7.3 cylinder walls

ju015dd · Oct 21, 2014

Just broke open the engine that was supposably rebuilt for me 4 years ago. Has always used or burnt oil and smoked. I thought the cylinder walls should look a lot different than this. Is this the reason it did smoke and burn oil. Also I noticed on two pistons that there was some valve contact.

Arisley · Oct 21, 2014

Yeah, that looks like a piston was wallowing around in the hole a bit.
Sorta like a hot dog in a hallway.

ju015dd · Oct 21, 2014

Arisley said:
Yeah, that looks like a piston was wallowing around in the hole a bit.
Sorta like a hot dog in a hallway.

all of the bores look this way. Not sure how much piston movement there is suppose to be. They all have a slight bit of movement in the bores.

Arisley · Oct 21, 2014

Not that much, And I bet the valve springs are weak also. And no cross hatching at all.

I have seen old 7.3's that you could still see factory crosshatching on.

Dan V · Oct 21, 2014

It looks like it was bored, poorly, too close to the finish size and finish honing didn't clean up the tool marks from the boring process.

ju015dd · Oct 21, 2014

Dan V said:
It looks like it was bored, poorly, too close to the finish size and finish honing didn't clean up the tool marks from the boring process.

this is what I was thinking, lucky me , got to love people who take your money and do **** for work

golfer · Oct 21, 2014

did you perform a compression test on the cylinders prior to pulling it apart??

the cylinder bores don't look like they've ever been bored or honed to me...

I've seen 250k mile engines with dusted engines, & lowwwww compression that had good looking cross hatch...just piston to bore clearance that were too loose.

so, while (visual) crosshatch doesn't mean anything...

something is obviously not right.

tough to see/read the numbers stamped on the pistons...what bore size are the pistons for?

you'll need to pull the pistons out, measure them with a mic...then dial bore gauge the cylinders to see what kind of piston to bore clearance you have

the amount of soot sticking to the pistons is generally indicative of poor combustion &/or poor piston ring sealing (and hence poor combustion).

ju015dd · Oct 21, 2014

golfer said:
did you perform a compression test on the cylinders prior to pulling it apart??

the cylinder bores don't look like they've ever been bored or honed to me...

I've seen 250k mile engines with dusted engines, & lowwwww compression that had good looking cross hatch...just piston to bore clearance that were too loose.

so, while (visual) crosshatch doesn't mean anything...

something is obviously not right.

tough to see/read the numbers stamped on the pistons...what bore size are the pistons for?

you'll need to pull the pistons out, measure them with a mic...then dial bore gauge the cylinders to see what kind of piston to bore clearance you have

the amount of soot sticking to the pistons is generally indicative of poor combustion &/or poor piston ring sealing (and hence poor combustion).

yes, on the compression test. I did it about 2 years ago so can't remember exact numbers but all cylinders were very close to each other and all around 365 -375 psi. I will get the numbers off the pistons once I get a chance this evening golfer.

Arisley · Oct 21, 2014

Those were sub par numbers for an old engine. My 365,000 mile motor that has been used and abused, has better numbers than that.

Glad my diagnosis pretty much matched Golfer's.

CSIPSD · Oct 21, 2014

Looks like .030 over... The motor I blew a year ago had better cross hatch then that with 300+k on it.

ju015dd · Oct 22, 2014

CSIPSD said:
Looks like .030 over... The motor I blew a year ago had better cross hatch then that with 300+k on it.

yeah, I was able to clean a piston up a little and it reads .030 on them. Just goes to show you can't trust anyone in this world. This engine supposably was rebuilt and has only 40k on it give or take 5k.