M12 Assembly Questions

[svt721 27]

Hey Group,

 

This is a continuation of my “green plastic chunks in oil” post.  I sent my block out to get machined .010 over (machinist measured the bore and for 1000 hours it was worn very little).  I purchased a rebuild kit from lilredbarn.net and have some reassembly questions.

 

- I reluctantly bought a set of crank bearings from LRB, but I’m very picky about bearing brands.  Hoped they would be name brand but they appear to be generic knock offs.  I could get a set of SKFs for around the same price I paid, am I better off returning these and going that direction or do you think the LRB bearings are sufficient?

 

- I plan to throw the block in my media blaster to clean it off and repaint it. Can’t tell if the cooling fins were painted from the factory or bare, any issue with painting them with engine enamel?

 

- The rod that came in the kit is made in Taiwan.  My original rod is in excellent shape, very little scoring on the rod or crank.  I plan to reuse that, any issues?  Also there are little brass dowels around the rod studs that got partially pulled out when I took the cap off - any tips on how to properly reset these so they don’t push out when tightening the rod cap?

 

- Original valves are in excellent shape, the seats look like brand new.  Plan is to lap them for a fresh surface and reuse rather than installing the new aftermarket ones.  Any qualms?

 

I think that’s it for now but I’m sure something else will come up.

 

Thanks,

Mike

[pfrederi 18,628]

Have rebuilt several Kohlers never found any that needed Crank bearings.  Were yours worn/loose?  If it makes you feel better get SKF but I wonder where they are made....

 

Did the Machine shop have the new piston before he bored it?  Did he cross hatch the bore...not sure I would Blast the block after machining

 

Did the Machine shop work on/measure the crank???

[svt721 27]

10 minutes ago, pfrederi said:

Have rebuilt several Kohlers never found any that needed Crank bearings.  Were yours worn/loose?  If it makes you feel better get SKF but I wonder where they are made....

 

Did the Machine shop have the new piston before he bored it?  Did he cross hatch the bore...not sure I would Blast the block after machining

 

Did the Machine shop work on/measure the crank???

There was plastic stuck in the original bearings despite them spinning mostly smooth so I figured better be safe than sorry.  I think the SKFs are made in Japan.

 

I’m bringing him the piston this morning to measure before he machines it to make sure the finish hone is correct.  I’ll also bring him the crank and rod to measure to be sure.

[953 nut 59,712]

48 minutes ago, svt721 said:

Hey Group,

 

This is a continuation of my “green plastic chunks in oil” post.  I sent my block out to get machined .010 over (machinist measured the bore and for 1000 hours it was worn very little).  I purchased a rebuild kit from lilredbarn.net and have some reassembly questions.

 

- I reluctantly bought a set of crank bearings from LRB, but I’m very picky about bearing brands.  Hoped they would be name brand but they appear to be generic knock offs.  I could get a set of SKFs for around the same price I paid, am I better off returning these and going that direction or do you think the LRB bearings are sufficient?    I would be comfortable with the LRB bearings but it is your choice.

 

- I plan to throw the block in my media blaster to clean it off and repaint it. Can’t tell if the cooling fins were painted from the factory or bare, any issue with painting them with engine enamel?     NO,  don't do it. The machine shop should have cleaned the block eliminating all debris, don't add more.

The cooling fins can be painted a single coat of high temperature enamel. Don't try to make them smooth, the roughness is good for heat transfer because it eliminates laminar flow of the air being blown through the fins.

 

- The rod that came in the kit is made in Taiwan.  My original rod is in excellent shape, very little scoring on the rod or crank.  I plan to reuse that, any issues?  Also there are little brass dowels around the rod studs that got partially pulled out when I took the cap off - any tips on how to properly reset these so they don’t push out when tightening the rod cap?    As long as the wrist pin fits the piston there probably isn't a problem but I would use the rod and wrist pin that came with the piston. The torque on used rod bolts is not the same as new ones (see below).

The alignment dowels will press back in as the head is torqued. Once the engine has been run up to normal operating temperature allow it to cool and then retorque the head bolts.

 

- Original valves are in excellent shape, the seats look like brand new.  Plan is to lap them for a fresh surface and reuse rather than installing the new aftermarket ones.  Any qualms?   Lapping in the old valves is fine.

 

I think that’s it for now but I’m sure something else will come up.

As the engine goes together use plenty of assembly lube and BE SURE the small hole in the rod cap faces toward the cam shaft.

Thanks,

Mike

This is from the Kohler Service manual for your engine. If you haven't downloaded the service manual please do so before you get started.

[squonk 43,689]

I wouldn't waste the time blasting the block. I have had great results with just cleaning the block with Dawn Power wash spray. Then a soft wire brush on the nooks and crannies and then painting with Rustoleum enamel and clear. 

 

 

 

Edited May 24 by squonk

[svt721 27]

23 hours ago, 953 nut said:

This is from the Kohler Service manual for your engine. If you haven't downloaded the service manual please do so before you get started.

Excellent info, thanks.  I’ll roll with the LRB bearings.  I brought the crank to the machine shop yesterday morning, he too suggested to use the new rod as the old ones can wear.  Hopefully the crank is in good shape and I don’t have to exchange the standard rod for a .010 under.  He’s going to hot tank the block after he hones it, so I should be able to mask it off and dust it with some paint.

 

Im obsessive about service manuals, have them for all my cars (over 13 books in 4 binders for my 1994 Saab convertible 😂) and the Horse so I’ve been going through the Kohler paper manual through this whole process.  Noticed there are different torque numbers for new and used rods.

 

Ive got a bottle of Torco assembly lube (was my dads favorite substance for building engines haha) and I’ll be applying it liberally.

[svt721 27]

23 hours ago, squonk said:

I wouldn't waste the time blasting the block. I have had great results with just cleaning the block with Dawn Power wash spray. Then a soft wire brush on the nooks and crannies and then painting with Rustoleum enamel and clear. 

 

 

 

I’ve been wanting to do a stack very similar to yours, I think there’s a guy on here that sells them?  Or did you build that one yourself?  My only concern is I don’t want it any louder than the stock muffler and I need the pipe to be above face level.  Do you know if he makes these with bigger mufflers and longer pipes?  What’s the noise level like on yours?

Edited May 25 by svt721

[squonk 43,689]

5 minutes ago, svt721 said:

I’ve been wanting to do a stack very similar to yours, I think there’s a guy on here that sells them?  Or did you build that one yourself?  My only concern is I don’t want it any louder than the stock muffler and I need the pipe to be above face level.  Do you know if he makes these with bigger mufflers and longer pipes?  What’s the noise level like on yours?

Bud Andrews made this muffler. He stopped making them. @jimkemp makes similar ones and Chad Burris makes some chrome ones

[953 nut 59,712]

Jim Kemp sells the mufflers on      They have a nice mellow tone, not nearly as loud as the stock muffler.

I added a brace below mine to help reduce the likelihood of damage to the engine exhaust threads.

 

 

[ebinmaine 72,317]

On 5/25/2025 at 8:08 AM, svt721 said:

 I’ll roll with the LRB bearings

 

 

Roll.....

Bearings.....

 

 

 

 

[svt721 27]

Hahaha - fun factoid.  Volvo was originally a subsidiary of the SKF bearing company.  Volvo is Swedish for “I roll”