Occasional Oil Pressure Light for 2-3 seconds in my 318. Should I panic?

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vames

vames

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I daily drive my 72 Swinger with a remanufactured 318 (probably has ~1500 miles on it at this point). I believe the reman motor was obtained through one of the big parts chains. The car starts/runs/pulls great. But every once in a while I get my oil light coming on for a couple seconds -- sometimes on a hard turn freeway entrance, sometimes going straight. I don't baby it, but I don't step on the thing too hard -- its a cool retro driver, not a performance car. I've been a good boy and have changed the oil and filter three times since the motor was put in, with zinc additive each time.

Facts and questions:

  • At my first oil change, I filled to the full line on the dipstick, and I was getting a frequent oil light. Ran it for less than a minute and put another quart in it and it mostly stopped. The old engine was fine at the full-line on the dipstick, so I'm not sure what changed.

  • It doesn't happen every time I drive, and it doesn't happen going down the freeway. It's mostly on the streets at < 40mph. Other than the hard-turn-freeway-entrance there is nothing obvious about the conditions when it does happen (its usually on flat road -- we don't have many hills around here). It's not getting more frequent or less frequent.

  • The pan is the original (I know because a PO must have long ago tried to jack up the car using the pan and it's slightly convex on the bottom). Is there a chance that the reman engine came with a pickup that doesn't go deep enough into the pan? Is it even a thing that there can be a "wrong pickup" or a "right pickup"? Could a marginally dented (but not leaking) pan cause problems like this?

  • Not sure on the age of the oil pressure sender -- could a bad one cause this?

  • Wix oil filter -- not sure of the # but it fits and clearly works. Running 10-40 dinosaur Penzoil. Long Beach CA (almost always below 100F and above 50F)

  • Not sure its relevant, but the guy who installed the motor accidentally sent the 90-degree oil filter adapter back with the core, so we just used the Mancini Racing plate and it all seems to work fine.
Or maybe this is all normal and I shouldn't freak out. Any ideas/comments/things to check from the community would be greatly appreciated.

dart.jpg
 
How bout telling us the important part. HOW MUCH oil do you run in it?
 
I don’t like that on a new engine. Install a mechanical oil pressure gauge and see what the oil pressure really is. Then proceed from there.

The oil pan should have been pounded out when it was off.

sure it could have the wrong or a damaged pickup.
 
Yessir. Pretty sure it has about 6 quarts in it (about 1/2" above the F mark on the dipstick)
 
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The pickup could have a crack in it.

What you describe sounds like low oil level.

When I have let my tired old 273 get 2 qt low it runs fine but when coming to a stop or turning hard corner it would suck a bit of air and the light would come on.

The sender that was on it recently I think was the original, it was sleeping a bit and turning the light on without the oil being low. I replaced it and now works as expected.

I would do as mentioned above and put a real guage on it. You can put a "T" and have both. If light comes on you can see if it is really low (less than 8 psi or there abouts)
 
If you still have 6 quarts in it, Drain the excess out.
First verify the correct amount of oil is in it. Not by the dipstick but the amount you actually put in.
Your engine takes 4 quarts plus one more for the filter.
As said above, a tee fitting so you can install a mechanical pressure gauge is the best way to go.
Once you can verify the actual oil pressure you can go to the next step if necessary.
Bent pick-up, split in pick up tube, oil pump, etc...
 
MoparLeo said:
If you still have 6 quarts in it, Drain the excess out.
First verify the correct amount of oil is in it. Not by the dipstick but the amount you actually put in.
Your engine takes 4 quarts plus one more for the filter.
As said above, a tee fitting so you can install a mechanical pressure gauge is the best way to go.
Once you can verify the actual oil pressure you can go to the next step if necessary.
Bent pick-up, split in pick up tube, oil pump, etc...
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Great advice ^^^^^
 
I’m betting the pickup is NOT touching the pan and it MUST touching it.

The only fix is to pull the pan and fix it. Adding oil doesn’t make the pickup function correctly.
 
After verifying proper oil qty. I’d plumb in a manual gauge to verify. If it’s verified to be actual pressure drop, I’d be contacting the installer. If they bought the engine to install they should have the paper work. I’d personally believe if it’s a brand name reman there should be a warranty. The warranty should cover any diagnosis. If the blame falls on the company that rebuilt it let them fix it. If it’s the installer and they put a damaged pan on it that forced the pick up up and possibly cracked the pick up or didn’t set the clearance to the pan correct. Shame on them. They should make it right. You paid your money to get a job done and they didn’t do it correctly, they should stand behind it. Sorry sounds harsh but you paid your hard earned cash. That’s my opinion.
 
I would be concerned. By the time the oil light comes on you pretty much have zero oil pressure. I would immediatly install a mechanical gauge so you can see what is actually going on.
The 90° filter has nothing to do with the problem. You only need it to clear exhaust on some cars.
 
maybe it has a full screen on the pick up and it is too close to the bottom of the pan after dent /does it change with oil temperature?
 
Dubob said:
After verifying proper oil qty. I’d plumb in a manual gauge to verify. If it’s verified to be actual pressure drop, I’d be contacting the installer. If they bought the engine to install they should have the paper work. I’d personally believe if it’s a brand name reman there should be a warranty. The warranty should cover any diagnosis. If the blame falls on the company that rebuilt it let them fix it. If it’s the installer and they put a damaged pan on it that forced the pick up up and possibly cracked the pick up or didn’t set the clearance to the pan correct. Shame on them. They should make it right. You paid your money to get a job done and they didn’t do it correctly, they should stand behind it. Sorry sounds harsh but you paid your hard earned cash. That’s my opinion.
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Hopefully it is just a bad oil sending unit or loose wire.
Does the engine noise change when the light comes on? It would sound very mechanical with 0 pressure.
Change the sending unit with a good name brand and check the wire going to it.
 
Wow this forum never disappoints! Thanks all.

Im not hearing any change in the engine sound when this is happening so hopefully this is a signal problem, not an actual pressure problem. Nonetheless, a car can’t run on hope, so I think i have my order of operations:

1. Pull the pan and either replace or pound the 25+ year old dent. I’m inclined to go with a new pan to get nice clean threads on the plug - the old one needs serious cranking to get that plug sealed. Are the pans offered on Summit or Rock Auto of good quality or should I look for something original? What’s the best pan gasket out there?

2. When the pan is off, inspect the pickup closely and replace if needed.

3. Check out the pressure sender (is there any way to bench test a sender?) and/or replace.

4. I’m not sure I want to plumb a mechanical sender, but I’d be willing to do an electric one. Any decent brands/options I should look for? I probably need something with a bracket I can put under the dash near the parking brake pull.

3. Drain/new filter/refill with 5 qts. See if it keeps happening.
 
If it has 6 qts in it,,, may not be as overfull as one might think. What vehicle is this in? Most trucks took 6.
Also if that was the 1st fill upon assembly, they usually take more upon the initial fill. With how the plug is on a 318 pan, you're not getting every last drop out of it. There's gonna be at least the thickness of the nut welded in the pan for the drain plug, left of old oil every time you drail the oil.
 
I certainly don't think 6 quarts is doing any damage. However, I used to fill the old 318 in this car with 5 quarts, the dipstick would read top of the range, and all would be fine. The reman engine has the same pan, probably the same pickup and sender, and the same dipstick/tube - and I'm getting these symptoms. Kinda wondering what changed that is causing this. My goal for this car is to have it look OK and function as close to stock as possible.
 
Nobody makes new pans. You'll have to find good used. Also, WHERE is your oil pressure sending unit? Is it in the side of the block or at the oil pump?
 
RustyRatRod said:
Nobody makes new pans. You'll have to find good used. Also, WHERE is your oil pressure sending unit? Is it in the side of the block or at the oil pump?
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TBH I don't know where the sender is -- I'll have to go out there and look later.

For new pans, I was looking at these.

1972 DODGE DART Summit Racing SUM-G3535 Summit Racing™ Stock Replacement Oil Pans | Summit Racing

1972 DODGE DART Trans-Dapt Performance Products 9311 Trans-Dapt Performance OEM Replacement Oil Pans | Summit Racing
 
Skip the chrome junk. Either way, both of those pans use an OE pickup and that pickup MUST be touching the bottom of the pan or 9 quarts won’t be enough.


STOP what you are doing and get a copy of the Factory Service Manual. It has all this stuff in it.

The biggest mistake I’ve seen is using an OE pan and pickup and not getting the pickup on the pan.

Then guys use the HV oil pump and they claim the pump is “sucking the pan dry”.
 
My apologies. I am getting your thread mixed up with another. I was thinking this was a slant 6. Please disregard my responses here. My bad.
 
rklein383 said:
Imagine the oil pan squashing up against the pickup opening significantly reducing the opening size, will absolutely affect discharge pressure. Also have seen debris clog up the screen causing low oil pressure.

View attachment 1716006155
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There is ZERO way that can happen. The pickup is designed to be touching the bottom of the pan. Not "squashed" against it, but touching it. You see that HUGE hole into the pickup? It's made intentionally like that so that the pickup can rest against the pan bottom. The reason for this is so that when accelerating or on decel, the pickup will have a constant supply of oil. Were it not all the way on the bottom of the pan, it might get subjected to air as the oil runs to one end or the other of the pan. It's in just about every single Chrysler service manual to place the pickup against the bottom of the pan, but I guess you're somehow self professing to know more than Chrysler engineers.
 
Check the oil pressure with a manual gauge or if you wish, replace the sender and see what happens.
 
Factory manual does say the strainer should touch the bottom of the pan. I have no idea whether mine does, or if its cracked, or even if its just an old crackpipe wedged in there. So I'm going to have to do some investigation. But when I install it, I will make sure it touches the bottom of the pan.

318 oil pan.PNG
 
Best bet is to put on a good temporary mechanical gauge and see what is really going on.
 
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