Intermittent oil-pressure loss, 98 Dakota

[BrokenPaw]

My Dakota has started just suddenly losing oil pressure.

It'll run fine for days or weeks, and then suddenly oil pressure will drop to "none".  Sometimes the dropout will self-correct in two or three seconds, but sometimes not.  When it does not, stopping the engine and restarting it always fixes the problem, and it'll run fine for a while again.

The symptoms make me believe it's not a faulty oil pump, because I wouldn't expect the all-or-nothing behaviour (more like "nothing or nothing", if the pump was bad).  There's plenty of oil in it, and it was changed fairly recently, and no leaks.

My gut feeling is that there's some debris in the oil pan that's occasionally blocking the pump's intake.  Stop the engine, oil pump stops, debris falls away, everything's fine again.

So two questions:

1) Does that sound like a reasonable diagnosis, and
2) Is there a way to correct it without dropping the oil pan? 

-BP

[mtnbkr]

Have you checked the sensor and/or gauge?

If you can get to the sensor fitting, put a "T" in it and connect a cheap mechanical gauge, run the line to your dash and mount the gauge where you can't miss it.  If the pressure drops on the mechanical in sync with the factory gauge, the problem is inside the engine.  Otherwise, it's a sensor problem.

A mechanical gauge from Autozone should be less than $30.

Chris

[mfree]

Are you watching an electrical or a mechanical gauge?

[BrokenPaw]

It's an electrical gauge, but I trust it, because of a detail I forgot to mention in the original post:

When the pressure drops, I can hear a "ticking" sound coming from the valve covers, that goes away when the pressure comes back up.  Which makes me believe that pressure is actually dropping, rather than me just getting a faulty read.

-BP

[mtnbkr]

Wouldn't the junk be flushed out with the oil change though?

Chris

[CNYCacher]

Does it happen when you hit the brakes?

[mfree]

It's probably sludge. Only way to be sure is to nuke it from orb.... uh.... drop the pan and look.

[mtnbkr]

Good point mfree.  IIRC, Dodge trucks from that era were prone to sludging.  A friend of mine lost an otherwise nice Durango to sludging.  Engine seized up...

Chris

[BrokenPaw]

Does it happen when you hit the brakes?

I haven't noticed that correlation, so I can't say that it doesn't happen more often when I hit the brakes.  I do know that it happens at some times when the brakes are not applied.

Ok, well, if mfree's right...how much of a hassle is it to drop the pan (and, more importantly, to get the pan back on right)?  Will ramps give me sufficient clearance?  It's the 4x4 model, so it rides reasonably high already.

This has been a really great truck, so I'd hate to lose it to sludge.  Sounds like I have a fun weekend project upcoming.

-BP

[French G.]

I agree with your debris assessment. Engine flushing with some kerosene or diesel mixed in the oil may cure it. Or it may loosen up a whole lot more stuff.   :rolleyes:By the time I had de-carboned my '91 F-150 that someone else had Slick 50'd and Quaker Stated I had done the following.

Multiple idle runs on engine flush, diesel, paint thinner, B-12 chemtool and anything else I had handy that seemed like a solvent. Run 5 minutes, drain, tons of black crap comes out, repeat.

Drag truck on rollback 70 miles to a proper work area, drop the pan, pressure wash from underneath and also down through the valve cover(not removed) with the strongest caustic soap we had. Rivers of black crap ran. Cleaned about 1/2 inch from around the mains with a putty knife.

Checked the bearings, replaced the oil pump with a high performance one, cut the shroud off the pump pick-up so crap would fall away from the screen, and brazed a sump onto the bottom of the pan to allow inspection of the screen and a place for crud to fall away from it.

After that it was back to the diesel/oil flush a couple of times, a couple of 10 mile interval oil changes, then 50, then 300, finally back to 3,000 with Rotella T. 35,000 miles later it is still a happy camper.

[Brad Johnson]

You can check for sludge by draining your oil, then scraping around the bottom of the pan through the drain hole with a bent coathanger.  The sludge will gunk up on the coathanger.

You can pretty effectively de-sludge an engine just by switching to a good synthetic.  The group IV stuff is okay (Penz Platinum, Mobil 1) but the best is a group V.  The only one I know that's somewhat readily available is RedLine, though you may have to order it online.

One other trick is to change the oil but substitute in a quart of ATF.  Change your filter every few hundred miles after doing this though.  It'll break loose a whole bunch of stuff.

Brad

[mtnbkr]

The only one I know that's somewhat readily available is RedLine, though you may have to order it online.

BP, if you want Redline, there's a dealer in Manassas.  I don't recall the name, but I can give you rough directions (near the bowling alley IIRC).

Chris

[BrokenPaw]

BP, if you want Redline, there's a dealer in Manassas.  I don't recall the name, but I can give you rough directions (near the bowling alley IIRC).

Ok, thanks.  I'm going to drain the oil out of it and use Brad's coathanger trick to check the pan for sludge.  If I don't find sludge, then I'll probably drop the pan and look for some sort of debris.  If I do find sludge, well, several folks have offered various ideas for correcting it (thanks, all!).  If I decide to go with Redline, I'll ping you.

I sort of feel like I should turn in my Man Card for admitting this in a public place, but:  I actually don't know a whole lot about cars, so I can't tell which of the offered solutions is the best/safest/most effective/what-have-you.

Won't running something like kerosene or ATF in with the oil jack up the viscosity enough to damage the engine?

-BP

[Brad Johnson]

Kerosene will, definitely.  It's relatively "dry", providing no lubricity at all.  It functions solely as a solvent.  ATF is already an oil so it won't hurt to do it short-term.

Brad

[Tuco]

On a 4x4, it may be harder to get at the oilpan if it's a solid axle.  Independent Front Suspension (CV Joints) will be much easier access.  The only way to find out is get underneath and look.  The hardest part, in my experience, is lining it up and putting it back on, without buggering up the gasket.  Sure, you might be able to get all the bolts out, smack it loose with a rubber mallet and wiggle it out, but without the clearance, putting it back in may be difficult.

Sometimes all it takes is dropping a tie rod end and swinging the drag link out of the way.  Also, jacking up the frame, letting the wheels and axle hang may open things up.  USE JACKSTANDS.

Loosen each sump bolt no more than 1/4 turn at a time, in a criss-cross pattern, working back and forth - front to back around the pan, avoiding bending or warping the mating surface.  Same with tightening upon reinstallation.
While it's out, look for the pickup tube (the suck end of the oil pump).  It should have a screen in it.  Clean it out.  Take it off and clean it if you can.

Permatex "Right Stuff" is a good gasket maker.  Don't mess with cork.  OEM gasket from the dealer or a quality parts house (NAPA) may be cheaper than a tube of Right Stuff @ 20 bones.

And, as Brad says, ATF won't hurt the motor, although it's probably too late for that to fix anything.  ATF is a good preventative cleaner.  The kerosene, diesel flush, etc... are not made to be driven.  Put it in a warm motor and let it idle (per directions on can).

If you have a dirty motor, Rotella oil in a proper viscosity is the bomb, and cheap.  But, again, this is for after the clean up.

If this is overwhelming, just do a bunch of oil changes in rapid succession, every couple hundred miles or so, using the flushes as directed.  Change the filter, too. After a thousand miles, you'll wish you just dropped the pan.

Good Luck

[Parker Dean]

Ok, thanks.  I'm going to drain the oil out of it and use Brad's coathanger trick to check the pan for sludge.  If I don't find sludge, then I'll probably drop the pan and look for some sort of debris.  If I do find sludge, well, several folks have offered various ideas for correcting it (thanks, all!).  If I decide to go with Redline, I'll ping you.

I sort of feel like I should turn in my Man Card for admitting this in a public place, but:  I actually don't know a whole lot about cars, so I can't tell which of the offered solutions is the best/safest/most effective/what-have-you.

Won't running something like kerosene or ATF in with the oil jack up the viscosity enough to damage the engine?

-BP

The thing about Dodge Magnum engines is that they form small bits of hard carbon that falls down into the oil pan and then gets packed into the oil pickup by the suction of the oil pump. I have seen several that had heavy varnish, but no appreciable soft sludge buildup, have almost completely blocked pickups. I suspect the carbon forms around the ring pack and enters the oiling system that way.

I'd strongly suggest verifying that the oil pressure is indeed dropping off with a mechanical gauge (just buy one of those cheap things from the local parts store, absolute accuracy is not required for this job) and if it is dropping off then drop the pan. Plan on replacing the pickup if you do because Ma Mopar decided to cover the bottom of the pickup almost completely, perhaps as baffling, and trying to get that crap out of there would be an exercise in frustration.

[French G.]

Definitely do not drive with kerosene or diesel flush in. No revs, no load. Idle 10 minutes and drain. Change filter, repeat.

[mfree]

varnish, carbon... hrmm. Isn't that "Zmax" stuff supposed to be excellent at dissolving carbon?

EDIT: heh, odd situation I'm in, almost opposite. My little Sonoma is coming up on 100K and it's always had a little tic that I think is a partialy collapsed lifter (minor enough that I've never bothered to track it down). But I started thinking about 20K miles ago that i wanted to give it a dose of a flushing agent... ATF, MMO, whatever, before an oil change.

Trouble is, that motor is supposed to be sensitive to overfill, and every place I've taken it to (my driveway is far too steep to get under the truck safely) has been anal about filling it to max hot... and the thing's never lost a drop of oil, ever.

Ah well, runs like a top anyways, figure I don't need it. Should focus on the bad steering box and blown shocks first, I suppose....

[richyoung]

When the pressure drops, I can hear a "ticking" sound coming from the valve covers, that goes away when the pressure comes back up.  Which makes me believe that pressure is actually dropping, rather than me just getting a faulty read.

The ticking noise is your hydraulic lifters turnin ginto NON-hydraulic lifters because there is no oil pressure in them to keep them expanded and taking up the slack in your valve train.  Your oil pressure IS actually dropping - I suspect something wonly with the oil pump pickup - either loose, or intermittently clogged with something.

[BrokenPaw]

The ticking noise is your hydraulic lifters turnin ginto NON-hydraulic lifters because there is no oil pressure in them to keep them expanded and taking up the slack in your valve train.  Your oil pressure IS actually dropping - I suspect something wonly with the oil pump pickup - either loose, or intermittently clogged with something.

Yeah, that's more or less what convinced me that it was actual pressure loss, and not just a gauge failure.  Though I didn't know about the hydraulic lifters; my engine-fu is weak.

-BP

[charby]

varnish, carbon... hrmm. Isn't that "Zmax" stuff supposed to be excellent at dissolving carbon?

EDIT: heh, odd situation I'm in, almost opposite. My little Sonoma is coming up on 100K and it's always had a little tic that I think is a partialy collapsed lifter (minor enough that I've never bothered to track it down). But I started thinking about 20K miles ago that i wanted to give it a dose of a flushing agent... ATF, MMO, whatever, before an oil change.

4.3 Liter? That tic might go away if you use a oil filter with a anti drainback valve.

[Parker Dean]

varnish, carbon... hrmm. Isn't that "Zmax" stuff supposed to be excellent at dissolving carbon?

There's different kinds of carbon of course. The stuff in the oil isn't like the stuff in the combustion chambers and on piston crowns, it's much harder. Almost as hard as glass and it'll do a real number on bearings. It's not given to being dissolved by solvents on any kind of short-term basis, and those solvents can actually make a borderline situation worse by freeing hard carbon that's adhered to sludge and varnish as it removes those items.

And I didn't see the part about the ticking lifters. I concur with richyoung, it's a clogged pickup.

[mfree]

I should have clarified, I was intending to keep the problem from re-occurring rather than unclogging the ports with an additive.

Change the pump, switch to true synthetics that don't coke or varnish (as badly), change the oil often for a while since additional crap will likely come loose.

My first wholly-owned car was an '84 Tbird 3.8 that had maybe 3 oil changes in 85,000 miles. It ran well enough, but was so ungodly slow... eventually got around to troubleshooting and running with the valve covers off noticed that the lifters for #3 weren't moving, the intake for #6 was just wiggling a little, and the exhaust for #5 had about half it's travel. The cam had gotten oil-starved and rubbed itself flat. There were indentations on the coke built up in the covers where the lifters moved. A new cam brought back a LOT of power and economy, but 20K later the oil pump pressure regulator stuck and blew up a few oil filters in a row, and 25K after that it lunched a rod bearing and got treated to a rebuilt motor.

Coked motors are no fun, you don't know where the next problem will crop up.