The turbo Cup race cars were fitted with a widefire head gasket
The Porsche part number is 951.104.374.02
1, take pictures while you're removing items, really does help when youputting it back together, especially of the 944T when it comes to the routing of the pipe work.
2, Try and remove as bigger bits as you can, i.e. no need to remove the fuelrail from the inlet manifold, take to whole manifold off as complete as possible.
3, When you've removed something, screw the bolts back into the thread they have been removed from, that way you shouldn't end up with bolts or nuts left over, and they are kept with the item they are meant for.
4, When rebuilding, make sure everything is very clean, and once clean, clean it again.
5, The exhaust manifolds can be a bit of nightmare, you'll find that once you've removed the bolts from the head and the undone the flange above the wastegate, they still won't come off. If you can get someone to help at this point, undo, the head, lift it, and the other person can wiggle the manifolds free.
6, The cam carrier and the head are both heavy, so having some else around at that point will help, as other things also happen at the same time (i.e. dropping tappets)
Specific problem areas on the 944T:-
Bolts holding the water fitting on the front of the engine, these have been known to get an amount of water in the threads and corrode into the head. When trying to remove these DO NOT RUSH, rounding one these will mean drilling and possibly tapping the head, so be very careful.
Also, the 2 bolts that hold the water channel to the block, I've had 1 of these snap, which would of meant drill and helicoiling the block, but I found the bores where scored, so the complete block was scrapped, but again take your time with these.
The fitting on the rear of the head, holding the bracket for cycling valve, the 1 bolt could take you upto 30 minutes on it's to remove, it position is a nightmare, you've got water pipes, electrical harness everything seems to be in this area. In the past, the only way I've found to remove it, is with an open ended spanner, moving a slight amount each time. If you've got a boost enhancer and can get away from refitting this bracket, then you'll save yourself a lot of time in the rebuild.
When you start, time the engine to TDC as a starting point, there is a timing mark on the camshaft sprocket, and a timing mark you can see through the bellhousing at the rear of the engine, get these aligned before removing the cambelt. Makes the rebuild easier, as you can start the rebuild at the same point.
When removing the cam carrier, the tappets are likely to want to fall out, once this seal is broken you'll have a load of oil drip onto the exhaust, don't worry about the oil, be more concerned about not dropping the tappets, once loose, lift the carrier slightly, and tilt in downwards to try and scroop the tappets into the carrier.
To remove all the water from the head, onto of the water pump, there is a hose that connects to the pipe that goes back into the car for the heater, remove the hose at the water pump and this will drain the head of water.
The wildfire gasket comes on its own. I did not want to pay the full price for another set of gaskets, nor did I want to re-use the old ones. So far, I have only found Porscheshop in Birmingham will sell individual gaskets- this will make it cheaper. However, the inlet manifolds are simple gaskets in gasket material, which Porschshop want 5.40 for plus VAT. Each. I will make my own, using the old ones as a pattern.
Before removing the Allan head bolts, "wake them" using a punch and hammer (no need to be hard, just 3-4 taps), and then use the hammer to tap the Allan key into the head. Using these, all bolts were surprisingly easy to remove.
Thirdly: the only nut which had its name changed to anglo-saxon last night was an innocent looking nut holding the dipstick to the inlet manifold. Removal is necessary but you cannot get a socket in there, or a spanner. I had to use a small 10mm socket and force an Allan key into the end. This makeshift tool was thin enough for me to turn the nut. Just don't use a 6mm or 8mm Allan key: you'll need good ones later on when removing the cam cover.
Cost so far: Wildfire gasket from Andrew Sweetenham and individual gaskets. Less then 100. (although I have not included a new rotor arm and distributor from Bert which I have decided to replace). I have taken 6 hours so far, and the "head" is the only thing left to remove. Nothing broken or stripped (yet)...
Tip 3: The head can be removed with the exhaust still attached. Rather then break the gasket at the manifold, go under the car and remove the 6 bolts attaching the manifold to the rest of the exhaust just before the wastegate (the latter does not get touched). Before loosening the head, use a pry bar to gently push the heat shield from the exhaust back into the bodywork. These are rarely flush, and if they protrude very far they will not give enough clearance for the exhaust.
Tip 4: Once the exhaust is removed, a small 13mm bolt can be seen in the block, to the right of number 4 cylinder (ie hidden from view by the exhaust). This is the block drain plug. When the head is off, block the remaining exhaust with rag and then remove, to release the water and any sludge. The amount of the latter which came out was surprising- some of which was very relieved to hear that the Berlin wall had come down!
Tip 5: the head bolts are torqued to 20 Nm (about 15 lb ft). The nice, expensive, calibrated one from Halfords I bought STARTS at 40 Nm.
I invested in a 3/8 drive from about 5-20 Nm. Apart from first torque settings on the head, it makes all the difference elsewhere. I use it on the timing belt covers for example - too tight and the insert spins in the casing, too loose and they'll fall out. A lot of the other castings bolted to the engine also use low torque figures, and I don't want to start stripping threads! (to be honest, on the 944 I now use the correct torque setting for every bolt. There are tables for standard ones not listed in the Haynes book of lies or Porsche manual). Also very useful in assembling the bottom end - the time allowed for getting the loctite on, and ladder casting assembled means having two torque wrenches, ready set at the correct torque saves vital seconds! The 3/8 drive one will fit in places a standard torque wrench won't, and a 1/2" drive adapter isn't expensive.
If you are careful, you could even add water to the cylinder liners to flush any remaining debris out.