Timing chain questions

[robert peesel]

I am preparing to have my timing chain replaced and have a few questions. I want to make sure I have the right parts on hand instead of having the
mechanic buy cheap parts.

I was told to replace the crankshaft seal during this repair, but in the parts interchange index I only see "Timing chain, Oil Seal". Are these the
same things?

If the engine needs to be lifted, I know not to lift against the oil pan. What are appropriate lift points?

Are there any other things I should tell the mechanic? Is this repair documented anywhere that I could show him?

Bob
--
Robert Peesel

1976 Royale 26'

Side Dry Bath

Conifer, Colorado

 

[Jim Hupy]

I would verify that the timing chain needs to be replaced. Do this by
removing the mechanical fuel pump and using a piece of stiff wire with a j
hook bent in the end, hook onto the timing chain and pull it towards you,
then push it back. 1/4" movement is O.K., 1/2" means not O.K. and time to
replace the chain set.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> I am preparing to have my timing chain replaced and have a few questions.
> I want to make sure I have the right parts on hand instead of having the
> mechanic buy cheap parts.
>
> I was told to replace the crankshaft seal during this repair, but in the
> parts interchange index I only see "Timing chain, Oil Seal". Are these the
> same things?
>
> If the engine needs to be lifted, I know not to lift against the oil pan.
> What are appropriate lift points?
>
> Are there any other things I should tell the mechanic? Is this repair
> documented anywhere that I could show him?
>
> Bob
> --
> Robert Peesel
>
> 1976 Royale 26'
>
> Side Dry Bath
>
> Conifer, Colorado
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[roy keen]

There are 3 oil seals one is the cover oil seal one is the rubber seal that fits the front of the pan and one is the crankshaft oil seal. You should
be able to get a kit with all included. You will need to remove or loosen the 3 or 4 front pan bolts on each side of the engine to be able to replace
the seal on the front of the pan. I used a short gantry type unit to lift the front of the engine with a come along from above the engine.
--
Roy Keen
Minden,NV
76 X Glenbrook

 

[wrightjohn 2646]

Bob,
If you do determine that you need to replace the timing chain you also need to change out some other parts at the same time.

I would also add replacing the Harmonic Balancer Assy.
You can use the following part numbers:
Autozone part# 594-117
Advance Auto part# 594-117
NAPA part# NOE6005272 (can search under 594117)

The oil seal part numbers:

NAPA has a regular time and a High temp units.
Regular temp seal part# NOS19922
High temp seal part# NOS19923

AutoZone offers 2 part numbers:
Duralast part# 472082
National part# 472082

Get A Cloyes Timing Chain:
Part# 9-3113 Original tru roller timing chain

https://www.summitracing.com/parts/clo-9-3113
Do Not go Cheap here

DO NOT jack or raise motor by lifting on the bottom of the oil pan. YOU WILL push the bottom of the pan into the crank. You want to use a lift tool that is home made to lift on the bottom of the block similar to this:

http://www.gmcmhphotos.com/photos/general-pictures/p44885-engine-jacking-jig-for-lifting-motor.html
http://www.gmcmhphotos.com/photos/general-pictures/p44883-engine-jacking-jig-for-lifting-motor.html
http://www.gmcmhphotos.com/photos/general-pictures/p44882-engine-jacking-jig-for-lifting-motor.html
http://www.gmcmhphotos.com/photos/general-pictures/p44884-engine-jacking-jig-for-lifting-motor.html

It will reach the block pan rail, just put it about a 1/3 back on the block.

JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan

>
> I am preparing to have my timing chain replaced and have a few questions. I want to make sure I have the right parts on hand instead of having the
> mechanic buy cheap parts.
>
> I was told to replace the crankshaft seal during this repair, but in the parts interchange index I only see "Timing chain, Oil Seal". Are these the
> same things?
>
> If the engine needs to be lifted, I know not to lift against the oil pan. What are appropriate lift points?
>
> Are there any other things I should tell the mechanic? Is this repair documented anywhere that I could show him?
>
> Bob
> --
> Robert Peesel
>
> 1976 Royale 26'
>
> Side Dry Bath
>
> Conifer, Colorado
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[LQQKatJon]

Couple things I learned:

Best to lift engine from top, just a little.

There is a rubber seal at bottom of timing cover, i struggled with getting timing cover in. I had made a jig to jack up front of engine by pressure
on the oil pan bolts. I think taking a couple of the front oil pan bolts loose and allowing a slight drop of the front of oil pan would allow that
seal and cover to sit properly in place. Jacking up the oil pan bolts did not allow that. I ended up
Trimming the rubber seal top corners carfully with a razor blade and used sealant.

A good 18v electric impact seems to take the crank bolt loose.

A new harmonic balancer would make me sleep better at night. The seal can wear a groove in the balancer. The have a little bushing you are supposed
to be able to install on the balancer end
To give the seal a better surface, but I am not sure
How that bushing can get pressed on without destroying it.

Good luck, looking forward to a good outcome and hear how it drives into your driveway on its own.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[roy keen]

You will also be removing the water pump which also has a gasket. It is a good idea to drain both sides of the block after draining coolent from the
radiator or you will likely get some coolent in the front sump of the oil pan which is a bad thing as it won't drain out if you change oil .
--
Roy Keen
Minden,NV
76 X Glenbrook

 

[robert mueller]

Robert,

See Maintenance Manual X-7425 / Section 6A - Engine / Page 6A-1 / Subject - Timing Cain and Gears - Page 6A-52.

It notes to remove the oil pan and when I replaced mine at the COOP we did not do that. We did have to support the front of the
engine because we had to remove the front motor mount. It was back in 2009 and my memory is a bit fuzzy; I think we removed the
thermostat housing and ran a chain over a 2 x 4 across the front of the engine access port and bolted it to the thermostat housing
bolt holes.

See Parts Book 78Z / Section 8 - Engine / Page 8-2 thru 8-7 / Group 8.005 Cylinder Block, Crankshaft, and Oil Pan.

For a clear photo of timing gear alignment see:

http://www.gmcmhphotos.com/photos/aa-miscellaneous-photos/p28476-timing-gear-positon-455-403.html

Regards,
Rob M.
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 Robert Peesel
Sent: Tuesday, July 25, 2017 1:32 AM
To: gmclist
Subject: [GMCnet] Timing chain questions

I am preparing to have my timing chain replaced and have a few questions. I want to make sure I have the right parts on hand
instead of having the mechanic buy cheap parts.

I was told to replace the crankshaft seal during this repair, but in the parts interchange index I only see "Timing chain, Oil
Seal". Are these the same things?

If the engine needs to be lifted, I know not to lift against the oil pan. What are appropriate lift points?

Are there any other things I should tell the mechanic? Is this repair documented anywhere that I could show him?

Bob
--
Robert Peesel

1976 Royale 26'

Side Dry Bath

Conifer, Colorado

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Unsubscribe or Change List Options:
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[jim miller]

> It notes to remove the oil pan and when I replaced mine at the COOP we did not do that.

The problem with not removing or lowering the oil pan is this: the timing cover has a bracket on the bottom into which a gasket fits. This gasket seals tightly between the bottom runners of the block and the half-moon mouth at the front of the oil pan. It is extremely difficult to get the timing cover into place if the pan is not separated from the block by a small amount so that the new gasket will be compressed as the pan is re-installed.

That said, I’ve done two timing chain swaps and in each case was able to finagle the timing cover into place with its new gasket without having to lower the pan at all. I had the radiators out of the vehicle so I could sit in that area and work directly in front of the engine with maximum leverage to get the cover in place.

Also: Dick Paterson has some suggestions about what to do when installing new timing chain sets. Per his advice I installed P/N 9-3113 adjustable Cloyes chain set at the +4 degree setting.

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[robert mueller]

Jim,

That last tidbit from Dick is interesting; by advancing the cam you shift the torque band lower in the rpm range, great idea for a GMC!

Regards,
Rob M.
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 Jim Miller
Sent: Tuesday, July 25, 2017 12:07 PM
To: gmclist
Subject: Re: [GMCnet] Timing chain questions

> It notes to remove the oil pan and when I replaced mine at the COOP we did not do that.

The problem with not removing or lowering the oil pan is this: the timing cover has a bracket on the bottom into which a gasket fits. This gasket seals tightly between the bottom runners of the block and the half-moon mouth at the front of the oil pan. It is extremely difficult to get the timing cover into place if the pan is not separated from the block by a small amount so that the new gasket will be compressed as the pan is re-installed.

That said, I’ve done two timing chain swaps and in each case was able to finagle the timing cover into place with its new gasket without having to lower the pan at all. I had the radiators out of the vehicle so I could sit in that area and work directly in front of the engine with maximum leverage to get the cover in place.

Also: Dick Paterson has some suggestions about what to do when installing new timing chain sets. Per his advice I installed P/N 9-3113 adjustable Cloyes chain set at the +4 degree setting.

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

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[jim miller]

> That last tidbit from Dick is interesting; by advancing the cam you shift the torque band lower in the rpm range, great idea for a GMC!

Hi Rob,

Dick spent quite a while - well over an hour - on the telephone giving me lots of good advice before I started on my first upper-engine rebuild - not just on the timing chain but lots of other things as well. After we were done with engine discussions I offered to pay him for his time spent on the phone but all he would take was an order for a pair of crossover block-off plates and modified intake manifold gaskets to go with them.

I didn’t have the GMC on a dyno either before or after the mod so I have no experimental data but I can say that it sure didn’t hurt anything to choose the +4 slot.

—Jim


Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[robert peesel]

Thank you all for your information. I am going to forward this chain to the mechanic.

I truly wish I could have attacked this myself, but life is dictating otherwise at the moment.

Bob

--
Robert Peesel

1976 Royale 26'

Side Dry Bath

Conifer, Colorado