Rear Oil Seal. Do I need Impact Wrench

[Mordan]

Hello,

I want to do my rear oil seal... however I saw in the manual that I will meet with bolts torqued to 400nm (the flywheel).

there is no way to remove them by hand right?

so i'm bound to buy an impact wrench and a compressor.
Is a 25L compressor enough for the job or do I have to buy a 50L compressor? (I hope not because they are big and I don't have much room)

I also want to be able to remove the front crankshaft bolt. I have seen a friend enable to remove that bolt with a basic compressor.

How much power do I need?

[yaofeng]

Where do you see the torque value? I am almost sure you are mistaken. There is no big bolt on the flywheel. The rear seal has m6 and m8 bolts. The front crank does require high torque but using an air impact won't give you that.

[Bill R.]

torqued to 105nm and the crank bolt on the front is torqued to 320nm

[Mordan]

Where do you see the torque value? I am almost sure you are mistaken. There is no big bolt on the flywheel. The rear seal has m6 and m8 bolts. The front crank does require high torque but using an air impact won't give you that.

which tool will give me high torque for the front crank bolt?

[Mordan]

torqued to 105nm and the crank bolt on the front is torqued to 320nm

thx. 105nm is a bit difficult to achieve by hand with the car on jacks on a turning flywheel.

isn't there any other tool other than an impact wrench?
what people are using?

[Bill R.]

you can lock the flywheel from turning with any number of things, put a socket of the front pulley to hold the crank from turning. And use a long breaker bar to break the bolts loose,76 ft. lbs isn't that bad. Now the front crank bolt is alot more fun without the right tools.




thx. 105nm is a bit difficult to achieve by hand with the car on jacks on a turning flywheel.

isn't there any other tool other than an impact wrench?
what people are using?

[Mordan]

any use for the crank bolt?

http://www.zdmak.com/wbstore/images/bmwsirs-078.jpg
http://www.zdmak.com/wbstore/main.asp?action=PROD&PROD=BMW3034SET&CTMP=1

[Jeff N.]

The front crank bolt is a completely different animal from the rear flywheel bolts. If you need to do that one, you'll likely need the following:

- the hub lock tool you listed above.
- a very solid breaker bar
- a jack handle or something that will extend the breaker bar handle for leverage

This will get it off.

To install correctly, you would need a torque wrench that will read up ~ 325 lbs. When we've done it, we've never had one handy so we've always estimated the torque. We do this by seeing how long the lever arm is on the breaker bar and the assessing the required pull based on that arm. For example, if you have a 3 foot arm, you need just about 100lbs of pull. If you have some experience, it's not too hard to estimate this how hard this is. A torque multiplier is also another tool that can solve this problem but we've never had one.

Done several front crank nuts this way, never had any problems.

[Bill R.]

torqued to 224 ft.lbs, so a 250ft.lb torque wrench would be fine and they are pretty commonly available




The front crank bolt is a completely different animal from the rear flywheel bolts. If you need to do that one, you'll likely need the following:

- the hub lock tool you listed above.
- a very solid breaker bar
- a jack handle or something that will extend the breaker bar handle for leverage

This will get it off.

To install correctly, you would need a torque wrench that will read up ~ 325 lbs. When we've done it, we've never had one handy so we've always estimated the torque. We do this by seeing how long the lever arm is on the breaker bar and the assessing the required pull based on that arm. For example, if you have a 3 foot arm, you need just about 100lbs of pull. If you have some experience, it's not too hard to estimate this how hard this is. A torque multiplier is also another tool that can solve this problem but we've never had one.

Done several front crank nuts this way, never had any problems.

[yaofeng]

IIRC, the front needs a 27 mm socket. A 1/2" drive breaker bar with extension and a bathroom scale will give you the approximate torque you want. As to the flywheel insert a 1/4" punch through a hole below the starter at No.1 piston TDC to lock it. Remove the plastic plug from the hole first.

[Jeff N.]

torqued to 224 ft.lbs, so a 250ft.lb torque wrench would be fine and they are pretty commonly available

Yeah, it helps to make sure you're considering the right car.

[whiskychaser]

As to the flywheel insert a 1/4" punch through a hole below the starter at No.1 piston TDC to lock it. Remove the plastic plug from the hole first.
I've got the flywheel locking tool but despite sanding down it wont fit. So I used an allen key. Great cos the bent bit enables you to jiggle it about in the tiny space between the 'fins' on the block moulding. Not so great when the allen key breaks and leaves a bit in the flywheel. Then you are hoping to fck the broken bit doesnt drop out of the flywheel and that your magnet on a stick will pull the broken bit out.

[Mordan]

Done several front crank nuts this way, never had any problems.

thx.

actually i confused people. sorry.

I have to do the rear oil seal on the M20 which is in the car and I have to do the crank bolt of the M40 which is out of the car.

have you done it with the engine out of the car, hanging on a hoist?

I will find a way eventually. Just want to invest my money wisely.

either
1) impact wrench + compressor
or
2) breaker bar + locking tool + extension