OIL PUMP WEAR

[ERB72]

Hello All. Can any one comment on the acceptable ammount of visable wear that is "normal" on the bottom plate on the oil pump,the one that the pump gears sit on.The circular area under the driven gear between the shaft and the inner edge of the teeth, on the pump I have just removed seems to be at least 100% more worn than the non driven side(and is quite "rough" to the touch.I have noticed too that some pumps (shallow sump) seem to be fitted with steel bottom plates,whilst the ones on the deep sumps are cast, is this relavant or just pot luck! but Im interested to know if there is a "tweek" to stop this wear, or is it O.K.? can different pumps run "tight" and not allow any oil to get into the area showing the wear? as the areas under the shaft and gear teeth are perfect with no sign of wear at all !................. I await enlightenment. ................Regards Erb

[John V Cliche]

On my engine re-builds.....ANY signs of wear in the oil pump itself, is cause for replacement.
The more clearance you have on either end of the "impellars" will allow "pressure loss "and we all know what that leads to.

Hope this helps

John

[ERB72]

This is a "BRAND NEW OUT OF THE ORIGINAL BOX" pump !!!! I replaced the previous pump because the pressure relief shuttle valve was worn /sticking and giving wildly different readings between zero one minute and 60 p.s.i. the next ! This pump has only been on for 26 miles!!!!when going to a recent event the truck and engine ran absolutly perfectly with an oil pressure range of 35 to 45 p.s.i. was quiet and seemed as good as one could get an engine to run. After a really nice trip with a couple of stops to call on friends,we arrived at the venue and going along the long drive up to the display fields at about 3 m.p.h the engine just stopped I thought I had stalled the engine,but on trying to start again the engine turned over but after a couple of minutes trying I just knew It wasnt going to restart. So because I was blocking the lane a tractor towed me on to the fields (the shame of it) to much enjoyment to every one else. The hood up revealed all as it should be EXCEPT a slightly loose dizzie, so slipped timing was the main suspect . the clutch cover came off the engine turned over on the ring gear and retimed, re started no problem , but horror of horrors again ZERO oil pressure, this time after much head scratching the dizzie was withdrawn and sad to say the flattened end that is the drive for the oil pump was COMPLETLTY SHEARED OFF dont mention bad luck .With the truck on a trailor and back at home the distributor was out and I tried to fish out the broken off part of the drive shaft,with a small magnet ,no joy. There was just enough of the slot clear to try turning the pump with a long screwdriver, but it would not move at all either way ,siezed??? so off with the sump again p.s oil was clear and no bits in the strainer or on a magnet dragged through the oil.with the pump out and apart the base showed the wear stated in first post it looks as if its" picked up" under the driven gear and a small flake has jammed the gears and locked the pump thus snapping off the drive shaft end has any one had this happen to them? what was wrong with the pump?

[John V Cliche]

Fortunately that hasn't happened to me ...yet....but it sure sounds like your New/NOS pump was defective
A thorough examination is order to locate all the "shrapnel "in the oil pan/ galleys
Is it possible that some obstruction/interferance occured in the "Dizzie" ( stateside Dist . ) and caused the shaft tang to shear ?
On second thought, the oil pump is driven by the dist. therefore the damge to the oil pump internals would have had to occur prior to the shaft tang shearing ( otherwise the pump would never have turned once the tang entered the pump cavity )
?????????
Hope this helps
John

[ERB72]

I now have another N.O.S. shallow sump pump,I cannot locate a deep sump type,I therefore EITHER have to replace the new steel bottom plate on the new pump with the original cast one OR fit the original ontop of(under)the steel one (has I have done on the previous pump)My concern is that I may get the same result a seized oil pump and a broken distributor drive shaft Has any one any suggestions has to the possible cause? the gear on the driven shaft was most definatly friction welded to the steel bottom plate so I welcome ANY SUGGESTIONS on what not to do when putting it all back together...as I really dont want this failure to happen again I may not get away so lightly next time.I also have a new dist drive shaft the drive collar on the broken one was rivited thru the 3/16th hole, I have drilled this out to remove the collar what are the thoughts on using a roll pin to attach the two together ...............Regards Erb

[John V Cliche]

I also have used roll pins in the past....but....I suspect that the "rivet's " hardness was used as a shear pin /damage control item
Unfortunately I don't/didn't know of a source for an OEM "pin"

Could your oil pump gear problem have come from an assembly using mis-matched parts

John

[ERB72]

Thanks for that, If the rivit was intended to be a shear pin, they certainly scorded a zero on that one as the dist drive shaft sheared 8mm from its lowest end. The pump could have been missed matched ,but I believe one of the aims of mass production was to manufacture hundreds of components within very close tolerences maybe the gear on the driven shaft was "not on enough"as the gears seem to be just a very ,very tight push fit. But as stated this pump was straight out of an unopened box ,still with all that protective waxed linen wrapping,thats usualy fills you with convidence about the contents.... it was packed June 1951 and seemed absolutly MINT.............Which is why Im worried about the next pump as it is exactly the same... so am I going to be in some sort of "Ground Hog Day" situation Thanks too for the vote of convidence on the Roll Pin thats what I will use on the re assembly,but I could still do with a bit more help on what to do about the bottom plate Thanks again Regards Erb

[John V Cliche]

ERB,
In the '70s ( my hot roddin' days ) we were building small block Chevys, in an effort to gain more oil pressure we would dis-assemble the oil pumps and "lap" the housing using valve grinding compound on a surface plate. this served 2 purposes , it made sure that the cast base was flat and perpendicular to the gears axis, and reduced the amount of space at the ends of the gears thus increasing the amount oil being pushed thru the gears/impellars as opposed to being lost ( bleeding by ) on the ends ( of the gears )

A straight edge and feeler gauge would be the way for you to measure the "clearance" and make sure the housing end is indeed flat . And you have the same clearance on both gears
"Lapping " both surfaces slightly would also insure a good parrallel mating surface.
you could also check your "old cast deep sump base " the same way ,improper alingment between the 2 surfaces may have allowed the oil pump gears to "walk" and bind ,causing your most recent incident

I will check in my CCKW engine TMs in the shop tomorrow and see if they have a recommended ( min/max )clearence for the oil pump/gears

On page 82 SNL shows cover
PN#2137862 as the deep sump 'pick up tube holder'
PN# 2135488 as the shalow version correct ?
PN# 2136438 cover that you are putting between the other base ?????? ( is this what you mean "ontop under of )??????? ( you would be using 2 bottom plates ?????? )
I'm thinking you should only be using PN# 2137862 to the oil pump body itself ( and check clearances )
I read the SNL as listing 3 pump bottom covers for 3 similar but different pumps correct ?
There is only 1 PN for gears and 1 PN for pump body so those items are the same
I agree that substituting either "pick -up" housing shouldn't be a problem ( providing that one or the other doesn't distort the housing)

You haven't mentioned the thrust washer in your previous posts you do have it in place correct ?

Any chance that upon your initial start-up the oil pump "starved "for oil mometarily causing the "gallin" that eventually led to failure?
As a rule I always pack/fill my oil pumps with " assembly lube " insuring an instant circulation of lube oil when staring-up for the first time.

Hope this helps (I have edited this post 4 times in an effort to put into words what my thoughts are )
John

[dr deuce]

With the WW2 GM engines, you can out a drill with a ~5/8" flat wood drill down the dist hole and spin the oil pump until you get oil that primes the engine before starting after a rebuild.

As an aside, you will be surprised at how much energy it takes to turn it!

[ERB72]

Thank you again for the time you have taken to reply with so much information .I hope my reply helps to clear some snags that you have highlighted,Back at the very begining of this problem,the pump on the truck when I aquired it & restored it was stripped cleaned and put back in having first run the pump using an electcic drill to drive it whilst sitting in a bucket of clean oil. All was well. During the rest of the body rebuid the engine was run up often and again all seemed well,however there then appeared the oil pressure problem (refered to in previous posts) I tried to solve this problem in various ways but eventualy the problem was singled down to worn/sticking relief valve.I could not get a N.O.S.pump at the time .So a D.U.K.W. pump with about 18 months wear was swapped out for the original pump.it was at this stage that I used the 2 bottom plates one as fitted to the pump and my old original so as to be able to connect up the relevant pipework in the sump.This pump ran well before gradualy the pressure became irratic and slow to lift off the "zero" on the gague.A N.O.S. pump had now been obtained and swapped out yet again having done all the previous checks and again fitting 2 bottom plates for the same reason.The engine had 4 static runs after that,total time 60 mins and every thing was perfect.UNTIL however I have not seen in any of the 3 pumps any sign of thrust washers is this the holy grail ? where should they be ? The lapping of the bottom plate seems a very good idea and I will do that to the original cast plate ,do I do the gears too ? that seems a silly question but I think best to check, this plate shows sign of wear under the gear locations Do I try to lapp all of this wear off or is it even helpful in this non racing mode as grooves where a little extra oil can settle and be under the gears on the first revolutions when the pump has drained back into the sump.Regards Erb

[John V Cliche]

ERB,
By using the 2 bottom plates ,I'm convinced that you are starving your pump for oil.
From my previous post The gears and the body are the same ,
The inner surface ( where the gears fit ) of all 3 types of bottom plates should be identical on the parts you have...correct ?
If so remove the bottom plate found on your your 'DUKW' pump and replace it with your 'Old/original " deep sump bottom plate as opposed to adding it on ( using 2 plates ) use the original cap screws and safety wire as opposed to the 2 scerws of the DUKW pump
If you need to, only lap the housings .....but....I think the root of your problem was leaving the second plate on the pump bottom itself ( causing oil starve )
I'm on my way to the shop now, I will post some additional info later today concerning specs.

The end clearance needs to be .0015 to .0045 but using a new pump I suspect the clearance will be within spec. same with the condition of the thrust washer
If it were me I would pull the main and rods bearing caps ( 1 by 1 and retorque ) and check for signs of wear ,since you already have the pans down.
I would recommend that you obtain a copy of TM9-1802A pgs 170 to 179 deals specifically with the oil pump ,inspection, repair ,and installation.


Hope this helps

John

[ERB72]

John, Thanks again.I agree about the use of the single original cast bottom plate,it seemed to work fine on the original pump,the problem there was the relief valve and will lapp the body to bottom plate face joint to check alls square.You again mention thrust washers Im still missing the point here as Im unsure as to where they are(sorry to be so dumb)With the mains and caps is it evidence of lack of oil to these that you suggest I look for or something else? I wonder if Ican down load those pages you mention from any where as even If I knew to a copy its going to take me time to get the T.M. itself where as I just need the suggested pages.Many thanks again for your help and I await your further specs...........Regards Erb

[John V Cliche]

My thought is ...if lack of oil galled the pump.....was it bad enough to start galling the bearings.....might be prudent to check now..... than when a rod starts "knocking" prior to exitng the block
The thrust washer is at the top of the drive gear shaft ( most likely OK since this a new pump )but I'm curious as to it's condition in the "bad " pump
I can try to scan and send the pages via e-mail to you ( pardon my computer illiteracy )

Hope this helps
John

[John V Cliche]

ERB,
According to TM 9 1802A
Torque the mains to 70 to 80 ft lbs
the rods to 40 to 50 ft lbs.

Good luck
Hope this helps
John

[ERB72]

UPDATE.The bottom half of all mains and rods where checked ,a little hint of copper in a couple but not enough be too alarmed.The original cast bottom plate was worn well beyond reusing so I refaced it on a lathe and honed it off with a stone to repolish it. I went with the last fitted pump body after checking all the clearances (as provided by John) The driven pump gear on the shaft was over size in length by .0004 which in use would have reduced the oil film underthe gear to .0011 at best and possibly less when warm with the steel plate in perhaps enough heat could not dissipate hence the "pick up" and siezure I cleaned up the gear base and lapped down to the correct overall length,rebuilt and ran the pump in a bucket of clean oil for a couple of hours using an electric drill,stripped the pump again to check. All was well with no visable change to the base , gears or clearances With the tested pump refitted with new oil and filter I ran the pump again with a long screw driver shaft in a drill ,through the dis hole to prove a reading at the gauge and reprime the pump.The rebuilt dis was installed with new points & condenser pushed the button !! and away she went oil pressure up to 38 ish and settled to 35 when up to temp.On a test drive the next day the engine ran for 5 hours non stop and the oil pressure was on the mark all that time So thanks to all that offered advice a big thanks to John V C for the clearance specs and downloads I just would not have been able to do the pump rebuild without that help Thank you again will keep you posted on any more updates Regards Erb

[John V Cliche]

John