I have a 89 740, 8 valve, 5 spd. What size is the nut? ( Ineed to buy the socket) and can just put the car in gear so the crank won't turn? Is it safe to use an impact wrench?

Thanks.

I put the car in top gear (4th in my case) and put blocks BEHIND the rear wheels when loosening and in FRONT when tightening. You need a long breaker bar or jack handle to get the turning effort. The bolt will be TIGHT. Regards.
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BillB

it's 24mm
With a 5-speed you should be able to put the car in gear, set the brake, and get the bolt loose.
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Matt L. -- Cary, NC -- '91 740 wagon

what do you do if its an automatic? lol I needed this info myself as I have a bad crank pulley in my 87 turbo auto 740.

...of the great Don Foster and his patented "Rope Trick".

It's in the FAQ under crank pulley or somethng like that.

You use a 39-cent piece of yellow nylon rope inserted into cyl #1 to block the piston movement, creating a frozen crankshaft to twist the bolt off against.

Sound crazy? you bet, and it works really well, too. I tried it!

Check it out!

Josh

Too late I already took off one of those plastic guards at the torque converter and stuck a jack handle in there, wedging the engine to a stop. Worked great but thanx for the info.