1986.5 Supra Restoration Project

quickstudy

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stock radiator is all you will need. It will take reasonable power upgrades. If not the radiator, look at ignition timing, and finally consider blown head gasket, even if it new. a slight dent installing a metal head gasket can let combustion gas get in the coolant, leading to exhaust gas in the radiator an coolant overflowing slowly.

I think this is my favorite supra thread. crazy to even try to fix this car, blows my mind you got it running at all.
 
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zhenya2002

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Could definitely be the coolant cap plug on the coolant rail next to the manifold. I wouldn't assume your radiator is fine just because water flows through. My original radiator before replacing with the mishimoto radiator, reacted this way. Turns out it was partially blocked.

As far as your rust issue in the coolant system, run oxalic acid through the system, it'll clean it out. Just make sure to flush it thoroughly afterwards.
I went to examine the car today and look for that coolant cap plug. Found it, reached in with my hand to see if there was anything obvious, and the whole thing crumbled and fell off in my hand. The rubber hose and the hard line under it both just rotted off....

We found the problem!! Now I need to figure out if I can just close it up somehow, or if I need to get a whole new hard line. There's not much space back there to see where the lines go.

stock radiator is all you will need. It will take reasonable power upgrades. If not the radiator, look at ignition timing, and finally consider blown head gasket, even if it new. a slight dent installing a metal head gasket can let combustion gas get in the coolant, leading to exhaust gas in the radiator an coolant overflowing slowly.

I think this is my favorite supra thread. crazy to even try to fix this car, blows my mind you got it running at all.
Checked the oil just to be safe, and there's no trace of coolant in it. Even though it's still the original head gasket, it's fine for now.

Thank you for the comment. It's definitely been a fun journey getting this thing up and running. Normally I would try to preserve something as cool as a supra, but because pretty much everything is broken, it gives me the freedom to do whatever I want.
 

JustAnotherVictim

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If I'm not mistaken there's a block drain plug down there somewhere as well. Might as well check that too if you gotta get in there..
 

Asterix

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I'll do my best explaining. It was always a tight fit compared to the Koyo rads. My fan always sat really close to the radiator core, but never close enough to impact it. It worked fine for me for 7 years until I started losing coolant from a spot I couldnt find. One day I noticed that it was leaking from the core itself and fan and core had matching damage. My hypothesis is that when the engine revs increased, the fan would flex outward bringing it closer to the radiator, so perhaps it was just a matter of time before they would contact each other. Mishimoto refused to warranty it, so I went back to a stock replacement after that.
Since I just had my 7M-GE apart replacing the timing belt, I measured 1.5" from fan to radiator fins. The fan is much closer to the shroud right at the top, at 3/4". My fan will definitely hit the shroud long before hitting the radiator. Interesting your fan was so much closer than that.

I thought I'd post measurements in case anyone is interested.
 

JDMMA70

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Since I just had my 7M-GE apart replacing the timing belt, I measured 1.5" from fan to radiator fins. The fan is much closer to the shroud right at the top, at 3/4". My fan will definitely hit the shroud long before hitting the radiator. Interesting your fan was so much closer than that.

I thought I'd post measurements in case anyone is interested.
Trust me I was scratching my head the whole time lol.

20190118_215027a.jpg
 

zhenya2002

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Turns out that the rubber line holding the drain plug on had completely rotted out and the coolant leaked until the cat overheated. The good news is that we were able to fix it with some spare hose we had in the garage and a few coronas. Did a couple of short test drives today and she seems ok. Staying at operating temp. Gotta love a free fix!