Last chance

[MA70Snowman]

ON GOING PROBLEM:
simply put.. the car over heats.
Now the fun part ::long breath:: car drives, boosts, starts, stops, FINE. The Napa leak down test (blow air through blue liquid watching to turn yellow) comes back NEGATIVE, (does not DIRECTLY indicate a BHG) While cruising, ~65MPH down highway (hot or cold mornings) it will heat up to right below red on a 15 min drive to work (starting from overnight cold) however if I put the engine between 1500-2000 RPMS the temp will NOTICABLY fall to operating temps. below 1500 will climb.. above 2000 will climb. however the temp does flicker while cruising. It over heats enough where I have to put ~1 gal of water in it everyday. The clutch fan does not seem to be malfunctioning but I am pretty unclear on the hot/cold test, and it doesn't fail the test thats in the TSRM. when I come home and its HOT.. air/vapor is comming out the Rad cap. and air/vapor/water is comming out the overflow. This issue has really been giving me pause for thought. I will be replacing the HG tomorrow but i'd like some FIRM, SOUND input before I dive in, in the off chance that it could be something else (probably by now my HG is getting ready to go anyway)

Aftermarket/performance parts:
HUGE front mount intercooler, w/ 2.5" piping from turbo to TB (could possibly be reducing airflow to radiator)
3" exhaust, turbo back
550 CC injectors
lex AFM, (electronics not hooked up)
MAFT Pro
Megan racing AFPR
Profec B Spec II boost controller (daily run 9-10 psi, highboost is ~14 psi)
HKS SSQV

thats all i can think of thats relevant.

Please any input is appreciated before I dive into the HG swap tomorrow. I'll be monitoring this most the night so please expect timely replies. JJ i'd love a comment from you.

 

[jdub]

- Check the thermostat...could be sticking shut. I always cut the jiggle valve off for a bit of flow at all times. Helps with a pressure build behind the stat that can hold it closed. Use a 190 deg stat...not a colder one for where you live.

- The radiator could have a number of clogged channels.

- Weak fan clutch. When you start cold, it should "howl" fairly loud for 45 sec or so, then quiet down.

 

[jetjock]

JJ i'd love a comment from
you.

As Jdub said assuming the thermostat is good everything you wrote points to a bad radiator...

 

[rawmk3]

Im sure this is kinda simple, but is your entire fan shroud there? And is your car AT or MT? Auto tranny cars have radiant heat from the trans lines that are cooled in your radiator, and if your tranny is overheating, it could cause that issue as well. How about your waterpump? There really are a ton of things that could be wrong. Have you back flushed your cooling system? It could be a clogged heater core, or something as simple as a t-stat stuck. I would try doing a back flush first or take it in and have someone professionally do it with the proper chemicals. That way it removes all the crap that could be in there, and everything is flowing correctly. That is the way I would go about it.

 

[carter]

truthfully I'd check the above and then check the rad cap, and if all else would fail, re bleed the system... but that would just be my guess...
Carter, J.

 

[jdub]

MA70 - just check the t-stat and the rad. Like JJ said, everything points that way.

It would take longer than a 15 min drive for an auto tranny to transfer enough heat (considering the volume of ATF), and even then you should never overheat as a result.

 

[MA70Snowman]

first off appreciate all the helpful posts I knew you guys would have some good insight

- Check the thermostat...could be sticking shut. I always cut the jiggle valve off for a bit of flow at all times. Helps with a pressure build behind the stat that can hold it closed. Use a 190 deg stat...not a colder one for where you live.

- The radiator could have a number of clogged channels.

- Weak fan clutch. When you start cold, it should "howl" fairly loud for 45 sec or so, then quiet down.

I'll try cutting the jiggle valve see if that helps that does make sense about it holding closed.. and it is a 190 (stock spec)

So if it doesn't howl then its a bad fan clutch? because i don't really notice a "howl"

how would one check to see if radiator is clogged?

Im sure this is kinda simple, but is your entire fan shroud there? And is your car AT or MT? Auto tranny cars have radiant heat from the trans lines that are cooled in your radiator, and if your tranny is overheating, it could cause that issue as well. How about your waterpump? There really are a ton of things that could be wrong. Have you back flushed your cooling system? It could be a clogged heater core, or something as simple as a t-stat stuck. I would try doing a back flush first or take it in and have someone professionally do it with the proper chemicals. That way it removes all the crap that could be in there, and everything is flowing correctly. That is the way I would go about it.

no its not a AT so thats ruled out. waterpump is good, no water leaking out. no grinding, nothing that indicates its bad.

what entails a "back flush", and if i want to take it in what would i ask for?

Honestly I'm glad for all your guy's input as that really was what I was thinking and was nice that you guys pretty much came to the same conclusion. Man I love supra fanatics, they never dissappoint.

 

[zachm611]

it sounds very similiar to the problem i had.. i replaced every little thing that i could think of i even tried one of those do it yourself prestone flush kits so i figured well shit must be the head gasket. its possible it was leaking a little but it was not too bad. after HG was replaced took it out for a cruise maybe 5-10 mins and started getting hot...pulled over and thought wtf. only thing i hadnt done was radiator. changed that and cooling problems solved.

sorry for the story but to make it short the radiator was my problem, its very possible it is or isnt yours. take it to be flow tested before buying a new one unless you got the cash and want the piece of mind for a new rad. good luck!

 

[rawmk3]

A back flush consists of a tee put in by your heater core lines that would have a water line hooked up to it. Then the Rad cap would be removed and they would put pressured water into the tee and flush the entire engine, radiator and all of any and all coolant and contaminants. If taking into a shop, ask them to back flush your cooling system with a cleaning agent. It will remove all the crap that is in your cooling passages from say an old BHG, or anything like that. But on a down side, it will show any blown gaskets that are being plugged up with corosion. If you have a MHG in there already, make sure you tell them that, so if they are going to do a back flush with a chemical, it will not damage any of the sealants in the HG. That would be my first step is to do a complete flush of the system after making sure the mechanical parts were in good order. So T-stat, water pump, and fan all working, try a back flush. If clogs in radiator or cooling lines it should really get em all out, unless its calcium build up. Any reputable shop should have the tools to do a complete back flush of your cooling system.

 

[flight doc89]

take your rad to a radiator shop and tell them to clean it out. should run ya about 40-50 bux.
Also, use a Toyota thermostat, not an autozone or adv auto therm.

Get a friend, start the car. when it warms up enough for the thermostat to open, have him hold it at 3k rpms while you look under the hood; if water starts going out the overflow tank before the engine overheats (as in, overheats but not to redline, just significantly over normal operating temp), then it is your rad.

burp your cooling system.

 

[MA70Snowman]

A back flush consists of a tee put in by your heater core lines that would have a water line hooked up to it. Then the Rad cap would be removed and they would put pressured water into the tee and flush the entire engine, radiator and all of any and all coolant and contaminants. If taking into a shop, ask them to back flush your cooling system with a cleaning agent. It will remove all the crap that is in your cooling passages from say an old BHG, or anything like that. But on a down side, it will show any blown gaskets that are being plugged up with corosion. If you have a MHG in there already, make sure you tell them that, so if they are going to do a back flush with a chemical, it will not damage any of the sealants in the HG. That would be my first step is to do a complete flush of the system after making sure the mechanical parts were in good order. So T-stat, water pump, and fan all working, try a back flush. If clogs in radiator or cooling lines it should really get em all out, unless its calcium build up. Any reputable shop should have the tools to do a complete back flush of your cooling system.

Hey thanks Raw for the informative bit there, definately helps out there. Well pulling the HG for the Piece of mind. once everything is together i'll take her to a shop to have the back flush done.

Since yesterday I did find one thing out.. I believe i had a NA fan clutch on my Fan. I was looking at one I had laying around the shop from my old engine, and noticed it was considerably meatier then the one that was currently on there. So swapped that out.

 

[WhtMa71]

Just make sure the fan clutch you installed isn't shot. When you spin the fan by hand(while cold) it should not really even make one full rotation. If it spins too easy, it needs a rebuild.
And as already stated, use a genuine Toyota thermostat.
My money is on the radiator being partially clogged too. You can check for cold spots on it while the engine is warm and the thermostat has opened.

 

[jetjock]

Sigh. The advice to flush is worthless because it won't solve the problem. Nor will the fan clutch. Fix it right instead...