Engine condition?

[dahodges]

I took the head off of my new (121K miles) engine today.

Head looks good.

Very little carbon deposit in the combustion chambers.

There are no crosshatch marks left on any of the cylinder walls. Very little ring grove.

Number 1 cylinder wall was nice and shiney like it shoud be. Spark plug was black like it was running a little rich.

The other three spark plugs were brown like they are suppose to be. But there was black squires/rectangle staining (carbon deposits) sideways on the cylinder walls. Not up and down in relation to pistion movement.

Question. Should I put in new rings? Scuff up the cylinder walls with some sandpaper? Break the glaze. Or just leave well enought alone.

Thanks

David

[jglutz]

How far down the cylinder wall...from the top down...is the "stainig"

If the only go from the deck to where the top piston ring is when the piston is all the way up...not to much to worry about.

This is normal carbon build up...be careful trying to take it off...sometime it's so baked on..it will take part of the cyylinder wall with it. They make a special tool for this purpuse called a ridge reamer.


Breaking the glaze with the piston install. I'm not to sure if anything is worth doing because the cross hatch needs to extend below the bottom ring when the piston is at BDC...not sure how to do that by hand.

[dahodges]

Its mainly about 1/3rd the way down. During the portion of the power stroke were pressure starts dropping off quickly.

[Dave G]

You didn't happen to run a compression test before taking it apart, did you?

[dahodges]

wasn't really able to.

David

[blkfordsedan]

I would leave well enough alone, unless you are planning to do a rebuild. New rings and a fresh hone won't do much good if the cylinders or piston skirts are worn. Are there score marks on the cylinder walls? I would not try to clean anything up with the pistons in. No need to use a ridge-reamer unless your putting new rings in it. The last thing you want is to get crud down in the ring lands. The cross-hatch pattern is done with a hone tool to prepare the cylinder walls for proper ring seal and is a good thing. There is an optimum angle to the hatch. I would suggest taking it to a trustworthy machine shop and have them take a look. They can tell the condition by looking and measure the bores and compare to new specs. You may get by reusing the original pistons and just just cleaning up the bores with a hone as long as everything measures round and piston to wall clearance is OK. If it ran good and didn't smoke or burn oil I would leave it. Just for curiosity, why did you pull the head?

[dahodges]

I could not hear the engine run. Want to check everything out make any repairs nessary so I don't have to pull the engine out later.

Thanks

David