Home » Public Forums » GMCnet » [GMCnet] bearings and filters
| [GMCnet] bearings and filters [message #208835] |
Sun, 26 May 2013 11:48  |
KB
Messages: 1262
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
Our engine developed a knock this week. The current
theory is it's a rod bearing problem. The engine was rebuilt
about 12K miles ago by a reputable re-builder, and ran well
until now. This naturally leads me to the question:
why this early bearing failure? (assuming that's what it is)
A brief search online shows that a leading cause of bearing
failure is debris in the oil. So why wouldn't this get
filtered out before doing damage? My theory is: the bypass
oil filter (WIX 51258). About 2 hours before the knock started,
my better half decided, for the first time, to see what 100%
throttle (WOT) would do on a freeway on-ramp. As I understand
it, during WOT conditions, the oil filter bypass opens,
and unfiltered oil flows into the engine. Seems like a
bad idea to me, since any junk in the oil can rapidly
plug passages or ruin bearings.
So: why do we need a bypass filter? Can we get a filter
without one, and would that be a good thing??
thanks
Karen
1973 23'
1975 26'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Karen
1975 26'
San Jose, CA
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208838 is a reply to message #208835] |
Sun, 26 May 2013 11:57  |
 |
ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
|
Senior Member |
|
|
Karen,
Isn't this making the choice between oil starvation from a plugged filter and passing dirty oil?
To my way of thinking oil starvation always harms an engine, whereas flowing dirty oil might not.
Larry Davick
On May 26, 2013, at 9:48 AM, KB <kab7@sonic.net> wrote:
> Our engine developed a knock this week. The current
> theory is it's a rod bearing problem. The engine was rebuilt
> about 12K miles ago by a reputable re-builder, and ran well
> until now. This naturally leads me to the question:
> why this early bearing failure? (assuming that's what it is)
>
> A brief search online shows that a leading cause of bearing
> failure is debris in the oil. So why wouldn't this get
> filtered out before doing damage? My theory is: the bypass
> oil filter (WIX 51258). About 2 hours before the knock started,
> my better half decided, for the first time, to see what 100%
> throttle (WOT) would do on a freeway on-ramp. As I understand
> it, during WOT conditions, the oil filter bypass opens,
> and unfiltered oil flows into the engine. Seems like a
> bad idea to me, since any junk in the oil can rapidly
> plug passages or ruin bearings.
>
> So: why do we need a bypass filter? Can we get a filter
> without one, and would that be a good thing??
>
> thanks
> Karen
> 1973 23'
> 1975 26'
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208852 is a reply to message #208835] |
Sun, 26 May 2013 12:46 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
oops, never mind. The WIX 51258 is NOT a bypass filter. We took
it apart and saw it has a rubber gasket and spring, which
I thought was for bypass. It's not, it's for anti-drainback.
Just grasping at straws here for the failure...
thanks
Karen
1973 23'
1975 26'
On 5/26/2013 9:48 AM, KB wrote:
> Our engine developed a knock this week. The current
> theory is it's a rod bearing problem. The engine was rebuilt
> about 12K miles ago by a reputable re-builder, and ran well
> until now. This naturally leads me to the question:
> why this early bearing failure? (assuming that's what it is)
>
> A brief search online shows that a leading cause of bearing
> failure is debris in the oil. So why wouldn't this get
> filtered out before doing damage? My theory is: the bypass
> oil filter (WIX 51258). About 2 hours before the knock started,
> my better half decided, for the first time, to see what 100%
> throttle (WOT) would do on a freeway on-ramp. As I understand
> it, during WOT conditions, the oil filter bypass opens,
> and unfiltered oil flows into the engine. Seems like a
> bad idea to me, since any junk in the oil can rapidly
> plug passages or ruin bearings.
>
> So: why do we need a bypass filter? Can we get a filter
> without one, and would that be a good thing??
>
> thanks
> Karen
> 1973 23'
> 1975 26'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Karen
1975 26'
San Jose, CA
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208853 is a reply to message #208838] |
Sun, 26 May 2013 12:50 |
mickeysss
Messages: 1476
Registered: January 2012
Karma: 0
|
Senior Member |
|
|
If you have an electric fuel pump it may have pushed gas into the oil?
just thinking what i have heard. If it is a new motor,
mickey :-) anaheim ca. 77 palm beach
On May 26, 2013, at 9:57 AM, Larry Davick wrote:
> Karen,
>
> Isn't this making the choice between oil starvation from a plugged filter and passing dirty oil?
>
> To my way of thinking oil starvation always harms an engine, whereas flowing dirty oil might not.
>
> Larry Davick
>
> On May 26, 2013, at 9:48 AM, KB <kab7@sonic.net> wrote:
>
>> Our engine developed a knock this week. The current
>> theory is it's a rod bearing problem. The engine was rebuilt
>> about 12K miles ago by a reputable re-builder, and ran well
>> until now. This naturally leads me to the question:
>> why this early bearing failure? (assuming that's what it is)
>>
>> A brief search online shows that a leading cause of bearing
>> failure is debris in the oil. So why wouldn't this get
>> filtered out before doing damage? My theory is: the bypass
>> oil filter (WIX 51258). About 2 hours before the knock started,
>> my better half decided, for the first time, to see what 100%
>> throttle (WOT) would do on a freeway on-ramp. As I understand
>> it, during WOT conditions, the oil filter bypass opens,
>> and unfiltered oil flows into the engine. Seems like a
>> bad idea to me, since any junk in the oil can rapidly
>> plug passages or ruin bearings.
>>
>> So: why do we need a bypass filter? Can we get a filter
>> without one, and would that be a good thing??
>>
>> thanks
>> Karen
>> 1973 23'
>> 1975 26'
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208857 is a reply to message #208835] |
Sun, 26 May 2013 14:02 |
|
ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
|
Senior Member |
|
|
After reading the trouble Ken H had with the thrust bearing I'd certainly do some kind of post mortem on that new rebuild. Could the torque converter have caused your engine to fail too?
Bad luck is no fun.
Larry Davick
On May 26, 2013, at 9:48 AM, KB <kab7@sonic.net> wrote:
> Our engine developed a knock this week. The current
> theory is it's a rod bearing problem. The engine was rebuilt
> about 12K miles ago by a reputable re-builder, and ran well
> until now. This naturally leads me to the question:
> why this early bearing failure? (assuming that's what it is)
>
> A brief search online shows that a leading cause of bearing
> failure is debris in the oil. So why wouldn't this get
> filtered out before doing damage? My theory is: the bypass
> oil filter (WIX 51258). About 2 hours before the knock started,
> my better half decided, for the first time, to see what 100%
> throttle (WOT) would do on a freeway on-ramp. As I understand
> it, during WOT conditions, the oil filter bypass opens,
> and unfiltered oil flows into the engine. Seems like a
> bad idea to me, since any junk in the oil can rapidly
> plug passages or ruin bearings.
>
> So: why do we need a bypass filter? Can we get a filter
> without one, and would that be a good thing??
>
> thanks
> Karen
> 1973 23'
> 1975 26'
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208862 is a reply to message #208852] |
Sun, 26 May 2013 14:27 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
|
Senior Member |
|
|
Any thought the new efi could be part part of the problem ? Lean cruse and such? I know of a new dist that took out a good engine;)
Gene
FREE WIFI @ Mickey D
On May 26, 2013, at 10:46 AM, KB <kab7@sonic.net> wrote:
> oops, never mind. The WIX 51258 is NOT a bypass filter. We took
> it apart and saw it has a rubber gasket and spring, which
> I thought was for bypass. It's not, it's for anti-drainback.
>
> Just grasping at straws here for the failure...
>
> thanks
> Karen
> 1973 23'
> 1975 26'
>
>
> On 5/26/2013 9:48 AM, KB wrote:
>> Our engine developed a knock this week. The current
>> theory is it's a rod bearing problem. The engine was rebuilt
>> about 12K miles ago by a reputable re-builder, and ran well
>> until now. This naturally leads me to the question:
>> why this early bearing failure? (assuming that's what it is)
>>
>> A brief search online shows that a leading cause of bearing
>> failure is debris in the oil. So why wouldn't this get
>> filtered out before doing damage? My theory is: the bypass
>> oil filter (WIX 51258). About 2 hours before the knock started,
>> my better half decided, for the first time, to see what 100%
>> throttle (WOT) would do on a freeway on-ramp. As I understand
>> it, during WOT conditions, the oil filter bypass opens,
>> and unfiltered oil flows into the engine. Seems like a
>> bad idea to me, since any junk in the oil can rapidly
>> plug passages or ruin bearings.
>>
>> So: why do we need a bypass filter? Can we get a filter
>> without one, and would that be a good thing??
>>
>> thanks
>> Karen
>> 1973 23'
>> 1975 26'
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208873 is a reply to message #208835] |
Sun, 26 May 2013 16:00 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
> Any thought the new efi could be part part of the problem ? Lean cruse and such? I know of a new dist that took out a good engine;)
I was too paranoid to turn on lean cruise. I'd guess knocks from
too much spark advance to take out valves and such rather than
rods, but wouldn't know. It has a working knock sensor, so
hopefully that would prevent damage. Also, the spark plugs were
fine; if it was detonation, those should have shown it.
How did the distributor take out the engine, and how could I tell if
that was it? Would that be something we'd learn from the oil analysis?
I'd sure like to know what caused it in case it's something we did.
thanks
Karen
1973 23'
1975 26'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Karen
1975 26'
San Jose, CA
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208874 is a reply to message #208835] |
Sun, 26 May 2013 16:13 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
> Was a high volume oil pump installed at the overhaul by chance? Without installing oil restrictors it could pump the oil out of the pan faster than it drains back. That is what cost me an engine, had about 8000 miles before it got bad enough and started knocking, didn't last long after that. Mike
Unfortunately, all I've got is a receipt showing the engine was
sent out for a rebuild, though it also lists 2 rods in the parts list.
The owner's complaint was "loud knocking from engine", and the shop said
it was "bottom end failure" and also mentions they had to "cut
the AC belt off the fan as it was wrapped around it."
Probably wasn't a very fun trip, and not long after,
that owner sold the coach to the folks we got it from.
thanks
Karen
1973 23'
1975 26'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Karen
1975 26'
San Jose, CA
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208912 is a reply to message #208835] |
Mon, 27 May 2013 01:25 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
|
Senior Member |
|
|
| KB wrote on Sun, 26 May 2013 09:48 |
Our engine developed a knock this week. The current
theory is it's a rod bearing problem. The engine was rebuilt
about 12K miles ago by a reputable re-builder, and ran well
until now. This naturally leads me to the question:
why this early bearing failure? (assuming that's what it is)
|
Wow, hate to hear this.
Check the oil in he sunlight after it as run a bit. Glittery is not good.
Rods usually knock most at "float", not really pulling and not slowing down. Without driving if you rev it a bit it will knock just before it starts to slow down.
Main bearing is a deep thump, especially at low RPM. Should hear that at idle in drive.
I like to listen with a light mop handle like stick. Watch the belt and fan but listen with the stick hard on your ear. Listen all over. Surprising what you can hear and where the sound comes from.
The following is just my opinion but I doubt the WOT going up a freeway ramp did the damage. It could be it was on the edge of failure and that quickened the process but an engine that can't run for a few seconds at full throttle is doomed to failure. EFI didnt do it either any more than a carb would. If lean cruise ruined engines every vehicle made after the early 90s would be sitting beside the road. Bad machining, assembly or antifreeze in the oil... Low on oil that causes the pump to suck air on a hill or corner... Those are the things that cause bearing failure. Even pinging is not going to ruin a rod bearing. Put pits in the top of the piston, perhaps, but rods and mains take the full hit of an explosion zillions of times. That's what they are made to do.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208933 is a reply to message #208835] |
Mon, 27 May 2013 09:06 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
|
Senior Member |
|
|
Shortly after getting my coach I had similar rod bearing failure after a kick down pass. I had changed oil and filter 3 times in first few months as mass rebuilt engine was neglected by PO. On the way home from Cinnabar (as they had done some house stuff on it) I had to be towed back as they were the closest option. I was running an AC PF24. On tear down there was about 1 quart of sludge in the pan that didn't drain out. Failure theory same as you have stated. But I bet you had very clean engine so not sure on theory for you or me now, though there are multiple oil bypass paths. I'm leaning towards not enough volume/pressure to rod bearings at high RPM. Supposedly the Cinnabar rebuild includes oil restriction to the valve train to help keep the critical low end parts happy. Slinging effect of crank may have been more than pump can overcome at high RPM. Anyway, knock (or no knock) on wood engine has been great as far as ticks or knocks, though with less than 10k on it there is a bit of cold piston slap which doesn't bother me other than wondering how tightly they checked fit in other critical. areas. I've had high mile Buicks and SBC's with piston cold rattle and they all quieted down in the first few mins so not to worry. Or I can tell myself its a race car fit in a motorhome. Uses no measurable oil. Let us know what you find.
John Lebetski
Woodstock, IL
77 Eleganza II
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208939 is a reply to message #208835] |
Mon, 27 May 2013 11:09 |
 |
John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
|
Senior Member |
|
|
Hi everyone:
The "spin on adaptor" on the engine itself, has the plugged oil filter bypass valve. In other words the filter bypass is a feature of the engine, not filter. The soft surface of the bearing will tolerate a speck of crud by embedding into the surface or leaving a groove in the bearing and or the journal. Im assuming you've done regular oil changes, so there really should not have been much junk flowing around unless some other problem arose. A knock requires most of the bearing surface to be damaged to increase the clearance. Or the bearing moving around in the rod. At high engine speeds the restriction of even a clean oil filter (MAY) bypass some oil anyway. (Depending on the pressure differential at the valve and the amount of flow out of all the "leaks" in the engine. )
Make sure you cut apart the oil filter and check to see how much it has been filtering to help you determine how long things have been developing problems.
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208953 is a reply to message #208912] |
Mon, 27 May 2013 12:35 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
Since it's simple and quick, I'd eliminate a failing exhaust gasket or manifold if I had a 'Knock under load". Simply pull the hatch, fire it up, put it in Drive with your foot clamped on the brake, and get down on the gas. As the engine loads, a leaking exhaust will be very apparent. It's unlikely, but worth looking, cos it's a cheap and easy fix.
--johnny
'76 23' transmode norris
'76 palm beach (with an exhaust leak)
From: George Beckman <gbeckman@pggp.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, May 27, 2013 2:25 AM
Subject: Re: [GMCnet] bearings and filters
KB wrote on Sun, 26 May 2013 09:48
> Our engine developed a knock this week. The current
> theory is it's a rod bearing problem. The engine was rebuilt
> about 12K miles ago by a reputable re-builder, and ran well
> until now. This naturally leads me to the question:
> why this early bearing failure? (assuming that's what it is)
Wow, hate to hear this.
Check the oil in he sunlight after it as run a bit. Glittery is not good.
Rods usually knock most at "float", not really pulling and not slowing down. Without driving if you rev it a bit it will knock just before it starts to slow down.
Main bearing is a deep thump, especially at low RPM. Should hear that at idle in drive.
I like to listen with a light mop handle like stick. Watch the belt and fan but listen with the stick hard on your ear. Listen all over. Surprising what you can hear and where the sound comes from.
The following is just my opinion but I doubt the WOT going up a freeway ramp did the damage. It could be it was on the edge of failure and that quickened the process but an engine that can't run for a few seconds at full throttle is doomed to failure. EFI didnt do it either any more than a carb would. If lean cruise ruined engines every vehicle made after the early 90s would be sitting beside the road. Bad machining, assembly or antifreeze in the oil... Low on oil that causes the pump to suck air on a hill or corner... Those are the things that cause bearing failure. Even pinging is not going to ruin a rod bearing. Put pits in the top of the piston, perhaps, but rods and mains take the full hit of an explosion zillions of times. That's what they are made to do.
--
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208959 is a reply to message #208835] |
Mon, 27 May 2013 13:32 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
> Check the oil in he sunlight after it as run a bit. Glittery is not good.
Unfortunately, I did see glitter. Hopefully the oil
analysis will tell us how bad it is. I'm religious about
checking fluids, so the oil was never low.
> Rods usually knock most at "float", not really pulling and not slowing down. Without driving if you rev it a bit it will knock just before it starts to slow down.
Good description, and I think pretty well matches what we heard.
Didn't hear it when coasting or under load, but in-between the two,
usually between about 10 and 25% throttle. By the time we got
it home (after climbing our 5-mile steep hill) it was a steady knock
at idle, but not a deep thump. I drained the oil for a sample after
it cooled enough to handle, and there it sits, awaiting results.
> The following is just my opinion but I doubt the WOT going up a freeway ramp did the damage. It could be it was on the edge of failure and that quickened the process but an engine that can't run for a few seconds at full throttle is doomed to failure. EFI didnt do it either any more than a carb would.
Thanks, that makes me feel better. It might also explain why I was
having trouble getting rid of knock counts -- whatever it is
was starting to fail and the knock sensor was picking it up long
before we could hear it.
So the questions become "why" and "can it be fixed in the coach,
or must it be pulled"? I'm assuming at this point it'll have to
come out.
thanks,
Karen
1973 23'
1975 26'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Karen
1975 26'
San Jose, CA
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208964 is a reply to message #208953] |
Mon, 27 May 2013 15:18 |
 |
mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
|
Senior Member |
|
|
| Johnny Bridges wrote on Mon, 27 May 2013 10:35 |
Since it's simple and quick, I'd eliminate a failing exhaust gasket or manifold if I had a 'Knock under load". Simply pull the hatch, fire it up, put it in Drive with your foot clamped on the brake, and get down on the gas. As the engine loads, a leaking exhaust will be very apparent. It's unlikely, but worth looking, cos it's a cheap and easy fix.
|
Another way to check for exhaust leaks is to stick an air hose (and a rag to plug it) up the tail pipe. It'll pressurize the exhaust system so you can listen and feel along the pipe, mostly the joints. For real little leaks you could even use a soap solution, but I didn't have to the one time I tried this technique. I had BIG leaks! 
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208984 is a reply to message #208835] |
Mon, 27 May 2013 19:05 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
|
Senior Member |
|
|
| KB wrote on Sun, 26 May 2013 09:48 |
Our engine developed a knock this week. The current
theory is it's a rod bearing problem. The engine was rebuilt
about 12K miles ago by a reputable re-builder, and ran well
until now. This naturally leads me to the question:
why this early bearing failure? (assuming that's what it is)
A brief search online shows that a leading cause of bearing
failure is debris in the oil. So why wouldn't this get
filtered out before doing damage? My theory is: the bypass
oil filter (WIX 51258). About 2 hours before the knock started,
my better half decided, for the first time, to see what 100%
throttle (WOT) would do on a freeway on-ramp. As I understand
it, during WOT conditions, the oil filter bypass opens,
and unfiltered oil flows into the engine. Seems like a
bad idea to me, since any junk in the oil can rapidly
plug passages or ruin bearings.
So: why do we need a bypass filter? Can we get a filter
without one, and would that be a good thing??
thanks
Karen
1973 23'
1975 26'
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
Karen i think you answered your own question? When you were at wide open throttle what was the RPM if it was around 4,000 RPM or higher for any length of time you likely spun #7 or 8 rod bearing as without oil restrict ors in the block the 455 tends to starve the oil pan and pump a lot of oil in the valve spring area of the heads. I overred mine a few years ago and that is what happened to a really nice engine.
Roy Keen
Minden,NV
76 X Glenbrook
|
|
|
|
| Re: [GMCnet] bearings and filters [message #208993 is a reply to message #208835] |
Mon, 27 May 2013 20:08 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
|
Senior Member |
|
|
If the crank is smooth I often wondered --if with the pan off you are only 2 rod bolts away from slipping in a new bearing and buttoning it up, why not. If it works it works. I once did a driveway piston replacement on a Buick 400-4 by pulling the intake, one head, pan and motor mount bolts for clearance. Ran perfect. It seems the Olds 455 is now a mid RPM motor, but I don't remember 442's or even W30s being know for rod bearings back in the day. And what about marine 455s. If that isn't tough service what is. Wonder what Dick Patterson would say here.
John Lebetski
Woodstock, IL
77 Eleganza II
|
|
|
|
| Re: [GMCnet] bearings and filters [message #209008 is a reply to message #208993] |
Tue, 28 May 2013 00:24 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
|
Senior Member |
|
|
| JohnL455 wrote on Mon, 27 May 2013 18:08 |
If the crank is smooth I often wondered --if with the pan off you are only 2 rod bolts away from slipping in a new bearing and buttoning it up, why not. If it works it works. I once did a driveway piston replacement on a Buick 400-4 by pulling the intake, one head, pan and motor mount bolts for clearance. Ran perfect. It seems the Olds 455 is now a mid RPM motor, but I don't remember 442's or even W30s being know for rod bearings back in the day. And what about marine 455s. If that isn't tough service what is. Wonder what Dick Patterson would say here.
|
Marine 455's were mostly used on jet boats the jet pump will put a load on the motor preventing it from going over about 3800 rpm with a Berkeley A impeller with a stock 455 10-1 engine. If you get the boat airborne it will over rev real quick. I've had my Tahiti for 35 years and the motor is still intact but I know of a few that spun bearings when they got the jet out of the water with their foot in it.
Roy Keen
Minden,NV
76 X Glenbrook
|
|
|
|
| Re: [GMCnet] bearings and filters [message #209041 is a reply to message #208835] |
Tue, 28 May 2013 12:22 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
|
Senior Member |
|
|
Karen,
Is is a loud pounding noise (rod knock) or a throbbing sound at idle?
I had a car with piston slap that made the throbbing noise
when cold, but went away as the engine heated up.
Also, can you make the noise change when turning on the
air conditioning or changing the idle speed slightly?
If you pull the valve covers, do you see a loose rocker arm?
Just thinking of other possibilities...
-Bill
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
|
|
|
|
| Re: [GMCnet] bearings and filters [message #209046 is a reply to message #208835] |
Tue, 28 May 2013 13:52 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
|
Senior Member |
|
|
Good point Roy about over-revving. I've no idea if oil restrictors
were installed during the rebuild, but would guess not.
I just went through the logs and the most during the 100% throttle
event was a touch over 3000 rpm. Later in the trip it was briefly at
3500rpm when the tranny downshifted going up a hill, but by then the
problem was already happening (though we didn't realize it at the time;
we can see in the logs where it started). We have a 3.5 power
drive tranny, so the RPM's are normally higher than stock.
thanks
Karen
1973 23'
1975 26'
At the moment, both are yard ornaments :-(
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Karen
1975 26'
San Jose, CA
|
|
|
|
Goto Forum:
Current Time: Sun Oct 06 02:19:57 CDT 2024
Total time taken to generate the page: 0.02154 seconds
|
GMCforum
Search
Help
Register
Login
Home
