Big End Bearing Crisis

[Moomoo]

Hello All

An alarming knocking noise started coming from within my engine, and on closer inspection the big end bearing had collapsed on piston no.3. The crank shaft journal is also scoured, and needs to be ground/polished to return it back to usable condition.

The engine in question is a Mariner engine model no 60PT4S from 2005, 60hp, 4 stroke, EFI and Bigfoot gearbox.

So far I have done all the work disassembling the block to remove the crank, and have found a company that will regrind the bearing, but I need to be able to find out if Mariner produce oversized bearings, and if so what tolerances they have. I have so far had no luck getting any information about these. Can anyone please help?

There is another possibility however. Does anyone have an identical crank shaft for sale?

Thanks in advance

Henry

[Alzi]

Originally Posted by Moomoo

Hello All


So far I have done all the work disassembling the block to remove the crank, and have found a company that will regrind the bearing

Hi , I am assuming this should have said crank.

I have had a similar problem in the past , A local Engine Remanufacturing Company Was able to Match me up some bearings that were Undersize, I just took them the Block(for main Bearings) ,Con Rod crank and old bearing, they only regroung the crank , then matched them up.

If you go on

www.ribsmarineparts.co.uk and register

You can get part no's etc , they do list 3 big end bearing numbers for your model engine (Depending on serial number) .

These may be different sizes , I do not know , but worth a look.

Alan.

[Bigmuz7]

Many manufacturers should do 2 or 3 sets of shells thicker than the originals .. (well they certainly do in my line of work) or the guys grinding the crank should be able to source similar ones. The only problem is how badly damaged the crank is, (did it get heated?) because sometimes it needs grinding beyond what the thickest shells will take, and is thereafter known as...... 'fecked'

[uncle al]

before you go to far i would recomend that you give the service manager a ring at barrus (ask for the obm service manager) or if you are freindly with a merc/mar dealer ask to have a look in the service manual the job could get complicated, good luck

[jcjcat]

I remember having seen this kind of repair 30 years ago, it was on a racing car crankshaft.

High strength steel had been added to the defective surface by projection (plasma ...?) then ground, the final surface was harder than original, with an identical diameter.

Possibly check this !

[9D280]

When I did my pistons both the Mallory & Sierra Marine catalogues had all sorts of over & undersized stuff at about half the price of the OEM kit.

They also did a "special" on Pistons for when you had reached the point that +0.030" was not going to cure it. Not sure if they do that for bearings.


Just a note - type Sierra Marine into Google or you'll get 50,000 pages about a certain Ford car form the 1980s...