Hello all,

I have a 1988 F150 I bought last year. It has an unknown history, but looks like it was a project someone couldn't finish. It has what looked to be a freshly rebuilt 460 swapped in, a very nice aftermarket aluminum radiator with electric fan setup, new 3" exhaust system, new bushings int the suspension, etc. Couldn't drive it as the gas tank and pump were loaded with crud. Got both replaced, truck ran fine until it started making a loud rattling noise from the motor, like the lifters weren't pumping up. This was after just a few miles of driving after the tank replacement. My mechanic tested the oil pump, and says it has about 20 PSI at startup, and drops to zero when it warms up. It never stops rattling. Based on what I've seen, I can either replace the oil pump, and hope no other damage was done (cheapest solution), or I can replace the engine with either a rebuilt one, or a used one. A used one is obviously a crapshoot, not knowing anything about the history, or even hearing it run. My mechanic says he has not had good luck with rebuilds, with them failing after a short period of time. We have no engine rebuilders locally, so I either buy one off the internet, or try to find one father away. Whichever way I go, I can afford to do this once. If it doesn't work out, I have to put it in my yard to essentially rot. I really like the truck-it is the body style I wanted, had the big block, ZF 5 speed, 4 wheel drive, excellent body.

Any advice or suggestions would be welcome.

Thanks.

 

Your oil pump is probably fine. Im guessing your oil galley plug behind your timing cover has fallen out and its now floating in the bottom of the oil pan. I've had this happen on a 302 and I had the same symptom. The good news is that your lower end is still getting a little oil. You may be able to pull the distributor and push a borescope down the distributor hole to inspect the presence of the oil galley plugs. If one is missing, you just need to pull the timing chain cover and punch a new plug into the block. Theyre about $3.

 

I would start with a new Melling HV oil pump
I've never seen any of those oil galley plugs just fall out
If those plugs were gone or 1 missing, I doubt you'd have 20 lbs. at idle
That is your problem, 20 pounds at idle cold
It should be 40-60
take the old pump apart and measure the rotor clearance and the gear to cover clearance
Pretty sure you will find excessive clearance and a worn housing and cover

 

I would check the oil filter first.
Pull it and cut it open and see what is inside. The motor might be toast already or have a filter with a stuck bypass valve.

Rattling top end could mean your cam is toast already and the metal debris or main bearing material. Your filter will tell you what the next step is.

 

Any news on this problem? Im curious what the solution to your problem is.

 

Me too.

 

Well, it's been sitting down at the mechanic's shop for the last two weeks. I don't have a garage or anyplace to work on it myself, and the weather is not good here (SE Washington) for outdoor work. I'm looking around for another truck to buy, and I'll see about fixing this one when the weather gets better. My mechanic doesn't think it's the oil pump, but really has no idea what else it would be. If/when I get this figured out, I'll let everyone know. I will probably start with replacing the oil pump, and see what happens.

 

I suspect worn bearings, main, rod and cam with an emphasis on cam bearings being the cause of the low oil pressure