Constant overheating
 

I just bought my fd about a month ago. It's not my daily so I really don't ever drive it, but when I do I notice it's constantly overheating. I did a lot of reading and found out the cooling system is horrible. But anyway, the car will overheat anytime I get on it and it will only come down to normal temp of the car comes to a stop. And when I turn the car off the temps rise. I drove to the store once and when I got back in the car the temp gauge was almost maxed out and the car wouldn't start until the temp came down some. I can't visibly see any leaks and the coolant isn't low. Are these issues unusual for the stock cooling system? The car only has a catback exhaust and fmic.
I ordered a koyo radiator and water temp gauge and looking to upgrade my intercooler setup in hopes of getting this to stop. Any ideas of why this may be happening or what other mods to be able to keep the temps normal?
Thanks

I would start with a coolant flush. The cooling system isn't horrible but it can definitely use some help.
Start here https://www.rx7club.com/3rd-generati...thread-571088/
Is the belt tension correct? (to drive the water pump)
Do the fans turn on?
Do you know when the last time the thermostat was changed? an easy test for the thermostat is to let the car warm up and touch the upper rad hose and see if its hot. If it is cool or luke warm then that could be part of the problem. If the thermostat is stuck closed or partially closed then you would over heat.

Also look at the radiator fins ect and make sure they are clear of debris and straight.
You could hold off on doing any of this, wait till your new rad comes in and do it all then. When you put your new rad in there is a product called Water Wetter that is supposed to help with heat transfer I have used it in the past I did't really notice a difference but my ambient air temps are quite low (25* C) with that in mind I will use it again :)

Good luck
Mike

It sounds like the waterpump is slipping, thermostat is stuck, or you have an obstruction in the cooling system. Two things rotaries do not tolerate is detonation and overheating. Overheat the motor one good time and you will have a coolant seal (analogous to a head gasket) let go, requiring a rebuild. In more severe cases you can warp the rotor housings. If you do not feel mechanically inclined or comfortable familiarizing yourself with this car, I strongly recommend taking it to a professional. Driving the car like that will certainly damage the motor if you haven't already not done so. A few quick things to check:

Is there sufficient coolant in the system? I only recommend the standard green coolant diluted 50/50 with distilled water.

Is the thermostat opening? Easy way to check is if the thermostat housing and radiator get warm once the car is at operating temperature.

Do the fans come on? Both fans always come on together.

Hope this helps.

And do you have an undertray?

As Ihor said, your seals may be compromised if the factory gauge goes anywhere north of horizontal. Keep an eye on the tell tale signs: white smoke, bubbles in your coolant, and overflowing overflo tank

I'm still new to rotaries and learning about them I don't really ever drive the car Bc of the issues it has now. I did check the coolant last night and it was full, I haven't checked to see if the fans are coming on or not and if the thermostat is getting stuck. I was planning on just replacing the thermostat and possibly the water pump as well, I have the koyo waiting to be put in.
Would rather bring the car into someone but only know of one place close to me as I'm on Long Island.

If the stock gauge "maxed out" the car has seriously overheated. See IRPerformance's comments above.
IMO not unusual for a streeted car with a FMIC. The steps you're taking are good ones. There are good choices for aftermarket SMICs out there, and if you feel flush and are able to do a little fabbing, VMICs.

Ok so here's what happened today. I swapped out the ast with an aluminum one and added coolant let the car run to get the air out and also to see if the fans would come on, the fans did come on but noticed it leaking from the bottom hose on the ast, adjusted the clamp and it stopped leaking. Let the car cool off and added more coolant, I had a funnel in the filler neck and filled it about a third of the way and it was bubbling like crazy and slowly started to rise, when I revved it a little bit bubbles like crazy and then it just started bubbling like crazy and coolant was overflowing out of the funnel I'm assuming at this point it was boiling. Shut the car off and added coolant out the cap on and left it as is. Never had that happen to me before
Ideas.....

Pressure test the cooling system. If you pegged the stock temp gauge, you've likely damaged a coolant seal...if it hadn't already failed.

The coolant gauge never pegged but it rose pretty high. I'm going to bring it somewhere to have a compression test done but that won't be until like next weekend

But my biggest question is bubbles when i rev the engine is def no good right

Post #9
https://www.rx7club.com/new-member-r...oblem-1032258/

Not compression test, but pressure test. You can usually rent a coolant system pressure tester for free (w/a deposit) from most chain parts stores.

Pressure test the coolant system. I use a Snapon tester at my shop but a cheaper one will do for a quick test. If you want to bring the car to me I'd be more than happy to look at it. There isn't anyone reputable in your area unfortunately. I don't recommend driving it in its currect state. If you can't arrange a tow I can set something up for you.

Okay. I may consider doing that. Having it towed to you and just having it rebuilt. I would feel more comfortable having the motor rebuilt plus I want to have it ported so this could be my reason to. Plus I don't know how many miles exactly are on this "rebuilt motor".
Would also have a bunch of other things done at that time also.

Definitely sounds like bad coolant seals. and rebuild time. IR Performance will take good care of you :)

Actually the cooling system cools the car just fine for street applications. The real problem with the stock sytem is:

1) the stock radiator has plastic end tanks that eventually give out... But it cools just fine.
2) The stock AST also gets brittle and tends to give out as well (though much sooner than the radiators)

Not the issues that you are having. For the most part these cars stay rock solid at the center of the temp gauge (track applications are a whole different animal). Note that it doesn't mean there is no change in temperature. The stock gauge is not linear and therefore stays pegged at the center for a wide range of temperatures. That is why it is a cause to panic when the damn needle moves past center. Only once in all of the years that I've had my car I've actually seen that temp gauge move that it wasn't due to a problem. It was a 105F day in the city and I was going home through the backside of LA (it gets hotter back there in the country side) anyway all of the sudden I was going through a valley when my temp gauge moved to the 3/4 mark. eek! I shut off my AC, rolled the windows down and turned on the heater. That fixed it. The guage climbed back down to center. Once I passed that valley I rolled up the windows, turned on the AC and continued on my merry way for the next 80 miles without a problem. What I figured was that the ambient temperature in region must have been quite high and my fans could not get the heat out fast enough.

As you already know the FMIC's are not the best for radiator cooling. I saw your set up and have some suggestions:

1) radiator is still left in the stock location so that can be a contributor
2) like someone else asked if the under tray still present (that is a huge contributor in cooling)


Edit-
Yeah that does not sound good at all. Exhaust gasses passing into your coolant system can cause that. :(

Glad you are having it towed and not trying to drive it to IR Performance. Sorry to hear about your problems. It's a painful and expensive learning curve with the cars sometimes but when they are running good they are a lot of fun.