Do you guys know if it's possible to drop the oil pan (without removing the engine) in the '87-91 2WD F-150's? I have a engine VIN code 'N' and have been running on 7 cylinders for awhile; probably have to replace the #8 piston.


Thanks,
Kyle

 

You want to drop the pan to replace a piston??? How do you plan to reseat the rings? As far as dropping the pan, I believe you'll be able to drop it enough to pull it off.

 

you say its running on 7 cylinders. what makes you think its the piston

 

I don't know it's the piston for sure, but according to AERA's Tech Bulletin 1662, Ford Truck 5.0L engines (VIN code N) made from 87-93 are predisposed to a lean mixture on #8 (due to a poorly routed PCV vaccuum line in the intake manifold).

I'm registering 0 compression on #8. I have not yet pulled the head, so maybe it's a valve. If not, it's possible that a minute hole burned through the piston. If so, I was curious if it'd be feasible to drop the pan and replace it without having to pull the whole engine. . .


-Kyle

 

There's no reason why you could not do it like you mentioned.
Pull the head and oil pan, remove rod bolts and knock the piston up out of the cylinder.

Before you tear it down, remove the rocker arms on #8 and hook up shop air through the #8 spark plug hole.
Listen for escaping air at the exhaust pipe, throttle body or oil filler tube.
This would let you know where your problem may be.
If the valves are leaking, you will hear the noise at the exhaust pipe or throttle body . Like wise at the oil filler pipe, it could be the piston or rings.

Good luck.