Home » Public Forums » GMCnet » [GMCnet] Strange Oil Pressure Drop
| [GMCnet] Strange Oil Pressure Drop [message #271871] |
Fri, 13 February 2015 08:21  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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We sometimes forget how many lurkers we have here, and their high levels of
expertise -- I often think that the wisest among us unfortunately keep
their thoughts to themselves. This morning one of those smart lurkers
called me with a question -- probably not because I was likely to have an
answer but because I'd ask Y'All.
He, a VERY experienced and capable mechanic, just replaced his 455 cylinder
heads with freshly rebuilt ones. He changed the oil immediately after the
change, just to be sure the old oil had been contaminated with coolant.
Since he owns a garage, he used the same bulk 10W40 for both fills. We can
be sure the job was done correctly and that there was no unexpected
modification.
Before, the engine oil pressure, monitored by the OEM gauge and an
aftermarket one, ran 35-36 psi warm at road speed. Now, it's 28-29 psi.
WHY??? The push rods were replaced in their original positions. The oil
filter is the same P/N as the replaced one.
Does anyone have any clue as to why that dramatic change could have
occurred? At the current ambient temperatures, the pressure is not too
disturbing, other than the unexplained change; but, when summer comes, that
pressure is likely to drop dangerously low. We need to figure out what
happened.
Thanks for your ideas.
Ken H.
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271875 is a reply to message #271871] |
Fri, 13 February 2015 09:18  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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Ken Henderson wrote on Fri, 13 February 2015 09:21We sometimes forget how many lurkers we have here, and their high levels of expertise -- I often think that the wisest among us unfortunately keep their thoughts to themselves. This morning one of those smart lurkers called me with a question -- probably not because I was likely to have an answer but because I'd ask Y'All.
He, a VERY experienced and capable mechanic, just replaced his 455 cylinder heads with freshly rebuilt ones. He changed the oil immediately after the change, just to be sure the old oil had been contaminated with coolant. Since he owns a garage, he used the same bulk 10W40 for both fills. We can be sure the job was done correctly and that there was no unexpected modification.
Before, the engine oil pressure, monitored by the OEM gauge and an aftermarket one, ran 35-36 psi warm at road speed. Now, it's 28-29 psi.
WHY??? The push rods were replaced in their original positions. The oil filter is the same P/N as the replaced one.
Does anyone have any clue as to why that dramatic change could have occurred? At the current ambient temperatures, the pressure is not too disturbing, other than the unexplained change; but, when summer comes, that pressure is likely to drop dangerously low. We need to figure out what happened.
Thanks for your ideas.
Ken H.
Ken,
It does not make a lot of difference with my response, but it is a little unclear. Did the drop in lube oil pressure occur after the cylinder head change or after the oil change??
In either case, I am going to suggest the same possibility. He won't like it. Remember I am no expert on the 455, but I have seen this on the old Chrysler LA (90°) engines. They have a plunger as the valve in the oil pump relief. Unlike the Chevy SB that uses a round ball, this can be held open a little by one tiny F-ing piece of micro-crud. As it is a piston and not a ball, this makes a pretty big leak. When cleaning the deck, there had to be some of those running loose.
Thing to try... This worked on phase1($$) prototype for the original V-10 motor, so I do know it can work. (I wish it had been my idea, but it was good anyway.) Try putting a priming shaft (long version of a distributor shaft in there and spin the pump as fast the drill motor will go. It can't be a cordless drill motor and it can't be larger than 3/8. A 1/2 drill motor will be to slow. The HP required will be more than most 3/8 can do for very long, but over heat the drill motor a couple of times and then put the distributor back in and try again.
The alternative is taking the pan down....
Please let us know how he does.
Matt - the engine lab refugee
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] Strange Oil Pressure Drop [message #271880 is a reply to message #271871] |
Fri, 13 February 2015 09:49 |
Dennis S
Messages: 3046
Registered: November 2005
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Ken
Probably not the answer -- but, the oil pressure on the OEM gauge dropped by a similar amount on my coach after sunset. Then I realized it corresponded to my turning on the headlights.
Does the aftermarket rely on a ground or is it mechanical?
Dennis
Ken Henderson wrote on Fri, 13 February 2015 08:21We sometimes forget how many lurkers we have here, and their high levels of
expertise -- I often think that the wisest among us unfortunately keep
their thoughts to themselves. This morning one of those smart lurkers
called me with a question -- probably not because I was likely to have an
answer but because I'd ask Y'All.
He, a VERY experienced and capable mechanic, just replaced his 455 cylinder
heads with freshly rebuilt ones. He changed the oil immediately after the
change, just to be sure the old oil had been contaminated with coolant.
Since he owns a garage, he used the same bulk 10W40 for both fills. We can
be sure the job was done correctly and that there was no unexpected
modification.
Before, the engine oil pressure, monitored by the OEM gauge and an
aftermarket one, ran 35-36 psi warm at road speed. Now, it's 28-29 psi.
WHY??? The push rods were replaced in their original positions. The oil
filter is the same P/N as the replaced one.
Does anyone have any clue as to why that dramatic change could have
occurred? At the current ambient temperatures, the pressure is not too
disturbing, other than the unexplained change; but, when summer comes, that
pressure is likely to drop dangerously low. We need to figure out what
happened.
Thanks for your ideas.
Ken H.
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271881 is a reply to message #271871] |
Fri, 13 February 2015 09:47 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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Ken,
In your message, It is not clear if the antifreeze in the oil was the result of bad heads/gaskets, or if it was from the process of R&R of the heads. If the contamination was the reason the heads were pulled, then the antifreeze may have damaged the bearings.
A few questions come to mind regarding the gauge used to monitor the oil pressure. Is it mechanical or electrical? Is it installed in the coach, or a hand held shop diagnostic gauge? Is it possible the gauge (or its connection) might have been damaged between tests? In the case of a hand held gauge, is it the same gauge used for both tests?
These are all comments that I assume would have been considered by an experienced mechanic, but it isn't clear in your message so I had to ask.
Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)
> On Feb 13, 2015, at 9:21 AM, Ken Henderson wrote:
>
> We sometimes forget how many lurkers we have here, and their high levels of
> expertise -- I often think that the wisest among us unfortunately keep
> their thoughts to themselves. This morning one of those smart lurkers
> called me with a question -- probably not because I was likely to have an
> answer but because I'd ask Y'All.
>
> He, a VERY experienced and capable mechanic, just replaced his 455 cylinder
> heads with freshly rebuilt ones. He changed the oil immediately after the
> change, just to be sure the old oil had been contaminated with coolant.
> Since he owns a garage, he used the same bulk 10W40 for both fills. We can
> be sure the job was done correctly and that there was no unexpected
> modification.
>
> Before, the engine oil pressure, monitored by the OEM gauge and an
> aftermarket one, ran 35-36 psi warm at road speed. Now, it's 28-29 psi.
> WHY??? The push rods were replaced in their original positions. The oil
> filter is the same P/N as the replaced one.
>
> Does anyone have any clue as to why that dramatic change could have
> occurred? At the current ambient temperatures, the pressure is not too
> disturbing, other than the unexplained change; but, when summer comes, that
> pressure is likely to drop dangerously low. We need to figure out what
> happened.
>
> Thanks for your ideas.
>
> Ken H.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271884 is a reply to message #271871] |
Fri, 13 February 2015 10:08 |
Gadabout
Messages: 124
Registered: March 2013
Location: Edmonton
Karma: 2
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Hi Ken,
Easy stuff first - Check the sending unit wire to confirm it is clean and properly connected. Also remove the sending unit and clean out the input hole. Some debris from cleaning off gaskets may have worked its way to the sending unit.
Were the lifters removed ? Lifter bore clearance can effect oil pressure. I had an engine with several "gummed" up lifters , but it had good oil pressure. After the lifters were removed and cleaned as part of a head change, the oil pressure dropped , and the lifter noise stopped.
Let us know what the problem was when you find it.
Carl Harr : Driver NASCAR Pro Series #2
1978 Gadabout-Restoring
1978 Palm Beach
1976 Glenbrook
Prevost Featherlite H3-45
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271885 is a reply to message #271871] |
Fri, 13 February 2015 11:14 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Let me add 2 things to the "sender" and "wiring" recommendations.
Taking the Intake manifold and the rad brackets in the sender area on and off makes it highly likely that the sender may have been knocked. Secondly: the sender wire needs to bee removed or at least pulled or strained because the harness goes across the manifold at that point
Also: I'm pretty sure (memory seems to fade with my hair line) the the gauge goes to full scale with wire off (high resistance ) and "0" with wire Grounded Low Resistance
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271887 is a reply to message #271871] |
Fri, 13 February 2015 11:38 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
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Just a wild guess.
Did he replace the oil filter?
Oh, I see he did replace it....
"The oil filter is the same P/N as the replaced one."
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
[Updated on: Fri, 13 February 2015 11:40] Report message to a moderator |
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271888 is a reply to message #271885] |
Fri, 13 February 2015 11:35 |
Dolph Santorine
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
Karma: -41
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I can speak to your memory on this issue - absolutely.
However, I don’t know a thing about your hairline
Dolph
DE N8JPC
Wheeling, West Virginia
1977 26’ ex-PalmBeach
1-Ton, Sullybilt Bags, Reaction Arms, 3.70 LSD, Manny Transmission, EV-6010
“The Aluminum and Fiberglass Mistress"
> On Feb 13, 2015, at 12:14 PM, John Heslinga wrote:
>
> Let me add 2 things to the "sender" and "wiring" recommendations.
>
> Taking the Intake manifold and the rad brackets in the sender area on and off makes it highly likely that the sender may have been knocked. Secondly:
> the sender wire needs to bee removed or at least pulled or strained because the harness goes across the manifold at that point
>
> Also: I'm pretty sure (memory seems to fade with my hair line) the the gauge goes to full scale with wire off (high resistance ) and "0" with wire
> Grounded Low Resistance
> --
> John and Cathie Heslinga
> 1974 Canyonlands 260
> 455, Manny tranny and 1 ton, 3:70 LS,
> TC4W "Too Cool For Words"
> Retirement Projects Galore
> Edmonton, Alberta
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271890 is a reply to message #271871] |
Fri, 13 February 2015 11:46 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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OH HELL my thumb touched send on the phone before I finished. Now for the rest of the story! I hate doing this on the phone. It takes forever.
First the wire. If the connector actally had some resistance as part of the connection- the reading would actually be higher than the actual pressure. (Low resistance = lower gauge - high resistance= higher gauge). You actually may have fixed a problem by sliding the connection off and on. The oil pressure readin now may be the correct reading. (Nothing to worry about)
Second the sender: that sender is out in the open and subject to water spray from the fan. Here is one of a few that I have changed.
http://www.gmcmhphotos.com/photos/engine-failure/p51648-sending-unit-will-not-return-to-zero.html
The swiper does not really move full stroke because of the corrosion. A knock from the manifold may have changed its position. There are a few more pictures in the album relating to this sender. (Also remember the gauge does not go to zero when ign is off) only during crank mode or if pressure is actually zero with the key on. This is why i change these.
In conclusion, i would think the actual problem is the cleaned conection and nothing is wrong. But change out the sender anyway because the corosion is very common in oil pressure senders they are not well sealed.
Best regards.
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271891 is a reply to message #271871] |
Fri, 13 February 2015 11:58 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
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What if there was so much contamination in the oil that the new oil filter became plugged?
Wouldn't the oil filter bypass valve then drop 5-6 PSI?
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271892 is a reply to message #271871] |
Fri, 13 February 2015 12:05 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Can debris from the valve job be blocking the oil pickup screen?
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271893 is a reply to message #271871] |
Fri, 13 February 2015 12:09 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Replace the oil pressure sender. I had one that I replaced several years ago. When I opened the old one it was full of rust. It is cheap and easy to replace. Make sure you get one for a gauge and not one for an oil light. AZ will give you one for a light. I got the correct one at Advanced.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271894 is a reply to message #271871] |
Fri, 13 February 2015 12:28 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Another longshot (real long) thought that has crossed my mind is.: While scraping the gasket surfaces a couple a pieces of crud dropped into 1 or 2 of the lifter orifices where the push rod sits in and is holding the metering disk (valve) of the lifter open. Allowing some oil to constantly escape.
I would imagine there would be other noise issues, but the lifter takes time to collapse and there is always oil going to the lifter keeping the inner piston high, so it might remain quiet.
There is really no other access to the oiling system pressure side that you have in doing the job you've done. Once the oil getts to the push rod, it's pretty well wide open at that point and just flows because the rockers do not hold oil pressure back.
Quite a Longshot maybe and I doubt it is the actual problem, but I can tell you that longshot thinking sure has helped direct me to solve some strange problems in the past.
Best regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271895 is a reply to message #271871] |
Fri, 13 February 2015 12:42 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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With all this talk of crud and junk. I really am assuming that as a competent mechanic you did cover the lifter gallery when you cleaned the gaskets however: All that sh#£ from the turkey tray carbon and manifold heat can go a long way if there is any carelessness or accidental spilling when removing that big gasket. You cant see some of those chunks in dark oil.
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271896 is a reply to message #271871] |
Fri, 13 February 2015 13:00 |
mercdave
Messages: 45
Registered: May 2014
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Assuming everything else mentioned is NOT the issue;
The only thing that I can think of that would change when replacing heads is the actual valve stem installed height between the old heads and the new ones. This will put the inner piston of the lifter at a different position in the lifter possibly allowing more oil to bypass.
Dave L
Lynnwood, Wa.
1976 GMC 26' Edgemonte Rear Twin
1973 GMC 23' Rear-Ended, Totaled
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271899 is a reply to message #271896] |
Fri, 13 February 2015 13:27 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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mercdave wrote on Fri, 13 February 2015 12:00Assuming everything else mentioned is NOT the issue;
The only thing that I can think of that would change when replacing heads is the actual valve stem installed height between the old heads and the new ones. This will put the inner piston of the lifter at a different position in the lifter possibly allowing more oil to bypass.
really good point Dave. Many Valve grind shops do not make allowances for the fixed rockers that the old Olds use.
Not very many come in anymore. It's also not uncommon that they use wrong seats too.
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271923 is a reply to message #271899] |
Fri, 13 February 2015 21:55 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Thanks to everyone for all the good ideas -- lots of new ones for me.
While I'm sure that his workmanship was meticulous, the debris speculations
are certainly valid and worth considering. It's strange but I, as a EE,
hadn't considered that R&R of the oil pressure sender could have affected
its accuracy. When I talked to him this morning his intention was to first
replace the oil filter. I'm sure that if that doesn't help he'll start
through this new list.
We'll let Y'All know what it turns out to be.
Ken H.
On Fri, Feb 13, 2015 at 2:27 PM, John Heslinga wrote:
> mercdave wrote on Fri, 13 February 2015 12:00
>> Assuming everything else mentioned is NOT the issue;
>> The only thing that I can think of that would change when replacing
> heads is the actual valve stem installed height between the old heads and
> the
>> new ones. This will put the inner piston of the lifter at a different
> position in the lifter possibly allowing more oil to bypass.
>
>
> really good point Dave. Many Valve grind shops do not make allowances for
> the fixed rockers that the old Olds use.
>
> Not very many come in anymore. It's also not uncommon that they use wrong
> seats too.
>
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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] Strange Oil Pressure Drop [message #271936 is a reply to message #271871] |
Sat, 14 February 2015 04:08 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Ken,
Direct your "mate" to this link: http://www.gmcmhphotos.com/photos/g6398-455-2f-403-engine-oil-flow-path.html
It has photos, line drawings, and schematics which show the flow path of the engine oil system.
Additional comments below in CAPS for clarity - not shouting!
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Henderson
Sent: Saturday, February 14, 2015 1:21 AM
To: gmclist
Subject: [GMCnet] Strange Oil Pressure Drop
We sometimes forget how many lurkers we have here, and their high levels of
expertise -- I often think that the wisest among us unfortunately keep
their thoughts to themselves. This morning one of those smart lurkers
called me with a question -- probably not because I was likely to have an
answer but because I'd ask Y'All.
He, a VERY experienced and capable mechanic, just replaced his 455 cylinder
heads with freshly rebuilt ones.
WHY DID HE REPLACE THE HEADS?
He changed the oil immediately after the
change, just to be sure the old oil had been contaminated with coolant.
I'M A BIT CONFUSED BY THIS SENTENCE. DOES IT MEAN THE OLD OIL WAS
CONTAMINATED WITH COOLANT?
Since he owns a garage, he used the same bulk 10W40 for both fills. We can
be sure the job was done correctly and that there was no unexpected
modification.
Before, the engine oil pressure, monitored by the OEM gauge and an
aftermarket one, ran 35-36 psi warm at road speed. Now, it's 28-29 psi.
WHY???
SINCE YOU HAVE PROVIDED SPECIFIC PRESSURES I ASSUME
HE HAS A REMOTE OIL PRESSURE GAGE. IS IT MECHANICAL OR
ELECTRICAL?
The push rods were replaced in their original positions. The oil
filter is the same P/N as the replaced one.
WHAT WAS THE MANUFACTURER AND PART NUMBER OF THE
OLD AND NEW OIL FILTER?
Does anyone have any clue as to why that dramatic change could have
occurred? At the current ambient temperatures, the pressure is not too
disturbing, other than the unexplained change; but, when summer comes, that
pressure is likely to drop dangerously low. We need to figure out what
happened.
Thanks for your ideas.
Ken H.
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Strange Oil Pressure Drop [message #271938 is a reply to message #271875] |
Sat, 14 February 2015 04:27 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Matt,
To lend some additional information to your suggestion; here's a link to a series of photos that show the engine oil flow path of a
455 and 403:
http://www.gmcmhphotos.com/photos/g6398-455-2f-403-engine-oil-flow-path.html
Here's an exploded view of the oil pump:
http://www.gmcmhphotos.com/photos/455-2f-403-engine-oil-flow-path/p53484-oil-pump-exploded-view.html
You can see the plunger you mention.
I assume that by spinning the oil pump with the drill the pressure output will be enough to lift the plunger off it's seat and clean
any crap that might be holding it open. Speaking of which I can't seem to find the pressure that plunger lifts at; anybody know?
There is another similar component that could be causing this problem; the bypass poppet in the oil filter adapter; see this photo:
http://www.gmcmhphotos.com/photos/455-2f-403-engine-oil-flow-path/p49551-oil-cooler-2f-filter-adapter-inside.html
Here's an exploded view of the poppet:
http://www.gmcmhphotos.com/photos/455-2f-403-engine-oil-flow-path/p49550-bypass-poppet.html
Note the flat portion at 7:00! That is why I noted Ken Frey makes brass replacements! It might be worth his time to remove the oil
filter adapter and check this poppet.
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Matt Colie
Sent: Saturday, February 14, 2015 2:18 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Strange Oil Pressure Drop
Ken,
It does not make a lot of difference with my response, but it is a little unclear. Did the drop in lube oil pressure occur after
the cylinder head change or after the oil change??
In either case, I am going to suggest the same possibility. He won't like it. Remember I am no expert on the 455, but I have seen
this on the old Chrysler LA (90°) engines. They have a plunger as the valve in the oil pump relief. Unlike the Chevy SB that uses
a round ball, this can be held open a little by one tiny F-ing piece of micro-crud. As it is a piston and not a ball, this makes a
pretty big leak. When cleaning the deck, there had to be some of those running loose.
Thing to try... This worked on phase1($$) prototype for the original V-10 motor, so I do know it can work. (I wish it had been my
idea, but it was good anyway.) Try putting a priming shaft (long version of a distributor shaft in there and spin the pump as fast
the drill motor will go. It can't be a cordless drill motor and it can't be larger than 3/8. A 1/2 drill motor will be to slow.
The HP required will be more than most 3/8 can do for very long, but over heat the drill motor a couple of times and then put the
distributor back in and try again.
The alternative is taking the pan down....
Please let us know how he does.
Matt - the engine lab refugee
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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