Cylinder Wall Discoloration

RoDyne · Post by **RoDyne** » Mon Dec 06, 2004 9:23 pm

Forgive me if this isn't the correct place for this subject.

A customer called to question me about oil consumption on a 2.1L DOHC Honda Prelude SI. The information he gave me was lacking and he should have done more diagnosing before opening up the engine. I inspected the be-headed engine and found nothing of importance execpt the "gray"ish coloration of the cylinder walls, evenly discolored throughout the ring swept area (bottom end still together and pan still on) and excessive carbon accumulation in the combustion chamber. The mechanic stated that there was a known exhaust leak in the EGR system but could not tell me anything about the tailpipe emissions. He could not tell me the amount of milage since I bored and honed the motor last November (1 year ago) but his customer was complaining about the excessive oil usage being 1 qt every 1000 mi.

The pistons and rings were Top-Line, with the rings being a chrome top, ductile iron second and standard tension oil ring.

I Used a 280 Sunnen stone at 27 degree crosshatch.

What is the cause for the gray coloration of the cylinder walls? Ring wear? Brand of Oil? Fuel? All of the aforementioned?

Walline · Post by **Walline** » Mon Dec 06, 2004 9:53 pm

Do you have pictures of the engine?

doublej · Post by **doublej** » Mon Dec 06, 2004 10:20 pm

Assume it's H22? What year? I think some early-mid 90's h22 blocks did have an iron liner. But the alloy bore blocks do "look" grey.

Your customer didn't give you much useful to go on!

Jim Justice

RoDyne · Post by **RoDyne** » Mon Dec 06, 2004 10:47 pm

Sorry guys, no pictures.

It's a '91 year model and it is a iron liner block. Nothing out of the ordinary, but I would bet the owner has driving habits that would make Dale Jr. take a dirt road.

Thanks.