Ok. I have been volunteered to be the mechanic for my brothers
1995 F150 w/5.0 liter. Here's the problem. The truck has 278,600 miles on it(no bull). Just in the last couple of weeks the truck has had a cooling problem. I flushed the radiator, changed the thermostat and filled with 50/50 anti-freeze water combination. This solved the problem for week or two. Yesterday driving down the interstate his oil pressure dropped. It usually ran at 35-40lbs. It dropped down around 7-10lbs. He got the truck to a relatives that lived close by. Upon inspection we found that the truck had NO OIL and was ready to blow the radiator top off. After letting the truck cool, we added oil and started the truck up to see if oil pressure would come back up. The engine sounded like spoons were playing in the heads. So we drained the oil only to find around 10 quarts in are drain pan. After adding new oil and driving the truck the problem seemed gone. After a few minutes that spoon sound came back. Checked the oil, no oil. This time we checked to see for a giant leak for oil in the cooling system. No luck. pulled the drain plug and here comes the oil. Could this be the oil pump is bad and the oil is falling in the sump that's why there is no oil reading on the dipstick? Or...could the engine be possessed by a chevy demon? Any help would be appreciate.

 

Sounds like the pump is pumping the oil into the motor faster than it can drain back. Could the motor be so filled up with sludge that the oil is staying in the top end and not draining back fast enough? Never actually saw this but what else could it be?
Mark

 

Bad oil runners, etc not letting the oil drain back down. This can cause the engine to overheat if the oil isn't cycling like it is supposed to. I would think that a 95 has internal oil cooler in the radiator. This may be a culprit to all of the problems.

Just an idea.

 

When you pull the oil pan drain plug - oil comes out - or you have to wait for the block to drain?


What I've been doing is running is a quart of Marvel Mystery Oil through every now and then to break down carbon deposits - it seems to work. I've heard of people using ATF and kerosene as well. (I do this more on my GMC stuff-for whatever reason it seems to help out)

Pull a valve cover off and take a look at how much oil is gettng up there. I'd expect it to be ponding up from what you've described.
Run/idle the truck with the valve cover off and see if it does drain slow.

 

I would think the oil cooler would be in front of the radiator or a/c condensor if it has a/c. The one in the radiator is for the transmission. It really sounds like the drain back holes in the block and/or heads may be nearly plugged with sludge.
Mark

 

Pull the valve cover as mentioned, you definitely have a drainback obstruction. How does the oil filter look?

BTW, the oil cooler would be located next to the oil filter if it has one from a towing package. Not sure an F150 would have one though.

 

I got confused with GM's set up and the internal oil cooler(no flames necessary as I am a convert now). I checked my 1990 F250 and there isn't an oil cooler that I can find. It was just a thought.

 

You could drain the oil, clean the dipstick then add it back at a very fast rate and check the level again. This would tell you if it's a drain back problem or not.

 

My '94 f-150 w/a 5.0 has a similar problem. Under normal driving the oil pressure will drop to nothing. if i let off of the gas, the pressure will usually go back up. to me, this seemed like it couldn't be the pump, if it was, the pump should work better at higher rpms. I just have to keep the oil changed at closer intervals, and occasionally run an engine flush though the system(same thing as the Marvel Mystery Oil or kerosene). Mine has been fine for over a year now.