Having read some of the recent posts, I went to check the head of my
1996 9000 Aero. They were not finger tight but were quite easily torqued up a bit with a torque spanner, and nothing like the force needed to give them that extra 90 degrees. I usually have to put the jack handle onto a solid socket to wind that up. So how do I go about tightening them? Loosen them off a bit, take them up to torque and then give them the 90 degree treatment?
See my other post for what I did. YMMV, torque with caution.
This is a multi post answer. Engine cold:You need a 40 torx bit to undo the cam cover or a 12 mm socket and a E16 torx socket for the head bolts, Do them 1 at a time; loosen and retorque to 60nm/44ftlb, then 80nm/59ftlb. then 90 degrees. This is meant to be a preventative measure and not a cure for a blown gasket, But if done in time can quite possibly save you a fair amount of money. Will the cam cover seal leak if reused?, It will or it won`t, but beware the over use of silicone. It seems to affect 16 valve engines with balance shafts the most, But I had a 1990 900 16v turbo the other day with a blown head gasket and the bolts on that engine were nowhere near tight enough. HTH Tom, Saabtech.
Thanks, just what I wanted to know. And yes, I use Loctite 518 rather than the dreaded silicone!!
Thanks Tom and Bob,
The one thing that concerns me is in doing this to stretch-bolts. Aren't they meant to go past their elastic limit on the first 90 degree yank? Won't doing a second one take them twice as far as they're meant to go? I wouldn't like to snap any...
Ah well, I'll check them for obvious looseness and then worry if I find any.
Cheers,
Colin.
I have done a couple of heads now and I couldn't believe the torque that the 90 degrees gives. I had to take the handle off my floor jack and then it was hard work. I was told to use the bolts again if none of them were stretched when compared. So far so good!
My jack handle won't fit. I normally use my garden fork instead, along with my "for abuse only" ratchet handle of course. I'm always hoping that I'll bend it on a particularly stubborn driveshaft nut or something, thus relieving myself of the ability to do any gardening. :o)
Cheers,
Colin.
Might be worth getting a solid "breaker bar" instead of using your ratchet. The breaker bar is usually good for about 200lbs... the ratchet will snap much before that.
I'm a bit tight-fisted and I've always told myself I'd get a breaker bar when the ratchet breaks or the garden fork folds up. I've been using the setup as my standard nut-mangling, socket-cracking and stud-snapping system for about fifteen years. So far so good. No doubt it'll snap when my knuckles are three inches from a brick wall...
Cheers,
Colin.
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