AC causing overheating???

[nickel and dimed]

Hey

I just got my car back form the shop about a month ago and it had a full rebuild will all new bearings, resufaced block, rebuilt head, hks MHG, arps @ 80ft/lbs, three new pistons, honed cylinders, new rings and all that fin stuff. I have about 4000 kms on it and before I got it rebuilt I got a new water pump put on so that was about 6000kms ago.

Anyways onto the problem. Driving on the highway at about 125ish with AC the temp will start to rise. Once I turn it off, it goes back down. Also when I let my foot get carried away and go past the 240km mark..... the temp rises as well. The alternator is whining so I think that needs to be replaced and apparently the tensioner pulley for the AC needs to be replaced.

Just wondering what it could be. I am running stock temp gauge but I also have amn EGT with probe just behing the 02 sensor and it is running 1200F when cruising at 125-130. and when the car is going 240km the temp jumps to 1400F (5000 rpm) but then drops once you let off.

Mods are ARPs @ 80, MHG, Cooleze DP and Blizt Nur spec.

Any comment or suggestions would be very much apprieciated

 

[Bishop92t]

AC will put additional heat into your system, but it won't cause overheating by itself. Something else has to be wrong. Check your radiator for corrosion, check the front of the radiator for leaf and other garbage blockage, change your thermostat, check your fan clutch. Are you losing any coolant (make sure you check via radiator cap NOT overflow)?

 

[jdub]

Yep...all of the above Your EGT's look normal for the speeds.

If your radiator is FUBAR, consider getting a larger volume one. The CSF is very good...especially for the $$$ and it's a direct fit. If you have an auto tranny though, you will have to get a tranny cooler.

 

[mkIIIman089]

AC will put additional heat into your system, but it won't cause overheating by itself. Something else has to be wrong. Check your radiator for corrosion, check the front of the radiator for leaf and other garbage blockage, change your thermostat, check your fan clutch. Are you losing any coolant (make sure you check via radiator cap NOT overflow)?

Couldn't have said it better myself. Just to reinforce checking via radiator cap not the overflow: When I was at the USGP over the weekend, one of the ISC valve hoses developed at pinhole leak, and it would suck in the overflow but never totally empty it; and the temps were fine for a while. One time on the way to my hotel the temps started jumping from 95-110... turned out I was able to put in nearly a gallon into the radiator; which was slowly emptying I just never checked.

This was with a PWR rad BTW, and no, I didn't just leave the leak, I had fixed it the day after. Thank god for nice managers at Pep Boys!

 

[nickel and dimed]

well I dont think I am losing any coolant because the resevoir is not full, there is nothing on the ground after a long drive and I always shut off the ac well before it over heats (afraid of another BHG :icon_conf ). As for the radiator, my mechanic said it was all right but you never know. I was thinking about getting an aftermarket radiator and since I am manual I have some good options.

But anymore suggestions would be apprecited.

Does anyone think the alternator and tensioner pulley could be causing this as they are forcing even more heat into the system?

And I will check the radiator cap tonight. thanks

 

[lagged]

pressure test your cooling system with a radiator cap tester.

your EGTs look high for that probe location, IMO.

have you read your plugs recently?

 

[Bishop92t]

Just to reinforce, you can't just check via the overflow reservoir. That part of the system only works if you have no leaks. Looking for coolant on the ground is not a great test either. It evaporates fairly quick at operating temps, plus there are many places in the engine bay for coolant to hide. Pressure test is the best way to look for leaks.

In a normal operating coolant system it works like this: system heats up and pressure builds up, excess pressure is vented out by the radiator cap into the overflow bottle, as the system cools down the coolant decreases in volume creating a suction, this suction pulls coolant back from the overflow into the radiator. When you've got a leak the system heats up, pressure builds, excess pressure is vented out of the leak, as the system cools down it pulls air into the coolant system, overflow stays the same because it has in effect been bypassed. It's easier for the system to pull in air then it is to pull coolant out of the overflow.

The PWR radiator is the largest aftermarket bolt on radiator you can buy for the MK3. I've been running it on my car for a year or two now and am very satisfied with the unit. It's a little on the pricey side, but worth every penny considering how finicky the 7m is with cooling.

What are you using to monitor coolant temp?

It's not really possible for an alternator or tensioner pulley to create enough heat to effect the system. They would throw belts or affect your charging system long before that.

 

[nickel and dimed]

pressure test your cooling system with a radiator cap tester.

your EGTs look high for that probe location, IMO.

have you read your plugs recently?

What do you mean by reading the plugs? are you talking about spark plugs? they were fine when they went back in.

 

[nickel and dimed]

Just to reinforce, you can't just check via the overflow reservoir. That part of the system only works if you have no leaks. Looking for coolant on the ground is not a great test either. It evaporates fairly quick at operating temps, plus there are many places in the engine bay for coolant to hide. Pressure test is the best way to look for leaks.

In a normal operating coolant system it works like this: system heats up and pressure builds up, excess pressure is vented out by the radiator cap into the overflow bottle, as the system cools down the coolant decreases in volume creating a suction, this suction pulls coolant back from the overflow into the radiator. When you've got a leak the system heats up, pressure builds, excess pressure is vented out of the leak, as the system cools down it pulls air into the coolant system, overflow stays the same because it has in effect been bypassed. It's easier for the system to pull in air then it is to pull coolant out of the overflow.

The PWR radiator is the largest aftermarket bolt on radiator you can buy for the MK3. I've been running it on my car for a year or two now and am very satisfied with the unit. It's a little on the pricey side, but worth every penny considering how finicky the 7m is with cooling.

What are you using to monitor coolant temp?

It's not really possible for an alternator or tensioner pulley to create enough heat to effect the system. They would throw belts or affect your charging system long before that.

I am only monitoring the coolant temps with a stock gauge. i know they are not accurate. But my gauge will stay constantly at a little less than 1/3 the way up with out the AC and after running the AC for a bit, the temp will rise.

I will see what I can do about pressure testing it.

 

[Aspec]

I didn't see it mentioned anywhere so I will ask. You do have a fan shroud right?

 

[nickel and dimed]

I didn't see it mention anywhere so I will ask. You do have a fan shroud right?

well it is chicken wired on. it broke a little while ago. I heard that may be the problem but there is no gap. it sits as if it was original for the most part

 

[Aspec]

Just a shot in the dark. I know before I replaced mine I would experience the same problem only a bit worse.

 

[nickel and dimed]

hmm, how much is a fan shroud? also if I were to upgrade, would the fan shroud still fit or would i have to get something else

 

[Yblegal91t]

had almost eth same problem until i took the a/c out

 

[Aspec]

$100.00 to $150.00 depending on your toyota dealer connections. That includes the top and bottom pieces with the clips for the bottom piece. I don't know what the aftermarket radiator fitment would be.

 

[lagged]

before you do anything else, pressure test the cooling system.

as i think bishop has said in other threads, the stock water temp gauge isnt good for showing you exactly whats going on, but it is good to let you know if something is wrong.

that needle shouldnt move at all. while on many cars the reading may be slightely different, on every car ive seen with no problems, itll sit a little below the half way mark. if it moves at all from there, especially if it makes it to the half way mark, something is probably wrong.

you could have a very small external water leak, or a small blown head gasket.

youve got to pressure test your cooling system to find the leak.

removing the AC is not a solution to your problem as it is not the cause of your problem. dont listen to whoever is telling you that removing it will fix the problem.