1mm piston

Have a buildup of something on the crown of the piston. Looks black till you wipe off the soot and oil. Sandy in color to whitish. Had a guy that used to work in a dealership look at it and he had seen it before and thought it was from biofuel. Something about the water they use to "wash" the bio. Going to try to post pic if not now later. Seems to be the reason that I galled two pistons. Any ideas?

 

Here are the pics of number three. Plus the tops of 1, 2, 4, 5 and 6. Depending on the way I uploaded pictures. May have done that backwards. Also liner from number three. Number one is getting replaced for sure also. Liners from rest look good. Debating on cleaning up the rest and putting rings on them or doing all six packs or do nothing and hope none of the buildup flakes off the others. Any feedback. Mr Haney?

 

no electrolsis that i could tell will look a little harder when i get at it tomorrow. head not cracked or gasket leaking into the cylinders that i could tell. head was replaced in january by cat after they left the injector tool in the motor during the overhead.cat replaced head one jake and cam. Had some white smoke after idling overnight right after came back from cat. Was told before the head came off that they may need to put in two cylinders but when all was said and done they did not replace. had no issues up until April 7th when galded the piston. That I know of that is.
Did have an oil sample pulled by petro in amarillo 6000 miles after work was done in january and there was nothing abnormal as far as fuel or water or metals go.

 

Oh, the only thing that I forgot about sort of. The truck ran around 150- 160 degrees since I bought it till around two weeks before the piston. It started running 190, no cooler, no warmer. Seeing a change, I thought a themostat was sticking and replaced them. Hindsight being what it is, they were probably sticking open before and just started working right. I don't know if that helps anybody but that about all I know of for now. shoo.

 

I will. If the last piston is the one you are referring the truck was outside for a little while with the head off and the gap of the hood was over number six and has a little surface rust since we have had so much rain this spring. If you are talking of a different cylinder please tell me.

 

I will definitely check that tomorrow. I don't know for sure if that was checked or not but it will be now. The buildup is mostly only on 1- 3. 3 being the worst then #1. #2 has some buildup. #4- #6 has practically none except around the outside of piston but above the rings of course.