One more thing....with crosshatching still on cyl walls...pretty low chance of piston slap? Not sure what that sounds like. Think Ill do what you said to check for rod bearing...if checks ok...plumb in a real gauge...then go from there. Seems if it was serious out wouldn't go away as soon as warmed up but I'm afraid to drive her now til I figure it out.

 

piston slap no but wrist pin yes...

sometimes when an engine sees a lot of low rpm there is no oil to the wrist pin... just like the camshaft it relies on splash off the crank and big end of the rods and what little if gets from the oil ring scraping the bores which again is from splash...

the way to find out of the shorting cylinder test... if its wrist pin or rod bearing when you short out that cylinder the knock will go away... it only knocks when the cylinder fires

 

I have volt meters but not a test light, will get if needed, but couldnt you just remove and replace plug wires on the distributor?

 

Ok, so I got home after work, went straight down and pulled each plug wire, one by one at the distributor.. doesnt seem to make any difference whatsoever. Best thought? I think the next step is to plumb in an actual oil gauge (always wanted to anyway) and see what the hell is going on pressure wise. Why Ford ever put a dummy gauge in is beyond me, whats the point? The reason people want gauges it so actually see what is happening, so have to replace a fake gauge with a real one..something I shouldnt have to do. Anyway.. my gut is telling me failing oil pump. It makes sense. the knocking is coming from I dont know where, but the way I have taken care of this truck mechanically I just cant believe that any bearings are shot. Could be, but I just find it hard to believe. I am guessing its low or slow on pressure and or volume. Once the oil starts warming up, gets a little easier to flow, tada, no more knocking. Just my gut feeling. Im just a shade tree mechanic, but from what I have done in the past, my gut us usually right on.. if not right on, pretty damn close. SO, we'll see. My old truck is rusty, 18 years of Iowa winters will do that to ya, but she has NEVER let me down. I have been thinking of doing a total restoration on the body, looks like I may be doing the engine as well. This truck has been the best truck I could have ever asked for and I guess I have a lot of sentimental feelings for it, I almost feel that I owe it to her to not let her die... not like this. To most, she may not be worth much. She is the only vehicle I have ever bought brand new, may sound crazy, but it just wouldnt be the same without this old truck around. If its just the oil pump, I guess that would be the best possible situation. Just a pain in the butt to change. anyway, enough of my rambling. Dr... Thanks for all your time and assistance, you have been more than helpful. I may require your assistance again, so hope I havent been too much of a bother. Dont know when I will get to this. I have another vehicle to drive, and too much other things going on right now, but my new shop is just about built, and the fist major project I do in there will probably be this truck. I would rather put the money into fixing her up, than buying a new one. Anyway, thanks, I will shut the hell up now, this has gotten way long and out of hand.

 

Sorry, I lied LOL, was just thinking.. whats the best brand of replacement oil pump?

 

Melling. Ford installed them in our motors for a reason. The aftermarket Melling pumps are as good as they get. Do not get a cardone or dorman. They have cheap guts and don't last near as long.

 

Agreed...Melling or SpeedPro (same thing)

Dont worry about being a pain... this is the exact reason I joined this forums (and others) to help people and to hopefully save them some cost in some repairs by doing it themselves...

Post/ask as much as you feel in doing no harm in learning....

I would say if the truck was knocking and you pulled the plug wire at the distributor cap all the way off so you know it wasnt sparking on each of the 8 cylinders and it still knocked it's safe to say the bearings are fine... there is a oil issue but it would seem bearings are fine in the Rods...

when you get to pull the pan I'd pull and check the Mains caps....

 

Rolling in a set of new main bearings while you're in there isn't a bad idea either. 5.0 are rough on mains especially the center main which is also the thrust bearing. Many a crankshaft has tried to walk out on these motors. Even pampered ones.

 

Well so far good news I guess. I am seriously dreading having to do this job. Whoever designed it so you have to raise the engine to take the pan off must never work on their own designs! I have read other places about jacking up the engine...not removing the intake....bad move? I think my wife wants me to let it go and buy something new next spring. Maybe most would agree.... But I love my old truck and dont think I could stand letting her die this way. So if she is getting fixed it looks like I am doing it. Also while I have your attention...the little exhaust pipe that runs...well...from the exhaust to the egr valve is pretty much rusted through...does this pose any problems? Can dirt enter the engine through this route at all?

 

on 2 wheel drive you do not have to remove the upper manifold... on 4 wheel drive you MUST take the upper manifold off or pull the engine... it will not come out as the drop member for the front axle is in the way...I've done both