Getting hot at 65mph
 

Had turbo in since Thursday. Been getting pretty hot, like 230-240 hot and I pull over... usually drops down to normal in a few seconds, sometimes before I even come to a stop. This is in the morning, 50* outside, not boosting, cruising at 65 mph... another mile down the road I get on the highway and go 75. coolant temp 205-215 max at this speed. I didn't have the belly pan on, left it off so I can check for leaks (read about this being a possible issue). Tried burping the coolant to no avail.

Today I put the belly pan on, trimmed the sides to fit the IC pipes, sealed off the top of the top of the radiator (ran out of tape, will do more later), and put on the aluminum plate from BEGi. Also installed a 180* thermostat and a bottle of water wetter just for kicks. Took a test ride, same temp now at night, if not warmer, same route I take to work and normally overheat, and only hit 200 maybe twice, both after a hard 3 gear WOT run on the highway. Other than that, I was at 190 +/- 5 degrees while cruising 65 all the way up to 90.

If this doesn't completely solve the problem, gonna have to do a reroute. Which to me seems odd because this was happening not even in boost... however, I will do the reroute before I hit the track again.

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You have a problem. It's not gonna be solved by a re-route. Possibly blown gasket

Well that's not what I expected to hear... i have a block test kit at work I can check for exhaust gases in the cooling system to verify. I don't see any type of bubbling of the coolant with the rad cap off or anything like that. And I've only ever been over 215* one time before which was my fault because the temp sensor wiring was messed up, not reading actual temp and not turning the fans on when I was at idle. And a compression check a few weeks ago had me over 200psi in each cylinder...

Don't think the belly pan was the culprit? I've seen lots of references to that playing a huge role in highway temp control...

Going to work tomorrow morning I will know for sure. It has happened literally less than 100 yards of each instance on the same road I take every day, and on the way home . Very repeatable. If it doesn't do it tomorrow, I'm probably ok...

Maybe I'm wrong. But a reroute is only really needed when beating on the car. If you're running way hot during normal driving, then there's an issue.

You said you replaced the belly pan and still running hot, right? Cause otherwise yes I'd say the pan was the culprit.

I completely agree.

And no, I put the pan back on and the rest of the list I stated, this evening. And after the test drive, all is well. The only variable was that the engine didn't go from cold (65* ect) to full hot, it was already warm from burping the coolant after thermostat install.

Just wanted to put this put there cuz I know there are plenty of other newbs like me that could use some ideas without having to dig back 6 years of threads lol...

rule #1 - you never, ever, leave the belly pan off. Even when n/a, you'll likely overheat

Welllll I didn't get that memo...

I installed the IC a few weeks ago and left the pan off since and had no problems, fortunately. I had no idea it would have such am impact till I did some research earlier today which prompted me to reinstall it...

There is one piece that I can't reinstall because of the IC tho. It goes from the front of the belly pan to the mouth opening. I tried widdling it down to hardly anything and it just can't fit under the IC. Big deal? Or go getting some sheet of plastic and create my own?

either works. unless you have some mammoth ic that most of us don't run, you should be able to cut it to fit too

Bah. I've done track days making 250rwhp in 70F temps w/o a belly pan and not had it overheat. (reroute, but an ancient FM radiator with basically zero ducting)

If the car is overheating when cruising down the freeway at 50F ambient then something is seriously wrong, belly pan or not. Head gasket, broken thermostat, clogged radiator, something like that.

--Ian

I agree with Ian. It might just be the whiskey taking, but maybe you have a bunch of air trapped in the cooling system? You said you "Tried burping the coolant to no avail" what exactly does that mean? Did you get bubbles or not?

Tried burping 2 nights ago after the first incident and got no bubbles. Burped after putting the thermostat in and it definitely let a lot of air out, but that's obviously because I opened the system.

Ian, I don't see any other signs of a blown HG... The 195* tstat I took out didn't appear to have any physical issue, not sure if it was possibly sticking or not tho. The radiator also isn't that old, always had clean coolant in it, and i have normal temps when I check the temps on the hoses. Nothing abnormal like a boiling hot upper hose and ice cold lower or anything lIke that.

The connection from the radiator to the bumper mouth is most important. All of the air entering the bumper mouth must go through the radiator or you're going to have a bad day.

And if your intercooler is placed so that all or even most of the air entering the bumper mouth must go through it on its way to the radiator, you are going to have a bad day. Air getting to the radiator is 10 times more important that air getting through the intercooler. Move the intercooler back from the opening and let the air go around or over it to the radiator.

Six, the IC mounts to the tow hook bolts. No way to really adjust it. Good news however, I just drove my normal route to work. Went from cold to 204, right at the same spot I normally reach max temp, and then it dropped very rapidly down to 187, and continued to stay between 190 and 197 all the way to work, even boosting.

I still want to fab up something to close the gap under the IC tho, and seal off the sides of the radiator.

I guess on a side note, this car always ran warm. 205 ish while NA all day long, maybe even a little warmer on track days during the summer.

This is what it looks like. IC blocks most of the mouth opening, and hangs low. The piece I am missing can't fit under the IC and up to the mouth to fasten to the tabs on the opening. I'll just have to get creative that's all.

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I run my car without an under tray or any ducting, just a koyo radiator and never had a problem. Find your problem, remove your thermostat, turn your heater on and see if it helps. your heater should keep the car cool even if the radiator is not doing a great job. my to cents

Friday and Saturday when it was getting hot, the heater was on both times...

You want to buy and then use it to burp your coolant. Install the funnel onto the radiator and then keep water in the funnel. Run the car until the stock fans turn on and back off 3 times. Install the radiator cap, then take it for a drive.

My buddy has one of those, might give it a shot.

I was using a home brew version of that last night after I put the thermostat in and it worked well. Got a LOT of air out.

I second the burping funnel. I used the funnel and raised the front end WAY into the air and I was surprised how much air came out in one big burp.

Do you have head studs?

Almost sounds like its lifting the head. Have you tried using one of those "Block Tester" kits?

Chi, I has the front end about 18" off the ground.

Boogie, this was happening not boosting at all. None. From a cold start up all the way up to that temp. And I'm only running 9psi as well, if that matters. It never got hot when in boost. Once it got hot and I pulled over and cooled off, I could drive it the rest of the 15 miles, with WOT pulls, and not get over 210*. It was like the tstat was sticking a little bit at first but once it opened and I slowed down, the cooling system caught up and everything was fine after that. Very odd.

I do have a block tester with me at work I wanna try just to see.

I think I'm all good now. I left work, warmed up to 198 and dropped down to 187 and stayed around 190 all the way home while driving like an ass. Raced a 240 from a roll and smoked him, and then got my ass handed to me by a SV1000 from a light.


Side note, does anyone know why my charge light comes on when I hit the rev limiter? I've tried adjusting the settings in the alternator options to make it less sensitive, but haven't been able to figure out how to make it stop doin that.

Since you say it gets hot quickly and then suddenly drops, you should check that the little bleed nipple in the thermostat housing is open. It tends to clog on older cars and causes this exact symptom. Basically, when Mazda moved the thermostat to the "front," they created a dead zone in the coolant that takes a long time to warmup, which means the t'stat will open really late. That nipple is there to eliminate the dead zone, but needs to be free of crud.

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i looked in there when i was scraping off the old gasket last night, did not see any obstructions in there.

How many miles on the alternator? When the slip rings start to wear out, the first symptom is that it can't maintain current at higher RPMs, so the voltage sags. Mine would hit about 10.5 volts when merging onto the freeway at night -- you could see the headlights get dimmer.

--Ian

no idea. it was fine when i had the OE ecu. I don't have any dimming of the lights or anything either.

Collect a datalog and check for voltage drop. Then you'll know if it's charging or not at high rpm. Take it from there...