Hello everyone,

Recently acquired a mix-breed vehicle. It's a 1997 Dodge Stratus and has a Mitsubishi built 24-valve 2.5L SOHC V6 engine -- which I believe it's the 6G73 (or maybe 6G72).

Long story made short: Water pump siezed, took out the timing belt which took out the timing belt idlers...it's a stinking interference engine and bent 8 of the 12 exhaust valves. Parts (at jobber cost) and a valve job on both heads ran me right at $1700...and that's with me providing all the labor (was ASE certified back in the early 80's). She's finally back in running condition, but with a twist.

Once this engine warms up, the oil light comes on at idle. Sometimes a flicker, sometimes on solid. Engine has fresh 10W-30 synthetic and a brand new (non-Fram) oil filter. Oil level is right on the mark. Engine runs smooth and quiet...has plenty of power. Only ticking sounds come from the fuel injectors which is normal.

Thought this might be a failing oil pressure sending unit...so I replaced it. The problem persists. I took out my old trusty manual oil pressure gauge and adapted it to the engine to get some meaningful information.

When cold, the engine holds 50 PSI oil pressure at idle and close to 70 PSI at 2000 RPM. Looks wonderful to me. As the engine warms up the oil pressure at idle gradually gets lower which makes sense -- oil thins as it gets hotter. When fully warmed up (elect. radiator fan comes on), oil pressure at idle is in the neighborhood of 7 to 10 PSI...yet is right at 40 PSI at 2000 RPM.

I know better than to drain the oil and then fill it with thicker oil (like 15W-50)...that's sure to trigger larger problems later on. Might just go to straight 30 weight though...

Some thoughts to the cause:

1) It could be that the rocker arms are bypassing too much oil. I did have to replace some of the hydraulic tappets because they weren't pumping up.

2) It could be the onset of early oil pump failure.

3) It might be excessive wear at the crankshaft...but...I did notice that the cylinders still had a cross-hatch hone pattern even though the engine has ~88k miles on it. I have no reason to suspect that the crankshaft would be so worn while the rest of the engine is not.

4) A combination of #2 and #3 perhaps?

5) These readings might just be "normal" for this engine.

My manuals don't mention the acceptable oil pressure ranges for this thing. Curious if anyone knows what the manufacturer's acceptable oil pressure range is for this engine...or if anyone has any wisdom to share that might help me correct this issue.

Thanks in advance,
-Me

After further spelunking, I've finally found that this engine is supposed to present at least 6 PSI of oil pressure at hot idle. I've measured 12-13 PSI. So this is "normal".

I've adapted a new oil sending unit to my air compressor (with a regulator and a gauge) to test the sending unit. The sending unit exhibits an open circuit at 4 PSI -- anything below that would signal the oil pressure light. So far so good.

Put the sending unit back in the car and ran it in the driveway until the radiator fan came on. No oil pressure light. Took the car for a spin to observe things like engine temperature, listen for odd noises and make sure the oil light didn't come on.

After about 30 minutes of driving around, I pulled up to a stop light. The oil light came on again. :o

Limped it home, pulled the oil sender and put the manual gauge back on the engine while the engine was still hot. Fired it up and sure enough, the oil pressure is less than 4 PSI at hot idle. :(

There's more to this than meets the eye I suppose. Not sure what to suspect at this point other than the oil pump. Perhaps the oil pump housing is cracked internally and doesn't present this issue until after everything is hot and has a chance to expand. :unsure:

Guess it's time to pull the oil pan / oil pump and inspect.

Anyone else ever encounter issues like this on the 6G73 or 6G72 engine?

Hi Phubar:
I joined this group so I could send you this message. I have the exact same problem with the oil pressure on my 2000 2.5L Sebring convertible. Did you ever figure out what the problem is? I bought the car with 20,000 miles on it and converted to Amsoil synthetic right away. I now have 95,000 and am getting the oil light when slowing down. There is none of the dreaded "sludge" that I see mentioned in the forums.
One thing that I noticed is, it seems to be taking a while for the oil to migrate back down to the crankcase. If I check the dipstick while the car is running, there is zero oil on the dipstick. If you get this, please reply to me directly. (Please remove the 0's from the email address.) 00dougaustintx@gmail.com

I don't know if anyone else is having an issue with the oil pressure on their 2.5L Mitsubishi engine ( 2000 Chrysler Sebring convertible), but I replaced the sending unit with a Sorrensen unit from Advance Auto Parts, drained the oil, replaced it with 10w-30 Amsoil synthetic, installed a Mobil 1 filter designed for synthetics ($10) and the problem appears to be solved. No more oil light when I slow down for stop lights. If I sit for a while with the car in gear, for some reason the idle gets slower and when it gets down to about 500 rpm I do begin to get a slight blink on the oil pressure light, but as I understand it, 500 is below the normal idle speed for an automatic. I also jacked the car up and crawled under the engine while it was running. I could hear no knocking or any other noise that indicated bearing problems.
Before performing these maintenance repairs, I seriously considered putting in a T-fitting on the oil port so I could connect a manual oil pressure gauge, but after looking at the old pressure switch, I think the threads are a slightly different pitch (and taper) from normal pipe threads.