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Old 09-20-2010, 05:56 PM   #1
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Default 89 Toyota Supra Turbo - Normal Operating Temperature

All - I have a love/hate relationship with my Supra. I love her - sometimes I really think she hates me.

Background - BHG diagnosed at 102K (07/10) - almost 22 years. Symptons - running hot, bubbles in radiator (no overflow), fog out the back, etc. Verified by NAPA Sniffer Kit (and very quickly at that). Had shop replace with all new Toyota parts/gaskets, as well as new Toyota parts not required but best to replace while in there (including starter, timing belt, water pump, tensioner, Ox sensor, hoses, etc.) and a new viscous fan (NAPA). Head had to be shaved by 10/1000", was pressure tested, cleaned, etc. with new (Toyota) valve seals before replacement. New ARP bolts at 72 lbs to put her back on.

Issue - Been almost 2 months since I got her back and just "seems" to run hot. Drove her through the summer and early fall here in DC and have been paying WAY TOO MUCH attention now to that temperature gauge in the car (seems like more than my gas gauge at times).

Owner's manual says anything between "C" (Cold) and a little below "H" (Hot) is okay - not entirely convinced. Also doesn't help that the gauge doesn't have numbers to convince me. As such, I'm trying to get a better idea where this thing should run as "normal" during highway driving before I start breaking this thing down again ...

Summary - Assuming "C" at 5 o'clock (100F?) and "H" at 1 o'clock position (260?), I'm generally running just below 3 o'clock or at 3 o'clock (220F?). Aux fans do come out as soon as I leave the highway. Car starts up in AM and (new) viscous fan pushes a lot of air for about 15 seconds (sounds like a jet); after that, I hit operating temperature in about 3 miles or 5 minutes. When all 3 aux fans come on at 212F, I can barely feel any air coming out the back end of that thing when I stop at idle in a parking lot. and open the hood. Similarly, when I turn on A/C on highway (no matter whether its 100F out or 75F like yesterday), I'm running between 4 o'clock and 5 o'clock, with every fan running and the wind in her grille.

Needless to say, I have pampered her since her operation and do not want to overheat her (especially after investment above) but I cannot recall where the "normal" temperature should be pegged at. No loss of coolant (been checking it every day), no need to fill either overflow or radiator, and I even hosed down condenser and radiator fins as best that I could. New radiator (NAPA) was installed in 2008 with new thermotat ("thought" it was 160F).

With 2K miles under my belt, I'm debating what to do (in addition to having a shop re-tighten the ARP bolts, just to make sure I'm good).

These are in no particular order -

(1) Vehicle emissions test is due next month - see if anything shows up in exhaust (compare to previous results)
(2) Replace thermostat (means opening her up again and I have the "burping" process).
(3) Flush that radiator (looks very clean through the anti-freeze but there are bound to be a few particles left over from the build)
(4) Remove radiator and professionally clean (also clean the condenser grill once radiator is out)
(5) Replace viscous fan (again)
(6) Have shop test timing (I really doubt they didn't get it right but ...)
(6) Replace radiator with larger one, replace fan with electric ones, etc.
(7) Call it a day - she's got a leak in the block somewhere ...

Any help/thoughts would be appreciated - I now know about the chronic BHG and temperature problems of these things. But she's still a great little car.
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Old 09-21-2010, 06:11 AM   #2
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a better rad is never a bad thing...
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Old 09-21-2010, 04:25 PM   #3
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thats a hell of allot of play for the toyota temp gauge. being a broad guage as it is. mine sticks in the middle and stays there. The toyota guage is set to measure it on the BROAD so to speak. if the car is just under hot. doesn't mean its "a little hot" its actually ALLOT hot. toyota designed it this way to reduce temp gauge flux and avoid having people freak out every 20 seconds.

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Old 09-22-2010, 04:02 AM   #4
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Something you may wish to consider, is the collection of debris between the AC condenser and the radiator.
This may be a moot point since the radiator has been changed recently.
Having said that, this "space" is an area which can not bee seen without IC removal.
Just a thought.
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