1917 D45 OIL PUMP

[Bob Engle]

I'm working on the oil pump today and some questions arose.  There was a paper gasket  .006" thick between the cover plate and the main body.  I removed the gasket and  used a sharpening stone to clean the surfaces of the plate and body.  There is no measureable wear on the plate, only swirl marks from the gears.  I put  green plastigage across the tops of the gears and installed the cover without a gasket.  upon removing the cover I checked the clearance gear to plate at .0025" to over .003" clearance.  Question 1, Is the gasket correct?  Question 2, Is a .003" clearance acceptable?  It is obvious to me that this engine has been worked on before, so I am not sure as to what is proper and correct or is it shade tree work..

 

Bob Engle

[raydurr]

Bob , years back when building modified SBC engines , I would shoot for .0025-.003 clearance. I avoided using a gasket and aimed for perfectly flat mating surfaces. If a gasket is required , thin is better and less likely to rupture. The Chevy gears are different size from your Buick but this gives you and idea. The larger the gear the more clearance the pump can handle before volume then pressure goes down. Be careful about removing too much material. Its best to use a lapping block or lapping plate. If too much clearance , sand the housing , if not enough sand the gear height down. Its not rocket science. Be sure to check oil pump mounting surface and all those soldier connections on the oil piping , if yours has them. Take time with the bypass valve  and spring.

Edited October 14, 2017 by raydurr (see edit history)

[Bob Engle]

Thanks for the info.  These systems are much simpler.  no bypass valves.  The drive for the oil pump is coil spring with the ends bent 90 degrees centered over the coils.  these ends fit in slots in the drive and driven shafts.  No misalignment problems.  The system is built for volume, not pressure,  The pump must provide enough oil to keep the troughs for the connecting rod dippers filled for splash to all other lower end components.   

 

Bob

[DonMicheletti]

I  in '19 instead of the "windmill" indicator Buick used a pressure gage. The engine is essentially the same. Without a gasket the pump puts out 4 psi when warm (per a friend with a good '19 Buick), so it isnt doing a heck of a lot of work - just supplying oil to the "squirt" rail.

Bearing clearance has nothing to do with pump performance.

I would leave the gasket out. I dont have one in my '18 (which was built in '17).

[raydurr]

Well you guys working on splasher type engines changes the rules some. My 29 is crude but very similar to a modern oiling system. 25-30 psi on a used Master series engine is more than adequate for many more miles.

[Bob Engle]

I reassembled the pump without a gasket.  A note for others working on this old stuff,  two of the six screws holding the bottom plate onto the pump had broken lock washers.  I replaced all with new lock washers.  I would suggest that any lock washers on the internals of these old  engines should get new lock washers to prevent some metal pieces ending up  where we don't want them.

 

Bob Engle

[JerryVan]

On ‎10‎/‎15‎/‎2017 at 11:52 AM, Bob Engle said:

I reassembled the pump without a gasket.  A note for others working on this old stuff,  two of the six screws holding the bottom plate onto the pump had broken lock washers.  I replaced all with new lock washers.  I would suggest that any lock washers on the internals of these old  engines should get new lock washers to prevent some metal pieces ending up  where we don't want them.

 

Bob Engle

 

Bob,

 

Great example of why split lock washers do not belong inside an engine, unless no others options are available.