Noisy oil draining back to pan. is this normal?

1990 Cherokee 4 L str 6 cyl

after shutting my jeep down I ve heard liquid moving. I decided to find the source. it turns out that I was hearing the oil draining back into the pan.

I was under the jeep with my ear next to the pan, no doubt of source.

this lasted about 15- 30 seconds before stopping. the front of the jeep was raised about 6", as I had parked it that way.
is this concerning?

I was recently going to change my valve/rocker arm cover gasket, but decided to wait because it did not seem to be leaking and I did not want to use the inexpensive cork fel pro gasket that I had bought, I decided to wait until I could afford the more expensive gasket.

I did notice thru my oil fill cap that there is a lot of crud under the cover and I am concerned that my oil return drains are partially clogged.
how can I clean these drains when I do change the gasket? since it has been strongly recommended here that I do not disturb the crud I m not sure how I should approach this. could vaccuming the loose crud with a shop vac be okay?

thanks, wes

ps. dropping the oil pan is not an option right now because of the extensive labor involved on this model and the expense of all the new seals and gaskets required. I ve bought 200 bucks worth of parts and fluids this month and it will be awhile before I can afford more.

right now I have brake shoes, tranny filter and fluid, above gasket, oil and oil and fuel filters waiting on me to work on, and other non mechanical things.

to summarize my questions…

  1. does noisy oil drainage concern you?
    2)how can I clean oil drains?
    a. can I pour kerosene thru to clean oil drains, and to help flush oil pan, which I can t drop right now?
    b. can I shop vac under the valve cover?
    c. should I add sea foam to oil for a bit before changing?

Wes, please get rid of that thing, for your sanity and ours. :wink:

how can I clean these drains when I do change the gasket?

Engine flush. Pour it right in. No matter what you use you should do an oil change afterwords.

@jesmed1, not happening unless the thing blows up.

I am trying to get this thing as reliable and maintenance free as possible now, in case I croak or my health worsens I want to at least leave my loved ones a car that they can use without problems until they get their lives back together.

none of this stuff is pressing, I just want to do as much as I can while I m still somewhat able.

it is tedious to have to learn so much new stuff at this time, and deal with the pain the repair work causes me, but I love my tools and might as well use em while I can. believe me, I m not enjoying this or getting much done each day

I d much rather be fishing as would my family, but I have my reasons for doing this. my computer is actually outside on my work table and I m just organizing my tools and putting off the actual work. lol

now if you ll excuse me I have to remove this poorly located coolant drain plug…

In answer to your original question, yes it is normal to hear oil draining back after shutting off the engine. As long as it is draining fast enough while running I wouldn’t worry about it. How’s your oil consumption? Do you see a puff of blue smoke when first starting the engine?

I wonder what oil draining into the pan sounds like. Are you sure it wasn’t the ping…ping…ping you get when a hot engine gets shut off and the metal starts contracting as it cools down? My parents’ 1991 Nissan Maxima was the first car I ever heard make that noise, and I guess it sounds like oil dripping.

As for your other questions kerosene and shop vacs won’t touch the type of hardened sludge that accumulates on cylinder heads. You have to scrape it off with scrapers, stiff brushes and solvent. If your gaskets aren’t leaking I’d leave them alone until and if you drop the pan.

I think at this point, if it’s not giving you trouble, roll the dice and leave it alone. There’s only so much you can do without taking it apart and properly cleaning it. Until you have an extra set of hands with you, I’d leave it be. It is after all a 1990. Can’t expect it to go forever. But, right now if it ain’t broke don’t fix it.

After a long drive quickly get a screw driver inserted through the oil filler neck and check it like a dipstick. If oil is not draining down quickly it will show up on the screw driver.

It’s normal. I would rather have an engine that allowed the oil to drain back quickly as to have an engine that limited the drain back or kept it from draining at all. Case in point: Chevy small blocks that hold the oil up in the valve covers. That’s not a good thing.

@Rod Knox, rod, its not draining quickly because I did what you said with my finger and I can see some oil standing in there with the flashlight. that s why I m concerned, and there is some hard loose crud in there as well, I could feel the rather large pcs with my finger.

its definitely oil dripping into the pan.

no, no smoke, its not burning oil, it leaks a bit at some of the many seals and gasket that are partially included in the oil pan removal procedure.

I m not worried about the hard sludge, it s the loose stuff in there that is concerning to me.

the gasket isn t that hard to change on the valve cover, and I don t anticipate having any extra hands soon. my son is very busy and is often out of town working. and yes I do expect it to last forever! :slight_smile: , well, 15 more yrs anyway, maybe 25 since I got it early enough before it started rusting, unlike my 75 fords which were pretty far gone when I got them.

its dripping but also holding oil in the valve cover, I think some of the drains are plugged, because the dripping was really noticeable today when the front was on ramps, so the drains that it needs when sitting flat may be the ones that are clogged.

does any one know how these drains are routed down to the pan, and their diameter?

thanks for all the responses

I did get my coolant somewhat flushed today. I did not remove the block plug but I drained the radiator and flushed it with hose. then refilled it and circulated the coolant and drained and flushed a couple more times before the brown stuff stopped coming out. then I refilled with water and coolant. haven t checked it with coolant tester yet but I think I got it 50/50.

it was not over heating or anything but I did not like the color of the coolant so I went ahead and changed it. it was good for -20 before I changed it. the radiator drain plug outlet was clogged and almost impossible to access since someone apparently put a wagoner radiator in there as a replacement, so I had to remove the bottom hose

My best advise on cleaning the drains is to remove the valve cover and thoroughly clean it. Then lift away any loose chunks and if a shop vac is available vacuum the loose crud. Then find the drain holes and pick out the crud that blocks them, then use a long screw driver to slip through to opening to confirm that it is not blocked. The greatest threat is causing the crusty debris to drop through to the pan where it can accumulate on the pick up screen or worse get in the oil pump and damage it.

If you pull the valve cover and find that there is no debris or heavy sludge just clean the valve cover and replace it. I honestly don’t think you have a serious problem with oil being trapped in the head.

thanks rod, I felt a good deal of loose debris in there. I think I ll do exactly as you suggested.

Perhaps you could remove the
Valve cover, get out the hard loose crud, button it back up with a new gasket, and run an engine flush in it.

that’s the plan fender… now to find the ambition… :slight_smile:

The valve covers will hold a little oil no matter what. They are designed that way so that there is some oil trapped to lube the components on start up.
The drains are straight passages to the bottom of the block and into the pan. They are casted in, not bored out, and are normally about 1/2 inch passages.

Do as @Missleman; said as a dip stick. If you shut it off and quickly check, and have more than one inch of oil you have a problem with oil passages.

I suppose you could use a shop vac, but that’s a lot of cleanup of the shop vac afterwords.

I’d leave it alone.
If you really need something to clean, I’ll get the carpet shampoo’er out. Let me know when you can come over. There are a lot of spots from the daughters puppy. I call her spot!!!


hey! I need a shampooer too!

yep, our daughters 9 month old pup made a few spots too, thank goodness she s past that.

if you excuse me I have to replace the bottom rails of our coffee table so that she will have something to chew on… (the pup, not my daughter). I swear the dog is part beaver. as long as she sticks to one pc of furniture I can live with it. she also likes pine cones, and certain types of wood. she will go to our firepit and pick her favorites out. she tried to pull a burning stick out two days ago, but changed her mind.

ps- thanks for the drain info, my shop vac doesn t mind getting dirty, and I have an extra hose too.

Maybe I am overly cautious, but I don’t like the shop vac idea around an engine. The shop vac motor is probably a brush type motor and there is a spark between the brushes and the commutator. Any gasoline fumes sucked into the shop vac could result in an explosion.

I ll be careful triedaq…, I don t want to blow up. I don t have any gas smell under the hood.

now if we were talking about my 75 ford your concerns would be justified :slight_smile: