Home » Public Forums » GMCnet » Engine rebuild has begun
| Engine rebuild has begun [message #351396] |
Thu, 16 January 2020 07:51  |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Many folks across NC, FL, and TN have listened to my now 8000 mile, PO rebuild by a non GMC shop to diagnose the knock that was mainly evident on hot restart. With no definite answers from some of the best mechanics, it is coming out to check the innards before a catastrophic or inconvenient failure. The warm week here has been favorable (though wet) to start. A local GMC'er that already had a trolley built is helping me, and I'm hoping to have the last few accessories off today to swing the 455 through the kitchen and cherry pick it out the door. I'm taking video and pics and will probably do some across Youtube, Facebook and the GMC photo site.
The first problem that I have found is a significant crack on the passenger side stock exhaust manifold. Anyone have a spare?
Stay tuned! I'll add a more in-depth post to this thread about the "why" of this rebuild...hoping for an answer to the main concern of the knock! Care to claim a cause this early in the process? Is it A) main bearing B) thrust bearing C) thrust plate D) broken piston sleeve E) other?
Tyler
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| Re: Engine rebuild has begun [message #351397 is a reply to message #351396] |
Thu, 16 January 2020 12:43  |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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I thought mine had a knock too, until further investigation with a hose stuck in my ear pinpointed it to an exhaust leak at the choke stove cover plate. Mine did not go away after warmup, but a cracked exhaust manifold will sound like that and then go away after it gets hot and closes the gap. Seen it several times on small block Ford trucks, probably caused by water splash from front tires, but not on my GMC as I still have the inner fenders installed.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Engine rebuild has begun [message #351400 is a reply to message #351396] |
Thu, 16 January 2020 20:27 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Call cinnebar for an exhaust manifold. Brand new About $300 to your door.
Good luck. One of our local club members had a low knock on a rebuild as well. He drove it a bit trying to verify it was indeed a knock and hoping it was something else. Eventually started on the engine build.
He had a new engine dyno'd sitting on an engine stand and on the way to the shop to get it installed it let go and busted everything including the cam in 1/2. No core refund for him.
So I am sure you have the right people involved now. Good luck.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Engine rebuild has begun [message #351472 is a reply to message #351396] |
Mon, 20 January 2020 18:23 |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Senior Member |
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And the winner is....number six rod bearing.
There was plenty of trash in this motor - one piece of a casting was as big as the end of my pinky finger. There were bits of metal scored and trapped in some of the other bearings, but the number six had moved. Silver/nickel color surface was worn off to gouges of copper evident on number six and one other rod bearing.
Took it to the machine shop and his first comments were that it looked like it had the wrong valve guides and springs.
Time to start ironing things out! Not all is lost...full assessment next and do what it needs for clean and to specs.
Oh, and the timing chain - with only about 8000 miles it had major slop. Did they put new gears and use original chain? Do not know the answer to that or several other things that have led to this rebuild!
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| Re: Engine rebuild has begun [message #351475 is a reply to message #351472] |
Mon, 20 January 2020 19:09 |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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A few years ago when I disassembled what was to become my spare engine I found that the previous rebuilder had put solid plugs in the oil galleries instead of plugs with a small hole in them.
The 455 uses the hole in the passenger side front gallery plug to shoot oil onto the timing chain and on the drivers side rear to oil the distributor gear. The lack of oil had made the timing chain and all-metal gears severely wear. The distributor gear on the camshaft was also very worn. The excessive wear on the crank journals, cam lobes, and the bearings was probably caused by all the metal filings floating around the engine. Supposedly it was a fairly low mileage rebuild, although I don't know it's true history.
When I rebuilt it I installed the proper oil gallery plugs with the small hole in them. I have not installed the engine in my GMC yet as the original 455 just keeps on going. I occasionally run the spare engine (did it again this afternoon) on a stand to keep in ready to go.
You might want to see of the previous rebuilder of your engine put the proper oil gallery plugs in your engine. As I found out, lots of excessive wear takes place without proper oiling.
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: Engine rebuild has begun [message #351477 is a reply to message #351396] |
Mon, 20 January 2020 20:24 |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Senior Member |
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Bob, you hit on something! You guys are awesome...
So I'm guessing that's why the bolts are two sizes, to put the one with a hole in the right place.
AND guess where a piece of debris lodged? I went out to garage and looked after I read your reply. Yep...the bolt does have a hole, but it is 100% blocked with one of those metal spits. Don't know which came first, but a slew of not goods that shall be remedied.
Thanks
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| Re: [GMCnet] Engine rebuild has begun [message #351645 is a reply to message #351396] |
Thu, 16 January 2020 10:23 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Thrust bearing issue can be easily checked by using a dial gage on the
crank and levering a pry bar carefully at the harmonic balancer and push
and pull.
On Thu, Jan 16, 2020 at 5:52 AM Tyler via Gmclist
wrote:
> Many folks across NC, FL, and TN have listened to my now 8000 mile, PO
> rebuild by a non GMC shop to diagnose the knock that was mainly evident on
> hot
> restart. With no definite answers from some of the best mechanics, it is
> coming out to check the innards before a catastrophic or inconvenient
> failure. The warm week here has been favorable (though wet) to start. A
> local GMC'er that already had a trolley built is helping me, and I'm hoping
> to
> have the last few accessories off today to swing the 455 through the
> kitchen and cherry pick it out the door. I'm taking video and pics and will
> probably do some across Youtube, Facebook and the GMC photo site.
>
> The first problem that I have found is a significant crack on the
> passenger side stock exhaust manifold. Anyone have a spare?
>
> Stay tuned! I'll add a more in-depth post to this thread about the "why"
> of this rebuild...hoping for an answer to the main concern of the knock!
> Care
> to claim a cause this early in the process? Is it A) main bearing B)
> thrust bearing C) thrust plate D) broken piston sleeve E) other?
>
> Tyler
>
>
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Engine rebuild has begun [message #351648 is a reply to message #351645] |
Thu, 16 January 2020 13:22 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Bet you have never heard this one. I built a 455 for a customer, which he
and some non GMC helpers installed. As he was a very knowledgeable
mechanic, and I gave him explicit installation and break-in procedures,
which he followed to the letter, I had no concerns that he had dotted all
the i's and crossed all the t's.
So, it surprised me a whole lot when he claimed that my engine had a
sharp knock. I drove to his location, verified that he indeed did have a
knock. So, I had him deliver the coach to my location in order for me to
repair it. I pulled the engine, and very carefully disassembled it,
measuring everything very carefully. After completing the teardown, I
installed another different 455 into his coach, and as I was inspecting the
flex plate from his old engine that I was re-using on the new engine, I
noticed that the slotted holes to the torque converter looked very shiny
where the heads of the bolts met the flex plate.
Hmmm? So, I checked the torque converter lugs with an inspection
camera, and lo and behold discovered that the bottoms of the holes were
marked by the fasteners. Turns out, he had replaced the torque converter
fasteners with new very high quality ones, but did not match the lengths of
the OEM fasteners that he discarded. Seems the new, high zoot bolts were a
touch too long. They bottomed in the holes before they clamped the flex
plate to the torque converter, and the firing impulses of the crank caused
the bolts to move laterally, making one hell of a knock. There wasn't
anything wrong with the original engine, that's why i could not figure out
where the knock was coming from. Go figure.
Jim Hupy
Salem, Oregon
On Thu, Jan 16, 2020, 10:49 AM Dave Stragand via Gmclist <
gmclist@list.gmcnet.org> wrote:
> The crack in your exhaust manifold just might be the cause of your
> knock. I had that exact issue on a 472 Caddy motor. How far apart do
> you have it? Can you swap out the manifold and try it before going any
> further?
>
> -Dave
> 1978 Transmode near Pittsburgh
>
>
> _______________________________________________
> GMCnet mailing list
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| Re: [GMCnet] Engine rebuild has begun [message #351702 is a reply to message #351477] |
Tue, 21 January 2020 06:54 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Tyler, et al,
What am I missing? Apparently I, exclusively on the mailing list, have
missed at least one posting, that from "Bob" describing some potential
engine problem which you verified. Please let me in on the "secret". And
if anyone understands how I might have failed to receive that posting,
please let me know.
Ken H
On Mon, Jan 20, 2020 at 9:25 PM Tyler via Gmclist
wrote:
> Bob, you hit on something! You guys are awesome...
>
> So I'm guessing that's why the bolts are two sizes, to put the one with a
> hole in the right place.
>
> AND guess where a piece of debris lodged? I went out to garage and looked
> after I read your reply. Yep...the bolt does have a hole, but it is 100%
> blocked with one of those metal spits. Don't know which came first, but a
> slew of not goods that shall be remedied.
> Thanks
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Unsubscribe or Change List Options:
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Engine rebuild has begun [message #351707 is a reply to message #351702] |
Tue, 21 January 2020 13:23 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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I'm on email and I don't see bob's posting either
________________________________
From: Gmclist on behalf of Ken Henderson via Gmclist
Sent: Tuesday, January 21, 2020 6:54 AM
To: GMC Mail List
Cc: Ken Henderson ; Tyler
Subject: Re: [GMCnet] Engine rebuild has begun
Tyler, et al,
What am I missing? Apparently I, exclusively on the mailing list, have
missed at least one posting, that from "Bob" describing some potential
engine problem which you verified. Please let me in on the "secret". And
if anyone understands how I might have failed to receive that posting,
please let me know.
Ken H
On Mon, Jan 20, 2020 at 9:25 PM Tyler via Gmclist
wrote:
> Bob, you hit on something! You guys are awesome...
>
> So I'm guessing that's why the bolts are two sizes, to put the one with a
> hole in the right place.
>
> AND guess where a piece of debris lodged? I went out to garage and looked
> after I read your reply. Yep...the bolt does have a hole, but it is 100%
> blocked with one of those metal spits. Don't know which came first, but a
> slew of not goods that shall be remedied.
> Thanks
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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Unsubscribe or Change List Options:
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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