Perkins AD3.152 Crankshaft balance

I am rebuilding a 1975 (approximate) MF 40 with the Perkins AD3.152. It is direct injection, non-turbo, diesel. The previous owner did not take care of it resulting in a spun rod bearing and a bolt knocking a small hole in the block.

The hole has been repaired and new parts delivered for YT.com. The crankshaft showed that it came pre-balanced with the weights already installed. I ordered new pistons, rods, rings, and bearings.

I took the crank to a machine shop to verify everything was balanced however it does not appear to be balanced well.

Does anyone have experience balancing an aftermarket crankshaft for this engine? Any information about rebuilding the bottom end would be helpful since there is not a large 3-cylinder market at machine shops in my area and they are scratching their heads.

Boy, it seems like a reputable engine
machine shop would know what to do or
what's right or wrong with the balance on a
crank. Do you have any racing/performance
shops in your area? Those guys specialize
in that type stuff, those high HP engines
they work on/ build don't last long if they
aren't properly balanced. I think for the
most part they usually drill holes into the
counterbalances to get the weight where
they want it. Good luck with it

I got involved with balancing an industrial refridgeration compressor at work 20-25 years ago. I found out
there's as many WRONG ways to balance a crankshaft with conn rods and pistons as there are engine machine
shops. Even our engineers that designed our compressors had NO IDEA how to balance them.

I'd Google Engine Balancing and spend the next week reading everything you can. Then find a shop that
suggests balancing your engine parts in a manner you agree with. There's parts of the engine that need to
be Unbalanced so when the engine is assembled and running it is in relative balance. The mix of rotating
and recipricating parts and parts that both recipricate and rotate requre the imbalance. The shop will need
the crankshaft, rods & caps plus bolts, pistons, rings, bearings, wrist pins and keepers, you will need to
tell the shop the operating rpm. Most shops drill holes in the sides of the counterweights and press in
chunks of heavy metal called Mallory Metal which is mostly Tungsten specifically used to balance engines.

If you can find it, C.J.Baker wrote an excellent article on engine balancing in Hot Rod magazine about 50
years ago.

(quoted from post at 11:23:52 11/19/17) I am rebuilding a 1975 (approximate) MF 40 with the Perkins AD3.152. It is direct injection, non-turbo, diesel. The previous owner did not take care of it resulting in a spun rod bearing and a bolt knocking a small hole in the block.

The hole has been repaired and new parts delivered for YT.com. The crankshaft showed that it came pre-balanced with the weights already installed. I ordered new pistons, rods, rings, and bearings.

I took the crank to a machine shop to verify everything was balanced however it does not appear to be balanced well.

Does anyone have experience balancing an aftermarket crankshaft for this engine? Any information about rebuilding the bottom end would be helpful since there is not a large 3-cylinder market at machine shops in my area and they are scratching their heads.

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would run away from a shop that said it wasn't balanced correctly but they didn't know how to make it correct!

My local engine shop, R&L Engines, will be happy to do it. (603)-742-8812. You don't say where you are. If you give your location you will probably get a shop that is within easy driving distance.

Be cautious, 3 cylinders are a different creature when it comes to balancing. I’m not familiar with the Perkins, but the Ford 3 cylinder have a front pulley that is counter weighted. I believe the procedure would be similar to balancing a V8 where you need to know the weight of the rod, rod bolts, piston, pin, retainers and rings to really do it correctly.

The bare crank by itself will appear out of balance.

Owings, Maryland

I believe that's what my guy is experiencing; the crank alone appeared unbalanced. however i gave him my old rod, piston, rings, etc and he said he has seen the pattern. Thanks for the response