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any headgasket write ups?

3K views 13 replies 11 participants last post by  SOAB 
#1 ·
i need a step by step guide to change the headgasket in my 91 9000. this is my first time doing this so any guide would he helpful.
 
#2 ·
new-body ever have to replace their headgasket? even the first few steps would help me out alot. never done this before.

like what do i take off first? then what? yada yada yada.

if anyones near baltimore and wants to lend a hand that be cool.
 
#5 · (Edited)
I've done my share on the c900. I'm sure that the basics are the same. There is a good step-by-step of the procedure on the Townsend site.

A couple other things:

Get some small zip-lock bags. Put the hardware you take off in individual bags and label them as to where the parts came from.

When you take the VC off, clean the cam sprockets and chain and put some alignment marks on the chain and sprockets. Also mark the cam and the cam cap. The tic marks on the cams aren't always accurate. It will make realignment that much easier. You can use a white paint marker.

Be careful of the chain guide when taking the head off, they are fragile.

You'll need a special torx socket to get the head bolts off. They are usually 3/8" drive, so you'll need a 1/2"-3/8" adapter for your torque wrench (which will likely be 1/2" drive). Make you you get a hardened impact-grade adapter. Anything less will break.
 
#6 ·
Sorry to thread jack but any ideas advice on the timing of a 1995 Aero? Ive got the valve cover off and I found a cap that looks like its supposed to open up to a notch to spin the timing chain but im scared to do it too hard.. does any body have any advice of how to turn the engine and just so im sure where to turn it to?
 
#7 ·
Bump.

Looks like I have a weeping HG, and will have to swap it out. Looking for a post that has a good description of the procedure. I do have the Haynes manual to help.
 
#8 ·
I couldn't find any write-ups when I had to do it, but If I could do it (with my need of painstakingly clear instruction) then I honestly think anybody could do it. I lucked out and had an engine hoist at the time making it a 1 man job! My tips would be disconnect the exhaust manifold from the turbo (less bolts to break) and bring the exhaust mani out with the head. Other than that basically its just nuts and bolts and some fluids. Take off anything attached to the head and get the special reverse torx (female style) socket to get the bolt heads out. The biggest thing is to Be VERY careful wit the timing. Your best bet is if you can lock everything in place so you can just put it back together the way you took it apart.

Best advice I ever got for this job is remember "Its just nuts and Bolts."

And remember it could always be worse!
 
#9 · (Edited)
The most complete way would be to buy a copy of the C900 Bentley manual - the procedure for removing the head and re-timing the cams and all that jazz is identical, just different manifolds, and then you have all the torque specs (if they aren't on a little sheet inside the new head gasket packaging) and photos and all that.

If you have someone to help you lift, the easiest way to do it is to leave the intake and exhaust manifolds attached, just disconnect the wiring harness, coolant and air hoses, upper engine mount & oil fill tube, remove the timing chain tensioner, remove the 4 bolts holding the turbine flange to the exhaust manifold and lift the whole thing off.

The only tricky part is that when you lift the head off, you have to go up a little, then tilt the head towards the front of the car to guide it off the timing chain guide where it sticks up above the deck. If you try to force it off with it caught it will break the top of the guide off.

It should be illustrated in Haynes and Bentley, I might have a photo of it somewhere too.

Found it, you can see how far up above the deck the guides stick. The rear one pivots, the front one doesn't.

 
#10 ·
The only tricky part is that when you lift the head off, you have to go up a little, then tilt the head towards the front of the car to guide it off the timing chain guide where it sticks up above the deck. If you try to force it off with it caught it will break the top of the guide off.
QFT...:th_MySaab900Like:

Oh man...what primo advice. This tip would have saved me much cursing (an an unexpected hit to the wallet) the first time around...

Only other thing I can say is to reinforce the timing issue. If you can get the engine to TDC before you pull the head, that will help.
 
#11 ·
I just ziptie the cam gears tightly to the chain, it is a little tricky to get the head on/off unless you have a helper, but then it will only go back together 1 way and you dont risk the timing being off.. Just another tidbit...
 
#13 ·
The Haynes manual describes the procedure quite well I think. Some advise though:

-First of all, drain the radiator.

-Make sure you have new head bolts and exhaust manifold bolts +nuts. The exhaust manifold bolts are prone to breaking, leaving a piece stuck in the head, almost impossible to remove without a welding machine. If this has not happened, you are lucky, and you should replace all the bolts with new ones.

-The cam gears arent that difficult to get back in the right position, just make sure they are. Marking the gears and chain with a permanent marker could be an idea, but if the marings on the crankshaft-wheel, the chain and the cam gears are in the right position you should be fine.

-Make sure the top is OK and not slightly twisted otherwise it has to be grinded straight.

-Make sure to use the right torque on all the bolts, and right torque, order and angle (90) on the head bolts.

Things you might need:
-New gaskets and bolts
-Permanent marker
-New coolant
-New hose clamps (if the old ones are rusty)
-Tool(s) to both fit on the head bolts, and long enough to torque it 40 Nm, then 60Nm and 90 degrees. The last one is quite heavy.
-Angle measurement tool to get the 90 degrees.
-A pipe plier to get the exhaust manifold bolts off.
 
#14 ·
OH! And the timing chain tension bolt thing is a PAIN to get to until you have done it a few times, I want to say I used a 21mm closed end wrench and had about 20 degrees of rotation to break it loose. Itll come you just gotta be patient.
 
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