How tight should the intake manifold nuts be torqued when installing a new gasket on a B21F? I can't find torque specs in Bentley. How do you guys decide how tight is tight enough? Do you re-torque them after some miles? Thanks as always.
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Thanks everyone for the advice. 81 242 Brick Off Blocks, Turbo bars and wheels, B21F, M46; 86 244, B230, 148k , auto.

I've never used a torque wrench there (I could count on one hand the places I have used torque wrenches) but I do try to tighten in stages from center outward, paying attention to which nuts seem to need more just after tightening one adjacent.

I've seen some pretty ugly intake manifold gasket failures, but so far none I've replaced, just ones that came with the cars. Am I running on good luck or are they all about to give up the ghost?

Nice pictures, Art. The gasket I took off had repositioned itself. It looks like 1/2 the thickness of the gasket had slid on the other half about a quarter inch. The side in contact with the head had shifted. All four holes had shifted about 1/4 inch toward the center, but only the layer of paper in contact with the head. The outer 1/2 of the gasket's thickness had stayed put where I left it about 6000 miles ago. All four intake holes in the head were effectively smaller, plus it leaked vacuum at #4. This time I learned the torque specs (15 lbs) and followed them with a good torque wrench on the six nuts I could reach with it, and by feel on the other two. This is noticeably tighter than the last two times when I did it just by feel. Also, I used a Volvo gasket this time. Last time I order an Elring, but the one I received had no name on it, and I think it might have been a generic who-knows-who-made-this gasket.

Can a K-Jet with good compression idly smoothly without the engine and shifter shaking? I'm not there yet, although the new gasket helped quite a bit.
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Thanks everyone for the advice. 81 242 Brick Off Blocks, Turbo bars and wheels, B21F, M46; 86 244, B230, 148k , auto.

The gasket in the picture had no internal separation, just very brittle almost like phenolic. It came with a car bought cheap with no service records; the PCV system was a mess. Not k-jet either, it was LH2.4, so the ECU does a lot with its learning capability to give wiggle room for the leaks.

As to your question about k-jet idle... I have two. The 79 is bare-bones, no lambda or constant idle system. It shakes early in the warm-up cycle but then smooths out in park or neutral after a minute. I do feel an imbalance in drive if the idle rpm is set on the low side. The 83 is an intercooled turbo with a constant idle system. That motor does no shaking; in fact it is so quiet, I will try to shame the 79 into behaving better by parking them side by side. Or something. Or maybe I had better look at the intake manifold gasket??
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Art Benstein near Baltimore Crrrrazy Ray's!

I used 16ft.lbs., as indicated by the Haynes manual, and after a year the gasket cracked at number one (Volvo OEM). I'm going to torque the replacement to 14ft.lbs.



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don '89 740ti, '81 242t,

The spec is 15 ft.lbs for the b23 and b230, so that should do it for the b21? I don't see a separate spec in any of my books for the b21. I start in the middle and work outward in an X pattern, and have never seen a book/manual that called for a re-torque
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'94 940 150k, '86 240 170k, '72 142 KIA, '70 144 KIA, '69 144 RIP