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Discussion Starter · #1 ·
hey guys.....when i drive on the highway....doin about 65 mph my tach give me a reading of 3000 rpms...is that normal? i mean...top speed is 85 (printed) but i think it should do better than that. Because the engine is running at 3000 rpms, i think it burns a hell of a lot more gas than normal... please reply to this post.....its annoying not knowing whats right....also my water temp is about 3/4 to hot....is that normal also? i wish it ran cooler because i would have more power i guess.....i changed the thermostat, water pump, belts, and put the Toyota Red coolant and it still runs 3/4 hot....it never actually goes to hot so i'm glad...i also let the car "burb" the air bubbles out...so i don't know if its ok....
 

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Refresh our brain again... What year is your Supra??? 5MGE, correct??

65mph @ 3K rpms in 5th gear sounds about right for a 84 - 86 5-speed w/ a 4.30 rear diff ratio.

Temp needle says 3/4 - hot??? Not normal!!!! Should be about 1/3 - 1/2 mark, the needle should be leaning just slightly to the left.

Let's see... Change the fan clutch, radiator cap & used a Toyota thermostat or aftermarket??? Is it the correct thermostat temperature (if aftermarket)???

Has the coolant system ever been flushed??? Possible there is some blockage in the radiator....
 

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Discussion Starter · #3 ·
its an 83 supra 5mge....i flushed the coolant system...but not with the machine....i used the radiator flush (prestone kind) added that in....let the engine run w/ the heat on ....then drained that and added coolant......u know that kind of flush.....change the fan clutch? why?i think the fan is fine.....u think maybe its not kicking in?....its a toyota thermostat...i bought it from a dealership....i put in a 13 lbs of pressure radiator cap....after market.......i talked to a tech fromt he dealership and he said for that year it might be normal because its a fuel injected engine and they run on 3/4-h temp.....i dunno thats what he said.....should i just buy a new radiator? i'm sick of buyin stuff and it doesn't do a damn thing....lol.....my friend (he;s a mechanic) suggested I buy a Fluidine radiator.....they're guarenteed to run cooler....or will an after market rad be just fine?
 

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while on this topic.... Chris, where does your temp needle on the slug live? Mine runs at about 3/4 also, and I heavily suspect this to be high. Thermostat has been replaced, but I do have a really leaky radiator (lots of pinholes in the tank). Where should the needle register? (Remember its a 5M-GE).

PS sorry for the thread hijack :mrgreen:
 

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Hrmmm... A pop quiz...

Let's see... The MKI's did tend to run a bit on the warm side, which kind of bothered me a bit. The temp guage was at the 3/4 mark on my Brown 80 MA46, and on the Slug, it's anywhere between the 2/3 - 3/4 mark (I've also done quite a bit of changing out coolant system parts. Next items I need to do, are the temperature guage sending unit & the water pump. And maybe a reverse flush. Probably would not hurt to air blow out the fins on the A/C condensor.

Are you still on the MKI radiator??? This also might be the reason why it's at the 3/4 mark.

Right now w/ all of this cold air, it hovers around the 2/3 mark. Sometimes it will stay at the 1/2 mark for about 20 minutes, but not very long. The custom 3-row radiator that I got from Don C & Shawn P helps quite a bit, but I wish I could get the needle to stay put in one place.

In all of the MKI's that I've test driven in the past 14 years, I've only come across ONE 80 MA46, where the needle stayed pinned at the 1/2 mark. Every other MKI has been at the 3/4 mark.

To confirm this even more. I've looked at several pictures of a few low mileage MKI's that have sold on ebay & they showed interior dash pictures w/ the motor running.... With the temp needle right around the 2/3 - 3/4 mark... Hrmmmm...... :?

HTH.... Wish Damon Saul was here on the forums, he would be another good person to ask!!!!
 

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Discussion Starter · #6 ·
what do mean if i'm still on the MKI radiator? i have an MKII and it has an MKII radiator....i spoke to one of my friends and he suggested that I flush my engine because it might be blocking deom coolant going to the engine therefore making it run hot because theres a restricted flow from the engine and the radiator....i dunno what to do.....either fluch my engine or flush my cooling system professionally, or get a new rad.....i dont have enough money to do either of those things....i just put in a new tociko suspension in.....so i have to wait....
 

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i found my car was overheating, and guzzling (so i thought) coolant...

found out i just needed a new rad cap, so i bought a store brand one, and i still had the problem... not as often, but still there.

got my spare cap, which is a 21 year old toyota part, and it works perfectly.

i think the couple extra bucks for toyota parts is worth it
 

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Goodfella,

Sorry about that, I was replying back to Sam (Black Dawg) who has a 81 MKI, thus the MKI radiator reference.

Anywho, try either flushing the radiator, or get the radiator rodded out first. The engine flush, you can always try later.
 

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Duno about the mk2's you fella's got but my 83 temp runs at 1/2 all the time....if it varies there is normaly a problem. the car is at 200,000klms plus and has never varied in all the 10 yrs ive had it

just my 2cents worth.
 

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Discussion Starter · #13 ·
should i just get a new rad? is an aftermarket rad good? or get a toyota? if there is a better rad than toyota, then what is it? besides fluidyne?
 

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Overheating on highway=Radiator

Overheating in town=Fan
 

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Back to the high revs while highway driving. I would love to get a tranni with the same gear ratios as the W58, but an extra taller overdrive for 6th just for highway cruising without a change in the rear end.

My '83 ran really hot on the highway, but always normal temprature in town (even Toronto rush hour traffic). I had the rad recored and the problem was solved. The rad originally was the factory unit and looked fine before recoring it.
 

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re coring is where they take the rad apart, and clean out the end tanks, then use a new center section, with the tubes and fins and cooling goodness.
then they solder/braize it all back together, and away you go.
 

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Get a rad shop to take both upper and lower tanks off and replace the cooling core. Sometimes you can get a core that has a greater cooloing capacity fitted.
 

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I suspect the 13lb rad cap isnt high enough pressure for a MK2. Get a Toyota one 1.05kg/cm2 = +/- 15lb. Stock spec for testing rad cap is 10.7 to 14.9psi.

Thermostat is either 82 degrees Celsius or 88C. Spec opening on the 88C thermostat is between 86-90C (186-194F)

And when installing the thermostat make sure the jiggle (bleed) valve is up.

The cause sounds like a clogged radiator as other members have commented on.
 

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Stock spec is up to 14.9lbs in kgs get the Toyota rad cap.

Goodfella615 said:
whats the pressure of the toyota rad cap? my aftermarket rad cap is 13 lbs
 
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