I have a 78 Ford E350 22' motorhome with 130K on it.
A few months ago while driving through Nebraska, the engine started backfiring out of the intake and lost oil pressure. I changed the oil pump, but that was not the cause of the problem. It now has a regular "pop" out of the intake, no oil pressure and the lifters are ticking. I pulled the oil sending unit out and started it up and the oil was coming out of the hole VERY slowly. I was told by a friend that I had spun a rod bearing, but I don't hear any bottom end knocking. What could be wrong?

 

Did you spin the oil pump drive shaft with an electric drill to see if the oil pressure guage shows oil pressure?
You may not be getting good drive to the oil pump which is letting the lifters collapse.
I used a Socket on the end of a long 1/4" extension, chucked into the Drill motor to turn the oil pump shaft.
I put a mechanical guage on the engine and the Drill motor turned the pressure right up to 40 Lbs. You wont get more than that because of the bypass valve in the oil system.
It's possible that you've spun a bearing. It might be a Cam bearing as well as a Main. If they are galled real bad, sometimes they dont knock.

 

I'm going to venture a guess at this.
One of your intake valve springs broke allowing the pushrod to fall out of place.
The cam lobe chucked the lifter out of it's bore allowing oil to flow freely out of the oil galley (relieveing the oiling system of any chance to build pressure)
Because of low oil pressure, the lifters are noisy.
The broken valve spring is not seating the valve, leaving it open enough for the piston to draw in the air/fuel mixture from the intake manifold and then blow it back out again (thus the popping)
I would pull off the valve covers and take a look.
If a looks (and feels) ok, start the motor and observe the rocker movement.
Good luck!

 

Seasons Greetings, I'm going along with 8 lugs on this one. I had a similar experiance on my 78 F250 where it had a very rythymic backfire through the carb and a loss of oil pressure but not extremely low but noticibly lower. As it turned out it was a lifter that came apart. When I took off the intake I found a broken, not bent pushrod, lifter parts laying in the lifter valley. The lifter bucket was still in the bore. That motor was high milage so thats what I attribute that to. Hope this helps!


99 explorer 4.0 sohc
89 f150 302 5spd 4x4
78 f250 460 c6 4x4 40"monster mudders

 

Thank you all for your replies.. I will pull the valve covers and have a look when I get the chance. I also had a feeling it was something valvetrain related, but I never checked into it. Hopefully I can get it running with oil pressure long enough to get it to ND so I can rebuild it.. was always a very strong engine with excellent torque..Thanks again for your suggestions

 

Hoo BOy, Ol' 8Lugs ought to get the Sixty Soggy ceegar butts for that guess. I'd be willing to bet on his answer too!