Head gasket replacement for a

Saab 900 8v Turbo

(in 3 hours)

Strip down

1. Remove the bonnet (disconnect washer jets) and the battery.

Take one 227,500 mile old '85 8vT....... This is what you start with, and also hopefully what the end result looks like.

2. Set the engine to top dead centre.

3. Remove turbo to inlet manifold pipe.

4. Drain radiator (if it needs doing, ours was already empty!!), and remove radiator top hose, also disconnect water hose on the inlet manifold just below the NTC sensor.

5. Mark distributor to cam cover position, then disconnect sensor cable carefully (these break), the advance / retard pipe and remove distributor with distributor cab, plug wires and wire clips.

6. Remove all fuel injection pipes, the washers are rubber inserted so be VERY careful or you will have to buy new ones. Protect the fuel distributor from dirt.

7. Disconnect all wires/cables which attach to the head, or attach to components mounted on the head (NTC sensor, water temp, warm up regulator, cold start injector, air bypass valve and the knock sensor as it routes through the inlet manifold openings / remaining pipework).

8. Remove the 4 bolts which hold the turbo to the exhaust manifold (remembering which length goes where) recover the metal gasket from between, these bolts will be difficult to get to, but will undo easily. You may want to remove the turbo heat shield to get better access (two nuts). Unbolt the gearbox dipstick from the exhaust manifold.

9. Remove throttle cable from butterfly carefully, the nylon adjuster gets brittle.

10. Disconnect all the vacuum lines from the inlet manifold (warm up regulator, boost gauge, brake servo / heater vacuum bottle) and unclip the dip stick tube.

11. Remove the breather pipe from the cam cover, the 8 hex bolts, 3 top, 3 bottom and 2 at the back and remove the cam cover.

Starting to look a bit clearer down there now! Note the covered fuel distributor.

12. Get an old screwdriver or equivalent 1.25" ish wooden / plastic handled device and insert handle first between the two inner faces of the timing chain. At the same time, release the tensioner and push the screwdriver down, forcing the tensioner in and creating slack in the chain. Leave the screwdriver there until reassembly. Now undo the three bolts holding the sprocket on and balance this on the chain guides being careful to not allow the chain to slip / jump on the sprocket.

13. Remove the two bolts going UP into the head from the timing chain cover between the engine and bulkhead at block level.

14. Remove the power steering pump and belt from its mount and prop it up, still connected to its pipes against the bulkhead.

15. Remove the rear engine mount bracket that the power steering pump was mounted on, 2 bolts into the head, and 2 to the rubber bush by the top wishbone mount. You may need to support the rear of the engine, we didn't. The engine will slump slightly, do not worry about this.

16. Unbolt the bracket on the oil feed line to the turbo. This is mounted just below the thermostat housing.

17. Unbolt the bracket from the lower bolt of the throttle housing.

18. Fetch out your E16 torx socket for '84 on engines,

The E16 Torx socket. One of two purchases for the job, the other being a head gasket.

or ordinary 17mm socket for pre '84 and slacken the head bolts in a spiral from the outside i.e.

3 7 10 6 2

Timing chain C1 C2 C3 C4 Radiator end

4 8 9 5 1

19. Now remove the bolts, and using the inlet and exhaust manifolds as handles, lift the head off being careful not to knock the timing chain or sprocket and remove the old gasket.

Reasons for leaving the inlet and exhaust manifolds on:-

The stripped engine, awaiting checking. Note the special red handled screwdriver top centre image. Also the PS pump and lack of engine stay. You can just see the turbo oil line bracket if you look carefully and the throttle housing bracket by the corner of the rag. Can you see which cylinder had the leak??

Clean, Check and fix

20. As you can see from above, cylinder 4 had the leak. Next we carefully checked both the aluminium head and the block for any signs of damage. Both appeared to be ok even after their 60 mile drive home with no water in the radiator. The cam lobes were also checked as the state of the oil implied that the water leak wasn't only into the cylinder, or if it was it was of such a size that large quantities made it down the bore to the sump. The cam didn't have a mark on it luckily.

The bores too were spotless even after nearly 1/4 million miles.

This is the culprit, and only 170,000 miles on it too!

A close up of cylinder 4, and the HOLE!	It looks like cylinder 3 was showing signs of going too.

The head, just as it was removed.	See the water / oil emulsion that's everywhere.

21. The mating surfaces were cleared of all material. We used a stanley knife blade (in one of those window paint scrappers). Be very careful as the No.1 and 4 pistons sit proud of the block at TDC, and are aluminium so are easily damaged. Likewise, be very careful when you clean up the head as it is very soft and you could easily nick it with the blade. Some people us a hard plastic scrapper instead.

22. After cleaning, all the surfaces were checked again for cracks, burn through or visible warping. Luckily these engines and heads are virtually bomb proof, and no damage was seen.

	The mating surface being checked before cleaning up. It was checked again more carefully after cleaning.
	The casting fault in the exhaust (see the white line going east west where the exhaust gases are escaping just below the three vertical ribs...). Oh well that's life, it's been there 227,000 miles, a few thousand more will not matter.

23. The head top side was then 'GUNK' cleaned to remove the horrible oil mess, and then WD40'd to prevent rusting while we got a head gasket to put the engine back together, The bores were also WD40'd.

24. While the engine was in this open state, we checked and changed the alternator mount bushes as we had noticed that they were going some months earlier, but couldn't easily reach them for changing. This was an ideal time! the turtle moves.

25. We also replaced and correctly routed the top heater hose, as it had been rubbing the alternator for the 3.5 years we've had this car, and was nearly through the packing hose we had put round the real hose.

Also think about other things you could change easily at this point such as air filter, clutch etc.

Build up

26. Rebuilding is the reverse of removal, remembering to use a new head gasket....

The engine prepared, and ready for the head refitting. Note the nice blue colour to the original Turbo. It was also noticed that the turbo is cracked between where the exhaust elbow casing mounts the main exhaust turbine, with the crack going neatly 1/2 inch towards the block. Highlighted in red! You can just see our patented screwdriver under the timing chain.

27. No, I can't be that nasty.

Drop the head back on without moving the timing chain and sprocket, and finger tighten the 10 head bolts (having lightly oiled them first if they were ordinary bolts - the torx ones can be used 5 times before oiling is necessary), also refit the turbo oil pipe bracket, and the throttle housing bracket.

With the head dropped back on, and the head bolts just finger tight

28. Torque up the head bolts in stages, spiralling in the reverse order of undoing, we ignored stage 3 and 4, as do most garages around here i.e.

8 4 1 5 9

Timing chain C1 C2 C3 C4 Radiator end

7 3 2 6 10

29. Refit the 2 bolts going up into the head from the timing chain cover.

30. Refit the 2 brackets, the one to the throttle housing, the one holding the turbo oil feed pipe

31. Refit the engine mount to the back of the head (you may need someone to pull the engine upright slightly to get the bracket back in.

32. Refit the power steering pump and belt.

The heads torqued down now, and those 2 brackets and the engine mount are back on. The 2 timing cover bolts back in going up into the head. The cam sprocket is going to be next and then the power steering pump.

32. Refit the cam sprocket, and then remove the screwdriver from between the timing chain, and allow the tension to be taken again.

33. Refit the rocker cover with its eight hex bolts, and refit the breather pipe.

34. Refit the turbo to exhaust manifold bolts remembering to refit the metal gasket and replace the heat shield if removed. Bolt gearbox dipstick back onto the exhaust manifold.

35. Refit the fuel injection lines.

36. Refit the distributor to it's mark, distributor cap, plug wire and wire clips.

37. Refit all the vacuum lines.

38. Refit all the wires/cables.

39. Refit the turbo to inlet manifold pipe.

40. Refit the top radiator hose and the water pipe to the inlet manifold.

41. Refit the throttle cable.

42. Add new water / antifreeze mix.

43. Drain oil (we also had 4-5 pints of water in here!) and remove filter. We added a flushing oil and cheap filter and ran the car for 30 minutes then drained and fitted new filter and oil.

And so it's all back together, and getting it's oil changed and water / antifreeze added

.

44. Refit battery securely, replace bonnet, and reconnect Washer jets.

Back in with the battery, and now it's being started for the first time. No problems, as soon as the fuel is through it fires on all 4. So, we are back where we started.

45. An evening's work over, time to have a test drive down to the pub.

46. Follow up report, it's now 6 weeks and 3,000 miles since the head gasket change and all is working fine, now the cold morning and evenings are here the boost is back to 1/4 into red as per normal and the oil and water / antifreeze levels haven't changed and look healthy.

Andrew.

E-mail :- wright@paston.co.uk

Last updated:- 16th Nov 1998