| 455 [message #350559] |
Sat, 07 December 2019 19:23  |
Melbo
Messages: 144
Registered: August 2018
Location: Albuquerque NM
Karma: 0
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I have done the fuel tanks and have the onan making electricity again. Now I am starting on the 455. I pulled the fuel pump and looked with a mirror at the cam timing gear. It appears to have the nylon coating on the teeth. It has a reddish looking material along the edge and teeth of the gear. The rest of the gear is silver. I'm guessing that is the nylon coating. When I used to replace them in the early seventies the nylon coating was typically white on the pontiac motors I worked on. If this is something different please let me know. So if I am going to pull the timing chain and gears would it be a good idea to check the compression before I do that JUST in case there is more work to be done? I will change the oil and filter pull the dizzy and run a drill on the oil pump and put oil in the cylinders before the compression tests. I would replace the water pump and have the alternator and starter gone over while I am into the motor BUT I am wondering if there is anything else I should do. If the compression is bad or majorly uneven between cylinders the project just got bigger. The odo only shows 60K and with the nylon coating still there I'm thinking that could be accurate. Any thoughts or sense of direction is always appreciated.
Melbo
Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
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| Re: [GMCnet] 455 [message #350561 is a reply to message #350559] |
Sat, 07 December 2019 22:29  |
johnd01
Messages: 354
Registered: July 2017
Location: Sacrameot
Karma: -1
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Senior Member |
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Does the brake pedal look like 60k, 160k or 260k?
On Sat, Dec 7, 2019 at 5:24 PM melmull--- via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I have done the fuel tanks and have the onan making electricity again.
> Now I am starting on the 455. I pulled the fuel pump and looked with a
> mirror
> at the cam timing gear. It appears to have the nylon coating on the
> teeth. It has a reddish looking material along the edge and teeth of the
> gear.
> The rest of the gear is silver. I'm guessing that is the nylon coating.
> When I used to replace them in the early seventies the nylon coating was
> typically white on the pontiac motors I worked on. If this is something
> different please let me know. So if I am going to pull the timing chain and
> gears would it be a good idea to check the compression before I do that
> JUST in case there is more work to be done? I will change the oil and filter
> pull the dizzy and run a drill on the oil pump and put oil in the
> cylinders before the compression tests. I would replace the water pump and
> have the
> alternator and starter gone over while I am into the motor BUT I am
> wondering if there is anything else I should do. If the compression is bad
> or
> majorly uneven between cylinders the project just got bigger. The odo
> only shows 60K and with the nylon coating still there I'm thinking that
> could
> be accurate. Any thoughts or sense of direction is always appreciated.
>
> Melbo
> --
> Albuquerque NM Bus Conversion 1978 MCI 1973 GMC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
*John Phillips*
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GMCnet mailing list
Unsubscribe or Change List Options:
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Johnd01
John Phillips
Avion A2600 TZE064V101164
Rancho Cordova, CA (Sacramento)
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| Re: 455 [message #350565 is a reply to message #350559] |
Sun, 08 December 2019 09:12 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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At 60K that 455 is just broken in good. Run it. And unless there's slack in the chain, leave it alone for another 40k or so.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: 455 [message #350567 is a reply to message #350559] |
Sun, 08 December 2019 10:12 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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The nylon turns brownish over time from combustion by products. It 60K it's not worn out but may he timed out for brittleness The nylon can leave in chunks. Not sure I understand the sequence here but I would run the engine, listen for ticks and knocks, then do compression test. Doing timing set is waisted time if there is bad compression or a knock.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: 455 [message #350656 is a reply to message #350567] |
Fri, 13 December 2019 11:19 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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I was told when I got my coach, that the nylon teeth on the cam gear wear out more as a function of age than mileage Jim Bounds, among other knowledgeable mechanics suggested that I replace the timing set before the nylon teeth start coming apart and end up plugging up the oil intake. I did that at about 70,000 miles and the teeth looked fine, at that point.
It makes sense to do as John L suggests and get the engine running for some diagnostics before you start tearing into the timing chain. You'll want the engine close to operating temperature in order to perform an accurate compression test anyway. I'm guessing you will find everything in order on a 60,000 mile engine unless it was abused or service was neglected.
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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