Help!! 7360SS Engine Overhaul Problems

[dumbfarmboy]

I started this project several months ago. Bought this non-running tractor with loader for $2600 with hopes it would be a relatively easy fix. Discovered low compression on 3 of 4 cylinders and after removing the head, found #3 had a significant ridge. I checked several of the parts suppliers and though most listed .50mm OS rings and pistons in the parts diagram, none had them. I called Mitsubishi in IL and found out both were available They provided me with the latest parts numbers based on the application and the serial number of the engine. They directed me to a distributor in Houston where I ordered 4 piston and rings sets. ($800+ thank you very much) We finally got the block back from the machine shop and began assembly. Crank installed fine but when we tried to install the first piston, it stopped at the top compression ring. When we pulled it back out and removed the ring compressor, the top ring was stuck in the ring groove. The other rings were fine. Removed the ring and checked end gap. It is a bit over the standard but well under the wear limit spec. The ring is a keystone/tapered type, the ring groove doesn't appear tapered at first glance but after checking the width with the feeler gauge, I can see it is. Maybe it isn't tapered as much as the ring, idk. We checked all 4 pistons and it is the same on all 4. With the ring on the piston you can tell it's not able to fit completely into the groove and has no side gap. I've called Mitsu and the distributor, neither have answers yet. It appears the rings are too thick. Being they are tapered, it is difficult to measure.

If Mitsu can't come up with a solution, I'm considering lapping the bottom/flat side of the rings down to the point they fit properly.

Any advice at this point would be appreciated.

TIA

 

[Gator6x4]

I started this project several months ago. Bought this non-running tractor with loader for $2600 with hopes it would be a relatively easy fix. Discovered low compression on 3 of 4 cylinders and after removing the head, found #3 had a significant ridge. I checked several of the parts suppliers and though most listed .50mm OS rings and pistons in the parts diagram, none had them. I called Mitsubishi in IL and found out both were available They provided me with the latest parts numbers based on the application and the serial number of the engine. They directed me to a distributor in Houston where I ordered 4 piston and rings sets. ($800+ thank you very much) We finally got the block back from the machine shop and began assembly. Crank installed fine but when we tried to install the first piston, it stopped at the top compression ring. When we pulled it back out and removed the ring compressor, the top ring was stuck in the ring groove. The other rings were fine. Removed the ring and checked end gap. It is a bit over the standard but well under the wear limit spec. The ring is a keystone/tapered type, the ring groove doesn't appear tapered at first glance but after checking the width with the feeler gauge, I can see it is. Maybe it isn't tapered as much as the ring, idk. We checked all 4 pistons and it is the same on all 4. With the ring on the piston you can tell it's not able to fit completely into the groove and has no side gap. I've called Mitsu and the distributor, neither have answers yet. It appears the rings are too thick. Being they are tapered, it is difficult to measure.

If Mitsu can't come up with a solution, I'm considering lapping the bottom/flat side of the rings down to the point they fit properly.

Any advice at this point would be appreciated.

TIA

The $800.00 dollar price tag would have me demanding from the Distributor something that works, not something to be modified and guessing it will work.

 

[JRobyn]

What Gator said!

 

[dumbfarmboy]

Well, I found out Mitsubishi gave me the wrong part # for the rings. New ones on order and they are willing to credit the wrong ones. Lo and behold they were in stock in IL as were the pistons. Wrong ones had to come from Japan and were $30 more expensive. Hopefully we'll know by Friday if they fit.

 

[Renntag]

Good luck. Following along as I just purchased a fixer upper 7360.

 

[dumbfarmboy]

Well it's finally coming together but now we found the fuel tank has pin holes from rust.

 

[Renntag]

Thats an easy fix.

 

[Richard001]

I don't know if replacing the old tank with any kind of tank is on your list, but if you want to keep it orignal, this place, maybe can fix your old tank.

Gas Tank Renu | Stop Rust Permanently

They may have a shop near you. I had them fix a fuel tank on my collector car and they did a great job.

Richard