Unbalanced diesel?

[Cheechako]

What does unbalanced mean? see this rebuilt 4-236 Perkins. : Perkins 4 236 Diesel Engines Remanufactured Complete | eBay

[boating2go]

This article explains it very well:

http://www.krugerfan.com/brochure/pu...ons/Tbn018.pdf

[zeehag]

unbalanced as in out of alignment or out of balance internally?

[Cheechako]

Yeah, I understand engine balancing etc. I just dont understand it's use in this application.. to the best of my knowlege most all rebuilt car engines (for instance) arent "balanced" like a hot rod or racing engine would be. I'm wondering if it's a non flywheel diesel? I know Kubota built a small diesel that had no flywheel 5-6 hp something like that. I made a couple of 12VDC generators out of those. The upgraded version was 8 hp and had a flywheel......? Maybe perkins engines that were used for waterpumps etc werent fly-wheeled... just thinkin out loud.

[gjordan]

Cheechako, You may have hit the nail on the head. A Perkins of any size will have a flywheel if it is in any application that has a conventional clutch. My own 4-236 in a tractor has a flywheel. In a marine application they will have a fairly light weight starter ring gear and a damper plate that is splined to the transmission. Automotive engines that are attached to an automatic transmission dont have conventional flywheels, they have ring gears. I have never seen an add written with that terminology, but that is the only thing I can think of. AH!!! another idea, some diesels (John Deere Luggers and Pathfinders) have a counter balancing shaft(I think that is the correct term) that is supposed to make them run smoother. Lugger brags about them, but I have never seen anyone brag about not having that design. As you can tell, I am just guessing at this point.____Grant.

[DeepFrz]

Grants suggestion about the counterbalancing shaft was my first thought about it. However I don't know if any 236 s have balancing shafts.

[Cheechako]

Yeah, the old VOlvo Marine diesels had the big flywheel up front.... but come to think of it, I guess a lot of the marine diesels dont have much of a flywheel. I sent a question asking the rebuilder what it meant.... Seems like a great price on a rebuilt 4-236

[RabidRabbit]

In early auto engines the internal parts were all balanced in the crank and the flywheel had "0" balance. As things became more massed produced motors were slapped together with less percision and the flywheels were weighted and drilled to bring the motor into balance. Just like a wheel weight on a new tire. For instance the 1975 ford 460ci truck blocks were the last year to run a "0" balance flywheel, in '76 the external balance was used. This may have nothing to do with the unbalanced claim on that engine.

[bobconnie]

Very very few small older diesels were internaly or externaly balanced. They were factory balanced. This ment they balanced one engine and tryed to make the parts for all the others the same weights! Ya can see how this is not the best !LOL but it is and was the standard for a lot of years! The newer small diesels are mostly internaly balanced, some even have semi flywheel weights! but as older diesels are really not balanced like most gas engines as they run at low rpms in comparision to gas engines.

[gjordan]

I will be curious what the rebuilder replies to Cheechako? . it is a an unfamiliar term.____Grant.

[OldRover]

I am curious what the response provided by the rebuilder was. My assumption would be that he was selling a motor without a flywheel. I know, as mentioned above, that some motors are built with each component balanced onto itself (internally balanced) while others use crankshaft balancers and/or flywheels to balance the rotating assembly. Case in point is I know of a rebuilder who strips all incoming motors and piles the parts, then chooses the 'best' when building a motor. This method did not work out when he did a small block Chevy that used an external crank balance wheel.
I have done a few Perkins rebuilds, but due to availability I have never been able to create a 'parts pile'. I am curious if Perkins used the flywheel to balance the rotating assembly or if flywheels can be swapped between engines. If anyone knows, let me know. I am working on a project using a Perkins 4.108 that has a large flywheel (often found on industrial applications) but need to use the smaller typical to marine applications.

[MarkSF]

I would take it to mean that the engine hasn't been subject to any special balancing.

[OldRover]

Could be. I was not aware anyone 'balanced' small diesels since they tend to run at low rpm. I have balanced plenty automotive engines especially for gains in quick rpm increase and high rpm running.
Oh, side note. In my boat I replaced the 4.108 with a rebuilt and swapped over all marine components including crank balancer/pulley and flywheel. So as far as I know, components are balanced. The fellow I am helping with the project says old Perkins were externally balanced as an assembly.
Thanks

[Cheechako]

Originally Posted by OldRover

I am curious what the response provided by the rebuilder was. My assumption would be that he was selling a motor without a flywheel. I know, as mentioned above, that some motors are built with each component balanced onto itself (internally balanced) while others use crankshaft balancers and/or flywheels to balance the rotating assembly. Case in point is I know of a rebuilder who strips all incoming motors and piles the parts, then chooses the 'best' when building a motor. This method did not work out when he did a small block Chevy that used an external crank balance wheel.
I have done a few Perkins rebuilds, but due to availability I have never been able to create a 'parts pile'. I am curious if Perkins used the flywheel to balance the rotating assembly or if flywheels can be swapped between engines. If anyone knows, let me know. I am working on a project using a Perkins 4.108 that has a large flywheel (often found on industrial applications) but need to use the smaller typical to marine applications.

I did eventually get a short answer to my question, I have since deleted it. But he said something along the line of internal balancing and mentioned the oil pump... HUH? You might consider posing your questions to Foley Diesel.

[perchance]

If parts form several different engines are used in the re-manufacturing process chances are the engine balance could be out to some degree and you wouldn't know till you ran it up to speed.