my 90 tII is still running hot. i just replaced the water pump, and put in a mazda brand thermostat. i cleaned all the crap out of the radiator fins. still, when i drive it for more than 15 min i can hear boiling in the radiator and overflow tank even though the temp guage stays in the middle. yesterday and today it really started to overheat, with the needle climbing up to hot. i of course immediately stopped and turned of, let it cool and put a gallon of water i had with me into it and drove the same distance home and the guage stayed in the middle, although it was boiling again when i stopped. please help, this is driving me insane

 

How's the radiator cap? Do you have your underpan in place? Di you bleed the system when you filled it up? Have you flushed the system with some type of radiator flush not just water?

 

radiator cap is brand new. i did bleed the system but the underpan is not on yet and i didn't use a radiator flush. could that be the problem?

 

I've been having overheating problems as well, and I've read that the radiator flush is pretty important. I can't find the page that I read it, I thought it was RETed's page, but I couldn't find it. I have it bookmarked at home. I'll keep looking......

**EDIT**

It was on RETed's page.


http://fc3s-pro.com/TECH/MODS/COOL/cooling.htm

 

I'd like to get RETed's comments on his page. Especially #4:

"Start the car and run till the cooling system boils over. Yes, you heard that right - till you see steam coming out of the overflow bottle. Stay calm and do not get alarmed when the temperature gauge hits "H" and the low coolant light/buzzer goes off. As soon as you gauge hits "H", calmly drive back home and kill the engine. "

After all I've read and heard about how overheating a rotary = instant death, why would anyone want to intentionally boil over the cooling system?

JB

 

That scares the **** out of me, too.

 

If you have a leak in the system it will not pressurize. And the pressurization is what increases the boiling point.

James

 

i know i don't have a leak because when it is blowing steam out of the overflow hose and i pinch it shut, the hissing sound stops. if i had a leak the steam would hiss out of that as well. anyhow, i put the plastic undertray back on and that has helped somewhat. the guage isn't going up all the way to hot, but i'm still boiling in the radiator. i get paid today so i'm going to have it professionally flushed. maybe this is related: last night i noticed that when i go over max boost instead of the fcd stopping the guage at around 38 mmhg, it goes to it then falls a little bit and just goes up and down and the car hesitates. not sure if this is related

 

just read reteds page, i think this is one of the few things i'd rather pay someone else to do, instead of risking that. especially the drive home after it hits hot part. when my needle hits the bottom hot line, the car goes off. period.

 

Flush the radiator.

If that doesnt work, buy a new one.

 

Does your heater work?? It could be that the heater core is stopped up... I had to bypass my heater core ...Do you have the correct mixture of Antifreeze to water..Not enough Antifreeze can sometimes cause a car to run hot...

 

You need an aftermarket water temp. gauge! You are trouble shooting this problem with blinders on. You have no idea what the temps actually are.

Also, do not forget the block drain.

James

 

First do a proper flush. If that doesn't solve the problem, you should get a block check done. This tests for hydrocarbons in the coolant to see if there is a leak between the combustion chambers and coolant system (usu bad water o-rings). Combustion gases in the coolant may be what is escaping into your overflow tank. This also may be the cause of weird boost patterns since intake pressure may be blowing into the coolant system.

 

No it couldn't.
I blocked mine off and converted to an electric heater core. No increase in temps via my aftermarket gauge.

Not enough antifreeze... also incorrect. Ideally, 30/70 antifreeze/coolant ratio is ideal, but not necessary for good cooling. Race cars run straight water and cool fine.

 

How about first: diagnose the problem, then fix the problem.
You wouldn't just replace the airpump b/c you failed emissions, would you?
Check for hotspots on the rad by running the car and then carefully running your hand over the front surface. cooler spots are clogs in the rad.

For a good diagnosis, I need more info however. Under what conditions does the overheating occur? What relevant mods?

 

One thing that nobody has asked/confirmed, do you have the stock fan shroud in place? The cooling efficiency of the belt driven fan (and the fan clutch) improve with those pieces in place.

With my car, I put a Fluidyne in, and could run in the 90 degree weather without the shroud, with everything on. After I repaired the broken shroud and re-installed it I noticed the temp gauge just a bit lower-- not much, but if your stock radiator isn't cooling as efficiently as it was when new, these two parts could make a difference.

Regarding the coolant/water ratio, I've always used 50/50 here in Wisconsin. Going to 70/30 really benefits the cold weather protection more than hot weather-- about a 50 deg drop on the cold, but only a 11 deg increase on the hot. Personally, I'd shoot for 50/50, and error higher on the coolant. The 1989 factory service manual suggests 65/35.

Greg O.

 

Im haveing temp probs too. I flushed the system but didnt drian the block I dont knowwhere the drain is on it !!!! I have a mazda stat and cap . Black magic elec fan . 50/50 mix and a mechanical gauge on it. With the ac on it runs 240 way too hot I think !!!! But with it off its about 210. still too hot for me. It a 87 GXL I dont lose any fluid and It dont boil over and no white smoke just is running very very hot . only thing not replaced is stock pump and rad .

 

I recently had the same problem of over heating! I bought my '88 gxl about about 2 months ago and the first month it ran ok, but the second month came around it over heated really bad, i had the radiator flushed, along with the usual new coolant. After a couple of weeks it still ran very hot..... then i finally took it to a radiator shop and they cleaned out the radiator, all the hoses and the engine block. I found out my problem was the radiator, it was cloged, as well as the engine blocks cooling system. When they had finished, my car ran very nicely it doesn't even reach the half way mark, and thats how i like it to run b/c i like to drive my car hard.

 

how much they charge you to do all that ?

 

It's shown in this pic from the FSM, it's item #10. It's a ***** to get to, but it's important the block is completely flushed.

 

I just went out and pulled that damn thing out let it drain and pulled the plug from the bottomof the rad drained all of it too. Then I put in 2 bottles of super flush to clean that damn thing it says run it for 6 hours . When that is done Im gona put on a new water pump and fill her up with prestone 50/50 and hope that works Im moving to MD august 6th and its a hell of alot hotter there then here in Michigan.

 

I had the same problem! I took out all the a\c ****! the condenser block so much air, with a bottle of water wetter(redline) and new coolent my TII runs a tad under the half,sitting in rush hour traffic with an electric fan

 

My car without the condensor and running a permacool stays right above the C. I love it!

 

Thanks for all the responses. I just figuered it out last night. I was driving the car and it was not accelerating properly, felt like i didn't have a turbo, even though the boost guage suggested that the turbo was working properly. I was about 2 mins from home so i drove back and oppened the hood to discover my turbo was glowing bright orange. I'm about to go and flush everything with the chemical. Hopefully the turbo survived the incident.

 

well, they wanted 150 bucks to flush it so i guess i'm gonna have to do it myself. i'm gonna try reted's procedure but not let it get more than 3/4 hot. hopefully i won't destroy anything. and the block drain plug isn't that hard to get to. just go in from the top with a box-end wrench then use your fingers when it's loose.