81 Bronco Engine

xouver · Oct 4, 2004

I want to know what to do with an engine that has low oil pressure when the truck is up to temp. I plan on rebuilding the 351m engine anyways, but i was just curious. I have noticed that on the oil gauge that the pressure is high when first started and cold, but then when it is warm then the gauge reads past low. and it also seems that there is a slight miss in the engine too.

4xfan78 · Oct 4, 2004

It needs to be rebuilt, the cam bearings are bad or the crank bearings thats more than likley why the oil pressure is low.

Seabronc · Oct 5, 2004

Ford sending units are notoriously lousy. Before you do anything drastic, borrow a pressure gague from a friendly mechanic, or buy one, and see what it actually is. It is possible that the sending unit is bad, could be the items mentioned by 4xfan78, could be the oil pump. Often just going up one viscosety level will take care of it. I run 10W30 in the winter and 10W40 in the summer, if I don't the pressure indication drops to zip when it gets hot and am setting in idle, with 10W40 it does not happen. Even if it needs rebuild, going up one level may keep you going for a while until you gather the parts.

Good luck,

>-

Windchaser · Oct 5, 2004

Oil Pump, & seals & bearings in bottom half of engine...at least that was the death of my 302, as it ran at 8psi when warm.

Seabronc · Oct 6, 2004

Right, sometimes a little SIMPLE

investigation can save you a whole pile of money

.

Good luck,

>-

Streetgang44 · Oct 6, 2004

Take out the stock sending unit just above and in front of the oil filter, and check the pressure with a mechanical gauge that is known good.....better if you use one that shops use, or borrow the "tool" from Auto Zone or like that.

Your stock set up is crap. Its just a glorified warning light, and will read "NORMAL" as long as it sees a min. of 6PSI. You can fix that problem by jumping out the resister an the back of the circuit board where the gauge is.....BUT, I highly recommend you buying a decent quality mechanical dash mounted gauge. The parts stores sell them with everything you will need for under $20. I mounted mine just under the ash tray area....wired its light to the ash tray light....so I can even dim it.

BTW: Your oil pressure should be 40-60 PSI @ 2000RPM.