1972 dodge dart with oil light flicking

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my love

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My 72 dodge dart has a slant 6 225 engine. The oil light flickers at low RPM but remains steady when I operate at normal road speeds. The oil and filter were just changed without any change in the flicking of the light.
This car has around 160k on the original engine.his
I checked the PVC and it is working fine.
What could be causing this oil light to flicker?
 
You may want to service the oil pressure relief spring per FSM instructions. After a ton of miles, that device can become gunked up, causing it to stick.
 
it could be a faulty sending unit maybe worn cam bearings weak relief valves spring in the oil pump but check the oil pressure with a mech gague first
 
Put a mechanical guage on it first. With that many miles on it. I would think
there is wear on all the bearings.
It's possible that the sending unit could be bad. Had a lot of them over the
years.
 
Godfatherofchry:
and if it was mine I would use a thicker oil like straight 30wt.
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This makes no sense, always use multi viscosity oil. That first number is viscosity of oil when cold, second number is viscosity when hot. Straight weight oil will not lubricate, disperse, or build pressure as fast as multi grade causing starter to labor excessively, and rotating components to be starved of lubrication during cold weather starts.
 
briankaplan said:
Put a mechanical guage on it first. With that many miles on it. I would think
there is wear on all the bearings.
It's possible that the sending unit could be bad. Had a lot of them over the
years.
Click to expand...
Yup, check with a live gauge first. If the oil pressure is indeed low, I'll pull the engine and put in new bearings. With that many miles, you might want to consider an complete rebuild. If you continue to drive it with low oil pressure, you may send a rod through the side of the block. If the pressure is good with a live gauge, you have a bad sending unit.
 
Oil is oil, is oil ,is oil. Straight weight? Wonder why engine builders like it. Wonder why it is recommended for inboard-outboards. Wonder why your lawnmower wants it.

It may be thicker, but it also doesn't run off of the bearing surfaces at shut-down.
 
Green1:
Oil is oil, is oil ,is oil. Straight weight? Wonder why engine builders like it. Wonder why it is recommended for inboard-outboards. Wonder why your lawnmower wants it.
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Is this a fresh built engine?

Is this a marine engine cooled by water intake never below 32 degrees, generally operated in waters 50 degrees and above?

Is this a fresh built engine on first start for break in, where oil will be drained in twenty minutes, and replaced with fresh multi grade?

Is this a small displacement air cooled, 3.5 hp. constant rpm engine with splash lubrication?

Oil is oil?

No, no, no, no, and no.

Just for the record, the last lawn mower and snow blower I purchased in 2010 recommended 10W30 & 5W20 weight oil.

A 1972 engine is not a pre fifties babit engine with huge bearing tolerances, which use to require single grade oil.

Reading list:
http://www.nordicgroup.us/oil.htm#How Sludge is Prevented
 
I agree with the other guys, test with a manual gauge first. You should have at least 10# at idle if the engine is healthy. If you have less, you need to look at the pump and bearings tmm
 
my love said:
My 72 dodge dart has a slant 6 225 engine. The oil light flickers at low RPM but remains steady when I operate at normal road speeds. The oil and filter were just changed without any change in the flicking of the light.
This car has around 160k on the original engine.his
I checked the PVC and it is working fine.
What could be causing this oil light to flicker?
Click to expand...

It may be as simple as turning your idle speed up a smidge.
 
guage it and then check bypass spring. The 340 spring is heavier but I think that just raises the bypass pressure.
 
One other thing to check....years ago I had a slant that was fairly clean inside, but the oil pump pickup screen had some solid chunks of sludge inside that was blocking good flow. Cleaned the screen out really good in the parts cleaner (and some Brakleen if I remember) and the light went out never to come on again. I say this just because its something else to check after you put a manual gauge on it and possibly get a low reading. If that's the case, check this before condemning the bearings. That motor was so well made they really can take a ton of abuse. I knew a cat that had his water pump go bad and still drove 10 miles to get home without killing the head gasket. Try that on any modern car and the engine is dead and stinkin'....
 
Suggest the following course of action to run down the problem.
  1. Check the oil pressure guage and sending unit against a known good mechanical guage.
  2. Check oil pump to insure proper output pressure. Adjust or replace as needed.
  3. Check oil pump pickup tube and screen. Clean or replace as needed.
If this does not identify the problem, then it is internal and will require replacement of bearings.

The only commonality that oils have is that they lubricate. IMHO the idea that all oils are equal is ill-informed at best, especially when it comes to mineral oils. Base stocks and additive packages (dispersants, flame retardants, detergents, etc.) make all the difference in the world. The additive packages in synthetics make them behave differently from each other.
There are many on this forum who can relate to having to use a paint scraper to clean valve cover interiors of engines that used Pennzoil or Quaker State. On the other hand, I've had no problem with Havoline collecting in the head or valve cover.
 
Thanks for all of your answers, so soon.
I will let you all know which solution worked
 
I like the thought of the pick up screen clog. I just did a 318 and the pick up sounded like a baby rattle when I was cleaning it. It was full of valve seal bits & pieces.
 
wjajr said:
You may want to service the oil pressure relief spring per FSM instructions. After a ton of miles, that device can become gunked up, causing it to stick.
Click to expand...

+1 from, what i have been told and read too this is on the basic maintenance list along with oil changes and tune ups but most times
people just dont do it.....
 
Step 1: Buy new oil pressure light switch, they're cheap. Make sure the wire isn't grounding out on something.
Step 2: Clean oil pressure relief valve.

If this fixes it, then the valve was sticking. Sometimes the valve hangs up because of wear, but usually it's a bit of crud. BUT, please clarify the original description, is the light OFF or ON steady as you increase RPM?!? That is, it is on most of the time, but almost goes out at idle. That would point to a supply problem. Is the engine a sludge bomb? You could have a bunch of crud sucked up against the pickup screen, in which case then...

Step 3: Remove valve cover and clean everything. Is it clean under there or nasty? Does it look like oil is getting up there? You'll want to remove the rockers and shaft. A wire brush and shop vac will work OK. Oil everything and adjust the valves.

Step 4: Put in a whole can of SeaFoam and cross your fingers. You may get lucky and the sludge will soften and pass through. If so, keep an eye on the oil, and change it when it starts looking dirty. If not, then...

Step 5: The pan comes off. Kind of a PITA. If the engine has been run very long with low oil pressure, the bearings are probably pretty beat. Then again, if I was pulling the pan, I'd just plan on replacing the bearing inserts and oil pump at 160K.

As for oil, thicker is seldom the answer. At best it will mask the real problem. I run Shell Rotella T6 5w40 (synthetic diesel oil) in just about everything I own. If you are flushing the engine, or it leaks/uses oil, then wal mart house brand 15w40 diesel oil would be my pick.
 
I vote for checking the wire grounding on something first. Disconnect it from the sender and wrap the end with electrical tape, but also to the sender so it sits in the same place. See if the light flickers while you drive, or even with the engine off, wiggle the wire everywhere and have a helper see if the dash light flickers.

My 69 Dart w/ 225 had the oil light come on during a trip in 1981. After a few minutes waiting, it was OK. It happened 6 months later and I assumed it needed a new oil pump. I was a clueless 22 yr old then. I tried to remove the oil pan and couldn't because of the steering linkage and didn't know about a Pitmann arm puller. I didn't even notice the oil pump bolted to the side of the block (no manual). I let the car sit for 3 yrs while I built a garage, then pulled the engine and had it rebuilt. I think it was actually just gunk against the screen since I had done the "can of engine flush" thing a month before. Perhaps if you drain the oil, then fill the pan with 1 gal of gasoline or kerosine, and let it sit a week, it will dissolve the gunk and it will flow out the drain. Leave a lamp under the pan to keep it warm. But don't run the engine like I did. I now know those engine flushes are bad (don't think they even sell them anymore).
 
I have a 65.000 mile 1966 /6 and it has never showed the oil light except when I start it and as soon as the pressure came up (2 seconds) then stayed off, Till one day a week ago The light came on and stayed on then I shut it down and pulled the wire off the sending unit on the side of the engine and cleaned the brass clip off and plugged it back in,,,, Scared me to death, you could just have a bouncing wire and a loose connection on the engine block sending unit .. True happening and all it was was a loose connection
 
Darter6 said:
I like the thought of the pick up screen clog. I just did a 318 and the pick up sounded like a baby rattle when I was cleaning it. It was full of valve seal bits & pieces.
Click to expand...
A partially plugged screen will cause bad oil pressure (because of restricted flow) at higher RPM's.... not at idle. If it's totally plugged, it will have bad oil pressure at all RPM's. The bypass valve is a possible cause if the valve is stuck open or partially so, or the spring is weak or broken. This is why you need a good live gauge to see exactly what you have for pressure and at what RPM.
 
You can pull cover off pump and blow compressed air down tru tube.Has worked for me in the past,if problem comes back ya gotta pull pan and do it correctly.Mark
 
As a flip-side to my and other's suggestion of possible "wire grounding", the following story supports the "gunk on pickup screen" issue.

When I was 13 yrs old, the oil light came on in our Valiant wagon w/ 225 engine during a trip. I knew enough to check the oil level, which was OK. My mom figured the oil light must just be acting up and kept driving, since almost there. She did stop at the first gas station 1/2 mi later, but no mechanic, so kept going. One mile later, the engine poured blue smoke and siezed. She proved you can kill a slant six. Her cousin towed us the rest of the way. He was an AMC Dealer and sold us a used Matador station wagon, a beautiful vehicle and very smooth on the highway. Mom came out ahead. Poor slant was probably crushed.
 
In my experience of non-abusive Slant six driving, when they start flickering the oil light at idle, they are worn out.

Another clue is to watch the oil light on cold start. When the bearings are worn it'll take 3 seconds to turn the light out.

Usually a rod bearing will go before a whole lot longer so I would probably bite the bullet and pull it for an overhaul.

I know the popular myth is that Slant sixes NEVER wear out and maybe they don't, but the bearings in them sure do. Plenty of old blocks around with a hole punched through at one end or the other.
 
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