Oil pressure mystery!!

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Randy Smith

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I bought a 97 Dodge Ram 1500 off Facebook marketplace. It has the same 5.2 318 engine as my previous truck (95 Dakota) with half the miles. Got it home and the oil light came on and the pressure gauge dropped to 0. I changed the oil sending unit. No change. Ended up taking it to a shop (never done that before) and they diagnosed the issue as a failed pump. They also said there was a lot of sludge in the pan and the pick up screen was clogged, and it likely would need to be cleaned out again. After spending $900 on parts and labor (new oil pump, pick up tube, oil pan and gasket) I picked up the truck and within 20 minutes the light came on and the pressure was dropping again. So back to the shop it went, where I spent another $300 on getting it all cleaned out a second time. All seemed well for about a week, and then the same issue happened AGAIN! Being all out of money, I went the route of YouTube university to teach myself how to do the repair. Dropped the pan and pick up screen, cleaned it all out as thoroughly as possible, fresh oil filter. I’m no mechanic so I was feeling pretty good about things when I filled her up with fresh oil and nothing leaked out. I felt even better when I let the truck run in the driveway for about 20 minutes to build up pressure and get to operating temperature. Gauge looked good! No oil lights on! Time for a test drive!! I got to the bottom of the driveway and the pressure started drop and by the time I got to the corner the light was back on!! ‍♂️ Feeling defeated, I parked the truck in the street and called it a night.

So my question is, anyone have knowledge on how I can actually fix this problem? I’m hesitant to use any engine flush methods as I’ve been warned by many mechanics that using those can cause more harm than good.

Keep in mind, I’m no mechanic by any means so if you comment on this, I’ll probably be asking some very obvious sounding questions haha!
 
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Randy Smith

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Update: I pulled the valve covers and cleaned them out as good as I could. Couple photos from that experience as well as a photo of the oil pan the second time the shop cleaned it out. And a photo of about half of the gunk that came out of the pick up screen. 1FF0EBBB-8A5F-4AD0-B34F-CD41A96690B8.png 1FF0EBBB-8A5F-4AD0-B34F-CD41A96690B8.png 92BF5CA8-EA04-4A15-8C4B-15F123639AE2.jpeg

EF0CFC7E-9A4A-4E76-BB8C-55C94211EEF1.jpeg

E5F696FF-D28F-4DC7-A342-234CF64BA7C1.jpeg
 

Sirriggs

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Now this is my thinking but others here might have a better idea. I would scrub and clean everything then maybe see if there is a way you can run something down the holes where the oil travels if possible to clean out and allow oil movement. I'm sure you could maybe use a little marvin mystery to help clean them and lubricate as well then maybe do a couple of oil changes till hopefully get your oil pressure back and steady. I'm a simple back yard do it yourself so see what others think. Good luck. I myself and trying to get my wife trucj back on the road as well its a 1999 with the 318\5.2L. pretty much same motor as yours.
 

Treburkulosis

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That is a lot of sludge. I watched my dad put kerosene in gunked up motors over the years.

 

Treburkulosis

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You could also try seafoam. I had a slight Hemi tick with my 5.7 and I ran seafoam through it and then switched to my Castrol Edge and puralator boss filter. No noise and no sludge that I can tell.
 

Spike95

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Somebody must’ve really not cared for that engine. Sadly, some people are completely ignorant of the most basic services an engine needs...
I know you’ve had mechanics recommend against flushes, and an engine that’s been well cared for with quality oil shouldn’t really need them, but in this case it’s already so bad that I think cleaning it out is priority. I’d buy enough cheap oil and filters to do several oil changes back to back. Add some marvel mystery oil and let the engine idle until it is good and warm, then immediately drain it. It would be a good idea to catch some of the oil in a clear container to get a good look at it (get the sample when you first start draining it). Open up the oil pan again and see if there’s anything nasty in it or the pickup screen. Clean anything you find. So long as you’ve gotten a good gasket for the oil pan, you’re probably ok without replacing it. You might need to repeat this whole process a couple times. If this gets it to run reliably, I would still do a couple more really short oil change intervals after that (under 1000 miles).
 

B250

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Just my thought - once the oil light comes on does it stay on when you start the engine the next day? If the cycle repeats after letting the engine cool down it suggests something is suddenly releasing the pressure in the oil galleries. There is a PRV on the oil pump, but if you have a new pump it shouldn't be that.

If the oil light stays on the next day when starting it up then there is a blockage somewhere. The crud in the oil galleries is like cholesterol in your arteries - it would increase the oil pressure as the pathways are narrowed. Then when you dislodge the crud through cleaning the engine a piece could block an oil way somewhere.

I don't have a diagram of the oil distribution system on this engine, but it's possible that the sensor keeps clogging and giving a false reading while the oil is still getting through to the engine components. On my B250 the sensor is on top of the engine rather than near the oil pump output gallery on other cars.
If you ran the engine for even a few miles with no oil circulating you would know about it from the bearings!

I don't know whether a mechanic would be able to connect to the oil gallery after the pump with a gauge to check the actual pressure coming out, but it depends on whether Chrysler put a test point on the engine like they did with the transmission.

It's also possible that it is an electrical problem in the sensor circuit although this seems unlikely from what you described

I've used the kero trick a few times - and even ran some gasoline through the engine for 10-20 seconds back in the eighties as a desperate attempt to clean it out

The photo of the sump pan worries me somewhat as the tan colored sludge in the bottom indicates coolant is getting into the oil, which means a head gasket has failed. On a OHV engine it's easy to change; not so easy on a OHC engine.

I hate to be the bearer of more bad news but my experience with engines that have been poorly maintained oil-wise will fail in the near future. Either the bearings will burn out or it will seize completely

Maybe the previous owner knew something was wrong with the engine and that is why he sold it using Facebook?
 

Daw14

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A flush will not do any more damage then not having oil pressure. No oil pressure will surely kill that engine, flushing it may kill it ,or possibly give it a new lease on life. It can not hurt more then no oil pressure .
 

Dean2

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There are only two choices with an engine that heavily sludged. Get aggressive with flushing it out or trade it off. Whether you use Kerosense or commercial flush agents makes no difference but if you don't get most of the sludge out the engine will fail soon.
 

Spike95

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When you have the engine idling and the pressure looks good, you ought to try wiggling the harness around that attaches to the oil pressure sensor. See if the issue suddenly returns. The fact that your pressure goes straight to zero does sound like a possible issue in the sensor circuit. It could be something as simple as a loose female terminal in a harness plug going to it.
 

MAC830203

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Pulling that engine is simple. But there are some remedies that can help. #1 buy about 10 oil filers. #2 get some Kero and mix with 30 weight oil 3:1 kero to oil. Pour half (3 qts) in each side of valve covers in 6 qt batches. Disconnect electrical wires to coil. Not the ignition wire to the cap. #3, make sure you have a fully charged battery. #4 turn over engine a whole bunch. Drain that junk. Fill with 6 qts and get an oil filter. plug in coil wires. Start engine. DO NOT REV ENGINE! When thermostat opens, idle 5 min. Turn off. Wait 5 min, drain and swap filter. Do this a few times. When you think you have most of the mud and chunks out, drop the pan, check pick up tube, clean pan and pick up tube screen. Reassemble, replace oil filter. Add 5 qts w30 oil. Start, and observe oil pressure. 30# or more, run engine at 2000 rpm, 5 min. STop engine, Now this gets messy. Remove oil pressure sender, and remove coil wire connector…again. If you have a fitting and tube, put in open port Before cranking engine. Crank engine one time. Do oil change and add 20/50 oil. Replace with new oil send unit. Run engine and take for a drive. Theres carbon chunks in that engine. Very hard to remove. You can do this over a weekend. It doesn’t have to be done at one time. If that doesn’t work, rebuild and use flat top pistons. Good luck.
 

smtty401

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Check out TSB 08-22-99, see if that describes your issue.
I have the same issue, I think. The TSB calls for the PCM to be reprogrammed, but I can't find a dealer equipped to perform it so far.
Even though the oil pressure reads zero and the light and bells come on, I still have pressure.
 

Skatulaki

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Your First mistake was paying the shop you took it to $900 dollars and the repair/service work failed. You should have outlined a test time to insure repair was satisfactory! ( Warranty ) You should have gone back, which apparently you did. Your second mistake was paying them $300 more, with no better result. After the first $900 you paid, you should have kept taking it back, until they got it right. If that indeed required more money then so be it, most places will work with you.
 
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Because you bought the truck used, it’s hard telling what the last owner did or did not do.
That being said, all these ideas are great from other forum members.
One thing that I did not see mentioned, I’d replace or clean the PCV (positive crankcase ventilation) valve. A clogged valve will cause sludge.
Got tell you, looking at your photos of the valve covers, they were rough.
After all is fixed and your truck is running good, I recommend a good detergent oil like Pennzoil platinum, or something similar that has a very high detergent in it.
Please keep us posted on your progress.
 

MikeysCars

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I've had 2 or 3 engines gunked up like that through the years. I would drop the oil and filter and put in a new filter and 3 quarts of oil and 2 quarts of diesel and run it a while then drain and repeat. You may do 2 quarts oil and 3 quarts diesel first then swap around. May take 3 or 4 times but it'll clean it out.
 

LouM

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Well this thread started in June so the OP has gotten the engine cleaned out or has replaced it by this time.
For what it's worth I have cleaned engines out with a blend of diesel and oil. I would not recommend it.
With the valve covers and oil pan offf that engine I be tempted to pressure wash it to get out every thing possible
and then get it buttoned up and oiled and run soon to prevent rusting. Usually when an engine gets that cruded
up the rings and bearings are shot.
 

Dean2

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Would be nice after all this help if the OP provided an update of what actually happened.
 

Dodge trucker

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One word for that engine NEGLECT.
I've only ever seen 1 318 that bad and I've been into plenty.
My parents bought (different brand I know) an olds wagon one time that was that bad when they got it. Started knocking, we pulled the valve covers and that engine was so sludged up that at least a quart of oil dumped out of each valve cover that was stuck in the head and couldn't drain back
We pulled the heads and sent them to the machine shop for a valve job and a trip thru the hot tank, pulled the pan and ran several gallons of kerosene thru there with the pan off, as well as cleaned the pan and pick up before we put the pan back on and the fresh heads back on. After all this that wound up being a great car for them for many years.
 
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