[kc27]

It is a 2007 Dodge Grand Caravan with 226,000 miles on it. I replaced the oil pressure sending unit with a new MOPAR unit. The light still comes on at idle and goes out when the vehicle accelerates.

I assume the next step is to pull the sensor and attach an oil pressure gauge. What readings should I see?

Has anyone had these symptoms, and if you resolved the problem, how did you do it? I have been pretty consistent with maintenance including oil and filter changes. Not sure if this is an indicator that the engine is not long for this world.

 

[beat_truck]

How long has it been doing it? Just for poop and laughter, I'd change the oil filter and see if it helps it. When I was still working at the shop, a Chrysler Sebring came in doing the same thing. The owner wanted a new oil pump put in, which was a huge job. I noticed it had a POS Fram filter on it. I suggested trying a new one before tearing into it. The problem went away and never came back. He was a local repeat customer, so I would have probably heard about it if it had.

 

[kc27]

How long has it been doing it? Just for poop and laughter, I'd change the oil filter and see if it helps it.

The oil light started coming on at idle two weeks ago. I changed the oil filter when I changed the sensor.

Recently I had heard an engine rattle when I started the vehicle for the first time in the morning. Thinking this might be because of a defective oil filter anti-drain back valve, I installed a NAPA Gold filter when I changed the sensor. I will find out tomorrow morning if the rattle is gone.

 

[Jeepman]

What brand and viscosity oil are you using? What's your rpm at idle? Slight increase make a difference?

There can be bad product on the shelves.

The Petroleum Quality Institute of America

pqia.org

Low Oil Pressure Symptoms and Causes – AMSOIL Blog

Low oil pressure can affect your vehicle’s performance and lead to engine damage. Here are the symptoms and causes of low oil pressure.

blog.amsoil.com

.

 

[marvinstockman]

KC27, remember, this is an older pushrod engine, and you can use a heavier oil. When I had my 2003, I was using Mobil One 0W40 without an issue.

I'd also do a mechanical oil pressure test, and you can look up normal oil pressures online.

With 226K miles, I wouldn't put too much money into this engine, as good low mileage engines should be quite plentiful. and cheap. Some yards even do the install and guarantee the install.

 

[Road Ripper]

If the engine isn't burning oil and no weird noises, no reason it can't go another 225,000 miles. Putting another used engine in it might get you the problem of burning oil, as 2005 and later 3.8's have been known to do.

I'm thinking oil viscosity is wrong (we just had/having a HOT spell!) or a defective filter. Anti-drainback valve isn't that important in these engines with the filter adapter, which holds the filter vertical so the oil can't drain out of it. I've been using the standard Fram oil filters for years on this van with no problems. The oil might be getting thinned by the fuel if it's old, or the higher ethanol in gas nowadays. But, why guess? You're on the right track with hooking up an actual gauge to the oil port and seeing exactly what the pressure is, avoiding guesswork and speculation.

 

[kc27]

What brand and viscosity oil are you using? What's your rpm at idle? Slight increase make a difference?

RPM at idle is 700 RPM - idle has always been 700 RPM. The light goes out when RPMs reach 800. I have run 5W-20 full synthetic oils from Mobil 1, Pennzoil to SuperTech (Walmart house brand). Oil got changed every 3 to 5K miles at the most. The vehicle was at the 3K mark since the last oil change, so I changed the oil and filter today. It did not solve the problem .

I spoke with the mechanic who services my vehicles. I asked him to do the oil pressure test. He was reluctant to do so, saying that the new pressure switch sensor was unlikely to be faulty, and that I could trust the oil light indicator. He agreed to check the pressure next week.

When I had my 2003, I was using Mobil One 0W40 without an issue.

Why did you decide to turn 0W-20?

 

[beat_truck]

The thinnest I would be running is 5w30. With high mileage and questionable oil pressure, I would go for 10w40. Especially in the summer heat.

And, I agree with Road Ripper. It's dumb to immediately throw in the towel and replace an engine just because it has high miles. Especially with another one that you know nothing about.

 

[Jeepman]

I used 5W-40 Super Tech Full Synthetic European Formula in a 2007 DGC 3.8L engine and it worked fine. I don't use 5W-20 in any engine, not even my lawnmowers. 5W-30 is my standard for the 2016 DGC 3.6L engine. 5W-20 is the norm there but Owner's Manual says 5W-30 can be used. When one has the option, go for durability. You will make the engine designers happy.

A bad replacement sensor is a possibility. I had one, a SMP one I believe, that only lasted a year. Replaced it with a Mopar unit that lasted.

 

[marvinstockman]

KC27, the main reason I used 0W40 was that my other two vehicles used 0W40, and I didn't want to keep two types of oil around.

Worked fine. My engine wasn't using oil before I changed to 0W40 nor after. The thing with oil is that the '0' is the cold number, and it is thicker than the '40' when the '40' is at operating temperature, say 200F.

If you can fix your problem with a 0W40 or a 5W40, do it and drive on!

 

[KENSTV]

At that mileage I'd be more inclined to believe its worn bearings, a thicker 40W should help, the cheep sensors can also cause it

 

[kc27]

If the engine isn't burning oil and no weird noises, no reason it can't go another 225,000 miles.

It has a brief knock when first started in the morning. It only last for a couple of seconds, then the engine is quiet.

A friend suggested, as some of you did, to switch to a higher weight oil. Or he suggested dropping the oil pan and changing the connecting rod bearings. If that is a reasonable and not too expensive solution, I would try it. I recently put tires, struts, and shocks on the vehicle. I would like to get a couple more years of use out of it.

I live in an area where roads are salted in the winter, so the vehicle has rust. It is the rust that would prevent me from spending the money to replace the engine, if it comes to that.

 

[beat_truck]

Assuming you can't do it yourself, it really shouldn't cost much for someone to throw a set of bearings in it. The pan is easy enough to take off. And, a pan gasket and a set of bearings are dirt cheap.

 

[Road Ripper]

I live in the same kind of conditions. I have two engines with 225,000 miles on them, and one with 215,000 miles. I've read of people getting 400-500,000 miles out of these engines, so they're good.

Brief knock on startup is oil pressure building up. Sometimes the hydraulic lifters can bleed down and need to be pumped up after sitting a while. Could also be oil filter leaking down a little, maybe due to a dried-up and hardened O-ring between the oil pump pickup tube and the lower timing cover (have to drop oil pan to change). It could suck air in and briefly slow the oil uptake.

My van started a mild vibration during idle the first winter I had it (owned for 4 years now). Also seemed to have a light ticking. I dropped the oil pan and changed rod bearings, that O-ring and gasket. Didn't help. It DID knock worse at startup immediately after reassembling everything, and threw a misfire on cyl 1 code. One of the hydraulic lifters for cyl 1 had bled down during the work, and set the code/misfired until it pumped up again. It never did that again, but the slight vibration at idle persists. It actually seemed to get better when idling with 0w-20 oil one July when I was late to my changing to 5w-30 summer oil. That tells me I have a lifter with decreased oil flow to it. My rod bearings still looked okay after 196,000 miles, but the ones at the ends of the crankshaft had more wear marks than the ones near the center (which get the oil first). That told me the van was sometimes run too low on oil (it did burn a little when I first got it). Using a little oil and the oil pan gasket leaking made the engine run low on oil sometimes. The oil burning has gone away with regular driving, and the new gasket really slowed the leak down. It no longer runs low on oil, and engine is pretty quiet. I still use the cheapest Fram filter on it, and don't have problems with filter leakdown. Maybe because I park nose down on my inclined driveway?

 

[Jeepman]

Engine noise is par for the course re 3.3L and 3.8L Chrysler engines, SO THEY SAY.

Dodge Caravan & Chrysler Minivan Engine Noise

Common engine noise complaints on these minivans include tapping, ticking, clattering, rattling, knocking, rapping, buzzing, whistling, squealing and groaning sounds from the engine compartment. In some cases, the noise is only noticeable immediately after starting the engine. Other times, the noise comes and goes, changing with engine speed or vehicle speed. With some minivans, the noise has always been there (for years!) but has never gone away.
Of most concern is ANY noise that suddenly occurs. If your engine has been relatively quiet but is not making a strange noise, it should be investigated without delay.
To date, Chrysler has never admitted to having an engine noise problem with their minivans, nor have they published any technical service bulletins on diagnosing or repairing engine noise on these vehicles. It's as if the problem doesn't exist! But according to many Dodge, Plymouth and Chrysler minivan owners who have the 3.3L and 3.8L V6 engines, noise IS a problem.

Shake, rattle and roll

 

[KENSTV]

Had a short block put in for this on my 92 3.3, was in extended warranty and tech support had them drop the pan and check the piston skirt clearance, noise was piston slap, would only rattle till oil pressure was up, too thick oil, when cold (15-40 etc. should be 5-30 or 5-40--new cars use 0-20 !! ) or poor filter can cause it too, at that mileage I'd bet on rod and main bearings and worn piston skirts, imagine how many strokes those pistons have made !!

 

[Road Ripper]

Piston slap is not caused from low oil pressure at start-up. Piston slap was a common GM problem, because of their crude assembly practices. We had an engine swapped in my wife's car because of that (under used car warranty) and the replacement engine did the same thing! Finally traded that thing off for a Dodge Magnum, and we've never gotten another crappy GM product again.

Again, with that mileage on a maintained engine, the rod and main bearings will still be good. When I pulled the pan on my 2000 T&C for it's second (!) timing cover gasket/O-ring replacement I pulled a rod bearing cap and looked at the bearings (especially the top one, which takes the pounding). It looked great! Felt all the rods for play and none were excessive, and engine still ran quiet. For that engine I DID use a filter with silicone anti-drainback valve because the filter sat closer to horizontal, and that helped against cold start rattle.

Some of those early 3.3s had ticking problems because of the valvetrain hitting the head bolt washers. An engineer made a big mistake trying to use the bigger washers from the 2.2L engines, and when a line worker who assembled engines brought up the concern of them being too close to the valvetrain, he was told "don't worry about it" by a superior. Well, that came back to bite someone in the a$$! A lot of 3.3's were torn down to replace "noisy lifters" when the problem was the head bolt washers. A QC person at Chrysler only found the problem after asking a line worker who assembled the heads how they do their job, after he himself assembled an engine with "bad" parts and not being able to cause the same noise.

 

[Valhallalla]

Had a short block put in for this on my 92 3.3, was in extended warranty and tech support had them drop the pan and check the piston skirt clearance, noise was piston slap, would only rattle till oil pressure was up, too thick oil, when cold (15-40 etc. should be 5-30 or 5-40--new cars use 0-20 !! ) or poor filter can cause it too, at that mileage I'd bet on rod and main bearings and worn piston skirts, imagine how many strokes those pistons have made !!

Engine oil pressure and piston slap really have nothing to do with each other. Excessive piston to cylinder wall clearance (the cause of piston slap noise) will not affect oil pressure. Likewise, low oil pressure will not cause piston slap. Certainly an engine without oil circulating properly might eventually experience excessive piston and/or cylinder bore wear. However, low oil pressure will cause many other much more serious engine maladies long before it has any effect on the piston to cylinder wall clearance.

Piston slap noise dose not change as a result of oil pressure coming up. It changes as the piston expands as a result of temperature increase.

It would be virtually impossible to accurately measure piston to cylinder wall clearance after only removing the oil pan. Nobody does it in that way. To properly determine the clearance would require almost complete disassembly of the engine (heads off, pistons out).

Piston slap is definitely not what is causing the oil light to come on here.

 

[Valhallalla]

The next step should be to measure the actual oil pressure with a gauge. These are the specs from the Chrysler service manual. The 5 psi spec at hot idle is the true bare bones minimum. I would much prefer to see it closer to the 10 to 20 psi range.

View attachment 66907

This is not a complete list but these are some possible causes of low oil pressure:

- Worn engine main and/or rod bearings. This would most likely be accompanied by some amount of abnormal noise.

- Worn camshaft bearings. Not very likely.

- Hydraulic lifter has come apart. Would probably be accompanied by noise and/or misfire.

- Large internal oil leak. Not common but I have seen oil galley plugs missing or fall out.

- Stuck open oil pressure relief valve. Also not very common but it happens.

I used to have a 1981 Dodge pick up with a 318. If I changed the oil and used the thin bulk oil we had at work (free!) the oil light would flicker when at hot idle. Raising the engine speed just slightly would turn the light off. The solution for me was to use thicker oil or add a can of STP with the thin oil. There was no singular thing wrong with the engine. It was just old and a bit worn. I sure wish I still had that truck.

 

[Special Edy]

MEASURING MAIN BEARING AND CONNECTING
ROD BEARING CLEARANCES

PLASTIGAGE METHOD
Engine crankshaft bearing clearances can be determined by use of Plastigage or equivalent. The following is the recommended procedure for the use of
Plastigage:
NOTE: The total clearance of the main bearings
can only be determined by removing the weight of
the crankshaft. This can be accomplished by either
of two methods:

PREFERRED METHOD
Shimming the bearings adjacent to the bearing to
be checked in order to remove the clearance between
upper bearing shell and the crankshaft. This can be
accomplished by placing a minimum of 0.254 mm
(0.010 in.) shim (e. g. cardboard, matchbook cover,
etc.) between the bearing shell and the bearing cap
on the adjacent bearings and tightening bolts to
14-20 N·m (10-15 ft. lbs.). The number of main bearing will vary from engine to engine.

ENGINE WITH 5 MAIN BEARINGS
• When checking #1 main bearing shim #2 main bearing.
• When checking #2 main bearing shim #1 & 3 main bearing.
• When checking #3 main bearing shim #2 & 4 main bearing.
• When checking #4 main bearing shim #3 & 5 main bearing.
• When checking #5 main bearing shim #4 main bearing.

ENGINE WITH 4 MAIN BEARING
• When checking #1 main bearing shim # 2 main bearing.
• When checking #2 main bearing shim #1 & #3 main bearing.
• When checking #3 main bearing shim #2 & #4 main bearing.
• When checking #4 main bearing shim #3 main bearing.

NOTE: REMOVE ALL SHIMS BEFORE REASSEMBLING ENGINE

ALTERNATIVE METHOD
The weight of the crankshaft can be supported by a jack under the counterweight adjacent to the bearing being checked.


PLASTIGAGE PROCEDURE
(1) Remove oil film from surface to be checked. Plastigage is soluble in oil.
(2) Place a piece of Plastigage across the entire width of the bearing shell in the cap approximately 6.35 mm (1/4 in.) off center and away from the oil holes (Fig. 3). (In addition, suspected areas can be checked by placing the Plastigage in the suspected area). Torque the bearing cap bolts of the bearing being checked to the proper specifications.
(3) Remove the bearing cap and compare the width of the flattened Plastigage (Fig. 4) with the metric scale provided on the package. Locate the band closest to the same width. This band shows the amount of clearance in thousandths of a millimeter. Differences in readings between the ends indicate the amount of taper present. Record all readings taken. Refer to Engine Specifications. Plastigage generally is accompanied by two scales. One scale is in inches, the other is a metric scale.

NOTE: Plastigage is available in a variety of clearance ranges. Use the most appropriate range for the specifications you are checking.

CONNECTING ROD BEARING CLEARANCE Engine connecting rod bearing clearances can be determined by use of Plastigage or equivalent. The following is the recommended procedure for the use of Plastigage:
(1) Rotate the crankshaft until the connecting rod to be checked is at the bottom of its stroke.
(2) Remove oil film from surface to be checked. Plastigage is soluble in oil.
(3) Place a piece of Plastigage across the entire width of the bearing shell in the bearing cap approximately 6.35 mm (1/4 in.) off center and away from the oil hole (Fig. 3). In addition, suspect areas can be checked by placing plastigage in the suspect area.
(4) Assemble the rod cap with Plastigage in place. Tighten the rod cap to the specified torque. Do not rotate the crankshaft while assembling the cap or the Plastigage may be smeared, giving inaccurate results.
(5) Remove the bearing cap and compare the width of the flattened Plastigage (Fig. 4) with the scale provided on the package. Locate the band closest to the same width. This band indicates the amount of oil clearance. Differences in readings between the ends indicate the amount of taper present. Record all readings taken. Refer to Engine Specifications. Plastigage generally is accompanied by two scales. One scale is in inches, the other is a metric scale. If the bearing clearance exceeds 0.076 mm (0.003 in.) replace bearing.

NOTE: Plastigage is available in a variety of clearance ranges. Use the most appropriate range for the specifications you are checking.