Sudden Drop in Oil Pressure

[holeshot]

Well, I think the $500 BII project needs a heart transplant.

This BII has been sitting for a few years and I got it running after draining the gas and putting some fresh gas and some octane boost in it. The guy I bought it from told me the tranny went out, which is why he parked it. So while doing some troubleshooting, I found out that the tranny is fine...the rear driveshaft was broken and just spinning inside the CV joint at the rear end. No big deal. I swapped driveshafts from my 86 and was eager to see if this thing was road worthy, but now I wished I didnt. My biggest mistake is that I didnt change the oil before driving it. I knew I shouldve, but I checked it and it was full and just looked a little dirty, so I thought a trip up and down the road wouldnt hurt it.

I was surpised...it ran great, shifted fine...I was thinking SUCCESS!!! Then when I got back from about a 2 mile journey I noticed the oil pressure gauge suddenly dropped below L at idle. At first I thought it was a faulty sending unit or something...but when I reved the engine a bit, I could hear what might be that dreaded knocking sound that we all fear.

I immediately shut her down. I will try to change the oil today and see if the damage is already done. Who knows...the motor couldve been on its last leg anyway....for $500, you never know what you are gonna get.

Anyone ever have issues with this? Maybe the oil pump screen is clogged?

 

[klogtruck]

put an after market oil gauge in it you'll get a better reading of what it really is.

 

[richard89]

Check the gasket between the oil pump and the block. Need to drop the pan. This happend to me after letting the truck sit. The gasket dried out and when the oil heated up it leaked so bad the oil press dropped to 0

 

[Mosinman76254]

I've got an 89 B II and when it idles the oil pressure gauge reads close to zero as well. As soon as you take it off idle like around a grand it goes right back up. Mine has a low pressure safety switch so it even ends up shutting the motor off. Anyways the trouble was the oil pump pick up tube and screen. It looked to be blocked but obviously some was getting through. I threw both in the parts washer and cleaned them out really well, reinstalled and now it's got normal oil pressure. Also I agree klogtruck and highly recommend an aftermarket oil pressure gauge too.

 

[holeshot]

No such luck this time. The motor is done. I attempted to change the oil (if you want to call it oil)...it was more like a syrup. As soon as I pulled the drain plug, about a quart came out....the rest just sort of oozed out. I have never seen sludge this bad in my life. I dont think the previous owner ever changed the oil in this thing. It was also very disheartening when I noticed the used oil catcher lid looked like I was panning for gold. I am not sure there is much left to the bearings in this poor engine. I let the sludge ooze out for about an hour and I slapped on a cheap filter and some cheap 10W 40 to see what would happen. I fired it up and it ran great and held pressure, but once the oil got to temperature she started knockin and the pressure went to nothing.

That poor motor has seen its last days. I will make it go out with a bang before I swap engines or decide to maybe go the 4.0 route.

 

[AllanD]

Just because the oil turned into Bosco all might not be lost...

Try adding a quart of Marvel mystery oil to it and idling it for half an
hour and changing the oil again...

I've "Rescued" more than a few "sludged" engines.

MArvel Mystery oil isn't my only trick...

the Motorcraft "Decarbon" liquid the stuff, you pour into the intake
that does a number on oil pan crap too but I'd try using MMO first.

AD

 

[MountainMike]

Were there any bits of metal in the oil? If not top it up with some cheaper stuff + MMO and follow what Allan said. You might do OK. And maybe pull the pan and take a look at the bottom end and gaskets. A couple hours work and maybe $100 isn't too bad.

*edit* never mind i see the gold panning reference. Still maybe you could just do the bearings.

 

[red93terror]

Yea if you go through with dropping the pan to check the pump, screen and gasket, I would do the bearings. Why not? theyre cheap and its good preventative maintenance. I mean well, preventing major damage to the crank. obviously the bearings are toast, but check the crank with a micrometer against the references in the fsm, and if its within the tolerances, slap the bearings in, address the pressure issue, and go another 300k miles.

 

[holeshot]

I will try some MMO, but its probably a safe assumption that with the amount of metal shavings i saw...the 2.9 may not be salvageable. shes knocking pretty hard under load. I like the idea of while having the pan off to replace the bearings, but for me it might be easier to just swap the engine from my 86.

thanks again for the advice guys!

 

[AllanD]

If you've got metal shavings save the MMO for something else.

And don't bother putting bottom bearings in a 2.9... when a 2.9 frags
is wrecks the cam bearings and it'll just burn up another set of mains.

AD

 

[Mosinman76254]

I agree with AD. Give it a proper burial!

 

[Mosinman76254]

So what do all of you guys think happen to this motor. Besides lack of maintenance.
I would say it was overheated badly for the oil to become thick like that. What else do you guys think could've happened? Even tho the motor is junk it may make for a good informational piece!