Mechanics

OIL PRESSURE

Ford F-250

1979 ford F-250 400 cid. With 91k. Low oil pressure after installing a new pump and timming chain. Also I can't turn the dist. To adjust the timming.
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Bmelton
January 21, 2007.



A little background: why did you replace the oil pump? Did you replace it with a high volume one? What does the oil pressure currently read? At cold idle and cruise it should be around the 40's, or " in the lower middle" of the gauge. During warm cruise it should be a bit lower, and during warm idle it should be a lower end of the gauge, or in the high teens to mid 20's.

Did you take out the distributor at anytime?

Tiny
Indyuke
Jan 21, 2007.
Lifters were making noise oil pressure was low around 20 at cold idle and even lower after it warmed up. And after new pump the pressure is the same. I wanted to adjust the timming and found that the dist. Was stuck. I did not remove it.

Tiny
Bmelton
Jan 21, 2007.
What type of oil are you using? Sometimes using an oil of the wrong viscosity will cause abnormal oil pressures. Assuming the new oil pump and oil type are correct, my next guess would be severly worn internal engine components. Do the lifters still make noise?

The reason I ask if you removed the dist, is because it is what drives the oil pump. If the dist was somehow comprimised, then it could give the oil pump trouble.

Tiny
Indyuke
Jan 23, 2007.
I'm using 10w40 oil. I did find that the timming chain jumped 180 deg. But the truck still ran. Would that somehow cause the oil pressure to drop like that?
Do I need to look at the rod and main bearings?
If the crank got damaged, is a shorter stroke going to give me more HP? Should I buy over or under size bearings?

Tiny
Bmelton
Jan 23, 2007.
Were you able to examine the bottom end of the engine when you had it apart to change the oil pump? Another thing that comes to mind is possibly a low quality oil filter.

I don't think I've heard of a timing chain jumping 180 deg. That's unique.

As far as the crank, you shouldn't need bearings of a different size than standard, unless you spun a bearing or otherwise had one fail on you in which case you would probably need to turn the crank to take out the scratches, and then get the proper size bearings for it. I'm not sure if a shorter stroke will give you more HP. The engine will rev quicker, but your piston displacement will be less.

Tiny
Indyuke
Jan 23, 2007.