Swapping crankshafts

[Pet982]

I am swapping the crankshaft from blown 12000 series vertical engine to a lawn mower engine that was running and had very minimal leak-down.

After assembly I checked the crank endplay and its now way out of spec.

1)Crank I want in the donor's crank case and new gasket .027 play
2)Crank I want in the donor's crank case no gasket .010 play

Donor engine

before tear down .008

I put the crank, I do not want, back in the crank case with out the piston or cam installed to see if something changed and here is what I got

3)with new gasket .017
4)no gasket .001

What am I missing?
Does Briggs have shims for the 12000 series engines? I can't find them on my parts list.
Where do the shims go on this engine? The service manual says on the PTO side except on the 12000.
What is the thinnest gasket I can get?

 

[Rivets]

Can you provide us with all engine numbers from both engines? That way we can see if the same crankshaft was used on both engines. You also want to make sure that the connecting rod bearing lines up. If the crankshafts are different, the connecting rod may be out of alignment. Briggs does shim their crankshaft end play using different size crankcase cover gaskets.

 

[Pet982]

The blown engine 126T02-0521-B1 date code 09071457
It may have been run low on oil but it was already rapping when oil was checked/added to. It ran for some more time before it seized. When I tore into it I found a broken piston skirt and the piston twisted onto its side, intern damaging the cylinder walls. All the crank bearing journals are in good shape and measure in speck. I might be able to bore out the cylinder, but found a similar good engine on a junk mower so I decided to take this route.

Donor engine 125K05-0186-E1 date code 04102757

Engine ran, no smoke, virtually no leak down. My plan is/was to just swap the crank, carb and mount/controls from the blown engine. (Its going back onto a lawn vac not a mower)


From what I found is the crank case and sump are the same P/N for both. The crank is different because the newer one has a plastic timing gear, and the piston, rings, and connecting rod are different because of design change in the piston.

Correct me if any of my information is incorrect. After I started this thread, I think I found out I am within spec .002 - .030 play, but I am at the high end and want to bring it down some.

 

[StarTech]

The 126T02-0521-B1 did have a 0.12 shim available PN 592587 for both the crankshaft and the camshaft. Nothing was listed for the 125K05-0186-E1. But your are wrong that the crankcase is the same on both models.The 126 has only crankcase and the 125 has two different crankcase. (a total of three different PN).

 

[Pet982]

The 126T02-0521-B1 did have a 0.12 shim available PN 592587 for both the crankshaft and the camshaft. Nothing was listed for the 125K05-0186-E1. But your are wrong that the crankcase is the same on both models.The 126 has only crankcase and the 125 has two different crankcase. (a total of three different PN).

Thanks! I ordered the shim from the dealer today... It appears it goes on the Mag end of the crank, is that correct? The dealer did not even know what this shim was or that it existed. He kept trying to tell me I wanted the flywheel key, guess they do not do internal engine work.

As far as the crank case goes I think they are the same or at least now they are. The Donor engine calls for P/N 697322 which supersedes to P/N 592645. The 126T calls for P/N 592645

 

[StarTech]

Normally the shims goes on the sump side or at least that where I have seen them most times. But in this case it may go the top side (magneto side). Personally I just don't many engine in this CuIn rang. 99% of the engine here are rider mounted.

 

[Scrubcadet10]

yep, goes on the flywheel side, but like star, i've always seen them on the sump side.

 

[StarTech]

Scrub you can't believe everything is layed out in order on the Briggs. A good example the valves in the image they got the exhaust valve illustrated as being on top when in reality it is on the bottom.

 

[Richard320]

If you shim the mag side, will that pull the flywheel down to where it starts hitting things?

 

[StarTech]

If you shim the mag side, will that pull the flywheel down to where it starts hitting things?

Yes it can depending if there is enough clearance or not. To me shims are a wear items which is why you see on the lower side most times.