| [GMCnet] Tid Bits. How you can be distorying your good running engine [message #331588] |
Tue, 01 May 2018 08:21  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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Senior Member |
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And you will never know it till it's TOO LATE. Your 403, or 455 came with a cam gear that had an aluminum gear sprocket center. That has a plastic gear around it. Most of us are concerned about the cam chain getting loose. Thus retarding the cam shaft timing. That WILL NOT destroy your engine. But when the plastic/aluminum cam gear plastic starts to break off the aluminum core. Next the steel chain starts chewing up the aluminum sprocket core. This then can produce lots of plastic/ aluminum contamination that then restricts ( plugs up ) the oil flow of your oil filter. Then all that contamination causes the oil filter bypass valve to open. So since the oil filter can't filter the oil anymore. Then this contamination starts to destroy your engine main/rod bearings. The replacement chain/sprocket sets are all steel. So if your engine is running great. And has never been rebuilt. You ARE on barrowed time. PIROID. So a couple of hundred to replace the chain set. Or a few thousand for a complete rebuild. This well happen at some point. When we bought or first 78 Royale in 2003. One of the first things I did was to change that chain set. Our origin cam sprocket was still fine. That 403 still runs great at 154,000 miles. Simple choice. Bob Dunahugh
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| Re: [GMCnet] Tid Bits. How you can be distorying your good running engine [message #331600 is a reply to message #331590] |
Tue, 01 May 2018 13:54  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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I think it is caused mostly by age, fatigue, heat cycles, etc. rather than mileage, Billy
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Tid Bits. How you can be distorying your good running engine [message #331608 is a reply to message #331607] |
Tue, 01 May 2018 19:29 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Not all of the 455/403 engines have the cylent timing set. In fact, the
agricultural engines were not factory fitted with them. That is not to say
that you will NEVER ENCOUNTER one in a GMC. 40 years is a long time, and a
whole bunch of stuff can happen in those passing years. If your engine is
fitted with them, best advise would be to remove and replace them with a
true roller set.
Jim Hupy
On Tue, May 1, 2018, 5:13 PM Bob Dunahugh wrote:
> I have a small inspection camera. Pulling the fuel pump should get a view
> of the came gear in that manner Bob Dunahugh.
>
>
> ________________________________
> From: Bob Dunahugh
> Sent: Tuesday, May 1, 2018 8:21 AM
> To: gmclist@list.gmcnet.org
> Subject: Tid Bits. How you can be distorying your good running engine
>
> And you will never know it till it's TOO LATE. Your 403, or 455 came with
> a cam gear that had an aluminum gear sprocket center. That has a plastic
> gear around it. Most of us are concerned about the cam chain getting loose.
> Thus retarding the cam shaft timing. That WILL NOT destroy your engine. But
> when the plastic/aluminum cam gear plastic starts to break off the aluminum
> core. Next the steel chain starts chewing up the aluminum sprocket core.
> This then can produce lots of plastic/ aluminum contamination that then
> restricts ( plugs up ) the oil flow of your oil filter. Then all that
> contamination causes the oil filter bypass valve to open. So since the oil
> filter can't filter the oil anymore. Then this contamination starts to
> destroy your engine main/rod bearings. The replacement chain/sprocket sets
> are all steel. So if your engine is running great. And has never been
> rebuilt. You ARE on barrowed time. PIROID. So a couple of hundred to
> replace the chain set. Or a few thousand for a complete rebuild. This well
> happen at some point. When we bought or first 78 Royale in 2003. One of the
> first things I did was to change that chain set. Our origin cam sprocket
> was still fine. That 403 still runs great at 154,000 miles. Simple
> choice. Bob Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Tid Bits. How you can be distorying your good running engine [message #331631 is a reply to message #331609] |
Wed, 02 May 2018 08:38 |
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I changed mine out @ 85,000 miles as advised on this list. The chain was
streched. Still truckin 55k miles down the road.
bdub
>
>
On May 1, 2018 7:31 PM, "Bob Dunahugh" wrote:
Carl S. I agree with your reasons 100%. I've seen this from high, and low
mileage engine that had those gears. I bought a 403 to keep around as a
core. Had been rebuilt. And had that the plastic/aluminum gear installed.
Ran well. When it was disassembled. A third of the plastic gear was gone to
the bottom of the oil pan. Found plastic shavings embedded in the rod/main
bearings. Bob Dunahugh
________________________________
From: Bob Dunahugh
Sent: Tuesday, May 1, 2018 7:13 PM
To: gmclist@list.gmcnet.org
Subject: RE: Tid Bits. How you can be distorying your good running engine
I have a small inspection camera. Pulling the fuel pump should get a view
of the came gear in that manner Bob Dunahugh.
________________________________
From: Bob Dunahugh
Sent: Tuesday, May 1, 2018 8:21 AM
To: gmclist@list.gmcnet.org
Subject: Tid Bits. How you can be distorying your good running engine
And you will never know it till it's TOO LATE. Your 403, or 455 came with a
cam gear that had an aluminum gear sprocket center. That has a plastic
gear around it. Most of us are concerned about the cam chain getting loose.
Thus retarding the cam shaft timing. That WILL NOT destroy your engine. But
when the plastic/aluminum cam gear plastic starts to break off the aluminum
core. Next the steel chain starts chewing up the aluminum sprocket core.
This then can produce lots of plastic/ aluminum contamination that then
restricts ( plugs up ) the oil flow of your oil filter. Then all that
contamination causes the oil filter bypass valve to open. So since the oil
filter can't filter the oil anymore. Then this contamination starts to
destroy your engine main/rod bearings. The replacement chain/sprocket sets
are all steel. So if your engine is running great. And has never been
rebuilt. You ARE on barrowed time. PIROID. So a couple of hundred to
replace the chain set. Or a few thousand for a complete rebuild. This well
happen at some point. When we bought or first 78 Royale in 2003. One of the
first things I did was to change that chain set. Our origin cam sprocket
was still fine. That 403 still runs great at 154,000 miles. Simple
choice. Bob Dunahugh
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Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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bdub
bdub.net
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| Re: [GMCnet] Tid Bits. How you can be distorying your good running engine [message #331769 is a reply to message #331631] |
Sun, 06 May 2018 05:46 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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Senior Member |
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Worked on installing axels this past week and had a bad thread in the
rotating flange on final drive. Couldn't use a tap handle as the shift
linkage from the tranny was in the way. Found a nut (3/8-16) and pressed
it on (bench vice) the square end of tap and used a ratcheting socket
wrench to clean out the tread.
On Wed, May 2, 2018 at 7:38 AM, Billy Massey wrote:
> I changed mine out @ 85,000 miles as advised on this list. The chain was
> streched. Still truckin 55k miles down the road.
> bdub
>
>
>
>>
>>
> On May 1, 2018 7:31 PM, "Bob Dunahugh" wrote:
>
> Carl S. I agree with your reasons 100%. I've seen this from high, and low
> mileage engine that had those gears. I bought a 403 to keep around as a
> core. Had been rebuilt. And had that the plastic/aluminum gear installed.
> Ran well. When it was disassembled. A third of the plastic gear was gone to
> the bottom of the oil pan. Found plastic shavings embedded in the rod/main
> bearings. Bob Dunahugh
>
>
> ________________________________
> From: Bob Dunahugh
> Sent: Tuesday, May 1, 2018 7:13 PM
> To: gmclist@list.gmcnet.org
> Subject: RE: Tid Bits. How you can be distorying your good running engine
>
>
>
> I have a small inspection camera. Pulling the fuel pump should get a view
> of the came gear in that manner Bob Dunahugh.
>
>
> ________________________________
> From: Bob Dunahugh
> Sent: Tuesday, May 1, 2018 8:21 AM
> To: gmclist@list.gmcnet.org
> Subject: Tid Bits. How you can be distorying your good running engine
>
> And you will never know it till it's TOO LATE. Your 403, or 455 came with a
> cam gear that had an aluminum gear sprocket center. That has a plastic
> gear around it. Most of us are concerned about the cam chain getting loose.
> Thus retarding the cam shaft timing. That WILL NOT destroy your engine. But
> when the plastic/aluminum cam gear plastic starts to break off the aluminum
> core. Next the steel chain starts chewing up the aluminum sprocket core.
> This then can produce lots of plastic/ aluminum contamination that then
> restricts ( plugs up ) the oil flow of your oil filter. Then all that
> contamination causes the oil filter bypass valve to open. So since the oil
> filter can't filter the oil anymore. Then this contamination starts to
> destroy your engine main/rod bearings. The replacement chain/sprocket sets
> are all steel. So if your engine is running great. And has never been
> rebuilt. You ARE on barrowed time. PIROID. So a couple of hundred to
> replace the chain set. Or a few thousand for a complete rebuild. This well
> happen at some point. When we bought or first 78 Royale in 2003. One of the
> first things I did was to change that chain set. Our origin cam sprocket
> was still fine. That 403 still runs great at 154,000 miles. Simple
> choice. Bob Dunahugh
> _______________________________________________
> 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
>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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