Engine overheats on highway with AC on

[DOUBL3 D]

Personally, I check the fan clutch right after shutdown, while it's hot. At that time, the clutch should have enough resistance that it takes a little effort to spin, and should NOT spin freely after you push the blades (ie: the fan comes to an immediate stop when you let go instead of pinwheeling.)

I'll also check when cool, that it's easier to spin, so that I have some indication that the clutch is doing what it's supposed to.

My last fan clutch failed in such a way as to have locked up entirely. Wow was that noisy...

I will go do this and report back. I went to the dealership today and ordered coolant and bolts for the fog light shrouds. It heated up a to half today, one click higher than normal albeit for only 2 minutes. It should be noted it was 102 degrees F with 60% humidity.


IJ if you read this, what does the under tray look like. I searched the EPC and didn't have any luck

 

[IJ.]

Big sheet of molded plastic.

Bolts up under the Lip the radiator support and the front crossmember.

 

[DOUBL3 D]

Big sheet of molded plastic.

Bolts up under the Lip the radiator support and the front crossmember.

I'm 99.9% I don't have that, ill go snap a picture real quick and post it. Thanks for your help thus far

 

[IJ.]

It's one of those things people seem to think are unneeded... they're often binned but the reality of a Mk3 is it's got a tiny frontal area and air foolows the path pf least resistance so if the blockers and tray are missing the Air spills off the radiator and around/under the car and you get a 5C temp rise at speed, couple that with a Marginal 20+ year old cooling system and it will run hot.

The stock Temp gauge once it reads hot is DAMN HOT and a BHG is minutes away.

 

[DOUBL3 D]

Alright IJ here is what I have.

I have the fog light shrouds, I went to the dealership today and ordered the bolts and clips for them, so they will he installed soon. I ordered some extras just incase I need em later on. I told the Toyota Dealership that ill soon be a familiar face I think tomorrow ok going to go to the junk yard and see if I can snag a shroud

 

[DOUBL3 D]

I haven't ruled BHG out of the question

 

[S.A. supra]

Do you have a thermostat?

 

[DOUBL3 D]

Do you have a thermostat?

Yes I do.

 

[S.A. supra]

My next guess would be possible bhg. Any coolant coming out the reservoir? Or gauge just getting hot?

 

[DOUBL3 D]

My next guess would be possible bhg. Any coolant coming out the reservoir? Or gauge just getting hot?

Do you mean into the over flow tank?

 

[hvyman]

Ya same thing different name.

Compression test and block test Could help in ruling out a bhg.

 

[S.A. supra]

Over flow tank boiling over? Not into, but out of the overflow tank. Like your cooling system is over pressurised. Also is your coolant rust colored?

 

[DOUBL3 D]

Over flow tank boiling over? Not into, but out of the overflow tank. Like your cooling system is over pressurised. Also is your coolant rust colored?

No it doesn't boil over, it went a few inches over the full mark today but it was 102 degrees outside. It's not rusty. It looks normal like green coolant in the radiator but the overflow tank doesn't quite.look that way. I will take pictures tomorrow. Thanks in advance for your help

 

[hvyman]

Overflow tanks usually look rusty on most mk3 over the years. Normal.

 

[DOUBL3 D]

Overflow tanks usually look rusty on most mk3 over the years. Normal.

This is good as mine is not pristine.

I will post my progress tomorrow along with pictures. Once I get my parts in from Toyota I will be able to install the fog light shrouds, and hopefully I can find an undertray from the junk yard (should be fun). I'm not sure how to do a compression test but I have a friend in town who can help me that I'm waiting to hear from.

Thank you everyone who has contributed this far

 

[radiod]

How to compression test:

http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EM&P=21

Fairly simple, and a compression tester doesn't typically cost too much if you don't have access to one through a friend

 

[DOUBL3 D]

How to compression test:

http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EM&P=21

Fairly simple, and a compression tester doesn't typically cost too much if you don't have access to one through a friend

Thank you so much for posting this, I've been looking around online for how to do it specifically for the supra. Should have RTFM

 

[S.A. supra]

Am always afraid of the results. But man it can save you a lot of time instead of chasing symptoms. I wasted a week on mine.

 

[DOUBL3 D]

Alright so here's whats up. I'm going over to my girlfriend's brother's on Monday or Tuesday to get help testing the car's compression. I will need to get a compression tester in that time so I will be looking for one from now til then. My plan is to also check the torque specs for the head while doing the compression test as well. I'm going to check the TSRM for how to do it, however if anyone has any input on how to do this it would be greatly appreciated. As for information about the current head-gasket, I know it was changed @ 55,000 (41,000 miles ago), I'm pretty sure it is a stock Toyota composite one and not metal. I will add more information as I find it.

I need to get this thing figured out because I don't like being paranoid when I drive I'm also looking for an undertray so anyone that has one please let me know. I will be posting in the WTB section as well. I've never had to deal with a cooling issue before so I'm trying to learn all this on the fly. Thanks to everyone who has helped

 

[Dan_Gyoba]

"Spare" undertrays are about as rare as hen's teeth. Mine's nearly wrecked, so I'm always on the lookout. So many people pull it off to get to something else, then never put it back on, and toss it. Then they figure out that it's necessary, and go looking for one, so if there's one on any cars in the wrecker, they disappear fast.

I'd have made one from fibreglass by now, but I keep thinking that there's got to be a better solution...