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Discussion Starter #1
Hello and a brief introduction.

Name is Leon, living in Leicestershire UK.

Car is a MkIII Supra MA70 3.0 Turbo with Manual "transmission" as you like to say over the pond ;)

Been fiddling with cars since I remember but this Supra is my first foray into the world of turbocharging.

Bought the car, on the way home it overheated badly, temp guage shot off the dial, engine fault light came on and I coasted to a halt with steam pouring out of the radiator.

Towed it home, let it cool off, charged the battery.

Engine fault codes were traced to CPS wiring after some help from the MkIII Supra forum in the UK. Rewired connections and cleared fault codes.

Tried restarting it. After a fair time (30 seconds?) cranking it actually started. Idled fine, very little white smoke, no blue smoke, but would misfire when revved.

Didn't take it round the block for fear of it dying and leaving me stranded.

Cooling system pressurises instantly, undoing the rad cap would result in huge gushes of coolant bubbling out. Definite smell of coolant in the exhaust fumes and low compression in cylinders 2-6, 6 being the worst. Compression in cylinder 1 was not too bad.

Decided to take the head off. Glad I did, multitude of perished hoses, split vacuum pipes, general years of neglect, thermostat housing and radiator badly silted up, rocker cover gaskets perished and literally pouring oil over plug 6.

Got the head off yesterday after skinning knuckles on the turbo bolts and nearly breaking my back leaning over to do the oil pipe bolts :D

Here are the pictures.













The close ups are of cylinder 6.

Observations:

1) Cylinder 1 has a good build up of carbon deposits - as I would normally expect when removing a head of a 180,000 mile engine. Cylinders 2-6 are perfectly clean, barring the oil on number 6 which has dripped down from the plug valley following plug removal.
Spoken with a couple of mechanic friends whos opinions I trust and general concensus is that there's a possibility coolant has been leaking across 2-6 and had a "steam cleaning" effect on the piston crowns.

2) No catastrophic damage to head gasket - or at least, I can't see an obvious failure point. This threw me at first, as every HG I have done has shown clear damage to the gasket, however a friend experienced in Toyotas has had similar when stripping down an MR2 with failed HG.

3) General debris is from the edges of the gasket itself. It's not bits of piston ring or anything like that, I took the shots straight away after removing the head.

4) Can't see any physical damage to head or block, but the head will be going to the machine shop this week to be checked anyway as it definitely overheated.

So, what do we think people? I've thrown this one open to a few forums and received a variety of responses.
Some agree with my thoughts above, others say the pics indicate massive damage to the head and likelyhood of the whole engine being scrap.

I await and appreciate your comments!
 

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Clean the pistons up along with the block surface with some scotchbright pads. Get your head to the machine shop to get cleaned and resurfaced along with getting new valve seals. Buy a toyota headgasket and some arp headstuds. Put it all back together and you should be good to go. In the picture of the headgasket it looks like there is a few places where exhaust gases were getting into the coolant passages.
 

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Clean that block up and inspect it good. I thought mine was good to go and after clean up saw hair line cracks from front to back. Had to replace the block.
 

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Looks salvageable to me.

And while the head is in the shop have them helicoil (or better yet use timecerts http://www.timesert.com/ ) the exhaust manifold studs. You do not want one of those to snap after you’ve put the head back on – ask me how I know.
 

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LEADED FUEL ONLY
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Just as Faded noted, I would HIGHLY suggest you helicoil the exhaust studs in the head. No matter what others say.. do it. It's very cheap insurance.

The headgasket does appear to be in decent shape. Altho some of the coolant passages on the exhuast side seem to be pushed into the coolant passage. This is a sign of combustion gasses getting into the cooling system. THis is also backed up by the fact the car overheats, it spits coolant out of the overflow bottle, and the cooling system pressurizes immediately after starting the car.

Clean the block up, clean the head up, slap on a new head gasket with some arp BOLTS (studs aren't needed and are a pain to deal with), torque it to ARP specs and enjoy it.

Also, don't forget to retorque the gasket after a few hundred miles.
 

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Discussion Starter #6
Cheers guys.

I think I will just flatten down the block surface and see how the head fares at the machine shop (as you call them)

When I was flatting the block down I noticed that piston 2 has a definite score running down the bore, but I'm not in the mood to investigate the problem further at the moment!
 

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pics pf the score?

block and head appear fine, get the head rebuilt while it's off to get all the carbon out, and definately replace the valve stem seals (main cause of carbon buildup that I've seen)

Your water jackets on your head look spotless, which is a good sign...
 

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Street Sleeper
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How tight were the head bolts when you took them out?? If not torqued down tight enough the head bolts back out over time this might be why the gasket doesn't look damaged. It was leaking due to not enough clamping force rather than a bad gasket.
 

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Just cruisin.
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I prefer the HKS beed style head gasket you can go to www.titanmotorsports.com and get a good price on heaad gasket and ARP bolts i agree studs are a bit overkill unless you are gonna have your head off anytime in the near future. If your head turns out unsavable you can find some fair priced ones of ebay that have been fully rebuilt and pressure tested for around US$500 or so. when redoing a supra head it is smart to go with ARP's torque spec because Toyota set the spec to low for some odd reason.
 

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Discussion Starter #12
I'm not using a metal head gasket, I don't think that decking the block is necessary myself.
 

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Dagger OCHO
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just make sure that if you do deck the block, to take in the back waterpump housing with it. i forgot to do that and i had to sit there with sandpaper and make sure it was perfectly level. but it doesn't look like it needs to have any material removed. i'm sure you already know it but it'll just increase your compression ratio just a tiny bit.
 
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