Straight 8 (248) oli pump

[John R. Hess]

Hi everyone

 

We're getting ready to investigate a low oil pressure problem on my '41 Super.  In case the problem is the oil pump, can anyone recommend a source for a replacement oil pump or would it be preferable to rebuild the existing pump.  If so, any recommendations for a rebuild kit?

 

Thanks in advance for any suggestions.

 

John Hess

Pennsylvania

[37_Roadmaster_C]

Hi John,

What year is the motor? Also, what do you consider "low" oil pressure? Has this problem happened slowly, quickly or is it just how you found the engine? These old motors do not have the oil pressure we are used to in more modern vehicles.

[EmTee]

Found this at Kanter's:

 

https://www.kanter.com/i-30563893-oil-pump-kit-1939-1953-buick.html#!year%3D1941||make%3DBUICK

 

[Ben Bruce aka First Born]

John, I am betting you will find the oil pump pick up screen is pretty plugged.  Next probable culprit will be the bottom plate on the oil pump.  If it has grooves worn into it from the floating gear the grooves can be  removed.   Oil pressure should be 35 psi at 35 mph, or close.

  

 Good luck

 

  Ben

[neil morse]

Hi John:

 

Here's a link to the part of my "Me and My Buick" thread dealing with the removal and partial rebuild of the oil pump on my '41.  (Click on arrow in upper right hand corner to get to the correct starting post.)  I think this will be helpful to you.  You will also see some discussion of what's considered "low" oil pressure.  Once you get the pick-up screen cleaned up and the bottom plate smoothed up, you will probably be fine.  Feel free to PM me if I can be of any additional help.

 

 

[John R. Hess]

First, thanks to all who have replied so far.  The information is very helpful. 

 

To answer 37 Roadmaster's questions:  The motor is the original motor to the car, 1941.    A previous owner (2 before me) told me the motor was overhauled but they did not replace the oil pump, as it appeared to be fine.   I'm not so sure this was a good idea.  The oil pressure NEVER goes above 35 lbs cold, when the motor is good and warmed up (normal operating water temp) the pressure never exceeds 15 lbs.  At idle, it'll go to almost zero but quickly comes back up to 15lbs. when the revs go up.  This low pressure was verified with a known to be working external gauge.  In  the next week or two, my guy is ready to pull the pan and see what's in there.  I have the car about 2 years and it never had the pressure the manual calls for.  Last driving season I noticed how low it gets.  I have to be honest that I can't say what it was 2 years ago as I don't constantly watch the gauge when driving.  But it never went over 35 lbs since I've had it.  The book says 45 lbs.  The thing that scares me is the low, warmed-up pressure at idle.  Definitely below 5 lbs.

[Aaron65]

This may or may not be your problem, but the major engine gasket sets seem to come with a gasket for the lower oil pump "plate."  My machinist installed the gasket, and it increased the clearance between the plate and gears to something like 4.5-5 thousandths, which was out of spec.  I had low oil pressure from day one.  It took me a few weeks to figure it out, but I pulled the pan, inspected the pump, and found the gasket.  After removing it, my oil pressure returned to a normal value on the car's gauge (hot idle oil pressure with my service gauge was no higher than 7 psi before).  If your engine was rebuilt, perhaps the rebuilder did the same thing.  

 

My car's a '53, but I believe your oil pump is similar.  It might be worth a look when you disassemble it.  

Edited March 26, 2023 by Aaron65 (see edit history)

[Ben Bruce aka First Born]

Aaron is spot on.    

  You are correct. That pressure is low.  I have never seen a pump that is worn bad enough to cause pressure so low.  The only wear I have seen is the bottom plate , as shown in Neil's picture. Another item I have not seen but heard about is the pressure relief spring being broken,  or the "valve" stuck partially open. 

 Sure wish we knew when the engine was overhauled and the miles since.  As well as what was done.  Your engine has insert main bearings and poured babbitt rod bearings, unless the rods have been "updated" to inserts.  If the pump is OK, hopefully your mechanic will check these.  Those should have been replaced at overhaul.

 

  Please keep us in the picture and pictures coming.

 

  Ben

[Gary W]

 

I replaced my oil pump in my '37 after about 850 miles.  I had my oil pump rebuilt by EGGE in California, but I'm sure there are many places that do this work.  It has made all the difference in the world.  She holds 45 pounds all day, and even hot, sitting at a red light it drops to around 30.  I'm very happy I replaced it.

 

Here's the link:

 

 

[John R. Hess]

OK.  We now know the truth.  We removed the oil pan and what was revealed was one of those "you're not going to believe this" events.

 

Attached are pictures of what we found as a picture is worth a thousand words.   The first picture is when the pan was removed and the oil intake screen was still in the motor.  Second photo is the oil intake screen on the bench.  What is hanging from the screen is what appears to be some sort of fabric, much like shredded cheese cloth!  Where this came from is ANYBODY'S guess.  My mechanic though that someone may have left a piece of rag in the engine.  It appears to be in the oil pan only, no where else in the engine.  I'm sure I know the answer to this but did Buick ever use a cloth based item in a filter or gasket or something like that?  Fortunately, the pieces are too large to go through the internal engine tubing  and the tubing to the oil filter.  As clogged as the screen is, my mechanic said it was a miracle the engine had ANY oil pressure!

 

Once everything is cleaned up, he suggested we replace the oil pump while it's apart, since the existing pump exhibits some wear.  Now the question is:  should we go with a new pump or rebuild the existing one?   What do you guys think?  As far as new, does anybody have any experience with this and can anyone recommend who to buy from (or perhaps who NOT to buy from)?  Same with a rebuild kit. 

 

Many have asked about a picture of the car.  That is attached, too.

 

Thanks

John Hess

[Ben Bruce aka First Born]

Goodness!   What a waste of a good grease rag! 😁

 Somebody was most careless!   The ONLY way for that to be there was being left in the pan when the pan was installed.

 

  You can/may do as you like on rebuilding the pump.  Are there any indications any threads passed through the pickup screen?   usually I would say the pump is probably OK.  In this case ,  not sure.  More pictures and measurements of clearances. INCLUDING rod and main !

 

 

   Like the shoe!😁

 

  Ben

Edited April 7, 2023 by Ben Bruce aka First Born (see edit history)

[EmTee]

Have you ever looked under the valve cover or the pushrod cover?  I would definitely look under the valve cover first and depending upon what is found, I would pull the pushrod cover.  Note that aftermarket valve 'silencers' for straight-8 engines similar to the ones shown below were sold back when these cars were daily drivers.  If yours had one installed under the valve cover it could have disintegrated and landed in the oil pan...

 

[neil morse]

I think the shop rag explanation seems more likely, but I'm amazed by the "Val-Vin-Hed" silencer idea.  Despite the 5 "important jobs" listed on the package, the only way it seems to stop the "tapping noise" is by providing some sound proofing!  Haha -- much easier than properly adjusting the valves.

 

[John R. Hess]

I am tending to thinking about something left in the oil pan.  We did remove the valve cover and everything in there looked good.  The bottom of the engine looks clean and "rag free".  I do believe the remnants were all collected on the oil input screen.

 

I never heard of valve silencers and I suppose anything could be possible but I have to agree that adjusting the valves would be a better solution!

[John R. Hess]

Hi Ben

 

I haven't seen the screen with the cover off.  Don't know if it's been taken apart yet.  I will say the oil pump has been disassembled and it is very clean and nice looking inside.  A tiny bit of wear on the bottom plate.

 

The Haines Shoe House, shown with the car,  was build in 1948 in suburban York, Pa.  It was built by the owner of a shoe factory and a regional chain of shoe stores.  The story can be found on google.  I thought it was a good place for a picture.  Only 3 miles from our house.

 

Nice '50!

 

 

[Ben Bruce aka First Born]

1 hour ago, John R. Hess said:

Hi Ben

 

I haven't seen the screen with the cover off.  Don't know if it's been taken apart yet.  I will say the oil pump has been disassembled and it is very clean and nice looking inside.  A tiny bit of wear on the bottom plate.

 

The Haines Shoe House, shown with the car,  was build in 1948 in suburban York, Pa.  It was built by the owner of a shoe factory and a regional chain of shoe stores.  The story can be found on google.  I thought it was a good place for a picture.  Only 3 miles from our house.

 

Nice '50!

 

 

Thanks. It is a fun toy. 

 Thanks for the info about the house.  

 The bottom plate can be "sanded". I used about 120 grit then 20, I believe,  on a piece of glass to insure flatness. Some glue the sand paper to the glass. I did not.  should be no gasket on the bottom plate.  Pull the relief valve and spring out and clean.  I will be surprised if the gears and shaft are worn and need to be replaced.

 

  Ben

[EmTee]

8 hours ago, Ben Bruce aka First Born said:

The bottom plate can be "sanded". I used about 120 grit then 20

I think you meant "120 grit then 220"?  Maybe finish with 320. 

[Ben Bruce aka First Born]

1 hour ago, EmTee said:

I think you meant "120 grit then 220"?  Maybe finish with 320. 

 Yes!    Failed to proof read, didn't I!

 

  Ben