I believe that i have to change the headgasket on my 87 supra turbo.My question is how hard is it going to be,and what parts other than the gasket am i going to need,i am not scared to dive into this my self,but it is my first supra and i really don't want to mess anything up,plus is there any inexpensive power mods that i can do myself.I'm still driving it right now,its just that it is blowing bubbles into the overflow and filling it up with coolant and then blowing it onto the radiator,but it runs fine other than trying to overheat during idle or some in town driving,and there is no water and oil mixture yet,already installed new waterpump and fanclutch,leading me to believe that the headgasket needs to be replaced.

Yes, it's definitely a BHG (blown head gasket).

Have done a couple of these on the two Supras I owned.

Ok, it's not a HUGE job but it is a big one and you need space and light to work. A workshop is the best.

You will need a new headgasket.

I'd suggest that if you haven't done one before, grab a digital camera and take LOTS of photos. All around the head, the front of the engine, the sides etc - the more photos the better. You will need them when it comes to refitting everything back later.

The first step is to remove the battery, drain the radiator, then disconnect everything top sides of the engine. All electrical connections, air pipes, breather tubes, fuel line (off the fuel rail down to the joint on the side of the block) etc. Heater hoses, forced air hoses... just keep removing stuff until it looks like there is nothing connected to the head or anything near it.

Ok, now for the cambelt. If it has been replaced recently, then all you need to do is remove the upper black cover from the front of the engine and loosen off the cambelt tensioner. This will allow you to slip the belt off the cam pulleys.

However, if the cambelt is old or you don't know if it has ever been replaced, now is a good time to do it.

Remove the fan and all belts. Take the black cover off the front of the engine. To get the lower part of the cover off you will have to remove the crank pulley. A gear puller is almost essential here.
Release the tension on the cambelt tensioner and remove the cambelt.

Remove the cam covers. You will need a 10mm HEX long shaft drive to undo the head bolts.

Remove them and store away safely.

Now comes the turbo. You can unbolt the exhaust manifold and leave the turbo in place, or unbolt the exhaust downpipe off the turbo at the flange and pull the whole lot out.

Once everything is unbolted, it's time to separate the head. Due to it being stuck down on an old head gasket it may need a slight pry to free it. This is ideally a two person job as the head is heavy - especially if you are removing it with the turbo and exhaust manifold still attached.

Lift the head off the block and place it down on a bench. Watch out for any valves that are sticking out - sit the head on two small wooden blocks - one at each end of the head to raise it off the bench.

Check the pistons and bores for any signs of damage.

I would at this stage recommend you have it professionally tested for cracks and levelness. There is no point in reinstalling it if it has warped or has cracks.

A few dollars spent at this point is well worthwhile. If you have a few tho planed off the head it will improve the performance as well.

If the engine has been overheated I would at this point have the block tested for flatness.

Once all this work has been done, it's simply a matter of laying the new gasket in place, and reinstalling the head in the reverse order of what you did to remove it.

TAKE CARE! There will more than likely be some valves that are open, therefore protruding above the surface of the head. Don't allow these to come in contact with anything hard such as the block or you could damage/bend one and that's a nasty expense you don't need.

Follow the head tightening sequence (google 7M-GT head tightening sequence).

Torque the head bolts down to 72 ft/lb. YES! This is what causes BHGs in the first place. The factory torque setting for the head bolts is TOO LOW! They specify 54 ft/lb. if you torque down to this level, your new head gasket will last all of 6 months then you will be back to square one.

Torque it down to 72 and you will never have any more problems.

Replace the cam covers.

Fit the new cam belt as per normal then manually rotate the engine (with the spark plugs out) one full revolution to ensure that your timing marks line up.

Re-assemble the rest of the fittings, pipes, hoses etc.

Fill the radiator and check for leaks.

Pull the MAIN engine relay (found in the black fuse box next to the battery) and wind the engine over on the starter until you have oil pressure.

Replace the MAIN engine relay and start up.

Check for any signs of distress, any leaks etc.


Ok, well this isn't a comprehensive guide by any means and I take no responsibility for any errors or omissions.
But it will give you a general idea on how to do it.

Good fortune!

Then there's the possibility that it's just a bad radiator cap. Get the cap tested first, a lot of places to it for free.





EDIT: Lol, wow this is old... not much traffic here. I'll leave this for future reference though.

And if your going to be running higher boost or just being hard on it I would suggest that you look into getting a metal Headgasket. you are also supposed to get new head bolts. I dont know if its absouly nessesary but i did when i replaced mine on a 91 supra. you can get kits that include a timing belt, head gasket and head bolts on SupraStore.com. oh and make sure you mark all of your vacuum lines. they can be tough to get back on in the right order.
good luck