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Discussion Starter #1
Hi,

when my supra is cold it only runs on 5 Cylinders. Veryl quickly after it warms up, it runs normally again. But when it warms up it runs ok. At the moment I do not have a thermostat in my car, but when I boost a bit or even when driving normally the temperature goes all over the place and then normalizes again. The engine was rebuilt not to long ago with HKS metall head gasket and the blcok and head where decked. I also used ARP bolts. But I do not why this is happening. Since the engine was reinstlled it has gone a few thousand kilometers now, but I did not retorque the head again. Will this help? What might the cause for my problems be?

Thanks a lot for your help

Mark
 

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what would jesus drift?
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i retorqed my head after about 2 weeks of driving mine..

you could be loosing compression through the hg and when every thing starts to warm up it tights and seals it self,

i would say thermostate and re-torqe should fix your problems.. if your scared you could always do a compression test, and then squirt some oil in there and redo the test, if it comes up higher, bad rings, if it doesn't affect it then it's some where in the head.. (maybe the hg :)
 

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Hardtop FTW
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Definately sounds like BHG, but as otheres have said, a thermostat and retorque should do the trick. Isn't it nice having a solid MHG that doesn't completely obliterate itself when it blows?
 

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Discussion Starter #5
Thanks for the answeres guys, but in what way will a thermsotat help my problem? I took the thermostat out in the first place because the temp when funny. And the thermostat looked a bit shitty as the plastik ring near the spring somehow was damaged. Do you guys think retorquing might help, then I will go and do it. Otherwise I also have a brand new radiator, so it is not the problem i guess.

Thanks
 

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Re-torque your HG. Mine was cool for a while but it had wiggled out so bad that every once in a while when i started it up, it smoke like there was no tomorrow. You couldnt see the car some of the time. But it only did that every like 10 starts. But it was definatly my HG. Do the re-torque just to be sure.

GL
 

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If you have a MHG and ARP bolts, and the job was done right, you shouldn't have to retorque. If your having a HG problem, retorquing won't clear the problem.
Get a coolant check like Assassin recommended. Take the guess work out of it.
 

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Discussion Starter #9
I will try to retorque the head on the weekend, I hope this helps, I wonder why this is happening. By the way, when the car starts overheating, why does the temp go up, and the then come back down to normal again?
 

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Discussion Starter #10
As the engine was rebuilt neither the head nor the block where lapped. Might this have caused my problems? I shortly was running 1.3 bar, but only shortly usualy I was running only 0.8 bar. I just spoke to one of the guys here in germany that takes care of the 7m. It would cost me about 3200 to have the engine redone, so that might be the end of my supra If I can't get this fixed.
 

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McMsk said:
As the engine was rebuilt neither the head nor the block where lapped. Might this have caused my problems?
Bingo.
 

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you said they where decked, it depends on the final surface texture of the block and head.

lapping isn't necessary if they do it right the first time...
 

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McMsk said:
Thanks for the answeres guys, but in what way will a thermsotat help my problem? I took the thermostat out in the first place because the temp when funny. And the thermostat looked a bit shitty as the plastik ring near the spring somehow was damaged. Do you guys think retorquing might help, then I will go and do it. Otherwise I also have a brand new radiator, so it is not the problem i guess.

Thanks

the thermostats costs next to nothing and is there for some reason so it couldnt hurt to replace it
 

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Discussion Starter #14
My Toyota guy is on holiday, so I will have to wait for the thermostat to come. Therfore I took out the olkd one, to see if the problem was better, but somehow I don't know. I might even put my old radiator back in and see if it better, somehow it seems a bit extrem at the moment. But I also cant tell that is pushes alot out of the overflow. Where else might the water be going, I cannot tell a big white cloud behind me. Might there be somekind of a leak which only occurs, when the engine is hot and the water under pressure?
 

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McMsk said:
My Toyota guy is on holiday, so I will have to wait for the thermostat to come. Therfore I took out the olkd one, to see if the problem was better, but somehow I don't know. I might even put my old radiator back in and see if it better, somehow it seems a bit extrem at the moment. But I also cant tell that is pushes alot out of the overflow. Where else might the water be going, I cannot tell a big white cloud behind me. Might there be somekind of a leak which only occurs, when the engine is hot and the water under pressure?
If your reservoir is filling up from coolant pressure, it will overflow while your driving and you may never see the leak. Otherwise, if it is your HG, it can leak into the cylinder/s where the breach is in the HG. While your car sits after you drive it, the pressure subsides and the coolant is sucked back into the radiator from the reservoir and at that point will go into the cylinder/s.
 
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