Engine @ ~100, 000 miles, runs good but all original, what to do?

[gmc260]

most all the coaches Ive looked at are approaching 100,000 miles and the engine history is mostly unknown but lets say you get one with 100,000 on the
clock that is running great and appears to be bone stock.

what service/maintenance, upgrades, and mods would you do to it right off the bat?

outside of the usual compression test, and from my reading up on these 455s so far:

-double roller Timing chain and sprockets
-remove intake manifold and install block off plates
-remove mechanical fuel pump and install block off plate and carter electric pump (or two)
-remove exhaust manifolds/headers and install remflex gaskets
-replace water pump with new roller bearing one and keep the old one as a known good spare for emergency useage
-replace oil cooler lines with new stainless braided lines
-upgrade to HEI ignition if existing one is mechanical
-replace starter with new and keep old one as a known good spare for emergency usage
-replace all belts, hoses, filters and keep old ones for spares

what else? is a knock sensor and indicator really a must have right away?

I havnt seen much stuff about any carb upgrades or mods except fuel injection and thats not something to do right away. how about adding an O2 sensor
or two and a mixture indicator gauge?

or what other engine stuff do you think should be done A.S.A.P.?

oh yeah, lower radiator grille/guard if it hasnt one already. anything else to do before you take off for a +1000mi road trip?

 

[thomas phipps]

If your exhaust manifolds are not leaking, do not remove just to install Remflex gaskets. Gasket set is cheap enough and consumes little storage
room-just carry set as spare. Easy enough to change almost anywhere. Most time would be spent waiting for the engine to cool down. Generally, on the
455, it is the passenger side that lets go. Read back in the forum, on the cautions on replacing the Remflex.

When you install the intake block-off plate/gasket set (Dick Patterson set), replace the turkey tray with the smaller one from JmK.

Starter is generally easily available from auto parts store. I would not replace a know good one, until it fails. You should remove the cables to the
starter and clean the crud off the cable ends and the starter studs. Apply anti-seize when reconnecting the cables.

Replacing the hoses and fan belts is a good idea. Keeping the 'old' ones as spare might be a good idea, especially the belts. JR's oil cooler lines
are an excellent replacement. Trash the old ones. You cannot break JR's oil lines. HEI yes.

It's your engine and your comfort zone.

Tom
--
2012 Phoenix Cruiser model 2552
KA4CSG

 

[john r. lebetski]

I would not remove mech pump
E pumps fail like clockwork.
Add a e pump via relay to Aux tank.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[robert mueller]

Tom,

I'm going to disagree with you; there is no need to reinstall a turkey tray as the block off plates reduce the temperature in the
lifter valley to 173F.

http://www.gmcmhphotos.com/photos/aa-miscellaneous-photos/p63426-intake-manifold-internal-temp.html

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Thomas Phipps
Sent: Friday, May 25, 2018 7:19 PM
To: gmclist
Subject: Re: [GMCnet] Engine @ ~100, 000 miles, runs good but all original, what to do?

If your exhaust manifolds are not leaking, do not remove just to install Remflex gaskets. Gasket set is cheap enough and consumes
little storage room-just carry set as spare. Easy enough to change almost anywhere. Most time would be spent waiting for the engine
to cool down. Generally, on the 455, it is the passenger side that lets go. Read back in the forum, on the cautions on replacing the
Remflex.

When you install the intake block-off plate/gasket set (Dick Patterson set), replace the turkey tray with the smaller one from JmK.

Starter is generally easily available from auto parts store. I would not replace a know good one, until it fails. You should remove
the cables to the starter and clean the crud off the cable ends and the starter studs. Apply anti-seize when reconnecting the
cables.

Replacing the hoses and fan belts is a good idea. Keeping the 'old' ones as spare might be a good idea, especially the belts. JR's
oil cooler lines are an excellent replacement. Trash the old ones. You cannot break JR's oil lines. HEI yes.

It's your engine and your comfort zone.

Tom
--
2012 Phoenix Cruiser model 2552
KA4CSG

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[Irish Rogue]

Fred:
Throw those old belts and hoses away after you have
acquired a good operational set and a 2nd (spare) set.
A spare set does not cost that much!
And - you don't want a worn/questionable set as your safety net.
Mike/The Corvair a holic

Sent from my iPhone

>
> most all the coaches Ive looked at are approaching 100,000 miles and the engine history is mostly unknown but lets say you get one with 100,000 on the
> clock that is running great and appears to be bone stock.
>
> what service/maintenance, upgrades, and mods would you do to it right off the bat?
>
> outside of the usual compression test, and from my reading up on these 455s so far:
>
> -double roller Timing chain and sprockets
> -remove intake manifold and install block off plates
> -remove mechanical fuel pump and install block off plate and carter electric pump (or two)
> -remove exhaust manifolds/headers and install remflex gaskets
> -replace water pump with new roller bearing one and keep the old one as a known good spare for emergency useage
> -replace oil cooler lines with new stainless braided lines
> -upgrade to HEI ignition if existing one is mechanical
> -replace starter with new and keep old one as a known good spare for emergency usage
> -replace all belts, hoses, filters and keep old ones for spares
>
> what else? is a knock sensor and indicator really a must have right away?
>
> I havnt seen much stuff about any carb upgrades or mods except fuel injection and thats not something to do right away. how about adding an O2 sensor
> or two and a mixture indicator gauge?
>
> or what other engine stuff do you think should be done A.S.A.P.?
>
> oh yeah, lower radiator grille/guard if it hasnt one already. anything else to do before you take off for a +1000mi road trip?
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[Matt Colie]

Noname,

Changing to HEI is only a little of an upgrade. HEI is know for its low reliability. (Some may choose to argue, but GMs warranty does not.)
It is still has points, that is a maintenance issue that can be corrected without having to hammer the air filter housing into submission.

Replace the point set with a Pertronix 1181LS and never look back.
While you are at it, disassemble and lubricate the distributor.

Want more spark?
Get a real CDI. MSD is one of these just not my favorite as I have had two fail.

Other than that, do what you have to do to enjoy your coach.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[Jim Hupy]

Just a comment about used water pumps as spares. When pumps are assembled,
they are lubricated with some consideration towards storage before they are
installed. After they have been used, the shaft and seal no longer have
that protection.
I have overhauled engines that took a long time to complete,
installed the old water pump and had them leak. Grrrrrrr. I put them in a
bucket of anti-freeze if I plan on using them over now, in hopes that the
seal won't dry out and leak.
I know, modern seals are not leather like old ones were and that might
change storage facts a bit.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Fred:
> Throw those old belts and hoses away after you have
> acquired a good operational set and a 2nd (spare) set.
> A spare set does not cost that much!
> And - you don't want a worn/questionable set as your safety net.
> Mike/The Corvair a holic
>
> Sent from my iPhone
>

> >
> > most all the coaches Ive looked at are approaching 100,000 miles and the
> engine history is mostly unknown but lets say you get one with 100,000 on
> the
> > clock that is running great and appears to be bone stock.
> >
> > what service/maintenance, upgrades, and mods would you do to it right
> off the bat?
> >
> > outside of the usual compression test, and from my reading up on these
> 455s so far:
> >
> > -double roller Timing chain and sprockets
> > -remove intake manifold and install block off plates
> > -remove mechanical fuel pump and install block off plate and carter
> electric pump (or two)
> > -remove exhaust manifolds/headers and install remflex gaskets
> > -replace water pump with new roller bearing one and keep the old one as
> a known good spare for emergency useage
> > -replace oil cooler lines with new stainless braided lines
> > -upgrade to HEI ignition if existing one is mechanical
> > -replace starter with new and keep old one as a known good spare for
> emergency usage
> > -replace all belts, hoses, filters and keep old ones for spares
> >
> > what else? is a knock sensor and indicator really a must have right away?
> >
> > I havnt seen much stuff about any carb upgrades or mods except fuel
> injection and thats not something to do right away. how about adding an O2
> sensor
> > or two and a mixture indicator gauge?
> >
> > or what other engine stuff do you think should be done A.S.A.P.?
> >
> > oh yeah, lower radiator grille/guard if it hasnt one already. anything
> else to do before you take off for a +1000mi road trip?
> >
> > _______________________________________________
> > 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]

If you have the original starter never give it up as a core. Have it
rebuilt by a professional.
It will last much longer than any remanufactured or new starters of today.

> Fred:
> Throw those old belts and hoses away after you have
> acquired a good operational set and a 2nd (spare) set.
> A spare set does not cost that much!
> And - you don't want a worn/questionable set as your safety net.
> Mike/The Corvair a holic
>
> Sent from my iPhone
>

> >
> > most all the coaches Ive looked at are approaching 100,000 miles and the
> engine history is mostly unknown but lets say you get one with 100,000 on
> the
> > clock that is running great and appears to be bone stock.
> >
> > what service/maintenance, upgrades, and mods would you do to it right
> off the bat?
> >
> > outside of the usual compression test, and from my reading up on these
> 455s so far:
> >
> > -double roller Timing chain and sprockets
> > -remove intake manifold and install block off plates
> > -remove mechanical fuel pump and install block off plate and carter
> electric pump (or two)
> > -remove exhaust manifolds/headers and install remflex gaskets
> > -replace water pump with new roller bearing one and keep the old one as
> a known good spare for emergency useage
> > -replace oil cooler lines with new stainless braided lines
> > -upgrade to HEI ignition if existing one is mechanical
> > -replace starter with new and keep old one as a known good spare for
> emergency usage
> > -replace all belts, hoses, filters and keep old ones for spares
> >
> > what else? is a knock sensor and indicator really a must have right away?
> >
> > I havnt seen much stuff about any carb upgrades or mods except fuel
> injection and thats not something to do right away. how about adding an O2
> sensor
> > or two and a mixture indicator gauge?
> >
> > or what other engine stuff do you think should be done A.S.A.P.?
> >
> > oh yeah, lower radiator grille/guard if it hasnt one already. anything
> else to do before you take off for a +1000mi road trip?
> >
> > _______________________________________________
> > 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

 

[Carl Stouffer]

I was advised to preemptively rebuild the engine and transmission on my coach when it hit 100,000 miles. I thought that was a dumb idea at the time,
who does that? But when they both failed at 104,500 miles, I wished I had done just that. I got away with rebuilding without having to replace the
block (I DID need a new crankshaft and rods), but had to spend money on things I wouldn't have had I taken that advice.

There are lots of exceptions, but the running gear of that era was generally good for not much more than 100,000 miles.

I totally agree with Jim H on the water pump. trying to reuse a used dried up water pump is asking for trouble. You WILL end up doing it again.

--
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

 

[george beckman]

> most all the coaches Ive looked at are approaching 100,000 miles and the engine history is mostly unknown but lets say you get one with 100,000 on
> the clock that is running great and appears to be bone stock.

Drive it. GM did a great job with their engines. Originals can go 140,000 and still use no oil. Rebuilds- Well, after 10K I would begin to trust it.
Block off might not be a bad idea, but every time you open something, you can have trouble. Put a new fuel pump on if it is not fairly new as new gas
can eat up the diaphragm. Just my take.
--
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George

 

[Jim Hupy]

In my experience, mechanical fuel pumps outlast electric ones, and they
perform consistently throughout their service life. They are susceptible to
alcohol deterioration, however, and when the diaphragm fails, they leak
fuel into the engine sometimes. Worth keeping a watchful eye on though.
They do stop pumping when the engine quits, which is a good thing.
Ask those who have had an underhood fire fed by an electric fuel
pump. Good idea to control them with a relay that opens when the engine
quits.
Jim Hupy

> > most all the coaches Ive looked at are approaching 100,000 miles and the
> engine history is mostly unknown but lets say you get one with 100,000 on
> > the clock that is running great and appears to be bone stock.
>
>
> Drive it. GM did a great job with their engines. Originals can go 140,000
> and still use no oil. Rebuilds- Well, after 10K I would begin to trust it.
> Block off might not be a bad idea, but every time you open something, you
> can have trouble. Put a new fuel pump on if it is not fairly new as new gas
> can eat up the diaphragm. Just my take.
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Tom Lins]

When we bought our first GMC we went by what someone said to us.
"Inspect and fix the things that will kill you first"
The tires, suspension, steering, bearings, and brakes
Then worry about the things that move you.
I would inspect all those things you mentioned and if anything is sketchy replace it and get rid of the old parts.
If you feel you need a spare buy a new one.
Change the oil and filter and when you get back send out a sample of the oil to be analyzed.

Then you will have an idea what you want to make improvements to.
There are a lot of GMCer's out there willing to lend a hand and advise, your not alone.
It is why we came back to our new GMC.

JMHO

--
Tom Lins
Elkton, FL
77 GM Rear Twin, Dry Bath, 455
Manuals on DVD
http://www.bdub.net/tomlins/

 

[gmc260]

I was thinking to replace the exhaust gaskets with known brand ones because that seems to be a very common issue and I'd rather do it at a convenient
time and place.

the mechanical fuel pump on the Olds 455 has the same potential as many others (even europeans) to leak fuel into the crankcase. I'd rather have an
electric one fail than that to happen even though its very rare. and it seems the e.pumps help eliminate vapor lock situations.

good point about the water pump drying out.. could try to seal it up in a bag with something in it but probably better just to get two new roller
pumps and keep one as a back up.

I wouldnt want to do a preemptive rebuild unless something is glaringly not up to the task but I do plan to acquire another 455 at some point to build
up from scratch and have on display on a stand and at the ready. someone here had mentioned a while back that a new block casting with improvements
has recently become available, that might be worth looking more into someday.

I will definitely "drive it" but before I go too far off into the distance I want to cover all the well known bases but yes, GM engines can go a long
time with proper service/maintenance.

 

[gmc260]

> In my experience, mechanical fuel pumps outlast electric ones, and they
> perform consistently throughout their service life. They are susceptible to
> alcohol deterioration, however, and when the diaphragm fails, they leak
> fuel into the engine sometimes. Worth keeping a watchful eye on though.
> They do stop pumping when the engine quits, which is a good thing.
> Ask those who have had an underhood fire fed by an electric fuel
> pump. Good idea to control them with a relay that opens when the engine
> quits.
> Jim Hupy

definitely will wire it up right. oil pres relay cut off and engine start position prime lead. another good point there though for sure. e.pumps can
be deadly if wired the easy way.

 

[roy keen]

If I purchased a coach that I believed had 100;000 miles on a 455 that was original I would be hesitant to make any long trips even with good oil
pressure. For sure the factory timing chain and gears are very loose. My main concern would be the rod bearings . When I bought mine with a bad
exhaust valve it had 95,000 on the motor ( in 1987). I kept thinking what if when I pulled the head with the bad valve. So I pulled the motor to ease
my mind. Turned out it was a good decision as # 7 and 8 rod bearings were in bad shape and would have left me stranded at some point. In my opinion a
455 should be refreshed if it has 100,000 miles on it even if all you do is replace the bearings and timing gear set.
--
Roy Keen
Minden,NV
76 X Glenbrook

 

[RJW]

> most all the coaches Ive looked at are approaching 100,000 miles and the engine history is mostly unknown but lets say you get one with 100,000 on
> the clock that is running great and appears to be bone stock.

I bought my GMC in 1998 when it had 119,577 on the odometer. The PO had changed the timing chain at ~80,000 miles. The extensive records I got at
the time of the sale showed that not much else had been done to it other than routine maintenance. It had the original water pump. I drove it until
175,547 miles without incident other than replacing the exhaust manifold gaskets 3 times and starter. The first manifold repair was by Cinnabar
(Remflex) that barely made it a year, next time by me, again with Remflex with about another year of service and then finally with Dave Lenzi's copper
gaskets. Those gaskets have been flawless for going on ~80,000 miles with no leaks (on 2 motors). I have over 53,000 miles on my replacement engine
with Dave's gaskets with no leaks.

I decided to replace the engine at 175,547 miles because it started to make a knocking/clicking noise. That noise ended up being caused by a
collapsed lifter. It was probably a good thing I did it at that time because I found a leak in the intake manifold that was causing coolant to flow
into the oil.

Because of the potential difficulty getting the exhaust manifold fasteners off, I would not want to attempt that sort of R&R on road.

--
Richard
76 Palm Beach
SE Michigan
www.PalmBeachGMC.com


Coop Roller Cam 455, Howell TBI + EBL, 3.42 FD, Quadra Bag, Macerator, Manny Tranny etc.

 

[gmc260]

good to know copper gaskets are available. Ive used them on other stuff with good results. I suppose that once you pull the intake off to install the
block offs, you would be able to see how much baked oil is in there.

if its alot then surely some of it has broke off and circulated though into the bearings.

what about Mobil-1 oil? I wonder if using it would run the risk of breaking up that crud baked oil in there? might be better off not using it until
after installing the block offs an cleaning some of that crap out as carefully as possible?

 

[john phillips]

Is there any truth to the rumor that Mobil-1 lubed engines leek more oil?

> good to know copper gaskets are available. Ive used them on other stuff
> with good results. I suppose that once you pull the intake off to install
> the
> block offs, you would be able to see how much baked oil is in there.
>
> if its alot then surely some of it has broke off and circulated though
> into the bearings.
>
> what about Mobil-1 oil? I wonder if using it would run the risk of
> breaking up that crud baked oil in there? might be better off not using it
> until
> after installing the block offs an cleaning some of that crap out as
> carefully as possible?
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*

 

[gmc260]

> Is there any truth to the rumor that Mobil-1 lubed engines leek more oil?

not from my experience. Ive got an '88 truck I bought new and started using Mobil-1 in it after the first 500 miles and it has had nothing else since.
it now has over 350,000 on it (SB V8) with no oil leaks and only minor seepage from the front of the oil pan but no drips from it.

I did have the cam seals start leaking in a FIAT Twin-Cam engine that I started using Mobil-1 in when I got it that were not leaking before then but I
dont know if it was because the Mobil-1 is slicker or because I was reving it higher and longer than the previous owner but I have heard it will cause
leaks to develop in older engines like the FIAT was that have actual rubber seals (real rubber) that has hardened over time.

but thanks for bringing that up, that is something to keep in mind since you cant take the oil pans off or replace rear seals easily in these. might
not be worth it. Rotella would be my second choice.

I doubt Mobil-1 would turn into that baked sludge from the exhaust passage in the intake like others do though but that would be one of the first
things I addressed.

 

[Carl Stouffer]

My personal opinion on exhaust manifold gaskets is that Dave Lenzi's copper gaskets are the best. I have used them on my coach and never had a
failure. The only time I have had to replace them is when I have had to remove the manifolds for some reason. I have heard of Remflex failures from
several other people and wondered why they keep using them. If you have headers, different story.
--
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