| [GMCnet] update on old engine problem [message #247396] |
Mon, 14 April 2014 13:28  |
KB
Messages: 1262
Registered: September 2009
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finally got to take a look at the number 8 bearing on our old engine and thought
I'd post an update here. The only sympton we had was a strange rattle that only occurred
under some load conditions. It started about an hour after my better half decided to
see what wide open throttle would do on a freeway on-ramp (scaring the bejeesuz out of me;
felt like I was in the space shuttle at take-off). This was last year, and we've since
replaced the engine with an S&J rebuild.
The noise kinda sounded like a big nut rattling around in a metal pan.
The oil pressure was fine, and leakdown and compression tests didn't show a problem.
An oil analysis only showed somewhat elevated aluminum. Grounding the number 8 spark plug wire
made the noise go away. This engine only had about 12K miles. Looked like a decent clean
rebuild and the radiator was supposedly replaced at the same time, but somehow a piece of
crud clearly got in there.
The amazing thing is we were able to make it home (~500 miles) without more damage:
http://www.gmcmhphotos.com/photos/member-galleries/p54262-engine-noise-was-numbe.html
http://www.gmcmhphotos.com/photos/member-galleries/p54261-engine-noise-was-numbe.html
Karen
1973 23'
1975 26'
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] update on old engine problem [message #247399 is a reply to message #247396] |
Mon, 14 April 2014 14:03  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Yeah Karen 7&8 are usually the ones that go .at least for me that is. When I lost mine the bearing spun too. It doesn't look like yours spun allowing you to drive home. I could only move a short distance or I would have wiped out the motor big time. Let's cross our fingers that we won't hear that awful sound again.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] update on old engine problem [message #247402 is a reply to message #247396] |
Mon, 14 April 2014 14:45 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Karen, from what I could see from your pictures, It appears to me to be
caused from abrasive materials lodged upstream from the oil supply holes to
that bearing. It takes surprisingly little crud to do that much damage. We
clean and clean, take out all the gallery plugs and run rifle bore brushes
of the appropriate sizes, blow out the crap with compressed air and
cleaning agents like Chem tool, paint the insides of the block with glyptal
or similar coatings, and STILL THAT STUFF HAPPENS. As one who has had
similar stuff happen to him, I really symphathize with you. Happens to
engines off the assembly line also, but not very often. Company
reputations ride on that kind of stuff. Man, I still hate it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Apr 14, 2014 11:28 AM, "KB" <kab7@sonic.net> wrote:
> finally got to take a look at the number 8 bearing on our old engine and
> thought
> I'd post an update here. The only sympton we had was a strange rattle
> that only occurred
> under some load conditions. It started about an hour after my better half
> decided to
> see what wide open throttle would do on a freeway on-ramp (scaring the
> bejeesuz out of me;
> felt like I was in the space shuttle at take-off). This was last year,
> and we've since
> replaced the engine with an S&J rebuild.
>
> The noise kinda sounded like a big nut rattling around in a metal pan.
> The oil pressure was fine, and leakdown and compression tests didn't show
> a problem.
> An oil analysis only showed somewhat elevated aluminum. Grounding the
> number 8 spark plug wire
> made the noise go away. This engine only had about 12K miles. Looked
> like a decent clean
> rebuild and the radiator was supposedly replaced at the same time, but
> somehow a piece of
> crud clearly got in there.
>
> The amazing thing is we were able to make it home (~500 miles) without
> more damage:
>
>
> http://www.gmcmhphotos.com/photos/member-galleries/p54262-engine-noise-was-numbe.html
>
>
> http://www.gmcmhphotos.com/photos/member-galleries/p54261-engine-noise-was-numbe.html
>
> Karen
> 1973 23'
> 1975 26'
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] update on old engine problem [message #247416 is a reply to message #247410] |
Mon, 14 April 2014 17:18 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Karen, yes honing grit is way high on the list of crud that can do that
damage. It is a slurry of silicon carbide, cast iron bits, and honing oil.
Kinda like a lapping compound. If original bore size with new rings are
fitted, a favorite cross hatching hone is called a "Dingle ball" hone. It
looks like a bottle brush with balls of abrasives material on the ends of
the bristles. It gets into ring reversal areas well, and does not remove a
great amount of metal. If a tech let's it go too deeply into the bore, the
brush ends whack the main webs and fracture leaving behind bad bad stuff.
Also, like you suggest, if the intake manifold is off when the engine is in
the bay, it is very easy to knock something down into the cam gallery. Who
knows for sure without very careful inspection? If that were my engine, it
would come completely apart and everything would be miked and cleaned.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Apr 14, 2014 3:01 PM, "KB" <kab7@sonic.net> wrote:
>
>
> no idea what the crud was or how it got in there. Would leftover honing
> abrasive do that kind of damage? Or is it possible to introduce things
> into a non-filtered oil path via the valve covers or intake manifold?
>
> Just for the record, the builder was JB Precision Engines in Victoria BC,
> according to the stickers on the valve covers. I've been told they are a
> reputable shop. It was installed by Cornell Chevrolet Oldsmobile, also in
> Victoria, per the receipts. This was done in 1997 so any warranty is long
> past.
>
> Apparently the previous owners had the dreaded "loud knocking from engine"
> while traveling, far from home. Must have been a serious bummer; they
> sold the coach not too long after.
>
> As they say, "stuff happens".
> We'll keep it as a good core to hopefully scare the new engine into
> behaving properly :)
>
> Karen
> 1973 23'
> 1975 26'
>
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| Re: [GMCnet] update on old engine problem [message #247417 is a reply to message #247396] |
Mon, 14 April 2014 17:18 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Karen,
So sorry to see that happen to you. But "welcome to the club". Some years
back, I bought a coach with the complete, uninstalled, front clip
completely refurbished from bare metal out; everything powder coated &
rebuilt to "new or better". The PO was a highly skilled mechanic who'd
hovered over the rebuilder ("the best in Nashville") throughout the
overhaul. Beautiful piece:
http://www.gmcmhphotos.com/photos/76-palm-beach-new-front-frame-clip/p8983.html
After installing the clip in the X-Birchaven, I made one circuit of my 25
mile test loop before #7 rod bearing went! :-(
No explanation for it; stuff just happens.
Ken H.
On Mon, Apr 14, 2014 at 2:28 PM, KB wrote:
> finally got to take a look at the number 8 bearing on our old engine and
> thought
> I'd post an update here. The only sympton we had was a strange rattle
> that only occurred
> under some load conditions. It started about an hour after my better
> half decided to
> see what wide open throttle would do on a freeway on-ramp (scaring the
> bejeesuz out of me;
> felt like I was in the space shuttle at take-off). This was last year,
> and we've since
> replaced the engine with an S&J rebuild.
> ...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] update on old engine problem [message #247448 is a reply to message #247415] |
Mon, 14 April 2014 20:40 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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It was my fault that it spun 30 miles from home at the beginning of a 2 month trip. I over revved the motor. The radio was turned up and I noticed what sounded like a screeching noise. I thought it was a belt at first. When I pulled over and lifted the hatch Paula said how long to fix it. That is when I heard the knock as I revved it I knew it was a rod knock so I called for the tow home.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] update on old engine problem [message #247449 is a reply to message #247448] |
Mon, 14 April 2014 20:42 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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| roy1 wrote on Mon, 14 April 2014 19:40 |
It was my fault that it spun 30 miles from home at the beginning of a 2 month trip. I over revved the motor. The radio was turned up and I noticed what sounded like a screeching noise. I thought it was a belt at first. When I pulled over and lifted the hatch Paula said how long to fix it. That is when I heard the knock as I revved it I knew it was a rod knock so I called for the tow home.
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How did you over rev the engine?
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] update on old engine problem [message #247451 is a reply to message #247396] |
Mon, 14 April 2014 21:18 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Karen the rod bearing big end can be sloppy enough to let the piston slap the ridge on the head. You will see a line across that piston. Dirt caused oil starvation will cause that. That aluminum rapping is a similar signature to detonation to the ear of the knock sensor. .
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] update on old engine problem [message #247461 is a reply to message #247449] |
Mon, 14 April 2014 23:55 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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| Bob de Kruyff wrote on Mon, 14 April 2014 18:42 |
| roy1 wrote on Mon, 14 April 2014 19:40 |
It was my fault that it spun 30 miles from home at the beginning of a 2 month trip. I over revved the motor. The radio was turned up and I noticed what sounded like a screeching noise. I thought it was a belt at first. When I pulled over and lifted the hatch Paula said how long to fix it. That is when I heard the knock as I revved it I knew it was a rod knock so I called for the tow home.
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How did you over rev the engine?
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I was climbing a fairly steep grade so I put the trans in super ,I was trying to contact an 18 wheeler on the CB that had come over the mountain and not paying attention put the trans in low and over revved it. If it weren't for the dang shift kit it wouldn't have gone into low. A lesson well learned.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] update on old engine problem [message #247474 is a reply to message #247396] |
Tue, 15 April 2014 08:32 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Another example of the non self destruct features that GM (Hydramatic) engineered into the vehicle, bypassed by the aftermarket. As if the aftermarket has any skin in the game other than to sell their product.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] update on old engine problem [message #247488 is a reply to message #247461] |
Tue, 15 April 2014 10:53 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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| roy1 wrote on Mon, 14 April 2014 22:55 |
| Bob de Kruyff wrote on Mon, 14 April 2014 18:42 |
| roy1 wrote on Mon, 14 April 2014 19:40 |
It was my fault that it spun 30 miles from home at the beginning of a 2 month trip. I over revved the motor. The radio was turned up and I noticed what sounded like a screeching noise. I thought it was a belt at first. When I pulled over and lifted the hatch Paula said how long to fix it. That is when I heard the knock as I revved it I knew it was a rod knock so I called for the tow home.
|
How did you over rev the engine?
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I was climbing a fairly steep grade so I put the trans in super ,I was trying to contact an 18 wheeler on the CB that had come over the mountain and not paying attention put the trans in low and over revved it. If it weren't for the dang shift kit it wouldn't have gone into low. A lesson well learned.
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Thanks Roy--I was curious about that since I usually rev mine to the limits in the mountains. Luckily I don't have a shift kit otherwise I'd probably be in the same boat.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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