Overheating on road trip

990 Views 10 Replies 10 Participants Last post by supraz, 12 mo ago

Jake1499

Discussion Starter · May 26, 2022

So i took my 85 Supra on a 3 hour road trip the other day and it started overheating towards the end of the trip. It was probably 85 degrees ambient temp. I had the AC on the whole time and around the 2 hour mark I started to see the temperature gauge rise. This was also about the time that the speed limit went from 65 to 75. Never got into the red but definitely started climbing. I flipped on the heater rolled the windows down and the temp gauge went back to normal immediately. Do these cars just not like the high speed or do they not like having the AC on? Do you guys think i should replace the radiator? Recently I had the water pump replaced and the cooling system flushed. Also car recently has had a new head gasket. Ive driven the car around town since with no overheating issues.

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gamble

· #2 · May 26, 2022

These cars have no trouble high speed road tripping in high temps, if you start racing it look into a bigger aftermarket one and upgraded cooling fan maybe, but for street use stock is great.

Did you have the thermostat replaced same time as well? If so stock temp thermostat IMO is best, the coolant has to have time to absorb heat from the block and the coolant in the rad has to have time to cool.

Your rad could also just be old and clogged, or the coolant flush could have clogged it a bit depending on how that was done. If you're planning on keeping this thing awhile and enjoying it on long hot trips with the ac on, get a bigger rad, new thermostat to be safe, and never worry again until those parts wear out years in the future.

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Tanya

· #3 · May 27, 2022

I would eye your fan clutch if you did not replace it with the waterpump

I drive around So. Florida with my A/C on all the time, stop and go, highway and the engine runs cooler with it on than off because of the condenser fan

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AJ

· #4 · May 27, 2022

Fan Clutch

Burp the coolant system as well to remove any trapped air...Steep driveway or ramps work...

Fan shroud was put back on after water pump ??

Having driven in summer here 95F + with AC on ( X33+ yrs) never had an issue, just pinging...

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RedP85

· #5 · May 27, 2022

And the engine splash tray does help cooling at highway speeds.

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TerryHronek

· #6 · 12 mo ago

Jake1499 said:
So i took my 85 Supra on a 3 hour road trip the other day and it started overheating towards the end of the trip. It was probably 85 degrees ambient temp. I had the AC on the whole time and around the 2 hour mark I started to see the temperature gauge rise. This was also about the time that the speed limit went from 65 to 75. Never got into the red but definitely started climbing. I flipped on the heater rolled the windows down and the temp gauge went back to normal immediately. Do these cars just not like the high speed or do they not like having the AC on? Do you guys think i should replace the radiator? Recently I had the water pump replaced and the cooling system flushed. Also car recently has had a new head gasket. Ive driven the car around town since with no overheating issues.

I know this sounds stupid, but check tire pressure. Coming back on the Florida Turnpike when my 84 was 4 years old and noticed the temperature rising. Went slower and turned off the ac. Pulled into a fueling station and noticed 2 tires were low. Put air in all 4 tires and no more problems. The aluminum rims were causing the tires to lose some air.

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racefanfoster

· #7 · 12 mo ago

I have taken a fan clutch apart and replaced the oil in it. That renewed it. Here is the Toyota PN for that tube of oil.

See less See more

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igorot

· #8 · 12 mo ago

racefanfoster said:
I have taken a fan clutch apart and replaced the oil in it. That renewed it. Here is the Toyota PN for that tube of oil.

What's the past number for this oil? The picture doesn't show all the numbers. all i see is ?8816-1001? Thank you.

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RedP85

· #9 · 12 mo ago (Edited)

Most generic parts starts with a 9 or 0, and you mist a 0. My guess is: 08816-10001

Good to know they are"re-fillable"

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Zerodrag

· #10 · 12 mo ago

Fan clutch shouldn't affect cooling at freeway speeds, should it?
Also one of the most overlooked, and cheap/basic cooling system issues is a defective radiator cap.

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