Well first off I'm new here. I've been browsing for a while, and finally decided to sign up.

Here is my problem:

If I crank up from after my truck has been off for more than 20 min, I get a couple of seconds of hard knocks. After a couple of seconds it stops and runs like a champ (other than a vacuum leak I've yet to find. Which only causes an issue until it warms up past about 180) Anywho, I've talked to a few mechanics and they say my bearings are going bad and either I need to have the engine rebuilt or I need to put a new motor in it. Now I find this hard to believe since I'm sitting on 102k miles. My truck belonged to my grandfather and he gave it to me about a year ago. He used it for back and forth to work and the occasional hunting trip. He only used the 4x4 about 8 times in it's entire life. I know anything is possible, but I also know that Ford engines are tough and I find it very hard to believe that something that major is going wrong with so few miles. Here is the other part. This is the part that made me really look into this. Yesterday on my way home from work I'm sitting in traffic and I notice that BOTH of my oil pressure gauges are sitting on 0. Now keep in mind my truck purrs like a warm kitten. No knocks, no grinds after the initial few seconds at start-up. I really would like an expert opinion before I drop $1500+ for repairs.

She's a 1986 F-250 with a 5.0L 302 V8. She's been running Castrol 10W-40 since she was a wee little truck. There is a deep sunk oil pan for an extra Liter. Can ANYONE give me any ideas on what is going on? I know there is an answer out there and I'd love to gain more knowlege on my problem. Thanks in advance!

-Kenneth

 

Both oil gauges? You have the factory unit and an aftermarket? Is the aftermarket mechanical or electrical - electrical will have a wire to the sending unit and a mechanical one will have a tube. If electrical it is possible to have an electrical problem causing both to read zero. But not if one is mechanical. And if the oil pressure did go to zero you have a serious problem.

 

The aftermarket gauge has a solid copper tube running to the back of the gauge.

 

Mechanical. They don't typically lie, so you have a serious, and I mean SERIOUS, problem. Either it is out of oil or the bearings are badly worn. (It is possible for an oil pump to wear out, but it isn't usual.)

 

I agree with G lewis . If a mechanical gauge is reading 0 , you have an issue . By the way .. Most only look at the bottom , crank & rod bearings . Do not overlook cam bearings if you rebuild ! Good luck !

 

Well that's what I'm trying to figure out. If it's an oil pump then it'd be a lot less than replacing the motor.. How could the pressure be so low without knocking? It's got oil that's not the problem.

 

Well I'm not going to rebuild this motor. It's got a 302 and I want a 351 carbed so if it's that bad I'll probably replace it.

 

Worn bearings let what little oil the pump puts out at idle get away without building up any pressure. As the revs come up so does the pump's volume and you get to a point where some pressure builds up. But it is highly unlikely that the pump is worn out and the bearings aren't. You are going to have to rebuild the engine.

 

I agree with that plan. A 351W has more torque at lower RPM than a 302 - all else being equal. Torque is what moves loads.

 

Well I think for now I might rebuild it. I'm not sure yet. I'm not a mechanic by any means. What all should I have rebuilt and around would should it cost?

 

The cylinders need to be bored out, probably .020", to ensure they are round. The crank will probably have to be ground .010" undersized on the main and rod journals to ensure they are round. The main bearings in the block and big ends of the rods will have to be resized for the same reason. And you will have to buy all new bearings for the mains, rods, and cam

Speaking of the cam, it needs to be checked for flat lobes or scored bearings. And the heads have to be checked - and the valves will need to be ground. In fact, some of them may need to be replaced.

As for price, I recently rebuilt an engine for $997. But the machine shop is run by a friend and he gave me a good deal. Further, I put it together. So, if you have someone do the whole thing I would guess about $2000.

 

Well I don't mean to annoy but I'm working on a budget. What all do I need to do just to fix my problem?

 

Pull the engine , plastigauge the crank ( at least ) hone the cyl. bores , change the cam berings, main and rod berings, rings , gaskets , seals ect . Better ,mic the cam journals , crank journals , cyl. walls , cam lobes ,lifters ...and on and on ... . It aint cheep to do it right . But can be " done " for cheep .

 

It is a waste of time and money to do anything short of what I outlined. If the bearings are worn then the rings are worn. The timing chain will be toast. And there's a chance the cam is flat. So if you aren't willing or able to do that then buy a used engine from the salvage.

 

Your cheapest and easiest option IMHO would be to find a running 302 or 351 and put it in. No mechanical back ground needed, just some brute force and turning wrenches, and way cheaper than tearing the motor down because once you do that, you always spend more than you originally planned for, especially if you do it right.

just my $.02

Good luck.