WOULD I BE OK JUST CLEANING THE CRANKCASE?

[lymer]

2018 800 Assault 4500 miles

I blew a piston and am wondering if I can just clean the crankcase really good and install a new top end. After it blew, I drove it about 5 miles back to the trailer. Using a Pneumatic Fluid Extractor, I flushed the crankcase out with gas. The first two bottles came out black with small specks of debris, with more flushing the gas came out clear.

Has anyone ever just cleaned the crankcase and had the motor last with a new top end?

Thanks.

 

[jim]

Man, that is a lot of hard metal (ring debris) that ran through the bottom end. I have re-used bottom ends after a piston failure many times with success, but I never had a piston that destroyed that I ran for awhile on the bottom end. Was more like "it seized...towing it out"...and never with a piston like that. Honestly, it's a metallurgical Christmas miracle, with a touch of an act of god, that piston even stayed together and didn't hang-up and toss a large chunk through the case or bend the rod...you can see a huge crack across the piston face...it was close to breaking away.

At a minimum, I'd remove those cases and split things apart, clean thoroughly, replace seals and check/replace bearings, etc. Or exchange for a fresh crank. With that mileage, you are pretty much due anyway. And with the cost of a top end, would be a shame to throw your crank or rod with a fresh top end and wreck it again.

Also, the PTO rod end looks suspect...is very dark like it overheated. I'd pull things apart for sure.

 

[lymer]

Not what I wanted to hear, but thanks for the advice. Good observation on the cracked piston.

 

[Fosgate]

I've done several in the past. It was hit or miss if it lasted or not inspecting with the naked eye for crank case damage or crank damage. Risk you also take with buying salvage parts. More sure way to inspect the crank and case for damage is to use RVI with ultraviolet dye penetrant and a UV Black light. Might be fine or you might be shocked at what you cant see with the naked eye. Currently I inspect vehicle damage for an insurance company and when it comes mechanical damage involving crash kinetics. I typically use the combo to inspect on a lift for frame damage when in question on trailers and vehicles. I seem to use it more frequently on Semi's and tractors though since many try to claim mechanical parts are part of a claim so I need to inspect to see if it is mechanical wear and tear or if it is related to the loss incident. The penetrant will also typically show you areas of wear and gouges in the metal. If both look good upon inspection I'd probably run the bottom end and crank again.

 

[lymer]

Interesting. Thanks for the reply!

 

[volcano buster]

My money says you will be buying some bearings as well.

 

[PSI 800]

I agree with what Jim said, take it right apart and inspect and go with a new crank and seals. that is a lot of miles.

 

[lymer]

My money says you will be buying some bearings as well.

I don't have a lot of experience with cranks, not sure I could tell if the bearings were bad unless it's super obvious.

 

[volcano buster]

I have to believe there is enough fine particles in the various bearings that it wouldn't last long if you reassembled it.