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Scored piston on DT466?
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Pat H
Posted 5/16/2009 17:43 (#715629)
Subject: Scored piston on DT466?


cropsey, il 61731
After a comedy of errors on assembly (mix and match rod caps) everything was fine for a while. I turned up the pump a little to match my other truck and ran it for a while. Would you know the minute I let someone else use it to haul a little gravel (definitely not overloaded) it starts making a knock. After we tore it down I found the number 6 piston is 'grooved' (I think that's a step up from just scored - see pics). I can replace the cylinder and piston and put things together (probably new rod bears, piston rings, and just maybe a head gasket ;) But, what would have caused the scoring? I have not replaced the injectors on this motor - could they be leaking?

Thanks,

Pat



(scored piston.jpg)



(good piston.jpg)



Attachments
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Attachments scored piston.jpg (85KB - 1003 downloads)
Attachments good piston.jpg (80KB - 867 downloads)
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RickB
Posted 5/16/2009 19:21 (#715720 - in reply to #715629)
Subject: RE: Scored piston on DT466?



Lincoln County. NC
My guess is excessive heat. Being #6 kinda backs that up having the poorest coolant flow around that sleeve.
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Rex Hellwig
Posted 5/16/2009 22:58 (#715931 - in reply to #715629)
Subject: RE: Scored piston on DT466?


I suppose somewhere, an injector failure caused a problem down belowfor someone. For what it is worth, I have never seen it happen. That claim will cover a lot of years and more brand names than I can quickly recall. Here is what I have seen that might cause this:

- Parts dirty/damaged during assembly
- A sudden load on a cold engine
- Coolant in the oil
- Overheat
- A worn cam lobe on that cylinder or anything else that results in short valve lift will do this. { Do check this on a 400 series IH- either valve. It will overheat that cylinder }
- Piston spray jet plugged
- Oil pressure low.
- Wrong liner to block o-rings, or using petroleum based lube to install silicon rubber o-rings
- Damage to the liner bore in the block. .... I used to do some follow-up repairs for a guy who would brag about not needing a sleeve puller to overhaul his customer's engines. His tools to remove sleeves consisted of a length of 3/4 inch shaft, and a four pound hammer. All was well until age got the best of his vision. Then he would "miss" with the driver and kiss the block with a big dent right below the o-ring grooves. This slight damage to the lower area of the block would be enough to distort the new sleeve into an eggshaped condition. The first time a good hard load was applied, the results looked just like your pics. I know this sounds crude, but I could usually fix this with a die-grinder, a lot of cleaning, and one new piston/sleeve.
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Pat H
Posted 5/17/2009 13:16 (#716388 - in reply to #715931)
Subject: Re: Scored piston on DT466?


cropsey, il 61731
Admittedly it was a not so nice rebuild - I have been successful on the 3 previous and I thought I could give a little direction to someone who had rebuilt engines (so he said - and I was wrong). The first wrong move was the rod cap mix up and it's been down hill from there. I'll get a new sleeve and piston, rings for other pistons, rebuilt injectors and a gasket kit and put it together myself. As far as the sleeve goes, I've always had success with a sturdy block of wood - the biggest problem is the mouthful of coolant when the sleeve pops out. I think I can borrow a puller and save some drama.

Thanks,
Pat
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catman95
Posted 5/18/2009 15:29 (#717437 - in reply to #716388)
Subject: Re: Scored piston on DT466?


Only other thing that I would make sure and look at is the piston oiler. Make sure there isn't anything plugging it up. That will sure make it score in a hurry to.
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Pat H
Posted 5/18/2009 15:36 (#717440 - in reply to #717437)
Subject: Re: Scored piston on DT466?


cropsey, il 61731
I'll take a look since I have the pistons out - I was thinking the jets were on the rod and so I didn't think I had them. How do you normally check them?

Thanks, Pat

Edited by Pat H 5/18/2009 15:52
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