overheating but no signs of BHG

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88tsupra

Guest
the car is overheating like crazy so we got a new koyo rad. for it and new rad cap. but it still over heats, the car shows no signs of a BHG only that it overheats. can someone give me any clues why its doing this. i dont want to take apart the head for no reason.
 
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PynkEye

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Mar 30, 2005
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Well, First off : simply the Thermostat might be stuck ''shut'' so there is no Antifreeze going around to your rad.....find the thermostat and change it, usually pretty cheap..some people run without it.

2nd..not sure if it works that way in our cars, but you have a Water temp sensor that tells your fan when to start, so if ever you are in traffic...no wind hitting the rad..and the car is heating up...at a certain temparature, the signal will go off and you fan will start up...cooling your rad (with thermostat open) to allow cool Antifreeze to go in your engine. But clutch fans...havent read up on those...gotta get to it. But should work the same..dont think our fan run all the time..would be dumb.

So for sure, check you thermostat...then that temps sensor im talking about. If the problem persists...tell me, might be something else
 
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JT87NA

New Member
Mar 30, 2005
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88tsupra said:
the car is overheating like crazy so we got a new koyo rad. for it and new rad cap. but it still over heats, the car shows no signs of a BHG only that it overheats. can someone give me any clues why its doing this. i dont want to take apart the head for no reason.
Click to expand...

You can try to do a block test. Your local autoparts store should have a block tester. It looks like a turkey baster and you fill it up with a special blue liquid. Get the car up to temp and then take off your radiator cap. Then you will pump the bulb on top of the tool and it draws up air from the cooling system up into the blue liquid, if the liquid turns yellow you have combustion gases in your cooling system which tells you that you have a BHG. Later.
 
Clinton

Clinton

Power Blue!!
Apr 8, 2005
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in addition to the thermostat, check for a plugged rad, our cars are notorious for getting their rads filled with crap.

it's probally not the thermostat, as they're designed to fail open, but it's always a good idea to change it whenever you can, since they're a 15-20$ part. It's not smart to run without your thermostat on a normal engine, since you need to reach proper operating temperature, and the thermostat is what makes that happen quickly by keeping coolant from getting to the rad during the warmup cycle.

have you looked into your water pump? are you overheating at really low speeds, or do you overheat when flying down the freeway too?

good luck with the overheating issue!

CCC
 
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Notorious_8.7.T

Guest
Clinton said:
in addition to the thermostat, check for a plugged rad, our cars are notorious for getting their rads filled with crap.
Click to expand...

Can't be that...he just got a new Koyo Rad...

heh put that front end on a ramp or jackstands and burp the hell out of it :D
 
ma71supraturbo

ma71supraturbo

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Mar 30, 2005
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When does it overheat? Freeway? idle? If you turn on the heater, does the temp come down? Does the air coming out of the heater go from hot to cold without you changing the setting? Are you loosing any coolant?
 
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88tsupra

Guest
yes we filled up the new rad. :squint: . we also got a new thermostat. we burped the fucker, and the heater when on is perfect. when you rev it, it goes up then down for the first rev after the other revs it stays at normal temps. when you drive it the temp goes up but not all the way up to the H, it stays below the H by 3-5 bars.
 
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IJ.

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Mar 30, 2005
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88tsupra said:
yes we filled up the new rad. :squint: . we also got a new thermostat. we burped the fucker, and the heater when on is perfect. when you rev it, it goes up then down for the first rev after the other revs it stays at normal temps. when you drive it the temp goes up but not all the way up to the H, it stays below the H by 3-5 bars.
Click to expand...
DAMN! 3-5 bars below H is HOT as!

I've been watching the digi readout on my standalone and comparing it to what the stock gauge does and 5 bars above C is around 74c!

Another 3>4 bars is around 98c!
 
ma71supraturbo

ma71supraturbo

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Mar 30, 2005
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88tsupra said:
yes we filled up the new rad. :squint: . we also got a new thermostat. we burped the fucker, and the heater when on is perfect. when you rev it, it goes up then down for the first rev after the other revs it stays at normal temps. when you drive it the temp goes up but not all the way up to the H, it stays below the H by 3-5 bars.
Click to expand...


Are you loosing any coolant, and what kind of thermostat did you use?
 
8

88tsupra

Guest
we're not loosing coolant and we got a NEW OEM thermo from the dealer
 
Clinton

Clinton

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Apr 8, 2005
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IJ. said:
Pull the Thermostat and drop it in a pot of water on the stove and watch to see if it's opening.

Not unknown to get a dud even when brand new.
Click to expand...

have you tried sticking a thermometer into the rad when it gets hot?

you may also have a bad temp sensor

CCC
 
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88tsupra

Guest
but if the temp sensor is badd, would the temp be fluctuating like it is? wouldnt it get straight to the H or stay on the C?
 
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IJ.

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Only time I've seen fluctuations in the needle have been when there's a big gulp of air in the system, I had to put a bleed port in my highest hose as I couldn't get it all out no matter how high I raised the front.

Clinton makes a good point though, how does the car run when it's reading that high? (as in does it run like a sack or drive normal?)

There are 2 temp sensors one for the gauge the other for the ECU, at those temps I'd expect it to be running pretty bad.
 
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88tsupra

Guest
actually the car runs fine when the temp is up it runs normally.
 
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IJ.

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88tsupra said:
actually the car runs fine when the temp is up it runs normally.
Click to expand...
Time to try either a mechanical gauge or another temp sensor!

What I wrote earlier about the stock gauge V's the standalone readout is interesting to me at least as with a stock gauge you never actually know what 1/2 is ?

1/2 of what ;) I know it's 1/2 of H and C but what are H and C ?
 
8

88tsupra

Guest
so if the temp sensor is messed up, is it ok to run the car? like drive it to work and back.
 
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