Help! Oil pressure dropping under acceleration

[40phil41]

Easy-out was what I removed mine with.

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Phil

[james curl]

You have the small plunger like I have in my 41 Dodge engine that I installed in my 48 P-15. The original engine from my 48 P-15 had the larger diameter plunger that the spring goes up inside of, not ride on the bottom lip of the plunger as the small one does.

[ActionGrant]

Wow I totally forgot to subscribe to this thread and see all the replies. I double checked the oil as was suggested, and it turned out to be low after all, adding more oil solved the problems. >_> Now that I appear completely incompetent, haha... Thanks for all the suggestions though! I'll definitely keep them in mind if I /actually/ encounter real oil pressure issues.

[aero3113]

a friend of mine will bring me one this evening (hopefully, so i can do a little more fishing. good idea!

i took a small mirror and a flashlight to look inside the plunger's hideout.

i couldn't see or feel any more pieces of the spring.

when i put the pieces next to each other, they add up to approximately 2",

which should be the right size if i recall that correctly.

the screw i used lays its head snugly inside the plug and is about 1" long,

the biggest piece of spring is fitting around the threads and now has enough

pressure to hold the plunger down with more force than before.

i'll try get a new spring somewhere, maybe stovebolt or even ford V8 parts will fit, who knows?

gotta make some calls...

anyway, i'm happy to know now. once again, thanks everyone!

Fred, Vintage Power Wagons have springs in stock. I will also have a spare spring once I figure out which spring to use. If you can wait a couple of weeks you can have my extra spring.

[Cpt.Fred]

hey aero, that's very nice of you, thanks!

does it fit a 201? it seems from recent posts that there are differences in pre and post war engines?

same friend who brings the tool also has a rich collection of various springs, he'll bring them along and i'll pick one that doesn't let the pressure rise above 40 at idle when cold, since i'm going to do an oil change today and start using SAE40.

i'll let you know about the outcome, thanks again!

best,

fred

[aero3113]

I received my Plunger and spring from Vintage Power Wagons today. As you can see in the picture the new(used) plunger is in much better shape than my original one. The spring they sent me was too short so I ended up using my original spring. Once installed I ran the car and the oil pressure went up to just above 40psi. I let the car warm up and noticed the pressure was slowly going down. I would rev the engine and let up off the gas and the pressure would shoot back up to above 40psi then slowly go down again. I went for a drive and the pressure would drop near 0 then when I would shift gears and let up off the gas the pressure would shoot up to 40psi then slowly go down near zero when I was on the gas. I found it very strange that it would shoot up to 40psi when I let off the gas to shift gears. When I got back home I sat in neutral and reved the engine steady and oil pressure would hold @ 40psi. I decided to change the oil. Went for another ride, same thing happened but when the pressure would drop it was not as near zero as it was.I think my spring might be weak? The spring that Joe sent me should be arriving any day, I am curious to see if his spring (green spring) is going to make a difference. What are your thoughts?

[jd52cranbrook]

If your going to keep that spring anyway, you might try stretching it some, or putting washer in to see if it rises.

I had a weird thing happen today. And it figures I would be reading about oil pressure this week.

Drove to a fellow mopar friend, on the freeway I glanced and noticed my pressure read about 40 lbs, usually its higher at highway speeds. Drove to my friends, talked about it,,,,,,,,,,,,, ( I still have a idiot light I use if it drops below 20 lbs, which never went on) Oil was full, pressure never went above 40, but never below 20 either. . Soooo

Drove it home, pulled the valve, everything looked good. Undid the line at the block, blew air in it,never got above 40. I have a spare gauge with a bad face, tried that shot right to 80.

So I undid the line at the gauge, blew that clear, hooked it back up, and it works normal now...

If there was garbage in my oil line, I'm afraid to think what would happen if it tried to go through a bearing passage instead. I'm not sure what happened. But took it out again its working normal now.

[james curl]

That line according to the manual should be clear of any oil. the gauge works on air pressure in the line. Look in the manual under oil presasure and you will find where it states to disconnect the line at the gage then the block and let any oil drain out. Reconnect the gauge first then the block, you want air in the line to dampen the pluses of the oil pump.

[jd52cranbrook]

Thanks for that info. Settles me some.

[aero3113]

I did a little bit of work today on the Plymouth. I took apart the line to the oil gauge and found some oil in it. I sprayed some alcohol down the line to clear it. I hooked it back up and went for a drive. It made a little bit of a difference but still was not right. I got back to the garage and decided to stretch the oil pressure relief valve spring. I stretched it about a quarter inch. Put it back in and went for another drive. At 30mph in first and second gear I have 40psi. At 50mph in 3rd gear I have 40psi. Any other speed I have about 10-20psi or a little less. At idle I have between 10-20psi but when I rev the engine steady it goes up to 40psi. Not sure what is going on:confused: At idle the engine sounds great,no knocking at all? Any ideas?

Edited June 28, 2010 by aero3113

[greg g]

It is not unusual for pressure to drop at idle, as a matter of fact the manual says that a low reading is fine as long as it comes up at speed. 40 lbs at cruising speed is just fine.

[aero3113]

It's just strange for it to do it all of a sudden. I am gonna try the green spring from Joe when it arrives and see what that does.

[aero3113]

I also want to find a pressure gauge and hook it up to the engine and see what that reads.