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| Changing the oil pump on a Cad 500 [message #237454] |
Sat, 25 January 2014 15:51  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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For reasons I don't need to get into, I am replacing the oil pump on my 73' Cad 500. Are you aware of any trick method of keeping the driveshaft (from distributor to pump) in place when putting the pump back on. With the engine in place, gravity wants to drop that thing out of its place and on to yer nose. IIRC last time I used a real thick grease on the distributor end of the shaft to kinda "glue" it up in there while I lined it up and got the first threads on the bolts started, but if there is a better way, I'm all ears. I would rather not pull the distributor because I do not have a timing light with me.
Thanks
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Changing the oil pump on a Cad 500 [message #237474 is a reply to message #237454] |
Sat, 25 January 2014 18:02  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Larry,
I'm a little surprised by your question. I've replaced the Cad oil pump at
least twice and had no problem at all -- the shaft didn't fall out and
re-engaging the gear posed no problem. Just position the gear in
approximate alignment position and pop the housing into place, perhaps
twisting it a little for fine alignment. What did I do wrong? :-)
(Betcha the "don't need to get into" wasn't nearly as dumb as that last
fiasco of mine!)
Ken H.
On Sat, Jan 25, 2014 at 4:51 PM, Larry wrote:
>
> For reasons I don't need to get into, I am replacing the oil pump on my
> 73' Cad 500. Are you aware of any trick method of keeping the driveshaft
> (from distributor to pump) in place when putting the pump back on. With the
> engine in place, gravity wants to drop that thing out of its place and on
> to yer nose. IIRC last time I used a real thick grease on the distributor
> end of the shaft to kinda "glue" it up in there while I lined it up and got
> the first threads on the bolts started, but if there is a better way, I'm
> all ears. I would rather not pull the distributor because I do not have a
> timing light with me.
> Thanks
> --
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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] Changing the oil pump on a Cad 500 [message #237477 is a reply to message #237474] |
Sat, 25 January 2014 18:23 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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| Ken Henderson wrote on Sat, 25 January 2014 18:02 |
Larry,
I'm a little surprised by your question. I've replaced the Cad oil pump at
least twice and had no problem at all -- the shaft didn't fall out and
re-engaging the gear posed no problem. Just position the gear in
approximate alignment position and pop the housing into place, perhaps
twisting it a little for fine alignment. What did I do wrong?
(Betcha the "don't need to get into" wasn't nearly as dumb as that last
fiasco of mine!)
Ken H.
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Ken,
Well, don't know what I did wrong several years ago, but I distinctly remember laying under it, getting ready to put the pump back in and having the shaft fall out and bonk me on the forehead. I eventually had to put the pump in without the shaft, and from the top, pull the distributor, drop the shaft in place then the distributor. I'd really like to avoid all that and simply just replace the oil pump and be done with it.
No, no big fiasco....this time....Oil pressure has dropped to just under 40lbs at a hot rev, and while guys at MTS say that is not low and not to worry about it, I am worried, and short of pulling the motor apart, this is a relatively easy thing to do. I like to see 45lbs or more at a hot rev, especially with 15-50 Mobile 1. I just got this hunch that I gotta play out. Better safe than sorry.
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Changing the oil pump on a Cad 500 [message #237496 is a reply to message #237454] |
Sun, 26 January 2014 08:11 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Larry,,,after reading a lot of posts about oil pump failures on the Cadillac Power Forum I spent about 2 to 3 hours on mine. The problem several others had more than once was the pressure reg. sticking. Resulting in no pressure at idle. The procedure they recomended was to polish the pressure releve valve.(piston and bore) I worked on it for a long time and noticed no difference. I would polish it with 1000 and then 1500. After an hour and half of polishing I noticed a difference. I would very carefully clean it and lube before checking. I also spent the rest of the time porting and polishing the ports and the block. Like in Doc Frommers book. Years ago my father taught me to check a drill bit by spinning it in the palm of my hand. When I did this with the rotors they would catch like a sharp drill bit. I rounded the ends of the gears with needle files, not a grinder. Finished with 600. No more sharp edges. I had noticed the iron block had scoreing from the rotor ends. I had 70-75 psi on an 18v battery drill on low gear. GL,,JWID,,,,PL
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| Re: [GMCnet] Changing the oil pump on a Cad 500 [message #237498 is a reply to message #237496] |
Sun, 26 January 2014 08:35 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Paul,
I don't quite understand your thesis: Are you saying that you accomplished
nothing by polishing the regulator piston but did by breaking the edges on
the rotors? I agree that the sharp edges on the rotors aggravate scoring
of the block, I can't imagine that causing a loss of oil pressure -- unless
the rotors lock up and shear the shaft.
What am I missing? Excessive end clearance on the rotors causing low idle
pressure?
Ken H.
On Sun, Jan 26, 2014 at 9:11 AM, Paul Leavitt wrote:
>
> Larry,,,after reading a lot of posts about oil pump failures on the
> Cadillac Power Forum I spent about 2 to 3 hours on mine. The problem
> several others had more than once was the pressure reg. sticking. Resulting
> in no pressure at idle. The procedure they recomended was to polish the
> pressure releve valve.(piston and bore) I worked on it for a long time and
> noticed no difference. I would polish it with 1000 and then 1500. After
> an hour and half of polishing I noticed a difference. I would very
> carefully clean it and lube before checking. I also spent the rest of the
> time porting and polishing the ports and the block. Like in Doc Frommers
> book. Years ago my father taught me to check a drill bit by spinning it in
> the palm of my hand. When I did this with the rotors they would catch like
> a sharp drill bit. I rounded the ends of the gears with needle files, not a
> grinder. Finished with 600. No more sharp edges. I had noticed the iron
> block had scoreing from the rotor ends. I ha
> d 70-75 psi on an 18v battery drill on low gear. GL,,JWID,,,,PL
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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] Changing the oil pump on a Cad 500 [message #237521 is a reply to message #237496] |
Sun, 26 January 2014 13:06 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Paul, this is a trick that I have used on oil pumps for years. (dates back
to my ford flathead days). Using a piece of flat automotive glass, and the
finest valve lapping compound you can find. Lap the cover of the pump until
it is uniformly grey all over. Do the same thing to the rotor housing with
the rotors in place until you have them all the same finish as the cover.
Usually takes a while to do by hand. I use a figure eight lapping pattern,
frequently rotating the object that I am lapping in my hand. This
eliminates any tendency I might have to exert more pressure on one side or
the other. Finish up by cleaning all parts and passages in hot soapy water
and rifle bore brushes. Assemble the pump by hand with a small dab of
prussian blue or white lead on the cover and screw the bolts finger tight
while turning the drive shaft by hand. When resistance is felt, remove the
cover and observe the transfer pattern on the ends of the rotors. When you
are assured of "0" clearance, then fit the .001" blue plastic oil pump end
plate gasket in place and loctite the cover fasteners. Polish the plunger
piston with jewelers rouge or a buffing wheel and then shim the spring to
obtain the pressure you want with hot oil. You will never have to look at
that oil pump again unless you twist off the drive shaft. Don't ask me how
I know that last part, the memories are painfully expensive. One more
blueprinting trick revealed. Another couple of years, and you guys will
know all of them.(grin)
Jim Hupy
Salem, Or
78 GMC Royale 403
On Jan 26, 2014 6:11 AM, "Paul Leavitt" <leavittpaul@yahoo.com> wrote:
>
>
> Larry,,,after reading a lot of posts about oil pump failures on the
> Cadillac Power Forum I spent about 2 to 3 hours on mine. The problem
> several others had more than once was the pressure reg. sticking. Resulting
> in no pressure at idle. The procedure they recomended was to polish the
> pressure releve valve.(piston and bore) I worked on it for a long time and
> noticed no difference. I would polish it with 1000 and then 1500. After
> an hour and half of polishing I noticed a difference. I would very
> carefully clean it and lube before checking. I also spent the rest of the
> time porting and polishing the ports and the block. Like in Doc Frommers
> book. Years ago my father taught me to check a drill bit by spinning it in
> the palm of my hand. When I did this with the rotors they would catch like
> a sharp drill bit. I rounded the ends of the gears with needle files, not a
> grinder. Finished with 600. No more sharp edges. I had noticed the iron
> block had scoreing from the rotor ends. I ha
> d 70-75 psi on an 18v battery drill on low gear. GL,,JWID,,,,PL
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Changing the oil pump on a Cad 500 [message #237550 is a reply to message #237521] |
Sun, 26 January 2014 17:21 |
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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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Jim,
I used the same method to lap cylinder heads and the top of cylinders on Harley-Davidson Evolution engines, one difference, I used a
piece of 3/4" thick tempered glass.
Regards,
Rob M.
-----Original Message-----
From: James Hupy
Paul, this is a trick that I have used on oil pumps for years. (dates back
to my ford flathead days). Using a piece of flat automotive glass, and the
finest valve lapping compound you can find. Lap the cover of the pump until
it is uniformly grey all over. Do the same thing to the rotor housing with
the rotors in place until you have them all the same finish as the cover.
Usually takes a while to do by hand. I use a figure eight lapping pattern,
frequently rotating the object that I am lapping in my hand. This
eliminates any tendency I might have to exert more pressure on one side or
the other. Finish up by cleaning all parts and passages in hot soapy water
and rifle bore brushes. Assemble the pump by hand with a small dab of
prussian blue or white lead on the cover and screw the bolts finger tight
while turning the drive shaft by hand. When resistance is felt, remove the
cover and observe the transfer pattern on the ends of the rotors. When you
are assured of "0" clearance, then fit the .001" blue plastic oil pump end
plate gasket in place and loctite the cover fasteners. Polish the plunger
piston with jewelers rouge or a buffing wheel and then shim the spring to
obtain the pressure you want with hot oil. You will never have to look at
that oil pump again unless you twist off the drive shaft. Don't ask me how
I know that last part, the memories are painfully expensive. One more
blueprinting trick revealed. Another couple of years, and you guys will
know all of them.(grin)
Jim Hupy
Salem, Or
78 GMC Royale 403
On Jan 26, 2014 6:11 AM, "Paul Leavitt" <leavittpaul@yahoo.com> wrote:
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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: Changing the oil pump on a Cad 500 [message #237567 is a reply to message #237454] |
Sun, 26 January 2014 20:10 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Senior Member |
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Ken,,,what I meant to convey was that for a long time I saw no difference in smoothness of the piston in the bore. It seemed pretty good. But after about an hour to an hour and a half it did get noticeably better. Jim H.,,, I don't have one in front of me but the cover for the Cad oil pump is the block. Scoring on the face of the block was noticeable and the edges of the "new" pump were sharp. Thus the deburing. Its my understanding that Cad oil pump gasket thickness is critical. But I don't remember what thickness is needed.,,,,PL
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| Re: [GMCnet] Changing the oil pump on a Cad 500 [message #237582 is a reply to message #237567] |
Sun, 26 January 2014 22:38 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Paul,
.007" is what is recommended.
Gary Kosier
77 PB w/Cad 500
Newark, Oh
-----Original Message-----
From: Paul Leavitt
Sent: Sunday, January 26, 2014 9:10 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Changing the oil pump on a Cad 500
Ken,,,what I meant to convey was that for a long time I saw no difference in
smoothness of the piston in the bore. It seemed pretty good. But after about
an hour to an hour and a half it did get noticeably better. Jim H.,,, I
don't have one in front of me but the cover for the Cad oil pump is the
block. Scoring on the face of the block was noticeable and the edges of the
"new" pump were sharp. Thus the deburing. Its my understanding that Cad oil
pump gasket thickness is critical. But I don't remember what thickness is
needed.,,,,PL
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| Re: [GMCnet] Changing the oil pump on a Cad 500 [message #237587 is a reply to message #237582] |
Sun, 26 January 2014 23:19 |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Senior Member |
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Larry,
Take the shaft and find the angle that fits into the dist. shaft and then put the shaft in the pump and if necessary rotate slightly till it drops up. 90 degrees is the rotation to fit , so you cannot be too far in rotation to fit in.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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