Engine problem

LQQKatJon

LQQKatJon

Well-known member
Oct 22, 2010
3,228
547
113
St. Cloud, Mn
lqqkatjon.blogspot.com
Cruising nicely and started to loose some power.

Seen some smoke and pulled off the road. Seemed ok on oil, but driver side front top of engine was wet down to final drive had oil all over the
cover anddripping on ground. Not power
Steering fluid.

Fired it up and here is what it sounded like:

https://youtu.be/lL5w52KpM9g

Had it towed home, pulled valve cover on driver side to see nothing wrong except gasket on that front was messed up when they installed that cover.

I cranked it and all rockers seem to look and operate.

Put valve cover on and engine noise did not show up asap, but came and went quickly and the. Consistant.

Checked assesorries and i dont think that is the issue. Pretty sure it is internal, but not as deep as a rod knock.... but I really have not much
experience in blowing up motors.

So guesses and suggestions welcome. Going to have some better ears come take a listen. And if verdict is not for sure, i will do compression tests
and maybe boriscope next weekend.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
Sounds like rod knock (bottom end) speed. Lifters would be 1/2 that speed. Could be a chunk out of a piston. If you lost power that could be loss of
advance and running retarded could cook a piston. Hope it's something less extreme
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Jon,

After listening to it again, I think it DOES sound like a rod knock. The fact that it doesn't make noise on cold start-up also points to that as the
cold oil (thicker) provides more cushioning to the loose bearing.

When I spun a bearing, it didn't make that much noise, but I never ran it with the hatch open, so it could have been that loud. When the engine was
torn down, you could see where the piston was making contact with the head on top and with the engine block at the bottom. That's how tight the
clearances are in there.

To diagnose it, try starting the engine and then pulling the spark plug wires, one at a time on the affected side. When you take the combustion load
off, the noise will mostly go away. If that happens, it is definitely a rod. Of course, if that is the case, you will need to rebuild. Hopefully
the crankshaft can be saved. I understand they can be reground down to a pretty significant undersize (maybe as much as .060) before getting through
the hardened surfaces of the crank journals.
--
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
 
Yes the Olds head has a shelf and when the rod bearing has too
much slop the piston comes up and whacks the head. Really makes s racket even when the bearing looks somewhat marginal.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I MIGHT agree to a 0.020"-0.030" turned crank; any worse than that, I'd
spring for a NEW crank, now that they're available:

https://www.summitracing.com/search/brand/eagle-specialty-products/make/oldsmobile/engine-size/7-5l-455

John Beaver, our local GMC owning NASCAR engine builder, recommends against
using any turned crank in a GMC MH because of the heavy loading.

Ken H.

> ...
> Hopefully
> the crankshaft can be saved. I understand they can be reground down to a
> pretty significant undersize (maybe as much as .060) before getting through
> the hardened surfaces of the crank journals.
> --
>
 
I agree with John. No turning is best.
Jim Hupy
Salem, OR

> I MIGHT agree to a 0.020"-0.030" turned crank; any worse than that, I'd
> spring for a NEW crank, now that they're available:
>
>
> https://www.summitracing.com/search/brand/eagle-specialty-products/make/oldsmobile/engine-size/7-5l-455
>
> John Beaver, our local GMC owning NASCAR engine builder, recommends against
> using any turned crank in a GMC MH because of the heavy loading.
>
> Ken H.
>

>
> > ...
> > Hopefully
> > the crankshaft can be saved. I understand they can be reground down to a
> > pretty significant undersize (maybe as much as .060) before getting
> through
> > the hardened surfaces of the crank journals.
> > --
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
True, best case is a standard size crank, but the journals are huge on a 455 crankshaft. I personally would not go any more than about .020, but the
machinist who rebuilt Dan Gregg's (second) engine felt that they could go smaller. By the sound of that engine, a new crankshaft would probably be
the way to go.

--
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
 
Jon,

Do the plug wire test, but don't pull a plug wire with the engine running as that can finish off an HEI right quick. You can, however, short a plug
to ground just have lots of insulation. A crack piston can also make noise like that and be accompanied with oil smoke. The excessive blow-by can
also cause the breather on the left bank to leak oil.

Now, let's start a bearing discussion here.
If you have spun a rod bearing or cracked a piston, the engine has to come out - that is a given.
Olds 455 have been sold with 3 crankshaft numbers. The most common is the cast. Most RV engines had nodular iron (often called noodle iron) cranks,
these are stronger than cast iron. The special 455s had forged cranks.

I can tell you that a nodular crank can be ground 30 under. I have one here that was removed with 70k+ miles on it and it looks good. The only
reason it is out is that I could not get new main shells quickly enough to satisfy me and I had a 0-0 N crack on the floor.

At this point, it is best to finish the diagnostic before anything else gets done.

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
 
> Jon,
>
> Do the plug wire test, but don't pull a plug wire with the engine running as that can finish off an HEI right quick. You can, however, short a
> plug to ground just have lots of insulation. A crack piston can also make noise like that and be accompanied with oil smoke. The excessive blow-by
> can also cause the breather on the left bank to leak oil.
>
> Now, let's start a bearing discussion here.
> If you have spun a rod bearing or cracked a piston, the engine has to come out - that is a given.
> Olds 455 have been sold with 3 crankshaft numbers. The most common is the cast. Most RV engines had nodular iron (often called noodle iron)
> cranks, these are stronger than cast iron. The special 455s had forged cranks.
>
> I can tell you that a nodular crank can be ground 30 under. I have one here that was removed with 70k+ miles on it and it looks good. The only
> reason it is out is that I could not get new main shells quickly enough to satisfy me and I had a 0-0 N crack on the floor.
>
> At this point, it is best to finish the diagnostic before anything else gets done.
>
> Matt

Matt...always the voice of reason here. A cracked piston makes sense. I have never experienced that issue, but the suddenness in which the problem
came on, the smoke, and the external oil sure makes sense. Either way, as Matt stated, the engine needs to come out, but maybe the crankshaft can be
saved.

--
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
 
We pulled each spark plug and did not notice any change in sound. I had my friend come listen and confirmed that it needs to
Come out. Noise is believed in being in one of the front cylinders either rod bearing, wrist pin or piston.

I am possibly looking at going the s&j route or there is a local builder I can use that has some other
Working 455 out there as well as other engines.

--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
Dang Jon,
Well you got some miles out of it
________________________________
From: Gmclist on behalf of Jon Roche
Sent: Wednesday, August 1, 2018 2:50 PM
To: gmclist
Subject: Re: [GMCnet] Engine problem

We pulled each spark plug and did not notice any change in sound. I had my friend come listen and confirmed that it needs to
Come out. Noise is believed in being in one of the front cylinders either rod bearing, wrist pin or piston.

I am possibly looking at going the s&j route or there is a local builder I can use that has some other
Working 455 out there as well as other engines.

--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/

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I just had powerline machine in Chippewa falls WI build a 455. I'm working on the installing it now. Talk to Larry 715 726 8691. Tell him Tim Kuhn
told you about him. We used Dick Pattersons Specs.
--
1975 eleganza,
3 stainless steel fuel tanks holds 90 gal.,
Thorley headers and 3" SS exhaust pipe,
6 Wheel disc brakes,
Quad airbag system
 
I also have a local Hammond, Indiana machine shop that I have known for about 55 years, build a 455 to Dick P's specs. It has now installed in a
local GMCer's Coach for about 3 years now and lots of miles. They will do the job right but they are not fast.

Contact me if you want more info.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
For how much fun it is to rnr a motor in one of these I’d gladly wait twice
as long knowing I won’t have to pull it again prematurely.

Sully
Bellevue

> I also have a local Hammond, Indiana machine shop that I have known for
> about 55 years, build a 455 to Dick P's specs. It has now installed in a
> local GMCer's Coach for about 3 years now and lots of miles. They will do
> the job right but they are not fast.
>
> Contact me if you want more info.
>
> Ken B.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
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