Engine/Transmission (1994 - 1998) oil drain back problem

[Sterling94803]

i have a 94 dodge with the cummins diesel..... when i got it there was 64k miles on it... ... when i would change the oil filter it would always be full of oil and make a mess when i removed it... ... it now has about 145k miles on it..... about 40k miles ago i noticed that the oil filter was only about half full and didnt get oil all over everything when i changed it... ... i also noticed that it now takes a full 4 seconds for the oil pressure light to go and for the oil pressure gauge to show pressure when i start it... ... even if it is only shut off for 15 minutes it takes a full 4 seconds..... the oil pressure is now much lower than it used to be..... i think that might be because of all the "dry starts" while the oil pump is filling the oil filter... ... .



is there a backflow preventer or check valve in the oil system that prevents the oil from draining back to the oil pan? i have checked the pressure relief spring and plunger and they are both as they should be... ... i have looked in the shop manual and the cummins parts catalog and cant find anything in the oiling system that looks like a check valve.....



hope somebody knows something about this... ... thanks

 

[gcorron]

When I drain the oil, I put the pan under the truck while warm, and let the oil drain for a LONG time, sometimes overnight if I can. The filter will not be nearly full if you wait until it cools off a bit to change it, voila, no mess! If you try to change it warm, it goes everywhere.

Perhaps your timing was different?

If the pressure gauge is showing acceptable pressure, I would have to say you don't likely have a big problem.

Just a suggestion,

George

 

[Dieseldemon]

most oil filters do not have a check valve to prevent drain back which is not a problem

 

[Sterling94803]

the problem is my filter is draining back to the oil pan because when i change the filter it is half empty... ... whatever used to prevent drainback from the filter is no longer preventing it... ... as i said in the original post it didnt used to be this way... ... even if i let it sit for several days before i changed the oil the oil filter always used to be full... ..... at this time the oil pressure is about half what it was at 64k mile when i got it... ... . when full warmed up and idling it is at the lowest end of the "normal" range and i am assuming that because of the "dry" starts (4 full seconds until there is oil pressure) there is more wear on the rod and main bearings and therefore less oil pressure..... this engine has never been worked hard or abused... ... and had 3k mile oil changes and it is still stock... ... i didnt think that it should have such low oil pressure with 145k miles on it... ... . oil pressure has gone from the high half of normal to the low half of normal on the gauge in 40k miles..... about the same amount of time that the oil filter has been draining back... ...

 

[gcorron]

I am not aware of any checks in the oil system. My experience tells me it is normal for the filter to be less than full, not certain of the 1/2 empty value, if allowed to sit after stopping the engine. Oil pump failure is extremely rare, and certainly in these engines. What type oil, and filters are you using?

Let me relate something that happened to me about 16 years ago.

I was a lifelong user of Pennzoil. It had always kept the engine clean, and I got long service from vehicles. I was driving a much prized 1980 Jeep 3/4 ton pickup at the time.

Oil pressures kept dropping, I kept looking for a cause. I even took the oil pan off, changed the oil pump, and tested bearing clearances, no problems. The oil pressure was erratic, and low. Finally, one evening on the way home, my beloved Jeep gave up the ghost. Bottom end bearing failure.

I bring it home, remove the engine, and rebuild. I sent the block out for 'boiling', and had the heads done, and block checked. I get it back together, put new oil in it. On startup, I notice the oil pressure is low, very low.

I am working, at that time, in close proximity with the mechanics at a large institution, and go over to get some ideas, before I ruin a newly built engine. Yes, I thoroughly check all values prior to rebuild.

One of the old grizzled guys there asked the same question, what type of oil are you using. I tell him Pennzoil, like I have always used. I tell him I buy several cases at once to have enough around for several oil changes in my vehicles. He tells me to stop by and get some Castrol on the way home. I think he's nuts, but 2 days later, I do just that.

Oil pressure doubled at startup! The pressure was not erratic, idle, or load!

I wrote Pennzoil a registered letter. I figured I had been a loyal, long term, customer, and they should be made aware that they hae shipped out some very bad product. Not being a litigious sort, I had no intentions of suing, nor did I expect any compensation.

I never heard a word, no reply at all. I have never, nor will I ever, use Pennzoil again!

I have always used Amsoil in the Cummins, no problems ever noticed, and as you can imagine, I keep a pretty close eye on the gauge.

It's not that the oil pump cannot fail, but it would be very rare. There are no known checks in the system. If you're using standard filters, there are no checks. oil pressure sending units are another matter, they do go bad. Since they are not mechanical, they also can have wiring issues.

Mine has also had the approximate delay you are experiencing upon startup, the gauge does not instantly register.

What type oil are you using? Change it and see what happens. Make certain it is rated for the Cummins, all are not.

Let us know.

 

[Dieseldemon]

Check with Napa their filters have check valves to prevent this (I would not use it as I dont trust their filter There is a check valve in the oil cooler also, if the pressure is a little low change the reulator spring (cummins part # 3925009) very simple thing to do

 

[cerberusiam]

Verify your oil pressure with a mechaical gauge before even considering any oil pressure problems. The sending units are know to be an issue, expecially with age.

Drain back is pretty normal even on a new engine. Just depends on the oil and wear in the system. As long as it meets the standards with a mechanical gauge I would not worry.

 

[Sterling94803]

thanks for this info... ... i will check the check valve in the oil cooler... ... ... i have always used fleetgaurd microglass filters... ... i am with you on the napa filters... . i dont know enough about them to trust them but the idea that they have a check valve in them is worth looking into... ... thanks

 

[Sterling94803]

thanks for the info... ... i will verify the oil pressure with a mechanical gauge..... i have always used the cummins approved valvoline or delo 400... . for filters i have always used fleetgaurd microglass oil filters and i change the oil every 3k miles..... i have never observed any change in oil pressures after changing the oil..... i figured that this engine was good for 500k miles before rebuild... ... the oil pressure is indicating rod and main bearing wear and excessive clearances and it only has 145k miles on it... ... . the only thing that i could come up with is that the 4 or 5 seconds of no oil pressure was giving a lot of wear on start up

 

[Dieseldemon]

Check with a manual gauge first like stated above use the plug on top of the filter housing

 

[Sterling94803]

will do in the next week or so

 

[ata]

SIDE NOTE I have never seen a 5. 9 have oil pressure at start-up. It always takes a few seconds. You have to remember that the oil sender is on the drivers side of the block and the oil pump and filter are on the front pass-side. The 5. 9 is a LARGE block with large oil passages and it takes a little time to fill them and build pressure. They DO-NOT remain full after shut-down. The oil filters for the 5. 9 have NO valves in them at all. In the oil cooler housing there is a pressue regulator and a by-pass valve. No anti-drain back and you will not find an anti-drain back filter for the 5. 9. Next on the 94-95-96 engines when the oil pressure gauge starts read low or irratic it's time for a new sender. It's getting ready to fail and leak oil. I think you are worrying about something thats not there.

 

[Sterling94803]

thanks for the info... ..... when i first got it it had about 64k miles on it and it took 1 to 2 seconds for the oil pressure light to go out and the gauge to start to register pressure... ... . now it takes 4 full seconds for the oil pressure light to go out and the gauge to start to come up... ... . i will be installing a mechanical gauge in the next few weeks and then i will have an accurate pic of what is going on with the oil press

 

[GAmes]

I think you are worrying about something thats not there.

Me too. Sometimes during an oil change the filter is full, sometimes not. I use Fleetguard Stratopores. If you are showing lower oil pressure than normal it is probably the sender going bad. Pull the wire connector off and check for oil in the holes. If it is wet, the sender is leaking internally and soon you will have a REAL leak. When you order a new sender be aware there are two types, round pins and flat pins. The flat pins are on late model '97s and '98s. If that is what you have, PM me. I have one from a '98 12 valve that I can't use.

 

[Sterling94803]

mine is a 94..... thanks