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1925 Buick Oil pump issue


dibarlaw
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3 weeks ago my 1925 Standard oil pressure gage started swinging from 10-15-5-0-15 etc. at speed. Settling to less than 10# at idle. After Reeve enterprise rebuilt my engine and oil pump over 3 years ago pressure had been steady at 22#. We have put over 1,000 miles on the car since then.

 I tried the SW 0-50# gage that was in the car when we bought it. At idle it was barely at 10# warm.

Well I pulled the oil pan yesterday....

 I investigated the oil lines to see if any of the solder joints at brass lines had developed a crack. I had already prepared a replacement oil line assembly from my spare engine to swap out in case. I put some pressure from my airbrush compressor into the system and do not detect any breaks in the lines. But this was probably only arround 10#. I will try a bit more pressure today closer 20# to see if there is any leakage. BUT...

When I checked the oil (rebushed/rebuilt) pump the relief spring was

1 5/16" as opposed to the spec. compressed length of 1 5/8". Free length of 2 1/8". The oil pump from my spare engine had a spring 1 3/4" long. Same # of turns and  same wire dia. The valve is a 1/2" dia. ball bearing. With the shorter spring that was in my car there was evidence of fresh rubbing on the bore by the spring coils.

DSC00673.JPG.fe948d5c04712aea4217b093af0adb63.JPG

Now my problem... to source an appropriate spring. I am reluctant to use the longer possibly 97-year-old spring from the spare engine.

I consulted EGGE who rebuilt Hugh's 1925 pump. They have no specs. on the spring they used when setting the pump at 25#. Their only suggestion was for me to send them my pump and match the spring under test. Hugh and I agree that the Buick factory specs may be in error. Shop manual calls for a spring 2 1/8" free length compressed to

1 5/8" at 10 oz.. The spare engine spring is already at 1 3/4" and to compress it to the 1 5/8" took nearly a pound. A similar sized spring (same # of coils and same wire diameter) from a hardware store took 6 lbs. to compress from 2 1/8" to 1 5/8".

 Any other suggestions?

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Try Lee Spring. I think they do have a minimum order so you may have to buy 10 of them. But, you can probably match the wire size and length very closely, if not exactly. When I was looking for valve springs for my Mitchell project I made a fixture to measure spring rate. It's just a frame with a screw that fits over a cheap postal scale. You set it up so you can depress the spring 1" against the scale...that should give you a close reading on the spring rate. I measured one of the original springs (I only had 2 of them) and then ordered some to match the rate.

Edited by JV Puleo (see edit history)
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Joe :

 Thanks for the lead.

I will work thru several springs I have.

 I spoke to Edinmass today and took his sugestion of trying a washer first on the old spring before trying other new springs to verify the problem was here at the pump spring. Since I did not have gasket stripped off of the oil pan he sad to just put it back up with 4-5 bolts add the oil and run the engine.

Ed:

 Thank you for the time spent with me on the phone today. We are moving in the right direction. I machined (2) 1/16" thick washers to try with the shorter spring. New gasket on the pump outlet face. Buttoned the oil pan back up with 6 bolts. Put the filtered old oil back in since I will be changing it out when things finaly stabilize. Start up at fast idle ..... steady 30 lbs!

DSC00674.JPG.07a72755e980a8f0e186a898e2e864e6.JPG

Then I wondered. How much over 30 is the pressure? Disconected the dash gage and ran the auxiliary Stewart Warner 0-50 gage. Just a hair over 30#.

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After about 5 minutes of warm up I slowed idle down to where the engine wanted to stall.

DSC00678.JPG.adc0ec150e1f1f9f9d5fdcb6a6ac0120.JPG

 Just to about 22# to where it had been before the problem. I will do a drive around the block tomorrow to see if it varies under turns and stops.

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1 hour ago, r1lark said:

It seems very odd, at least to me, that the spring would lose tension all of a sudden like that. 

 

 

Could be the ball/piston hanging up. I haven't seen the design. 

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Ed:

 A photo of the car as requested.

DSC00579.JPG.fe0b31e4e81f20e2683e8646dce8d629.JPGDesign of my pump.

DSCF2220.JPG.10eb0a728e391906792070aec2d032f0.JPG Photo when I first got into the pump back in 2012.

 Again, since then it had been re-bushed and fitted with better gears when Reeve's rebuilt the engine in 2019.

1223264421_OilPumpdimensions2(1024x769).jpg.51b17a9600339fe99d7976307067a13e.jpg This is what Hugh sent me for specs on what was in his car. He had a washer on his when removed prior to all being rebuilt. The spring I tried yesterday with 3/16 thick washer was the same free length at 1 5/16". What I tried today was a new spring at 1 9/16" free length.

 

This is what I had posted over in the Buick Pre War Forum.

27donb

 I tried the car out on the road today as suggested by Edinmass. Solid 30# on the 3 mile drive but almost to 0 on a right turn but imediately back up to 30 when straightend out. Oil level was probably a bit low after the 3rd drain and refill.

My 1925 BUICK Motor Car Operation and Care states on pg 162.... At a car speed, on high gear, of 15-20 miles per hour the oil pressure is approxomatly 15 pounds per square inch. but will increase or decrease above or below this figure with any increase or decrease in engine speed. Maximum oil pressure is 30 lbs. whilst the minimum figure, as when the engine is running very slowly, is slightly above 0 on the gage."

Well today after the 3-mile trial drive I tried a new spring and it was up to 40lbs. After warm up at fast idle it was at 30 lbs. Slowing down to just about stalling it was around 10 lbs. At my normal idle range it was holding at 25-28. Reving the engine higher up to say running at 30 mph got back to up 40 lbs. 

 I believe I will try a bit shorter spring to get back to 30 lbs. max so I will not be pegging my 0-30 lb. National gage in the dash.

 I am getting faster at draining, dropping and reinstalling the oil pan!

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2 more shorter springs have been tried. Pressure 36# and another shorter yet by 1/16"= 32# I made 2 washers from old, well squished copper crush gaskets, well faced and cleaned up, for a thickness of .095 and placed it under the spring cap nut to bring out the cap out that distance. I wanted to keep as many coils on the spring as possible. It is right at 30#pms. now and does not move further at higher rpms. I will disconnect the test 0-50 gage and reconnect my 0-30 gage in the dash to see how it is effected.

Pan up and down 4 times today.

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I am calling it good.....
Last night I finally dressed the pan to install the new gasket...
 6 times at removing, trying another spring length, bolting up with 5 or 6 bolts and testing again, repeat. The previous spring was what I felt was the same spring rate as the previous sample 5.5 lbs. per 1/2" except it was bright zinc plated just about the same # of coils but at 1 1/2" free length. It pressured up to 34 lbs. I did not want to lose any more coils so I cleaned up some well used copper/asbestos spark plug gaskets bored them to fit, lapped them flat for a total of .095 under the cap to get that spring out farther. 
image.png.22594418d841fa170f9c521f44394b68.png
Pressured up at 32 lbs. 
 The springs for comparison in the photo above left to right. The new 1 7/16" I had tried, the original 1 9/16" free length spring from the parts Kentucky engine pump and the 1 5/16" original from my subject 1925, Beulah.  Again, trying to keep below 30lbs. so as not to continually peg the meter. After this I tried the 1 7/16" spring and it was still too high. I tried one more spring at 1 3/8" and remover the copper washers. The last cold start was 26lbs. So, I called it good, cleaned the pan installed gasket. Cleaned bottom face of the crankcase and installed front and rear new corks. Fresh 10W-30. Final pressure as of last night at 11 o'clock was 25 lbs. If I left one washer in it may have been between 26 and 30lbs. But I had had enough!
 
Edited by dibarlaw
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