Oil light flicker

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VSTwister

VSTwister

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Does this at idle when engine runs for a while and gets warmed up. Replaced oil sending unit some time ago and recently put in a new oil pump and pickup tube/screen. Still does it. Just flickers a bit until you rev engine or get moving. Never does it once off idle speed. Is this common?

318 Scamp btw.
 
my old 72 dart with a 318 did it and my 74 duster did it before the light burned out, my cousinns 73 swingers does it when it warms up so it must be common. Oil pressure drops when warmed up and idiot light sees it as a problem, but i never had any problems with the oiling system
 
thanson_mopar said:
my old 72 dart with a 318 did it and my 74 duster did it before the light burned out, my cousinns 73 swingers does it when it warms up so it must be common. Oil pressure drops when warmed up and idiot light sees it as a problem, but i never had any problems with the oiling system
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The oil preasure light switch on most autos is set to turn the light on at 7 PSI!
You need to put a good quality mechanical oil preasure gauge on it to determine if it is a faulty dash light or low oil preasure. My guess is very low oil preasure do to excess bearing clearance or wear.
 
So, look in your owners manual. Mother Mopar said this was acceptable! OEM Mopar light senders were either 5 or 15 PSI. Personally I wouldn't get too excited and just throw a set of bearing inserts at it sometime this winter. Plastigauge will let you know where you stand. Since Mopar V-8 bottom ends were pretty stout, and oiled well, I would guess your engine either has a lot of miles, had infrequent oil changes sometime in it's past, or both.

Now, if this light comes on going down the highway its no longer a "low oil pressure" light, it's a "you just bought an motor" light.
 
I have a slant six duster that does the same, as soon as you rev it up a bit the light turns off
 
C130 Chief said:
So, look in your owners manual. Mother Mopar said this was acceptable! OEM Mopar light senders were either 5 or 15 PSI. Personally I wouldn't get too excited and just throw a set of bearing inserts at it sometime this winter. Plastigauge will let you know where you stand. Since Mopar V-8 bottom ends were pretty stout, and oiled well, I would guess your engine either has a lot of miles, had infrequent oil changes sometime in it's past, or both.

Now, if this light comes on going down the highway its no longer a "low oil pressure" light, it's a "you just bought an motor" light.
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They this is acceptable for heading off warranty claims, When oil preasure is this low it is time to find out why.
 
I used to work for a company that OEM'd oil pressure senders (among other parts) for Chrysler, Ford and GM. The senders to trip gauges were all calibrated to turn the light on between 4 and 7 psi.

It is pretty common for a hi-mileage engine to have the light flicker at idle.
 
The fix for this problem on an 87 Fury and a 70 ElCamino I've had was
drop the pan, clean the pick up screen and strech the spring in the oil pumps relief valve just a little.
 
Try using a heavier weight oil.

I had a 383 that would do that with 10w-30 oil. I put 20w-50 in and it stoped. I have also used 10w-40 without issues. Since going to heavier oil I have put in a mechanical gauage and my pressure is never below 25 psi.
 
Thanks everyone.

The motor has 81k on it, so it's high but not bad for a 36 year old car, IMO. I will try some of the suggestion here though. It's basically not going to stay with this motor forever so as long as it keeps me going for now I'm okay with it.
 
I run Mobil-1 15w50 in my 340 dart and it is the best I have used in it since building the engine in 1984.Run the good stuff
 
I asked about very low oil pressure over on BBD, it was suggested to run Lucas oil treatment (3 qts, with the rest being good oil). I'm dealing with a 130K mile 440 that runs so good, I can't see taking it apart. No noises, but low pressure once it warms up. I'd say you have worn out bearings, and don't go on long trips
without your AAA card.
Mike
 
Probably is a worn bottom end, but I would pull the sending unit and screw in a gauge to see what the real pressures are? If they are lower than say 10-15PSI at idel then just go with a heavier oil for now. If you live in a cold climate then do a 20-50, if it is warm all the time do straight 50.

Also if the pressures are OK, then you ould have a poor ground or a loose wire to the sender, or even a bad sender.
 
i had the same problem with my light comming on when it was warmed up to. i just put in a mechanical oil pressure gauge in. it shows that i have around 30 pounds oil pressure. i would just buy a gauge set and take the bulb out of the dash.
 
I bought a gallon of oil treatment (Lucas), and screwed around yesterday trying to get 3 qts of it into my 440. That stuff is like honey!. I topped it off with 20-50. Now I have 40 PSI at idle, and more at speed. I'll post again when I get a chance to get it good and warmed up. In my case, I've already got a mech gauge, so it's definately work bearings. Check yours with the mech gauge first, just to be sure. Good luck.
Mike
 
my 71 challenger had same problem. it never gave me any problems. but i decide to rebuild my tranny and remove the oil pan to check the rear mains and rod bearings. the man that sold me the car thought the engine only had 23,000 miles on it. the car was real clean. well, i found the flickering light problem. the rear main bearings were already worn down into the babbit material of the main bearings. i replaced all lower end bearings and flicker problem went away. good luck,
KUHL DART
 
Thicker oil (or oil thickening schmutz) is NEVER the answer. In fact a heavier oil, especially now that we are going into the cooler weather, will accelerate wear. I lost an engine due to STP+20w/50 one cold morning.

Sure we've all thrown STP into a sick automatic, or filled differentials with bacon grease and sawdust to get something sold. But this is only a "fix" and not a REPAIR. Verify your actual pressure and decide what to do then. If you have at least 5 psi at idle, and 30 or so going down the road, you should be fine for a while on the street.

BTW 81k is pretty low mileage for a 318 to be causing oil pressure problems, unless it seldom saw an oil change, or was used for short trips.
 
I had a low oil pressure at idle problem in my Nissan (P.S., I do have 383-S Barracuda) that was caused by the oil pan being bent up into the pickup. Once I straightened the oil pan, everything was great. It's not always the bearings.

This is kind of funny. I had a friend in the navy put small block chevy lifters into a small block ford. They rattled around in the bore, which wasn't noticed during installation (I think beer was involved). Oil pressure was non-existant at startup.
Rod
 
C130 Chief said:
Thicker oil (or oil thickening schmutz) is NEVER the answer. In fact a heavier oil, especially now that we are going into the cooler weather, will accelerate wear. I lost an engine due to STP+20w/50 one cold morning.

Sure we've all thrown STP into a sick automatic, or filled differentials with bacon grease and sawdust to get something sold. But this is only a "fix" and not a REPAIR. Verify your actual pressure and decide what to do then. If you have at least 5 psi at idle, and 30 or so going down the road, you should be fine for a while on the street.

BTW 81k is pretty low mileage for a 318 to be causing oil pressure problems, unless it seldom saw an oil change, or was used for short trips.
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I got to agree with the Chief (just this once LOL). Varify with a mechanical guage what your pressure is and if it is 5 to 10 lbs at idle ask yourself a simple question. Do I want to calve this engine and have to hunt up a new one or is a set of crank and conrod bearings a cheap and dirty fix, I know what I'd do. BTW my 383 runs 25lbs at idle, hot, and I run Rotella 10-30.

Terry:burnout:
 
Will check into it to get real pressure reading. Like I said, I already put in a new oil pump and also did the rear main seal while I had the pan off, but now it looks like I might have to drop that pan again (which means removing the center steering link again too) and replace the bearings. Wish I'd known to do this when I had it apart before. Of course I will check into the pressure readings first with mech gauge.

Ran the car today and no light at all this time. As others have mentioned, it doesn't come on until engine is hot (and oil is thinner of course). Running 10w30 (or maybe it's 40, I forget at the moment) in it. One of the two though. It does get cold here in Ohio but I only run the car in the late spring/summer/early fall.
 
C130 Chief said:
Thicker oil (or oil thickening schmutz) is NEVER the answer. In fact a heavier oil, especially now that we are going into the cooler weather, will accelerate wear. I lost an engine due to STP+20w/50 one cold morning.

Sure we've all thrown STP into a sick automatic, or filled differentials with bacon grease and sawdust to get something sold. But this is only a "fix" and not a REPAIR. Verify your actual pressure and decide what to do then. If you have at least 5 psi at idle, and 30 or so going down the road, you should be fine for a while on the street.

BTW 81k is pretty low mileage for a 318 to be causing oil pressure problems, unless it seldom saw an oil change, or was used for short trips.
Click to expand...

Don't know how it was driven before me, but basically that's all I've done with it for the years I've owned it. It did sit in storage for long periods of time at one point, but I always put in fresh oil first when it sat for so long. The oil light always did this since the time I bought it though. Definitely going to put a gauge on it.

I can find it in my manuals, but anyone know offhand what normal operating pressure is for a 318?
 
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