×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Engine Crankshaft Seal Failure causing bearing failure

Engine Crankshaft Seal Failure causing bearing failure

Engine Crankshaft Seal Failure causing bearing failure

(OP)
The main bearings #1 and #2 of a G399 Cat engine failed after 17000 hrs. The inboard crankshaft seal was leaking for a long time prior to failure and heavily at the time of failure. The failed bearing closest to the seal showed the most damage and indicated metal to metal contact. The #2 bearing showed damage also but not as severe as the #1. There was no damage on the other bearings. We beleive the bearing failed due to seal failure. Documentation on causes of engine bearing failure state " The track of the pair of bearing shells nearest the seal exhibits symptoms of seizure, due to the oil film rupturing as a result of loss of oil pressure. " Can someone explain further how seal leakage in an engine causes bearing failure? We are being told that the crankshaft seals do not hold pressure and are only to prevent oil coming out of the block where the shaft pertrudes.

RE: Engine Crankshaft Seal Failure causing bearing failure

Hi Yats
I have never seen a crankshaft seal designed to keep oil in the main bearing. Normally the bearing starts to fail which increases the clearance. As the shaft wobbles around inside the bearing, the seal is subjected to large deflections, and tears. Perhaps the failed seal let dusty air into the crankcase. But since the bearings are under oil pressure, this should take out all the bearings if the filter is defective.
Unfortunately, I have to agree with what you are being told and not what you believe. You have no doubt checked your oil pump and galleries.

Good Luck

Steve

RE: Engine Crankshaft Seal Failure causing bearing failure

smckennz looks to be right on the money. The crank seak is there to keep the oil in and the c**p out. If the mains were worn the crank would deflect and either damage the oil seal, or the oil seal would be unable to effectively contact the shaft. Either way an oil leak is the result. It looks like you have got the cause and effect the wrong way round.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources