bonehead mistake?

lendaddy · 05:27 AM

I was just talking to my uncle (huge BMW freak, forgive him) and I mentioned that I forgot to oil my flywheel seal before I installed it. He says pull the flywheel back off and do it right. Keep in mind this was not on a rebuild this was just a partial teardown so I am sure an oil film was present, but how much? Give it to me straight guys I will do what is right if I have to. Thanks.

Oh yea, all have on is the flywheel right now. Not that it should matter I guess.

Zendalar · 04-11-2003, 05:26 AM

Well...if you are sure there was oil, it should be ok.

I recall that I put oil everywhere that one could put it in, lots of it.

But if there was no oil at all..well the rubber will burn.

Jdub · 04-11-2003, 06:02 AM

He's speaking as a true BMW motorcycle fan ;>

Greasing this area is religion for Beemer motorbikers. But then again, detaching a swingarm and sliding a trans back is a whole different kettle of fish from doing this on a Pcar.

John

ChrisBennet · ChrisBennet's Garage

Did you clean the oil off the crank before you installed the seal? If you didn't, I'd call it oiled.
-Chris

lendaddy · 04-11-2003, 07:35 AM

No, I didn't clean it off, but the motor has been sitting for 10 months now. I am thinking I should just do it right and have some piece of mind.

sammyg2 · 04-11-2003, 09:33 AM

You can eiter roll the dice or make sure. I'd pull the flywheel and grease it, but I always loose my @ss in Vegas so I'm not a very good gambler.

Wayne 962 · Wayne 962's Garage

It's probably a non-issue. Still, you'd hate to have to fix it once the engine is back in the car. I thought you were going to drop the engine again and seal it. I like to put a bit of Curil-T on there for extra assurance (see the new book). Okay, I would pull the flywheel off, but I also don't recommend reusing flywheel bolts, because they are stretch bolts.

So, if you are going to use new flywheel bolts, then do it. If not, then don't.

-Wayne

Wayne 962 · Wayne 962's Garage

Then again, I do know people who reuse flywheel bolts, and they haven't had a problem. Use red Loctite if you do though...

-Wayne

lendaddy · 04-11-2003, 10:13 AM

Wayne, the motor is out. It is on a stand in my garage. I will do it over. I don't need the anxiety.

k9handler · 04-11-2003, 10:25 AM

pull it and go with a lightweight flywheel if you don't already have one...they are quite nice! I would take it apart and do it right.

Early_S_Man · 04-11-2003, 10:54 AM

You will probably have full oil pressure within 10 - 15 seconds at that end of the crank after startup, so I really don't think is is worth the trouble or expense! Non-issue, IMHO!

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by Early_S_Man
You will probably have full oil pressure within 10 - 15 seconds at that end of the crank after startup, so I really don't think is is worth the trouble or expense! Non-issue, IMHO!

Warren,
I thought something similar at first but then I thought about it some more and reconsidered. Since this is a seal, some part of the seal lip should be dry. I.e. The oil won't reach the outside of the seal (unless the seal leaks) so part of the seal might remain dry even though pressurized oil was only 1mm away. Does that make sense? Or does a seal initially leak a small amount until the oil pressure obturates/expands the seal?
Inquiring minds want to know...
-Chris

Neilk · 04-11-2003, 11:30 AM

Chris,

obturate

Thanks for the word of the day. Hadn't heard that one before.

sammyg2 · 11:40 AM

There is no such thing as a perfect seal. All seals are designed to leak but the leakage is supposed to be so small that it is acceptable. Lip seals (and mechanical seals) are lubricated by the product they seal. A very small amount of oil will leak past even the most perfect lip seal and lubricate the sealing lip. The leakage can be as small as a film only a few molecules thick. If a lip seal did seal absolutely 100% it would burn up in a matter of minutes, maybe quicker.

We actually measure the amount of leakage on seals where I work, anything under 500 parts per million is acceptable. That is not very much leakage. It would take a lot of hours of run time to even make a stain at those rates.

The designers are so anal that in a pefect design the liquid being sealed stays in a liquid form for 65% of the entire width of the sealing face and then flashes into a vapor from the friction creating a high pressure zone that can seperate the seal from the shaft like a buffer and also keep the rest of the liquid from leaking out.
Darn, I gotta stop mixing work with Porsches.

ChrisBennet · ChrisBennet's Garage

Ah Sam, you have shined the light of knowledge on this problem.
much thanks,
Chris

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by Neilk
Chris,

obturate

Thanks for the word of the day. Hadn't heard that one before.

You might if you handloaded. (handloading=make your own gun ammo).
-Chris

lateapex911 · 04-11-2003, 09:58 PM

Quote:

Originally posted by k9handler
pull it and go with a lightweight flywheel if you don't already have one...they are quite nice! I would take it apart and do it right.

Isn't this typical of projects like this!?? You say to yourself, "While I'm here" and POOF! thousands of dollare somehow fly out of your account, and new shiny cool things get dropped at your door by the UPS man. Aint life great?!?