Supra Head gasket blown....or maybe not

[hackett]

Hello Ph'ers

I've just bought a Supra 3.0ltr manual non turbo. Bought it for £150 as the head gasket has gone. The guy selling it to me said he knows the head has gone because its kicking lots of steam out. I've started it up and had a wee butchers around it and i'm 50/50 as to whether the head has gone....

Coolant is at Max mark and hasn't moved, no oil at all in the water, car doesn't over heat. There is major emulsification of the oil which is obviously a sure sign of HG failure but this car has been stored for over a year with every tom dick and harry coming in starting it running it for 30 secs and then switching off. We all know that short runs are bad for engines and i know that a big 3.0ltr will take ages to warm up and hold lots of condensation which will then ultimately turn the oil butterscotch.

It has a misfire which also could be down to HG or maybe just plugs/leads.

My question is, as i bought this fully intending to replace the HG should i just go for it and get the head off although its by no means an hours work as these engines are quite difficult to do. Or do i just change the plugs leads and take it for a wee blast to see if i can burn off the years worth of condensation.

Any mechanics or DIY'ers advice appreciated.

Thanks

[GreenV8S]

Given the amount of work involved, before starting repairs I'd be inclined to do a cooling system pressure test and coolant HC test as a minimum, a block test too if you have access to an air line. Those tests should make it pretty clear whether you have HGF or some other problem.

[hackett]

thanks for reply mate i will do a block pressure test, didn't think of that....thanks

[aww999]

Normally they blow between cylinders (5 and 6 is the favourite) which means you don't get any coolant loss, just lack of power, misfire and a loss of compression. or they blow between the c7yliner and the waterways, which gives gurgling behind the dash, water being blasted out of the expansion tank, and intermittent steaminess. I've never seen one go which caused oil emulsification but yours could be the first

The ignition system on these is pretty strong (I use standard ignition coils etc at 25psi on a big turbo) so a misfire is often down to HG problems. If and when you decide to take the head off, always get it skimmed as they invariably warp, and check the block isn't pitted or anything. The standard bolts are pretty poor, and are NOT designed to be reused (especially after 20 odd years!). for the price of new Toyota bolts you can get decent ARP studs from the states which are much less prone to stretching/slackening. I think about 65ft/lbs of torque would be right on a composite gasket. Also check the condition of the radiator and waterpump impellors.

If you need any more help let me know, I've been through the mill with these cars a few times!

[hackett]

Cool mate thanks for that, i'm going up tonight to have a bash at it and will probably end up wipping the head off. Good to know theres some experience of these engines on here....i may call on your knowledge at some point.


Thanks