Re: Piston Skirt Recoating
 

Just was at the dyno Monday with a friends bracket motor. 383 SBC. The guy who did the motor used pistons with Line2Line coatings. All the clearances and assembly and break in was done as per the instructions from Line2Line. Horsepower was down. Changed oil 3 times and oil was black from the coating and the filter had coating material in it. Leakage ranged from 9-55%. Going to tear it down in the next couple days to see the reason but I'm sure the rings are damaged or gummed up from the coating.

Re: Piston Skirt Recoating
 

That is sad to hear. I was doing a leak down on one of my cylinders which showed 20%. I disconnected the air line then plugged it back in, heard a little pop and now it was at 2%. This happen again on another cylinder. I drained the break in oil and cut open the filter. I did not see any thing plugging the filter but on one of the runs, the oil pressure dropped to 30 at idle with the break in oil. I poured 2 quarts of 5-20w mineral oil in and let it flush out the pan. I sprayed each cylinder with Marvel Mystery oil in hopes it would loosen up the sticky rings. Had nothing to lose at this point. Installed new filter and Lucas 10-40 semi-synthetic race oil and started the engine, ran to 140 degree water temp. The blow by was significantly reduced. Have not checked the lead down yet since I do not think the engine if fully broken in. Don't have much fuel.

Re: Piston Skirt Recoating
 

Bob,
Did you tear it down and what did you find?

Bob

Re: Piston Skirt Recoating
 

Basically the coating started coming off the pistons. Everything was done including the break in procedure as per the instructions. When the guy who did the motor contacted the piston manufacture they said "bad rings" We'll send you out a new set. It almost looked like the coating was coming off in bits. Not good for any lubrication. Going to bite the bullet and put in a new set of non coated pistons. Suppositley they ask for the cylinder size and coat the pistons to match the bore. Then you take scotchbrite and lightly sand the piston to just fit into the cylinders. The coating then wears slightly to have proper piston clearance. I think the coating itself is a good idea but with proper clearance and a minimum amount of coating on the piston. It almost looks like it was put on real thick.http://i.imgur.com/rOCz3vP.jpg

Re: Piston Skirt Recoating
 

SWAIN Coatings....

Re: Piston Skirt Recoating
 

Hey Bob when you put a caliper on the skirt did it come within spec per piston to bore and piston skirt diameter after the break in,and did you run it up to full rpm on the break in.

Re: Piston Skirt Recoating
 

The way the coating pulled away does not seem that it would cause a ring sealing problem. Did it look like the cylinder walls had the coating bonded to the honing grooves?