oil pan and pressure

i have a 93 b3000 ,3 lire, 2 wheel driveAUTOMATIC that has the oil pan rusted out and a strange pressure problem. first when the engine is fully waRMED UP IF YOU GIVE IT A SHOT OF GAS IN PARK.AS THE REVS SETTLE DOWN THE OIL GUAGE WILL FLUTTER ONCE AND THEN RETURN TO NORMAL,ALMOST AS IF FOR A MOMENT IT IS STARVING FOR OIL.I SHOULD MENTION THAT IT WILL DO THIS OFTEN WHEN COMING TO A STOP,BUT ONLY ONCE THEN O.K. THERE ARE NO STRANGE NOISES AND IT RUNS GOOD.AS FOR THE PAN CAN IT BE DONE IN THE TRUCK OR WILL THE ENGINE HAVE TO BE PULLED.IT LOOKS LIKE A BEAST TO DO HOW MANY BELL HOUSING TO ENGIE BOLTS ARE THERE AS I CAN ONLY SEE 4 ANY HELP IS APPRECIATED

I dont recall ever having to pull an engine on a rear wheel drive vehicle to drop the oil pan. U may have to drop the front brace, but the pan itself has about a zillion small bolts that can be removed and the pan can then be gently pried away from the engine block and changed. I also never recall seeing a n oil pan rusted out. Did the vehicle get submerged in H20 or something?The pressure fluctuation can be any number of things, but I would first try this: Obtain a can of Seafoam cleaner, change the oil and pour a 1/2 can of the Seafoam in.Run the truck about 500 miles and change the oil again and put 1/4 can of the Seafoam in and leave it until time for normal maintenance. It may solve ur problem BJ

i have tried everything but it appears as though the lip for the back seal extends past the spacer plate and the pan will not go far enough ahead to clear it, i am in the midst of pulling the engine and am going thtrough hell trying to r4emove the top 2 bellhousing bolts. any ideas thanks sam

Probably easier to disconnect tranny linkage,disconnect front u-joint and pull tranny and engine as a unit.BJ

Bump. OR-Loosen motor mounts and tranny mounts, lift engine a smidge and see if pan will not clear spacer plater that way. BJ

finally gave up and pulled the motor but before i put it back in am going to replace the pump as i still see nothing to cause the oil pressure as there was absolutely no sludge.any ideas on the pressure problem sam

I have had oil pressure drops related to worn bearings. Just an old engine thing.
I would try changing your oil to 10w40. I have heard of that fixing some others Mazda pressure issues.

Other thing is depending on age and miles on the engine,ur oil presure sending switch may be bad.BJ