Unusual marking on cylinder wall - The 1947 - Present Chevrolet & GMC Truck Message Board Network

straight6chevyguy · 01-31-2021, 09:17 PM

Anybody know what caused this? Is it serious?
I'm hoping it's not a crack!
Engine is a Chevy 250, cylinder #6

straight6chevyguy · 01-31-2021, 09:22 PM

The Piston From that same cylinder.

cadillac_al · 01-31-2021, 09:49 PM

It looks like it rusted. The engine might have sat in a barn for 20 years at some time in its life.

**truckster** · 01-31-2021, 10:11 PM

I agree. Water sitting in the cylinder for a long time.

straight6chevyguy · 01-31-2021, 10:27 PM

Thanks guys, I think that did cross my mind.
The engine had been running not long before I purchased it but no clue what has happened earlier in it's life.

**truckster** · 01-31-2021, 11:16 PM

I would say they got it running with the damaged cylinder wall and the scoring on the piston skirt is a result of the rough surface of the cylinder wall.

**kwmech** · 02-01-2021, 01:29 PM

All of the above, time for a cylinder sleeve

Dead Parrot · 02-02-2021, 11:17 AM

Agree with the water sitting in cylinder thoughts. The piston scoring probably happened on the initial start when the rust was being scraped off the walls in both directions.

Might want to flush all the oil passages in case some of the rust escaped past the filter.

Fix might range from something as simple as a good honing and new rings for something that will see only occasional use to boring out all the cylinders and installing new oversized pistons.

**AussieinNC** · 02-03-2021, 09:53 PM

Would suggest new pistons....plus 030 or 060...and a rebore....

New pistons are around $100 a set....

**'68OrangeSunshine** · 02-07-2021, 05:09 PM

Rebuild. Bore 30 over. Rods and crank may be reusable. Look into a cam upgrade.
No worries. Lasts a long time.

vince1 · 02-07-2021, 08:53 PM

New rings, polish the piston and you're good to go, for a while. Or splurge on a new piston and it will go even farther. For the few miles I drive a year it would outlast me.

01-31-2021, 09:17 PM	#1
straight6chevyguy Registered User Join Date: Dec 2018 Location: yamhill OR Posts: 785	Unusual marking on cylinder wall Anybody know what caused this? Is it serious? I'm hoping it's not a crack! Engine is a Chevy 250, cylinder #6 Attached Images __________________ 1965 chevy c20 292 4speed http://67-72chevytrucks.com/vboard/s...d.php?t=777601 1976 chevy c10 250 4speed http://www.67-72chevytrucks.com/vboa...d.php?t=787037 1998 chevy c1500 4.3L 5speed (My current driver) 2002 Chevy s10 4.3L auto 4x4 1971 mercury monterey wagon 400 auto To many projects!

01-31-2021, 09:22 PM	#2
straight6chevyguy Registered User Join Date: Dec 2018 Location: yamhill OR Posts: 785	Re: Unusual marking on cylinder wall The Piston From that same cylinder. Attached Images __________________ 1965 chevy c20 292 4speed http://67-72chevytrucks.com/vboard/s...d.php?t=777601 1976 chevy c10 250 4speed http://www.67-72chevytrucks.com/vboa...d.php?t=787037 1998 chevy c1500 4.3L 5speed (My current driver) 2002 Chevy s10 4.3L auto 4x4 1971 mercury monterey wagon 400 auto To many projects!

01-31-2021, 09:49 PM	#3
cadillac_al Registered User Join Date: Oct 2013 Location: Maine Posts: 2,332	Re: Unusual marking on cylinder wall It looks like it rusted. The engine might have sat in a barn for 20 years at some time in its life. __________________ 76 Chevy K20 76 GMC K15 77 Chevy C10 77 Chevy K10

01-31-2021, 10:11 PM	#4
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,791	Re: Unusual marking on cylinder wall I agree. Water sitting in the cylinder for a long time. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

01-31-2021, 10:27 PM	#5
straight6chevyguy Registered User Join Date: Dec 2018 Location: yamhill OR Posts: 785	Re: Unusual marking on cylinder wall Thanks guys, I think that did cross my mind. The engine had been running not long before I purchased it but no clue what has happened earlier in it's life. __________________ 1965 chevy c20 292 4speed http://67-72chevytrucks.com/vboard/s...d.php?t=777601 1976 chevy c10 250 4speed http://www.67-72chevytrucks.com/vboa...d.php?t=787037 1998 chevy c1500 4.3L 5speed (My current driver) 2002 Chevy s10 4.3L auto 4x4 1971 mercury monterey wagon 400 auto To many projects!

01-31-2021, 11:16 PM	#6
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,791	Re: Unusual marking on cylinder wall I would say they got it running with the damaged cylinder wall and the scoring on the piston skirt is a result of the rough surface of the cylinder wall. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

02-01-2021, 01:29 PM	#7
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,388	Re: Unusual marking on cylinder wall All of the above, time for a cylinder sleeve

02-02-2021, 11:17 AM	#8
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,472	Re: Unusual marking on cylinder wall Agree with the water sitting in cylinder thoughts. The piston scoring probably happened on the initial start when the rust was being scraped off the walls in both directions. Might want to flush all the oil passages in case some of the rust escaped past the filter. Fix might range from something as simple as a good honing and new rings for something that will see only occasional use to boring out all the cylinders and installing new oversized pistons.

02-03-2021, 09:53 PM	#9
AussieinNC Moderator Join Date: Jun 2017 Location: Cherryville, NC Posts: 2,153	Re: Unusual marking on cylinder wall Would suggest new pistons....plus 030 or 060...and a rebore.... New pistons are around $100 a set.... __________________ Family and country before all others... 2006 Chevy Silverado (Daily Driver) 2012 Chevy Equinox

02-07-2021, 05:09 PM	#10
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,029	Re: Unusual marking on cylinder wall Rebuild. Bore 30 over. Rods and crank may be reusable. Look into a cam upgrade. No worries. Lasts a long time. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

02-07-2021, 08:53 PM	#11
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,164	Re: Unusual marking on cylinder wall New rings, polish the piston and you're good to go, for a while. Or splurge on a new piston and it will go even farther. For the few miles I drive a year it would outlast me.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.