Oil light on after start up

Perhaps, I am not mechanically inclined whatsoever. The “knock” has been called a "tap’ and a slight ‘tick’ by others. I’ve also heard that startup "noise’ on these engines is quite common. Not saying that there couldn’t be something very wrong with my engine but other’s have been able to go thousands of miles with similar sounds. Hoping for the best…if anyone can actually figure it out.

There’s a big difference between knock, tap and slight tick

Knock implies a low sounding, bottom end problem . . . bearings, pistons, rods, etc.

tick is more like valve clatter, sticky lifters, or possibly exhaust leak (think manifold)

It probably isn’t an exhaust leak, because the additive seems to have improved the situation

A skilled mechanic with some patience ought to be able to pinpoint the noise, or at least narrow it down

A tap or a tick could be from an oil filter with a lousy anti- drainback valve. I know Motorcraft filters have a very good one.

Wix and Mopar-branded filters have good anti-drainback valves too. The cheap Fram filters do not.

Will know on Monday and post then. Thanks for the helpful comments.

A ticking sound on start-up can also have nothing to do with the oil, might be a small exhaust leak for example. Open the hood and listen carefully. Does it sort of sound like fft fft fft ?

There’s several issues here, some may be red herrings. But one mystery certainly is a mystery, why does the oil light come one when a shop gauge installed in that some port presumably shows the oil pressure is fine?

I can think of two possibilities

  1. New oil pressure switch is still bad, just like the last one.
  2. Problem in the wiring harness between the switch on the engine and the light on the dashboard. Cracked wire or loss of insulation.

Hey…have the answer coming soon as the truck is in the shop right now. As far as the pressure switch it was tested along with the surrounding wiring and according to the mechanic that installed 2 of them on this truck within two weeks said that it was in working order.
But, I honestly have a feeling that the noise I hear at startup is the cause. As everything warms up the truck runs and sounds great. I have done my own research and apparently as engines wear the “clearances” with the metal parts in the engine get larger. If I understood it correctly. or like many of you have suggested there is sludge buildup somewhere.
Not really sure how much more I want to spend if the Dodge Dealership can’t figure this out.

Ok…so truck was taken to Dodge and this is what they suggest.

Performing an engine flush with PCV update kit ensuring contamination and sludge removed from engine to prevent new sensor from becoming damaged.

So…replace PCV, engine flush and replace sensor and connector with harness. DODGE
(900.00 dollars)

My Mechanic…

Says the PCV is not why my oil light is on. Also said that the switch and connections are good. Engine flushes are sometimes to aggressive and cause more problems that is why he put transmission fluid in oil. He said doing this is just preference. His next step would be to pull the oil pan and check for buildup.

So…any suggestions?
Thanks, Mike.

I lean twoard your mechanic on this one. However you didn’t tell us what weight oil you are using. If you are using a 5w- 20 or 30 I would try a 10W-30.

How many times may we ask…what is the actual oil pressure when the light is on ?

Old timer…oil used is what’s recommended for the truck…I believe 5w-30. Howie…I’m not sure all they said is it’s low and only at cold startup…and both mechanics said that. Right now I’m leaning towards my mechanic only because it doesn’t sound sensible that a little condensation would cause low oil pressure.
One thing Dodge did say that I didn’t quite understand…“Performed system scan, oil pressure to low, disconnected oil pressure switch harness and verified signal circuit. Switch state changes from low to high when grounded. Note corrosion found at wire into connector and slightly pinched. Must replace sensor and connector with harness. More, sensor appears recently replaced, possibility of defective sensor or contaminated”.

Sounds like their saying they think either the sensor and it’s whole setup is bad and that it is all sludged up. My mechanic says thats all been checked and passed. Who to believe…???

My first ever oil light issue and hopefully my last.

I am confused, your original post says your oil light comes on after cold startup with a tapping noise,then goes away for a few minutes, Then comes back on to stay until you shut off the engine.

Oil pressure is highest at cold startup which is why an oil filter that allows the oil to drain back to the engine would make sense. While the oil pump is re-filling the oil filter, the engine is running without oil or pressure.

The fact that the oil light comes back on suggests that there is significant wear on your bearings from the miles on your engine and all those dry startups.

That is why I suggested a better oil filter and a heavier oil.

Now in your last post you say it is only coming on after cold startup???

A normal working PCV system won’t have pressurized oil running through it, just crankcase vapors. A new PCV valve is only a couple of bucks. A bottle of Gunk Motor Flush is about $6. The new sensor and harness can’t be that much, either. They took you for one hell of a ride ($900!?!)…anyway, you might want to just use a good thick synthetic oil and a GOOD filter (Purolater, Wix, Napa Gold, etc) and see what happens. I wouldn’t use any additives such as Lucas.

Oldtimer…oil light comes on when I start the vehicle and stays on for a bit…maybe a minute roughly then shuts off. After it flickers very briefly then turns on until shut off. When I restart the vehicle light does not come back on and functions like it should. Sorry for the misunderstanding.

Billfrank 85…I didn’t get the work done because I only trust my mechanic lol. I did pay for an hour labor to get a second opinion. ($150.00)
Next step is going to be removing the oil pan and also checking the oil pump. After that I will definitely discuss a synthetic oil and quality filter with my mechanic.

Shannon11, that would be my next step, is to remove the pan and see whats going on. Looking for sludge, blocked oil pump screen, and would also have the bearing clearances checked. I would first remove a valve cover and see what it looks like up on top. If gunked up its time to pull the pan and hope for the best. Keep us informed and good luck.

From everything you describe, I don’t think you have an oil pressure problem, I think you have a light problem.

WOW! I would stay away from that dealer. $150 and didn’t even check the actual oil pressure with a mechanical gauge. In my pinion that should have been 1of the first things done. That would have either confirmed or ruled out a lot of things right there.

From what I understand your mechanic has put a shop gauge on the oil port and determined the oil pressure measures low at start-up. That would contraindicate a sensor or wiring problem. The sensor is probably working as it should. It’s just the oil pressure is low at start up, and that’s what the sensor is saying when it turns on the oil pressure light on the dashboard.

That’s a common symptom of a worn engine. As the parts wear they distance between them increases, which creates tiny leaks for the oil to go through. It doesn’t leak onto the ground, but back into the pan. It’s like trying to blow up a balloon which has tiny leaks in it all over the place, no matter how hard you try, it just won’t hold pressure.

I think your mechanic is spot on to want to remove the oil pan for a look see what’s going on in the oil pump and crankshaft bearing area.

As mentioned above, pcv valves cost less than $5 new. They can usually be tested just by shaking them, but if you want a new one, I’m sure your mechanic would be happy to replace it for you for a very small fee, less than $25 I expect.

Yeah I think your spot on. I’m curious to see what my mechanic finds when he gets into the pan area. So, I’m assuming a worn engine is just a ticking time bomb? Does anyone know what the cost for a rebuild would be if it’s a bearing issue? Engine plus labor to install? Engine is a 4.7 litre magnum.

If the oil pan is dropped I would suggest removing a few main bearing caps from the end of the engine fartherest away from the oil pump. This only takes a few minutes.
:If the bearing shells are showing all copper it could be that wear over time has scrubbed enough of the bearing surfaces away to cause pressure problems due to excessive oil clearance.

Depending upon crankshaft journal condition (scoring, out of round, etc) it may be possible to slap a new set of rod/main bearings in it and motor on.

Most oversize bearings are in increments of .010s which means grinding the crankshaft. However, bearings in .002 oversize are available and which are used to offset crank journal wear to bring oil pressure back up while providing some additional engine life.