I had the block honed and decked by a machine shop, and it was in perfect condition 1000 mi ago. I installed eagle rods and CP pistons.... had a headgasket leak (I think due to the fact that I didn't shorten my dowel pins)... and I noticed this:





These weren't here when I assembled my motor. There's a bunch of them... and I can catch my fingernail on them. What would cause this problem?

I'll probably just put the head back on and run it until it becomes a big issue... and then resleeve it.


Modified by servion at 12:02 PM 7/10/2003

 

Did you coat the walls in oil or wd40? It could just be some rust type ****.

 

Loks like the coolant scoured the pistons. Are those scratches on the sleeves also? Something ain't right. Debris?

 

Sorry, I'm pointing out the scratches on the inside of the cylinder walls....

The pistons just have some carbon on them that is partially clened off... the splothing on the pistons is ok... I'm worried about the scratches on the cylinder walls

 

What are we talking about here? The cross hatches? Those are supposed to be there. I don't think you should be able to catch your finger nail on them though. My motor has about 110,000 miles and it still has those.

 

I had my block sleeved by Golden Eagle and my Head built by KMS (resurfaced as well)...Do the dowl pins need modified? How do you know when you should modifie them?

Sorry to ***** up your post

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">Sorry, I'm pointing out the scratches on the inside of the cylinder walls....</TD></TR></TABLE>

Piston rings... what gap did you run when you put the pistons in? Stock gap is ok (?) but anything smaller is asking for trouble... rings expand and push out and scratch the walls.

Did you check the piston/wall clearance?

 

My machinist said the piston to wall clearance was alright when he honed it, but I didn't check it myself. They're 81mm CP pistons with a hone done on the block. I gapped the compression rings both to 18 thousandths.

For those who don't see it, I was talking about the vertical scratches in the sleeves.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote">

For those who don't see it, I was talking about the vertical scratches in the sleeves.</TD></TR></TABLE>

Ooooooooooohhhhhhhhh, I see now. Ouch. That would have to be the rings.

 

What about the rings would do this? Did I do something wrong when I gapped them or something? I gapped them (both compression) 18 thoushandths... and I de-burred the ends with the file... any thoughts?

I'm planning on just putting the head back on and running it until its a problem... and then sleeve it. But, when I assemble the motor again when its sleeved I don't want to have this problem again. Could this be somethign having to do with the ringlands? I certainly hope that's not the issue because I'm usting CP pistons, and I tuned it myself (street WB /w hondata) to ~11.5:1 under boost

The valve reliefs look fine, and from what I've seen... they'll usually chip away first

 

I circled the bad part in the images....

 

yeah dude that's the rings. they weren't seated in their notches when you assembled the engine apparently and scored the cylinder before either seating or filing themselves down upon break-in.

especially the one in the first picture. you can see how both sides of it caught on the cylinder wall...

 

So... can you explain... do you mean that I didn't have the ring completely in its place on the piston when I tapped them into the cylinder?

I had a big problem with the ring compressor popping out of place and not keeping the rings compressed... it took multiple trys for most of the pistont to get them into the block. Are you saying that I did it putting them in... or was this after the motor was ran?

 

also, did you have anything covering the edges of the rod's big end cap when sliding it down into the cylinder? Exposed rods could cause damage to the side of the wall too, especially with several in/outs to get the piston rings to compress properly.

 

could have had something go down the intake (like a peice of welding slag from an intercooler pipe). my race car has a scratch in the cylinder wall like that, never had a problem with it in 3 years.

 

it looks like the honing is wearing off a little bit at that one point. If they aren't detectable by feel, then you are alright.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scott - 93HB Si &raquo;</TD></TR><TR><TD CLASS="quote">also, did you have anything covering the edges of the rod's big end cap when sliding it down into the cylinder? Exposed rods could cause damage to the side of the wall too, especially with several in/outs to get the piston rings to compress properly.
</TD></TR></TABLE>

No, I didn't think of that... I'm pretty sure that I was alright as far as that goes... but I'll definitely do that on the next motor I assemble. Even if some of them are due to that, there are many other smaller scratches that I can't feel.

The ones pictured, however, I can catch with my fingernail.

 

^^^