VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1928 geared oil pump too much pressure geared oil

I have a 28 with a Billy Possum oil pump. It pumps oil at 25 to 30 psi and has blown 2x oil gauges todate. Is it possible that the oil could be too pressurised and not lubricating the main bearings as intended.
1. Reference is made about modifying to oil lines when installing a Billy's possum oil pump. What is the modification? Anyone got photos?
2. How can I reduce the pressure the oil pump produces?
3. I have a modern flow through oil filter installed with out the 1/16th restriction like the original pump had, would this add to the problem, I wouldn't have thought so..
Thanks any advice appreciated
Regards Peter

I would start with reading and watching the videos here.

a good read to start

I know what you mean as it is nerve racking not knowing if the motor is getting proper oil as you wold not know until it is to late.

thanks for that info Didier.
At present my results are in line with CJP 29.
If any one has been able to reduce the pressure produced by the geared pump I would like to know how they went about it.
thank you.

When I first posted my investigation of a gear pump, it was summer time. Now, in winter, it's colder outside (50 degrees F).

The gear pump in my '28 only shows a max of 15-20 psi when cold (using 10-30W) and still shows 5 psi when warmed up.

I suspect you have a restriction somewhere in your lines. I replaced the '28 oil filter with a 1950s style oil canister. In doing so, I removed the oil restrictor, which creates back pressure for the gauge. Here's a discussion and some pics on that conversation: https://vccachat.org/ubbthreads.php/topics/346964

Hope this helps. Keep us posted on what you find.

Dean

Will not the oil distributor valve send the high pressue to the center main bearing (on a 1928) and oil pressue gauge only. The items fed by open end lines will get low side pressure flow only.

The oil distributor on a '28 has an orfice that directs a stream of oil at the oil reservoir above the center main bearing to keep it full. The center bearing is the same low pressure (reservoir-fed) design as the other two main bearings.

You can see the oil stream in the video below.

Notice that in the video, the oil pressure gets up to 40 psi. The same pump in my truck only reaches a max of 15 psi. I theorize the difference being that in the test video, I had the filter line plugged at the oil distributor. In my truck, that line is open (going through an oil filter) which relieves pressure from the oil distributor.

So, I still suspect that you are experiencing a restriction somewhere that is blowing your gauges. My guess would be either the stream hole in the oil distributor is plugged or there's a restriction somewhere in the oil filter line. If either of these conditions exist, it is important to fix.

One solution that I can think of for protecting the gauge would be to plumb a pressure-relief valve in the line that goes to the gauge. Have the overflow side of the relief valve dump back into the oil pan.

All my best, Dean

Test video:

Thanks Dean,
When I get a minute I will investigate for restrictions or blockage to to oil line.
I'm going to :
A. Fit a temporary modern gauge that can handle higher pressure
B. Test with oil filter line disconnected to see if any difference to pressure reading.
C. Test with restrictor reinstalled as per original oil filter set up check pressure
If all else fails reinstall original vane type oil pump.
I disassembled one today they seem to be really simple.
If any one has refurbished one please provide details.
Thank you.
Regards Peter