Blue Christmas!
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Fleet Owner
Joined: Dec 2000
Posts: 25,361
Likes: 5,376
From: Central PA
Blue Christmas!
As some of you know my truck has not run well since late summer. I had the carb rebuilt, put on a new fuel filter, tuned it up, timed it, etc, etc. Several weeks ago I took it to my local garage and they said it probably needs a valve job.
I called a kid I had in school years ago, he is no longer a kid, and is quite a mechanic. After his compression test, he believes it needs a total rebuild not just the top end. Some of the spark plugs were fouled by gas leaking from the carb. His theory is that over the years, the bowl leaked gas and it glazed the cylinder walls. This screwed up the rings, and so on. So I am shopping around for someone to rebuild it.
Two questions: 1) Does this scenario sound plausible? 2) Should I put hardened seats in?
Thanks! And I am not really blue nor depressed because of my truck problems. Life is good and we are blessed with so much that we have to have our priorities straight especially at Christmas!
I called a kid I had in school years ago, he is no longer a kid, and is quite a mechanic. After his compression test, he believes it needs a total rebuild not just the top end. Some of the spark plugs were fouled by gas leaking from the carb. His theory is that over the years, the bowl leaked gas and it glazed the cylinder walls. This screwed up the rings, and so on. So I am shopping around for someone to rebuild it.
Two questions: 1) Does this scenario sound plausible? 2) Should I put hardened seats in?
Thanks! And I am not really blue nor depressed because of my truck problems. Life is good and we are blessed with so much that we have to have our priorities straight especially at Christmas!
Postmaster
Joined: Mar 2000
Posts: 3,730
Likes: 13
From: Waynesville, OH
Good to see you again Abe.
I had my 272 rebuilt from the bottom up and it was pretty expensive. I have to admit I asked the shop to do everything, including the hardened valve seats you mentioned. In the total bill, those seats were a very small cost, so I'd suggest you go ahead with them.
I had my 272 rebuilt from the bottom up and it was pretty expensive. I have to admit I asked the shop to do everything, including the hardened valve seats you mentioned. In the total bill, those seats were a very small cost, so I'd suggest you go ahead with them.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
I would take what he says for what it is -- the worst case scenario. If you want your engine to be like brand new, yeah you might need to bore it and put in new pistons and rings, put in new bearings, grind the crank, etc. But you may get a good-running engine with just a quick hone, new rings, and clean up the head, valves, all new gaskets, etc.
These older engines were run on oils that weren't anything like today's, so they wore their cylinders pretty hard. Add excess gas and it just gets worse. Whether the cylinders are glazed, or the rings got washed with gas and are just worn out, you can't tell til it's apart. I'd pull the head and pan, see what's what, decide how to go from there.
Hard seats aren't needed IMO.
These older engines were run on oils that weren't anything like today's, so they wore their cylinders pretty hard. Add excess gas and it just gets worse. Whether the cylinders are glazed, or the rings got washed with gas and are just worn out, you can't tell til it's apart. I'd pull the head and pan, see what's what, decide how to go from there.
Hard seats aren't needed IMO.
Posting Guru
Joined: Nov 2001
Posts: 2,156
Likes: 5
From: Akron Ohio
I'm guessing some oil in cylinders after the intial test brought the numbers up indicating rings? Do you notice alot blow-by out the draft-tube/smoke? I have yet to tear-apart a original y-block that didn't have a excessive ridge and need at least a .010 overbore but some people get lucky.
Although I have a original y-block that doesn't seem be bothered by unleaded gas, my rebuilt 292 has hardened seats installed. I would recommend hardened exhaust seats at the very least.
Although I have a original y-block that doesn't seem be bothered by unleaded gas, my rebuilt 292 has hardened seats installed. I would recommend hardened exhaust seats at the very least.
Lead Driver
Joined: Jul 2003
Posts: 9,357
Likes: 1,722
From: AKRON ohio
Abe,
Compression readings tell a lot, as 4speed mentioned did they come up when a "wet" test was performed? Also did the young man perform a leak down test to verify that it is the rings? He is assuming the cylinders have been "washed" by the excessive amounts of fuel. It is very possible.
I wish you were closer so I could take a look at it while its still in the truck.
Compression readings tell a lot, as 4speed mentioned did they come up when a "wet" test was performed? Also did the young man perform a leak down test to verify that it is the rings? He is assuming the cylinders have been "washed" by the excessive amounts of fuel. It is very possible.
I wish you were closer so I could take a look at it while its still in the truck.
Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
Hardened seats are only required on engines that are under heavy load for extended periods. Installing them on heads that weren't designed for them opens up the possibility of weakening the head to where it cracks under heat/stress. Sure, they may give some extra confidence but it is not without risk.
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Fleet Owner
Joined: Dec 2000
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From: Central PA
I'm guessing some oil in cylinders after the intial test brought the numbers up indicating rings? Do you notice alot blow-by out the draft-tube/smoke? I have yet to tear-apart a original y-block that didn't have a excessive ridge and need at least a .010 overbore but some people get lucky.
Although I have a original y-block that doesn't seem be bothered by unleaded gas, my rebuilt 292 has hardened seats installed. I would recommend hardened exhaust seats at the very least.
Although I have a original y-block that doesn't seem be bothered by unleaded gas, my rebuilt 292 has hardened seats installed. I would recommend hardened exhaust seats at the very least.
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Thread Starter
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Fleet Owner
Joined: Dec 2000
Posts: 25,361
Likes: 5,376
From: Central PA
Abe,
Compression readings tell a lot, as 4speed mentioned did they come up when a "wet" test was performed? Also did the young man perform a leak down test to verify that it is the rings? He is assuming the cylinders have been "washed" by the excessive amounts of fuel. It is very possible.
I wish you were closer so I could take a look at it while its still in the truck.
Compression readings tell a lot, as 4speed mentioned did they come up when a "wet" test was performed? Also did the young man perform a leak down test to verify that it is the rings? He is assuming the cylinders have been "washed" by the excessive amounts of fuel. It is very possible.
I wish you were closer so I could take a look at it while its still in the truck.
He did not do a wet test or a leak down test, just the compressed air test.
He did say the old girl is tired!
I had the engine rebuilt in 1979. I bought the truck in 1977 with 103,000 miles on the odometer. But the odometer was not working until I rebuilt the truck in 1999. So I figure the engine had well over 110,000 miles on it before the first rebuild, and if I averaged just 4,000 miles a year from 79 to 09 that would be over 120,000 miles, which is a modest estimate cause I used the truck early on as a second car. So the rebuild lasted longer (30 years) than the engine out of the factory... So I guess it is due!
I am checking a couple of places around here and my brother has a guy that does his work in Lancaster.
Posting Guru
Joined: Nov 2001
Posts: 2,156
Likes: 5
From: Akron Ohio
A wet test would of helped confirm ring/cylinder wear. I'm guessing all cylinders were on the lower side for compression, which is usually a indication of a tired engine. If it was one cylinder I would be more curious but it sounds like he knew what saw. Besides with the estimated miles on it, it sounds like she's time for a rebuild. -4speed
