Premature main engine bearing failure mystery
#41
Charter Member#568
Charter Member
Everything to from the remote oil filter is 1/2 inch and stock Merc parts. I removed all the lines after the season and having a guy here on OSO to make me up some new ones. Have never seen pressure above 50 psi and figured it was just my gauge. Also been noticing some lower pressure late in the season, so bought a mechanical gauge to check pressure in spring
https://photos.google.com/photo/AF1Q...h4LNTcK2dqLYE-
https://photos.google.com/photo/AF1Q...K4AhS95WByo3We
https://photos.google.com/photo/AF1Q...Al_0-ysgq6wBt1
https://photos.google.com/photo/AF1Q...h4LNTcK2dqLYE-
https://photos.google.com/photo/AF1Q...K4AhS95WByo3We
https://photos.google.com/photo/AF1Q...Al_0-ysgq6wBt1
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Straight bottoms and flat decks
Straight bottoms and flat decks
Last edited by bck; 12-31-2016 at 12:23 PM.
#42
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iTrader: (2)
The title says main bearing failure xxxx..
So , this motor wasnt rod knocking , didnt wipe a rod journal , just lost oil pressure and or getting noisy?
On a low hr motor like that , heat induced issues often will leave darkened areas around the journal or journals in question.
If the rod bearings are noticebly less worn than the mains , you may be looking at a assembly error especially with the new stroker rotating parts that are in the mix . Can happen to anybody. But would definetly put the preoiler on it after its fixed and before it goes back in and make sure everything is right.
So , this motor wasnt rod knocking , didnt wipe a rod journal , just lost oil pressure and or getting noisy?
On a low hr motor like that , heat induced issues often will leave darkened areas around the journal or journals in question.
If the rod bearings are noticebly less worn than the mains , you may be looking at a assembly error especially with the new stroker rotating parts that are in the mix . Can happen to anybody. But would definetly put the preoiler on it after its fixed and before it goes back in and make sure everything is right.
#44
Platinum Member
Platinum Member
iTrader: (6)
Im guessing this is a twin application, any problem with the other engine ?? or did you loose them both...........what does your engine builder say happened, like Mike said were all just guessing not seeing any of the parts.
#45
Platinum Member
Platinum Member
This whole thread and every suggestion is a waste because there is literally no info. You've pulled one main cap. Pull the engines out and take to your engine builder and get a professional diagnosis. Any engine builder that has been around over 30 years didn't stick around that long by giving customers the shaft.
90 hrs run time...the engine builder did his job. I'd let him take a look at it so he can tell you what really went wrong so you can avoid this down the road. There are about 15 things that could contribute and it may become more clear to someone who builds engines for a living.
Good luck
90 hrs run time...the engine builder did his job. I'd let him take a look at it so he can tell you what really went wrong so you can avoid this down the road. There are about 15 things that could contribute and it may become more clear to someone who builds engines for a living.
Good luck
#46
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I don't believe the 300 degree oil temp hurt the bearings That being said I have build circle track engines for many years and have seen many of those engines well over 300 degrees and no bearing problems.
I would say debris and tight clearances may a good place to start.
You said it was line bored I Not a fan of just line boring main lines should be finished with an align hone period.
I would say debris and tight clearances may a good place to start.
You said it was line bored I Not a fan of just line boring main lines should be finished with an align hone period.
#48
Registered
We Only Line Bore IF , a Bearing has spun damaging the housing bore , but we do run the hone through them occasionally if the bearings show something , that may
indicate that we have a misalignment in the housing.
Last edited by dunnitagain; 12-31-2016 at 06:29 PM. Reason: forgot something
#49
Registered
I would think after 90 hours , only pulling #1 Main from a Supercharged engine and seeing the overlay just showing the copper . Maybe .0025 is alittle tight , but by no means
constitutes a main bearing failure.
constitutes a main bearing failure.
#50
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I had the exact same thing happen to me. Built a new 540 with a new block and crank and used the stock 502 mag oil lines and cooler. After 30 hrs noticed some loss in oil pressure. Main bearings looked terrible. Polished the crank, put in some new bearings, upgraded the lines and cooler and now 5 years later it is still running with no issues. Lack of volume combined with high oil temps is not a good thing.