Sudden 0 oil pressure!!! 1979 Chrysler LeBaron

mopower76

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Hi all!
It’s been a long time since I’ve had an M Body and I am thrilled to have yet another… Or until about an hour ago.

I bought this 1979 Chrysler LeBaron I found on Offer Up from a guy in Tucson AZ. It was driven until 2020 daily and pretty neglected but the guy seemed to have been doing fairly regular maintenance, oil changes anyway.

It sat for the next 2+ years because of suspension issues and a leaking freeze plug.
I got it for $300 with a clear notarized title because he “lost” the keys.

What a steal! She is sunburnt and was really gross but I got it back home (Mesa 2 hours north) and went crazy with the steam cleaner!
After getting the gross off of the majority of the car I started in on my normal maintenance routine.

Changed the freeze plug and replaced the starter, plugs, wires ect.

Upon start up it was running rough so I checked compression and found somewhat low but fairly even 95-115psi per cylinder.

Bore scope prior to all and before cranking showed more carbon build-up than any I’ve seen. SeaFoam cleaned it right up and it ran really smooth!

Took it for a drive (after straightening the suspension out) and got about 4 blocks and the oil pressure went from 25-30psi at idle 45 driving to 0 and the lifters immediately started ticking and sounded like it was completely out of oil.

No Rod knocking but it definitely wasn’t getting oil to the cam/heads at all.
Checked the oil and it was at the full mark (there was oil more than halfway up the dipstick tube when I first pulled the dipstick out)

I’ve never had anything suddenly loose all oil pressure without punching a hole in the pan… I did not run it hard at all, just a leisurely test run.

Any ideas? It has a mechanical gauge mounted to the steering column that works.

It does have a rear main leak I want to fix so that’s the time to replace the oil pump with a good high volume unit but I’m wondering if anybody has experienced this themselves and what the outcome was.

I drained the oil and changed the filter and saw no indication of bearing/shavings etc.

The car has 81k actual miles and was SO quiet, I was very surprised and excited until the test drive.

Any suggestions are greatly appreciated!

Oh yeah, her name is Dirty Grandma!

Thanks I’m advance!

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Duke5A

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I'm guessing something clocked the pickup. The lifter racket confirms the gauge is working. You can pull the distributor and drive gear and use a priming rod to run the pump without rolling the motor over to see if it develops pressure, but it is probably time to drop the pan. Have you ever had the valve covers off? It's probably a sludge bomb in there.
 

Aspen500

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Possible the pump drive twisted off. Would explain the sudden pressure loss. Usually that happens if the pump locks up from dirt, sludge, etc. Worth a look.
 

mopower76

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Both Excellent reply's!!
I didn’t think of priming the pump.. Good tip!

Can you run the pump in reverse and possibly blow out where the clog is? Shot in the dark, I was hoping to drive it to work Monday.

So, a little guidance on replace the rear main seal…
I’m assuming the oil pan can’t be removed without raising the engine and any tips or a walk-through would be appreciated.

Thanks again guys!!
 

mopower76

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Hard to make it out but I used a bore scope through the oil drain hole… I believe the SeaFoam and good temperature loosened some funky sludge.

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Duke5A

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No, you can't run the pump in reverse. Besides, if it is a clogged pickup then you'll just be blowing it back into the pan for it to be sucked up again. Forget about driving it on Monday. First step is pulling the distributor and pump drive gear for inspection. Next up is priming the system and see if it registers pressure on the gauge. After this, regardless of those results is to pull the pan.

Pulling the pan with the motor in the car isn't easy, but it can be done. You'll need to disconnect the exhaust, unbolt the motor mounts from the K frame and lift it two inches. I don't know if there is enough slack in the radiator hoses to do this without disconnecting them. It's been a long time since I did this.

Clean the pan out, pull the pickup tube and clean that and check a main bearing and rod bearing or two while it's accessible.

Might as well do your rear main while it's apart. I don't know if it's possible to do that though with the transmission in place. Someone else is going to have to chime in.
 

mopower76

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I guess that’s about what I thought, it’s been a long time since I pulled a pan with the engine in the car.
I cant Get the oil pump drive gear out because of buildup on the bottom of the shaft I’m assuming and don’t have a tool that can get under and twist and the long nose Vice grips won’t hold tight enough to twist end pull. ☹️
I’ll bite the bullet and raise the engine and just put in a new pump.
Hopefully the trans can stay in place and the rear main can be changed.

I hate pulling things apart like this just to clean and not have the money to do improvements and modifications!!!

I need reliable so cleaning and maintenance is it for Dirty Grandma, and hopefully looking a little better.

I’m still hoping to bring it to the MATS Vegas show and run it in the Jalopy class in the autocross and make some extremely high quarter mile passes just for fun! it’s 5 hours both way so it’s got to be reliable and a good road car. The AC does work so that’s a plus this far… Trying to see the positives… it’s not got a spec of rust and that’s definitely a good thing!

Thanks and I’ll be relying on you all again soon!

Thanks for the great responses!!
 

mopower76

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Hey all! Sorry it’s been so long!

I did figure it out. Clogged F’ing FULL of Carbon!!

So I dove in head first… Steam cleaned the entire underside and under hood then;
I pulled the intake and valve covers, removed the exhaust, and cleaned/flushed (diesel fuel and Marvels Mystery) engine top to bottom, rotating, scraping And scrubbing anything I could get to.
I removed and replaced the oil pump with a Sealed Power High Volume Pump from RockAuto, new pan gasket and reinstalled everything.

The engine would barely turn on a breaker bar trying to get it to TDC and reinstalling the distributor… WTF???

Decided to drop the pan again.

Pulled brand new Sealed Power HV pump off (yes, I bench primed the pump and it was pretty tight when turning ) , walked to bench put it in the Vice and tried to turn it, locked up!!!

I pulled the top plate off the pump and it had a bunch of little dimples on the face of the cap. Put it back together and it would spin about a half turn and stop!
(Engine rotated easily with pump removed)
That was a frustrated last Sunday… nobody local had even a standard pump so I ordered a new Melling HV oil pump through Autozone online and with the instant $10 off and free delivery it cost $61 to my dooor!!!

Worth the wait as it got here today finally!

So lesson learned, buy a good oil pump… Especially when it’s inside the F’ing Pan!!!

I’m my defense, I have always bought Melling pumps, never had a bad one but I’m on a thin budget with Lebron so I tried this super cheap Sealed Power pump-
On another forum a few people stated that Sealed Power oil pumps are made by Melling… Don’t believe the Hype!!!

Well, at least it’s all clean underneath and the new hood HV pump will be in place Saturday morning if all goes as planned!

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Duke5A

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I hope none of the other passages in the block aren't clogged. Did you check any of the bearings while it was apart? And I really hope you didn't install that HV pump yet. Those things are supposed to be used with higher capacity pans. You could end up emptying the pan faster than it can refill. Nothing wrong with a standard pump on an otherwise stock motor.
 

6PKRTSE

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I had an oil pump drive shaft shear off on a 318 that lost all oil pressure. Luckily, I was just down my street coming home when it happened. Started to hear some valvetrain clatter by the time I got it in the back yard. I was able to get it out from the top thru the distributor hole with an extendable magnet to get the gear out first, then went back in after the driver shaft. Put another one in and all was good after that.
 

mopower76

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Well, a little late on the HV pump…. It’s now installed.
I ran the engine with a mix of oil, trans fluid and seafoam after installing the new pump and another pan gasket kit.
0 oil pressure and drivetrain clatter for a few...then some oil pressure… 10-15 psi and suddenly fluctuated to 25+ and went to 0 and valve train clatter again.

I shut it off and checked the oil, full so started it again, chattering and back to 10 psi but not knocking and pressure dropping to 0 then to 20 back to 0.

I decided I’m driving it to see if it changes. Almost immediately it came up to 30lbs and got quiet!!
So I ran 2 miles to the gas station to fill it up, knowing not to turn it off (just in case) right as the pump clicked off valve train clatter.
I jumped in to see Lebron once again dropped all oil pressure, I took the chance and drove it home sitting at 3 stoplights just hoping it makes it back and sounding Terrible!!
It made it home, got in the garage and shut it off… temp was good, tried to restart and it wouldn’t fire.
Let it sit for a few hours and again just cranked… Slowly. (original starter)
I put the battery charger on boost and cranked better but still nothing. On a chance I bumped the timing a little advance and it fired up and almost instantly shut off like I turned the key off and there was smoke on the drivers side inner fender! Shut off and removed the negative cable. One of the fusible links burned, one that feeds to the bulkhead and when gone no crank.
I replaced the fusible link with new fusible link wire (not sure amp rating, 20?) tried to restart and crank no start again.
This morning I pulled the valve covers off, pulled the oil filter and rocker arms. I blasted seafoam and lacquer thinner through the oil passages the no blew them out with 165 psi from the compressor repeatedly until I could hear air blowing into the oil pan. Replaced the rocker arms and shafts I had new that were on a set of heads I ran roller rockers on.
I then drained the cocktail from the oil pan and added fresh oil and filter, straight 30w Rotella and some Lucas Oil additive.

It started! It had 35psi of oil pressure!! It was Silent!!! It really sounded great and ran smooth!!
And… it shut off again like I turned the key off. This time no smoke but would not restart.
Checked for spark, nothing.

Checked for 12v everywhere, tested coil, ballast, ECM… Changed all… Nothing.

I ran a separate plug and wire to check again and noticed when I turn the key from crank back to off there would be a very weak spark… WTF…

Any ideas?!?
Obviously something has happened in the wiring when the FL burned.
I’ve checked most of the grounds I thought could be related but all are good.
It seems like something has grounded out.
Could the ignition switch have something to do with this??

Oh man do I need a wiring diagram!!!

I really needed and wanted to drive Lebron tomorrow to work.

They are never easy when they have been neglected and abused but this is really frustrating.

As always, thanks so much for the responses.
 
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