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 Author  Topic: 4m2500 parts

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: Jan 27, 2012 - 8:11pm
Does anyone here have a source for major engine parts for a 4m2500? My buddy has one in his shop that was in for a clutch problem and he found bearing material in it. Thought it was likely the thrust bearing because the hydraulic actuator the customer was using was exerting constant high pressure on it when it was engaged. Got the sump off it and the thrust is fine, however 2 sets of rods are not. Turned the big ends black. Crank can likely be salvaged.

So does anybody have/know of 2 sets of rods and a crank just in case?


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  Jerry Gilmartin


Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jerry Gilmartin   Send Email To Jerry Gilmartin Posted on: Jan 29, 2012 - 8:54am
Hi Kevin.
As the operators of 3 of these engines in running order on board PT658, we have been in your shoes for the last 15 years. These engines are pretty much as rare as hens teeth, and whenever you come across a one, it would be wise to snap it up. I dont think there is a commercial supply of any parts, much less major engine components. There is no place that I have ever heard of that has any inventory of parts to order for these engines. The methods of obtaining spares that we have found that works best is A) Find a scrap engine and rob it of parts or B) Make the parts with the help of a machinist.

I have read on this board that the guys in New Orleans at the National Museum of WW2 are rebuilding some engines for PT305 as well and may have some parts. You may want to contact them and see if they have some spares you could get.

We do have a parts engine that has already been dissassembled and we have 10 spare rods and a spare crankshaft. I dont know if we can spare them, but if you contact me offline (use my email address under my profile) I could ask our head mechanic if he would be willing to part with them. I have never heard of these engines breaking a crankshaft although I have seen them snap the 1 inch diameter supercharger drive shaft like a twig! (Engine backfired due to carburetor misadjusted)

Additionally, we are also in the process of rebuilding our Starboard Engine Transmission, the friction material for the reverse band had failed and we are resurfacing it now. A local shop is working on it and it should be completed next week. It is constructed similar to a brake band with riveted strips of (asbestos?) friction material on the inner surface of the band. This inner surface contacts the drum and engages the reverse gear. The residue from this reverse gear band leaves a lot of powdered residue (similar to brake dust) inside the transmission housing. Maybe that is what you are seeing as well.

Oh by the way, we also found that the main crankshaft bearings contain silver and regular oil with detergents will cause this silver to be corroded away, and leave deposits in the oil sump. We had our oil analyzed and switched to aircraft grade "Aeroshell" made just for this purpose.

Good luck in your endeavors to find parts for these magnificent engines. Jerry PT658 Portland OR

Jerry Gilmartin

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