Home » Public Forums » GMCnet » [GMCnet] Subject: GMC engine suggestions needed
| [GMCnet] Subject: GMC engine suggestions needed [message #141911] |
Wed, 31 August 2011 20:58  |
rallymaster
Messages: 662
Registered: February 2004
Location: North Plains, ORYGUN
Karma: -4
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Senior Member |
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Subject: GMC engine suggestions needed
Everybody:
As far as I know, the attached rebuild data sheet is the last major work
done on the engine.
January 1989 at 141,200 miles. 1978 Oldsmobile 403 cid.
The only thing most of the rebuild info means to me is it was rebuilt a
long time ago to RV specs, and sounds expensive to fix.
If I remember correctly, the other 7 cylinders had about 140-145 #
compression.
The current rebuild has about 135 thousand miles on it.
ignoring option 1, the cheapest solution, who has suggestions, and why?
If I have to have the engine rebuilt, I'd prefer to have a solution that
doesn't rely on oil change places using only the oil I tell them to use.
That probably means a roller tappet system - $$$.
Of course, some of the engine people say that large amounts of ZDDP only
matter during the break-in period. Some say, until it's well broken in,
others say, FOREVER!
Feel free to disqualify yourself for any reason...
thanks,
Ron
Pics available if anybody wants to see them.
Ron, Today the intake manifold came off. As you can see in the pictures
the following is what we found:
1 bent push rod.
1 broken push rod.
1 bent rocker arm pivot. (hard to see)
2 disassembled lifters. (not shown)
1 oddly worn cam shaft lobes for #7.
Possible cause of the bent push rod and rocker arm pivot valve seized
in the valve guide.
Possible cause of the broken push rod when the rocker arm pivot bent
the push rod was hitting the hole in the head while it continued to spin
scoring the push rod until it broke.
Possible cause of the 2 disassembled lifters without the push rods to
keep the lifter loaded it lost the keeper and plunger inside the lifter.
Possible cause of the worn cam shaft lobes unloaded lifters bouncing on
cam shaft lobes.
Possible solutions:
Cheapest replace pushrods, rocker arm pivot and lifters with used
parts. No guarantee. May not fix what caused the problem in the first
place. Cam may eat the lifters.
Mid cost rebuild heads, install new cam, lifters, push rods and rocker
assembly.
Most cost rebuild engine.
Do you know the history on this engine? Someone has been in it because
the inside has been painted. If the engine has a lot of miles on it,
rebuilding the heads only can turn the engine into a big oil pump. The
compression on the other cylinders did look OK so the mid cost option is
a possibility.
EngineExcerpt from engine rebuild data
Automotive Test Equipment
24990 S. Kirchner Rd.
Oregon City, Oregon 97045
5036327080
Jan, 1989 141,000 miles
Rebuilt (Automotive Test Equipment OR City141200Jan-89
Engine (with above)Gas & Vent LinesBrunetto141200Jan-89
Engine (with above)Mondello Camshaft & lifters141200Jan-89
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Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II
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| Re: [GMCnet] Subject: GMC engine suggestions needed [message #141948 is a reply to message #141911] |
Thu, 01 September 2011 06:56  |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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Senior Member |
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| Quote: |
.....
1 bent push rod.
1 broken push rod.
1 bent rocker arm pivot. (hard to see)
2 disassembled lifters. (not shown)
1 oddly worn cam shaft lobes for #7......
|
Ron, Sounds to me like the cam just wore out; ate up the lifter till there became too much slack in the valve train that the push rods failed. After ruling out a seized valve stem, I'd replace the cam with a replacement flat tappet cam and run it. Worn cam lobes will continue to eat up lifters. Compression test reveals that the rest of the engine is good. Going with a roller cam is a lot of machining and parts = $$$$$$$$. You couldn't buy enough zddp to offset the cost of a complete engine. If you run Delo 400 it's relatively cheap; is available in straight weights; and has more than enough zddp.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: [GMCnet] Subject: GMC engine suggestions needed [message #141951 is a reply to message #141911] |
Thu, 01 September 2011 07:18 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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I agree with John Sharp. All of the valve train problems could easily be
attributed to camshaft wear. The problem here is that all the metal that
wore off the lobes most likely went through the engine. Dump the oil and
send a specimen to Blackstone labs. Take the sample from mid-drain. If
you're going to pull the engine, put it on a stand and remove the pan. Do
it the hard way, with the pan towards the floor. What is in the bottom of
the pan? Once it is pulled, rotate the engine and pull the oil pump for
inspection. Pull the main caps and inspect the bearings. At this point,
you will know the extent of what you have to do.
If you have determined by now that you need to rebuild, there is no cheap
way out of this that will give you peace of mind when you're on a trip far
away from home.
On Wed, Aug 31, 2011 at 6:58 PM, <rallymaster@juno.com> wrote:
>
>
>
> Subject: GMC engine suggestions needed
>
> Everybody:
> As far as I know, the attached rebuild data sheet is the last major work
> done on the engine.
>
> January 1989 at 141,200 miles. 1978 Oldsmobile 403 cid.
>
> The only thing most of the rebuild info means to me is it was rebuilt a
> long time ago to RV specs, and sounds expensive to fix.
>
> If I remember correctly, the other 7 cylinders had about 140-145 #
> compression.
> The current rebuild has about 135 thousand miles on it.
>
> ignoring option 1, the cheapest solution, who has suggestions, and why?
> If I have to have the engine rebuilt, I'd prefer to have a solution that
> doesn't rely on oil change places using only the oil I tell them to use.
> That probably means a roller tappet system - $$$.
> Of course, some of the engine people say that large amounts of ZDDP only
> matter during the break-in period. Some say, until it's well broken in,
> others say, FOREVER!
> Feel free to disqualify yourself for any reason...
> thanks,
> Ron
> Pics available if anybody wants to see them.
>
> Ron, Today the intake manifold came off. As you can see in the pictures
> the following is what we found:
> 1 bent push rod.
> 1 broken push rod.
> 1 bent rocker arm pivot. (hard to see)
> 2 disassembled lifters. (not shown)
> 1 oddly worn cam shaft lobes for #7.
> Possible cause of the bent push rod and rocker arm pivot valve seized
> in the valve guide.
> Possible cause of the broken push rod when the rocker arm pivot bent
> the push rod was hitting the hole in the head while it continued to spin
> scoring the push rod until it broke.
> Possible cause of the 2 disassembled lifters without the push rods to
> keep the lifter loaded it lost the keeper and plunger inside the lifter.
> Possible cause of the worn cam shaft lobes unloaded lifters bouncing on
> cam shaft lobes.
> Possible solutions:
> Cheapest replace pushrods, rocker arm pivot and lifters with used
> parts. No guarantee. May not fix what caused the problem in the first
> place. Cam may eat the lifters.
> Mid cost rebuild heads, install new cam, lifters, push rods and rocker
> assembly.
> Most cost rebuild engine.
> Do you know the history on this engine? Someone has been in it because
> the inside has been painted. If the engine has a lot of miles on it,
> rebuilding the heads only can turn the engine into a big oil pump. The
> compression on the other cylinders did look OK so the mid cost option is
> a possibility.
>
>
>
> EngineExcerpt from engine rebuild data
> Automotive Test Equipment
> 24990 S. Kirchner Rd.
> Oregon City, Oregon 97045
> 5036327080
> Jan, 1989 141,000 miles
> Rebuilt (Automotive Test Equipment OR City141200Jan-89
> Engine (with above)Gas & Vent LinesBrunetto141200Jan-89
> Engine (with above)Mondello Camshaft & lifters141200Jan-89
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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| Re: [GMCnet] Subject: GMC engine suggestions needed [message #141972 is a reply to message #141911] |
Thu, 01 September 2011 10:01 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| rallymaster wrote on Wed, 31 August 2011 21:58 |
Subject: GMC engine suggestions needed
Everybody:
As far as I know, the attached rebuild data sheet is the last major work done on the engine.
January 1989 at 141,200 miles. 1978 Oldsmobile 403 cid.
The only thing most of the rebuild info means to me is it was rebuilt a long time ago to RV specs, and sounds expensive to fix.
If I remember correctly, the other 7 cylinders had about 140-145 # compression.
The current rebuild has about 135 thousand miles on it.
ignoring option 1, the cheapest solution, who has suggestions, and why?
If I have to have the engine rebuilt, I'd prefer to have a solution that doesn't rely on oil change places using only the oil I tell them to use.
That probably means a roller tappet system - $$$.
Of course, some of the engine people say that large amounts of ZDDP only matter during the break-in period. Some say, until it's well broken in, others say, FOREVER!
Feel free to disqualify yourself for any reason...
thanks,
Ron
Pics available if anybody wants to see them.
Ron, Today the intake manifold came off. As you can see in the pictures
the following is what we found:
1 bent push rod.
1 broken push rod.
1 bent rocker arm pivot. (hard to see)
2 disassembled lifters. (not shown)
1 oddly worn cam shaft lobes for #7.
Possible cause of the bent push rod and rocker arm pivot valve seized
in the valve guide.
Possible cause of the broken push rod when the rocker arm pivot bent the push rod was hitting the hole in the head while it continued to spin scoring the push rod until it broke.
Possible cause of the 2 disassembled lifters without the push rods to keep the lifter loaded it lost the keeper and plunger inside the lifter.
Possible cause of the worn cam shaft lobes unloaded lifters bouncing on cam shaft lobes.
Possible solutions:
Cheapest replace pushrods, rocker arm pivot and lifters with used parts. No guarantee. May not fix what caused the problem in the first place. Cam may eat the lifters.
Mid cost rebuild heads, install new cam, lifters, push rods and rocker assembly.
Most cost rebuild engine.
Do you know the history on this engine? Someone has been in it because the inside has been painted. If the engine has a lot of miles on it, rebuilding the heads only can turn the engine into a big oil pump. The compression on the other cylinders did look OK so the mid cost option is a possibility.
EngineExcerpt from engine rebuild data
Automotive Test Equipment
24990 S. Kirchner Rd.
Oregon City, Oregon 97045
5036327080
Jan, 1989 141,000 miles
Rebuilt (Automotive Test Equipment OR City141200Jan-89
Engine (with above)Gas & Vent LinesBrunetto141200Jan-89
Engine (with above)Mondello Camshaft & lifters141200Jan-89
|
Ron,
135k in 22 years does not sound like it was ignored, but there are still many possibilities here including a hydraulic lock on fuel.
Question 1: Do you have an electric fuel pump?
Question 2: Do you remember a hard stop during cranking?
It is unfortunate that which parts of valve gear damaged were not specified. There are an number things that could cause this, but there would have to be better definition.
Assuming that all the listed damage is to #7 cylinder:
The damage could not have been caused by the worn cam, but the converse is quite possible.
- The lifters (lash adjusters) often blow apart with oil pressure when there is no valve train load to keep them contained.
- The pushrod and rocker pivot damage is most uncommon. The extension of that damage could have happened in mere moments of operation after the original casualty.
- The damage as stated could have been the result of both the intake and exhaust valves being seized in the guides, but that would have required a single cylinder overheat on the wrong end of the head. (Highly unlikely)
Any case, my assessment (free advice may be worth less than its cost to you) would be that #7 took some sort of serious hit. The bottom end MAY have sustained some damage, but you will not know unless you look. An engine on a stand will be much more at ease when telling you the whole story.
When you get the engine out and open (what I believe is the best option), you can do a plasti-gage on the bearings, evaluate the top ring travel step, inspect the oil pump, and pull up #7 piston and look at the ring lands.
We are talking about a 135k mi engine here. While the bearings may be in service limit, but I would be surprised if the same were true of the piston rings.
The camshaft job (now essential) will be much easier with the engine out. I do not know the additional cost of a roller cam, but it is worth investigating.
All of this will be much clearer with the engine open. I find that one of the most common problems with mechanical stuff is that often not enough is disassembled and inspected.
That is my vote.
Please tell us what you find if you do open it up. Others may benefit from your experience.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Subject: GMC engine suggestions needed [message #141981 is a reply to message #141972] |
Thu, 01 September 2011 10:39 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I am going to tie onto the end of this thread. If there is a wiped cam lobe,
then the pushrods likely hopped out of the socket after the bottom of the
lifter and cam lobe went away. My experience has been that the worn metal
usually circulates throughout the oiling system and frequently lodges in the
crankshaft drilled passages in the form of a grey metallic paste. The mains
and rod bearings as well as the cam bearings will also show excessive wear.
It is overhaul time in my opinion. May not be too much cylinder wear, but I
suspect that the engine might have been rebored when last overhaul was done.
I don't recommend more than a .030 " overbore on a 403. You might be looking
for a good rebuildable 403 in the near future. Just my opinion based on many
common experiences with olds engines.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Thu, Sep 1, 2011 at 8:01 AM, Matt Colie <matt7323tze@gmail.com> wrote:
>
>
> rallymaster wrote on Wed, 31 August 2011 21:58
> > Subject: GMC engine suggestions needed
> >
> > Everybody:
> > As far as I know, the attached rebuild data sheet is the last major work
> done on the engine.
> >
> > January 1989 at 141,200 miles. 1978 Oldsmobile 403 cid.
> >
> > The only thing most of the rebuild info means to me is it was rebuilt a
> long time ago to RV specs, and sounds expensive to fix.
> >
> > If I remember correctly, the other 7 cylinders had about 140-145 #
> compression.
> > The current rebuild has about 135 thousand miles on it.
> >
> > ignoring option 1, the cheapest solution, who has suggestions, and why?
> > If I have to have the engine rebuilt, I'd prefer to have a solution that
> doesn't rely on oil change places using only the oil I tell them to use.
> > That probably means a roller tappet system - $$$.
> > Of course, some of the engine people say that large amounts of ZDDP only
> matter during the break-in period. Some say, until it's well broken in,
> others say, FOREVER!
> > Feel free to disqualify yourself for any reason...
> > thanks,
> > Ron
> > Pics available if anybody wants to see them.
> >
> > Ron, Today the intake manifold came off. As you can see in the pictures
> > the following is what we found:
> > 1 bent push rod.
> > 1 broken push rod.
> > 1 bent rocker arm pivot. (hard to see)
> > 2 disassembled lifters. (not shown)
> > 1 oddly worn cam shaft lobes for #7.
> > Possible cause of the bent push rod and rocker arm pivot valve seized
> > in the valve guide.
> > Possible cause of the broken push rod when the rocker arm pivot bent
> the push rod was hitting the hole in the head while it continued to spin
> scoring the push rod until it broke.
> > Possible cause of the 2 disassembled lifters without the push rods to
> keep the lifter loaded it lost the keeper and plunger inside the lifter.
> > Possible cause of the worn cam shaft lobes unloaded lifters bouncing on
> cam shaft lobes.
> > Possible solutions:
> > Cheapest replace pushrods, rocker arm pivot and lifters with used
> parts. No guarantee. May not fix what caused the problem in the first place.
> Cam may eat the lifters.
> > Mid cost rebuild heads, install new cam, lifters, push rods and rocker
> assembly.
> > Most cost rebuild engine.
> > Do you know the history on this engine? Someone has been in it because
> the inside has been painted. If the engine has a lot of miles on it,
> rebuilding the heads only can turn the engine into a big oil pump. The
> compression on the other cylinders did look OK so the mid cost option is a
> possibility.
> >
> > EngineExcerpt from engine rebuild data
> > Automotive Test Equipment
> > 24990 S. Kirchner Rd.
> > Oregon City, Oregon 97045
> > 503 632 7080
> > Jan, 1989 141,000 miles
> > Rebuilt (Automotive Test Equipment OR City141200Jan-89
> > Engine (with above)Gas & Vent LinesBrunetto141200Jan-89
> > Engine (with above)Mondello Camshaft & lifters141200Jan-89
>
> Ron,
>
> 135k in 22 years does not sound like it was ignored, but there are still
> many possibilities here including a hydraulic lock on fuel.
>
> Question 1: Do you have an electric fuel pump?
> Question 2: Do you remember a hard stop during cranking?
>
> It is unfortunate that which parts of valve gear damaged were not
> specified. There are an number things that could cause this, but there
> would have to be better definition.
>
> Assuming that all the listed damage is to #7 cylinder:
> The damage could not have been caused by the worn cam, but the converse is
> quite possible.
> - The lifters (lash adjusters) often blow apart with oil pressure when
> there is no valve train load to keep them contained.
> - The pushrod and rocker pivot damage is most uncommon. The extension of
> that damage could have happened in mere moments of operation after the
> original casualty.
> - The damage as stated could have been the result of both the intake and
> exhaust valves being seized in the guides, but that would have required a
> single cylinder overheat on the wrong end of the head. (Highly unlikely)
>
> Any case, my assessment (free advice may be worth less than its cost to
> you) would be that #7 took some sort of serious hit. The bottom end MAY
> have sustained some damage, but you will not know unless you look. An
> engine on a stand will be much more at ease when telling you the whole
> story.
>
> When you get the engine out and open (what I believe is the best option),
> you can do a plasti-gage on the bearings, evaluate the top ring travel step,
> inspect the oil pump, and pull up #7 piston and look at the ring lands.
>
> We are talking about a 135k mi engine here. While the bearings may be in
> service limit, but I would be surprised if the same were true of the piston
> rings.
>
> The camshaft job (now essential) will be much easier with the engine out.
> I do not know the additional cost of a roller cam, but it is worth
> investigating.
>
> All of this will be much clearer with the engine open. I find that one of
> the most common problems with mechanical stuff is that often not enough is
> disassembled and inspected.
>
> That is my vote.
> Please tell us what you find if you do open it up. Others may benefit from
> your experience.
>
> Matt
>
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumiere (say show-me-air) Just about as stock as you will
> find
> SE Michigan - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Subject: GMC engine suggestions needed [message #142007 is a reply to message #141911] |
Thu, 01 September 2011 16:06 |
rallymaster
Messages: 662
Registered: February 2004
Location: North Plains, ORYGUN
Karma: -4
|
Senior Member |
|
|
Hi, Guys
I really appreciate the info and help in coming to a decision.
However, I think those of you who asked for more info as the inspection
proceeded are out of luck.
Because the labor involved in the suggested inspections, and the miles on
the engine since the last rebuild, and the fact that this engine is not
actually rebuildable because it has already been bored .030 over, we've
decided to replace the engine.
Don't know particulars of that yet (short block, long block, crate
engine, etc). DJ has the coach, and I've asked him to get us some
figures on various means to that end.
RonC
Ron & Linda Clark
1978 Eleganza II
North Plains, ORYGUN
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Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II
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