oil pressure regulator

darlyn

darlyn

Junior Member
I have 1936 5w with a 1940 engine. The problem I'm having is after you run to running temp I lose oil pressure. I was wanting to know if anyone can tell me how to test the oil pressure regulator and where to buy one if that's the problem? I'm running SAE30 and 40PSI when cool but drops straight to 0 when warm. Thanks in advance for any info.
Darrell
 
I would start by adding an aftermarket oil pressure guage to determine what oil pressure you actually have
 
JSeery said:
I would start by adding an aftermarket oil pressure guage to determine what oil pressure you actually have
Click to expand...

Amen to that. After replacing several oil pressure senders I concluded that the stock gauge was never going to read right - always way too low - so I installed the mechanical gauge in my glove box and pressure is always great, even when the stock gauge shows 0.

For a temporary check before installing the mechanical gauge get a cheap mechanical gauge such as this one from AutoZone for $18.00 here: http://www.autozone.com/autozone/acc...ier=267574_0_0_:
4

And temporarily screw it in place of your oil sender:
OilGauge1.jpg


Run the tube up the firewall
OilGauge2.jpg


And under the hood. Then hang it on the windeshield wiper temorarily
OilGauge3.jpg


And read it through the windshield while driving around to see what the real pressure is cold to hot, stopped to high speed.
OilGauge4.jpg


By this method I just found out that my oil pressure that has never read higher than 16 psi on my dash gauge was actually just great - 40-50 psi cold, 30-40 hot, and no lower than 13 psi hot idling (usually went to 0 on my dash gauge). Good news.
 
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if you find with a mechanical gauge that the pressure is too low, there is a pressure relief valve under the intake, it is a spring and plunger with a small slot under a very large hex head cap. I have found this spring broken and "sprung"--try replacing or put a 1/4" flat washer underneath the cap. Bad cam bearings, worn main/ rod bearings also can be the cause. try changing to a 20W50 oil this could help, or add one of the extender oil treatments
 
I've bought an oil pressure gauge to double check but I'm sure it's low because it starts to knock when it drops. That's why I'm hoping it's the regulator, but I can't find anyone who sells the spring. Does it have a specific tension spec? Or can I just stretch it out a little?
 
if it is not broken, stretch it or put a 1/4" flat washer or two on the plunger shaft and put the spring back on. but if it is knocking, I think you have deeper problems, like worn bearings. I know where a 36 with a 59ab engine that runs at 25 lbs and idles at about 5lbs and has been for many miles
 
Most hardware stores (especially older ones) usually carry a selection of miscellaneous springs. If you take it apart and find there is a definite problem with the spring, you should probably be able to find something that you should be able to make work. From the sounds of it, though, I agree with the guys here who think it's probably a more serious problem.
 
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The pressure springs in either the front of the engine or in the
later type pumps should not have the springs stretched. Use
1/8" pipe about 5/16" long as a shim on top of the spring.
Remove the spark plugs and with a mechanical gauge screwed
into the 1/4" pipe fitting on the rear of the drivers side of the
block spin the engine with 12 volts. The pressure you see on
the gauge will be the pressure at 35 MPH and up. You can adjust
the pressure by changing the thickness of the shim. G.M.
 
If the bearings are worn so they knock i dont think adjusting the spring will fix that.
Thicker oil may improve the situation but not cure it....
 
flatheadmurre said:
If the bearings are worn so they knock i dont think adjusting the spring will fix that.
Thicker oil may improve the situation but not cure it....
Click to expand...

You adjust the pressure valves FIRST, then go from there.
40/50 Castrol oil has improved 100's of flatheads oil pressure. G.M.
 
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