The oil pressure gauge in my truck ('93 W150 5.2) drops to the lowest point, and the oil pressure light comes on. This only happens after the truck has been running for aprox 10 miles when i come to a complete stop. I changed the oil pressure sensor thinking that would fix it, it didn't. So i went ahead and changed the oil pump, and this too did not fix the problem. The engine does not make any abnormal noises, before or after the oil pump/sensor change. This leads me to believe i have a wiring problem. The oil pump shaft looked to be in good condition, and i made sure it was not stripped or damaged. I also made sure the oil pump was fully seated before i completed the install. I also replaced the oil pickup just to be safe, and threaded it into the pump as far as i could by hand only.

on a possibly related issue, once the truck is warm and has been driven about 10 miles and i shut it off, it is hard to start. sometimes when this happens i have to blip the throttle to get the engine to start. The engine is the Magnum 5.2, and has no trouble codes that show up.

is there a way to test the oil pressure without relying on the gauge? sorry for the long post, and help would be greatly appreciated. Also the engine looked good when i had the oil pan off, the bores felt smooth, and i saw no evidence of low oil pressure damage. I did notice some metal shavings in the bottom of the oil pan, and there seemed to be a little slop in the connecting rods, i could twist them (grabbing the bolts) about 1/32 of a inch. I don't know if this is normal or simply the way then engine is.

John

 

This is not uncommon issue with these trucks,oil pressure can drop to around 5 to 7 psi and that can cause the light to come on.

 

Mine does it when it's warm and I put it in gear. Sometimes it will die and takes about a minute of cranking to start, but always does start.

 

Go to the hardware store and get a 100 PSI gauge and screw it in where the sending unit is. This will tell you what the actual oil pressure is and you can then make a decision on what further is needed if anything.

 

so is this "normal" or just another quirk about a 17 year old truck. Is oil pressure that low something i should worry about, or just drive it till it goes bang, then rebuild?

 

I never had this happen, and I've owned 2 93's now. I'm sure glad cause something like that would have freaked me out - especially years ago when I had my first one.

I just changed the oil in mine, went from 10w30 (with some 20w50 mixed in when I needed to change it) to 10w40. Might just be the fresh oil, but I think it just likes the 10w40 better. It was getting to where when I let off the gas, it would slow down real quick like (maybe 5mph in a half mile or so), now it coasts along barely loosing any speed (maybe 2 or 3 mph per half mile).

So maybe a differant oil will do ya engine good?

 

How many miles is on it?

 

ODO reads 105,XXX right now. i am curious what is causing this, in my mind if it is not the sensor, and not the pump what could it be?

 

Worn bearings.

 

There is only 1 question at this point. What is your oil pressure? If you can't answer that you have no information at all and are only guessing at everything else.