Oil Pump Tight

[jimthesail]

Ahoy ! Whilst attempting to prime the oil pump on a rebuilt ex SD1 3.5 the rechargeable drill I use stalled. When trying to turn the shaft by hand it seems, to me, stiff. I would guess a foot/pound or two to rotate. Also notchy as when teeth mesh and also a tight spot. Can't say I have ever spun one before but a trifle concerned ! It has been standing on an engine stand for a long time before I rescued it. Bottom end has been rebuilt with new bearings. Any ideas ?

[DaveEFI]

The pump does get stiff when it builds up enough pressure to operate the pressure release valve.

[jimthesail]

But this is stiff to hand pressure ?

[jimthesail]

As it is a fairly simple dismantle job I will strip down tomorrow and have a look. I suspect something has dropped in !

[ChrisJC]

I've done a pump prime with a cordless drill a few times. The drill slows down when the oil gets picked up, but certainly nowhere near stalling!

Chris.

[jimthesail]

Think we have a solution ? The pump was packed with petroleum jelly, I assume, and when cleaned up it was obviously the original used item.
So; marked two teeth with pencil, pushed together and rotated in fingers. Graunching feeling when tip of tooth met next tooth halfway down. Moved on one tooth and repeated. Changed idler end for end and carried on. At one mesh the graunching was greatly reduced and was consistent and disappearing if pressure was released Bingo ! Assume that worn pump gears exaggerate any inaccurate machining if not replaced as was ? Will do and see what happens !

[Stagrover]

Slight deviation but same general topic.

Has anyone had experience of using a steel interface plate instead of refacing the aluminium face of the pump body?

Refacing removes any trace of the original anodising leaving a soft bearing area which must wear more quickly than originally.

Got a vague memory that I read somewhere that the Buick pump bodies were/are cast iron so a steel plate would be going back to first basics.

Interested as I’ve been on the receiving end in the past of a “refaced” base that was as bent as a banana and It does look like new bodies are in the category of hens teeth.

[jimthesail]

Nah ! Pump still tight and having loosened cover plate it is freer but still 'graunchy' ! Having checked with Northwich Steve who says it should spin by a screwdriver 'nudge' I will order a new pair of gears as I suspect that these originals have been misaligned since new and contributed to the demise of the engine ; it has a bottom end rebuild ? 'I'll be back!'

[harvey]

Pattern gaskets can be too thin and that can make the pump tight.

[ratwing]

If there's 'notchiness' then you're right, fit new gears.
I needed a replacement pump base a few years ago and couldn't find a new one, I ended up using a new Mocal remote filter base instead - it worked out well since I could then choose a remote filter head to take a much bigger filter too.
I'd also echo Harvey's comments on the gasket, it took several attempts for me to get one to give the right clearance.

[jimthesail]

New gears arrived today from Shop 4 Autoparts; very reasonable at £48 ? Rolling them together the teeth do not touch till the one rolls into base of next valley which looks and feels good with no 'notchiness' Fit tomorrow !

[jimthesail]

Weather a bit warmer so out to Marlin to play ! Measured new gears. Idler same depth but driver is .05mm shorter which with the gears nicely meshing made a difference. Pump stiffer than I would imagine but 'notchiness' gone. (It is also primed with petroleum jelly ?) Will press on and run !

[jimthesail]

Slept on it and evolved a cunning plan ! Tapped oil pump drive shaft firmly using steel bar and large hammer, rotating in steps. (Cover plate to pump is alloy so deformed slightly or at least flattened any high spots.) Then span with rechargeable drill and managed top speed and 20 pounds pressure so 'alles wunderbar !'