well my oil pressure is good no major leaks aside from that crummy seal from the pan, i just replaced the o rings and my pressure at idle is sitting about 30-35 psi

 

i have 137k

 

With the car on and the cap(s) open can you tell if the coolant is flowing?

Try and take off the radiator and spray water through it both directions and see if rust comes out. Also see if you can do this with your rad hoses.

 

Thats what I thought(bout the pressure tester)just curious,so is your radiator clean? scale build up can be a killer. never thought about the omp system.did you try the resivior thing?was it blowing bubles?and how clean is the radiator itself like the fins where the air flows through?

 

i've doen the test before.. but i'll pull the fuse and crank it in a lil bit to see if theres any bubbles, but i'm not sure if my radiator is dirty or not i mean its the original from 137k and that car has sat for months before i drove it around again... it sat in 05 before i drove it all year in 06, now its sitting in my garage and i have a new M6 but i miss my 7

 

any other idea guys?

 

i just past the bubble test of cranking with no egi....