Author Topic: Headgasket job: Rotate bottom end before placing head on? (Read 2980 times)

bmwpower · « **on:** January 13, 2008, 09:00:51 PM »

The Bentley says to rotate the bottom end back 45" CCW before placing the head on the block. This is to avoid banging the valves on cylinders #1 and #4 (since they are at the top of their travel before turning).

Do you guys do this? I've done another headgasket job in the past (different car) but I skipped this step and I was fine.

D. Clay · « **Reply #1 on:** January 13, 2008, 11:09:31 PM »

Never done it myself either. How did you do the cams if they were removed? There's a special tool to hold them with even pressure so they don't break. I've never removed them on an M42. On most V8's you just back off the rockers, I read or heard somewhere that the reason was M42 cams are hollow. I can see where you might break one if you started at one end and completely removed the bearing caps but not if you backed them all off at once a little at a time.

bmwpower · « **Reply #2 on:** January 13, 2008, 11:40:13 PM »

Quote from: D. Clay;41169

Never done it myself either. How did you do the cams if they were removed? There's a special tool to hold them with even pressure so they don't break. I've never removed them on an M42. On most V8's you just back off the rockers, I read or heard somewhere that the reason was M42 cams are hollow. I can see where you might break one if you started at one end and completely removed the bearing caps but not if you backed them all off at once a little at a time.

I didn't remove the cams. I didn't have the tool, so I left it to the professionals at the machine shop @ VAC. I had them completely rebuild a used head since the original was cracked.

RED IS 91 · « **Reply #3 on:** January 14, 2008, 08:27:22 AM »

Before you removed the head you were supposed to turn it (counter clockwise) 45*.Of course this is after installing the special cam tool and removing timing chain gears.
It is step 31 on page 113-5 in the E36 bentley manual.
After you get the head back on your supposed to turn it clockwise 45* to get it back to TDC so you can re install the special tool to hold the crank at TDC.

good luck

PS I'd like to know how to turn the head bolts 90* when torqueing. Does everyone do it by eye or is there a tool that you use.

bmwpower · « **Reply #4 on:** January 14, 2008, 10:10:38 AM »

Yea, I didn't rotate anything back before removal.

You use a torque angle gauge like this one:

RED IS 91 · « **Reply #5 on:** January 14, 2008, 10:48:44 AM »

It sounds like a precautionary thing I guess .Are you not using the special tools (camshaft tool and tdc crank tool)?
Back to the torque angle indicator ,do you torque all the bolts to 22ft lbs then turn them ninety and then ninety again

bmwpower · « **Reply #6 on:** January 14, 2008, 01:03:27 PM »

Quote from: RED IS 91;41190

It sounds like a precautionary thing I guess .Are you not using the special tools (camshaft tool and tdc crank tool)?
Back to the torque angle indicator ,do you torque all the bolts to 22ft lbs then turn them ninety and then ninety again

No, that's the one tool I don't have. Use a straight edge along the top side and make sure both cams are level and you should be good.

I don't have the specs in front of me, but yes, that's generall how you use the torque angle gauge. Sometimes there is a wait in between each turn. Do them in the correct tightening order, too.