Low oil pressure VAC

A few years ago, I was talking to a gentlemen at our local steam engine show and mentioned the fact that my VAC has low oil pressure and likely needs to be overhauled. He mentioned you can increase the oil pressure by making some adjustments to the oil pump. Does anyone know how to do this?

I realize it needs to be overhauled at some point, but it doesn't smoke or use oil and isn't worth the $ in my opinion to do an overhaul.

most of them have low oil pressure. Just run it that way. Bill

Make sure you still have the oil filter tube still in the housing and connected. They can pull out when changing the oil filter and you don't notice.

First thing to look for: IF you have an oil filter on your tractor it should have a tube from the middle of the base that goes up through the filter. They often stick in the filter when changing oil and the person doing the work does not notice it. If that should be the case, you can make a tube out of copper. Second thing: If you have an aftermarket oil gauge that reads more than 30 lbs, you might think pressure is too low. My tractor has about 13 lbs oil pressure, which I understand is about average for these tractors.

Connor beat me too it, with a picture as well.

12 to 15 pounds is what my books say.

The factory oil pressure was determined by the oil pump relief valve. The adjustment referred to was usually to install a stronger spring/stretch the existing relief spring and/or added washers under the retaining cap.


Missing oil filter stem tube circulates inlet oil directly back to the sump without the restriction provided by the filter media. Depending on the condition of the pump and bearings that can drop the oil galley pressure 2 psi or more and mainly to the detriment of the top deck oil flow.

The cylinder head top deck is the end of one branch of the oil pressure system and the furthest from the pump. Pull the valve cover, idle engine, should be enough oil flow to lube the rocker arms, enough top deck run off to have some oil down each pushrod hole to lube the lifters and cam lobes. The cam shaft center and aft bearings are also lubed with this runoff.

Joe

Since nobody else has asked, how low is it?

Cold oil pressure is ~ 14, warm oil pressure is < 10.

My tube is missing from the oil filter assembly. I am going to try that first.

Thanks to everyone for their replies.

There are some posts here some time ago on how to fashion the tube. As for me I fond a piece of copper that fit the hole, then cut the end in a V so it pierces the filter easily. I squeezed the v shut and then drilled a few small holes below it that in theory will deliver oil to the upper part of the filter. I have heard of guys just sticking a dowel in the hole which you could do to test it I guess, but I am happy with my setup.

If your going to do a short test unbolt the filter base and insert a blind gasket. If you intend to run it without the filter for days or longer use a piece of tin with a gasket on each side.

I prefer soft drawn 1/4 inch thick wall (refrigeration grade) copper tubing mainly since it is easy to work with and it pretty much matches up with exiting VA. You will probably have to sand down the end a little for an interference fit into the base socket.

This filter base is typical of VA & 300 series tractors. Tube O.D. 0.252, tube height above press socket 3-11/16, add about a 1/2 for the socket. One hole at the tube top that I am not sure about the dia anymore. There were several different configurations used in The VA & 300 series. I have seen one, two, and three hole stem tubes. The filter media is the primary restriction to regulate the flow. Typical engine bypass filter systems are designed to circulate 10 - 15% of the oil pump capacity from the oil galley through the filter and back to the sump.



I usually solder the top of the copper tube shut, round the end of with emery cloth and drill straight through the tubing about 5/16 inch down from the top with a nr 50 bit (0.070 inch) or slightly smaller bit. The hole size doesn't have to be precise.

Joe

Joe, thank you very much for your thorough guidance. I had a couple of follow up questions on your post as follows:
1. I ordered a small piece of copper and aluminum from Amazon that would appear to be close to the correct diameter. Should I go with copper or Al?
2. I have only done a small amount of soldering in my life. Any particular type of solder I should use? Any risk the solder comes off and gets in the engine?

Thanks so much!

A short piece of 5/16 brake line works excellent. Will tap in and stay tight. Your filtering system is a by-pass system, and I don't see how this will increase pressure. The fact that you have 14 psi when cold, then drops to 10 is an indication of pressure loss other than the relief valve. Could be a worn pump, Crankshaft bearings, or cam bearings, although the only cam bearing that is pressure fed is the front bearing. Please get back after you make the filter pipe fix.

I don't use brake tubing because it is hard to drill with a small fractional bit. I think most people just flatten down the brake tube top. I use soft drawn refrigeration copper tubing and the old lead based solder because I have an abundance of each. It's easy to drill, solder and round off the top so it slides into the filter media smoothly and is more likely to stay in place at the next filter change.

Replacing the tube adds the restriction of the filter media vice just dumping the oil from the galley through the filter base back to the sump. If your oil pressure gauge is accurate there is no doubt your engine is well worn. This is just something you are going to have to do anyway if you want have filtered oil and it may raise the pressure up a couple psi that to an acceptable warm operating pressure of about 12 psi.

Blinding off the oil filter base and running the engine is the quickest way to check if replacing the filter tube is going to result in a pressure increase. Checking top deck with engine running warm at idle checks if you have enough oil flow to lubricate the valve running gear and enough run off down the pushrod tubes to lube the lifters, cam lobes, and cam center and aft bearings.

Joe

Lieu, If the oil pressure is 10 lbs idling with hot oil you have a pretty good engine, Before I became a full time Case mechanic I farmed with a 39 DC which I still own and pull. On a hot day with # 30 Case oil plowing or harrowing the oil pressure would drop to about 5 lbs wide open working and worked for hours at a time that way, never worried about it as everything was getting wet. Allis Bs and Cs don't even have a drilled shaft, depend on drip from the rocker arms running down to lube them, got a hole in the rod to let oil in to the shell as it rotates. 10 lbs, don't get worked up to bad. When I redid the 39, I line bored the mains with a steel shim under the block shell and started over fresh, tightened up the oil pump gear end clearance and now the pressure is pretty much rock solid cold or hot, but I never worried about it coming apart with low oil pressure.

your oil pressure is ok. as for the tube ,i discovered a codenser from an old refrigator had the right size tube to fit in filter housig.
i cleaned the hole well and end of tube i cut shaped the end and cleaned other end .put drop of red locktite in hole spread some on end of tube n tapped the tube in the housing. let it set over nite. was 15 years ago n its still secure in the housing

Thank you to everyone's great advice.

I made my own stem from a piece of copper tubing and it seems to have increased my oil pressure ~ 2 lbs.

I've replaced missing tubes on VA, 300/300B models filters and ~2 psi rise seems to be about average in the 124 & 148 cid engines. I think that points more to an inaccurate gauge or oil pump weak relief spring than exsessive engine bearing wear. I always check the top deck for run off to lube the lifters, cam lobes & cam bearings, if that is ok then good enough.

Joe