yes, damaged cats can throw your o2 sensors causing lean or rich conditions...

 

Just a quick update. I'm just now finishing up the plugs, coils, and wires. Getting the anti-seize out of the spark plug sockets was not as hard as I thought it would be. I just soaked a rag from an old t-shirt in lacquer thinner and stuffed it down the holes with a segment of a cheap aluminum rifle cleaning rod. I'm sure I didn't get it all, but I got a lot of it.

A couple of the screws that hold the left coil broke. The easiest way to get them out was to remove the bracket so I could work on it at my bench. It still took a torch to get the one out. The other was so close to the adjacent wall of the bracket, I couldn't get anything on it to twist it back out, so I had to drill it out anyway.

All of the screws were in pretty rough shape, so I figured I'd just replace them all since I already needed to get at least two. Finding replacement screws was not entirely easy. They are M5 .08, with a 9.8 strength rating, about 35 mm long. It's actually a ridiculously long story as to how I finally found them; like if I related the whole thing, I should give you a chance first to go don your sleep apnea c-pap machines. Suffice it to say, I wound up finding some at Home Depot.

So that bracket was pretty corroded, and I figured that I might as well clean it up before putting it back in the truck. I wire wheeled it and soaked it in vinegar to eat off the rust. Right now it's got a coat of black machinery enamel drying on it.

While I was hunting for screws, I got bored and starting picking at the wheel bearings and brakes, which also need attention. I'll start a different thread for that. I'll post another followup on the engine once the new coils, wires, and plugs are actually up and running. I just thought I'd post one here before I started asking about bearings and brakes.

 

Here's an update on this thread for anyone who was following it. It's taken me awhile because I decided to fix some other unrelated things while I was at it. I installed the new coils, wires, and plugs. That seems to have completely remedied the one problem, the hesitating and clunking sound that occurred under the truck. I think that was basically just misfiring, and fuel perhaps getting into the cats and popping off. All of that is gone; the engine sounds smooth as silk at idle.

However, the other problem is still there----that knocking sound that I recorded in the video posted on the first page of this thread. It is a knocking sound that you seem to get only at certain rpm levels; it seems to happen mostly when you let off the gas. I am able to hold the throttle at a point where the engine will make it constantly, but that never really happens actually driving. I still don't know what it is. It's not exhaust leak; I tested for that. Does anyone know if a bearing or lifter will do that, knock only at certain rpms? Or do they pretty much do it constantly when they go out? My other guess is something loose or cracked with the flywheel. But I can't tell anything by looking in through the view port. I'd like to have a better idea of what this might be before I just start dismantling stuff and possibly fixing stuff that doesn't fix anything. Any additional help would be greatly appreciated.

 

I don't know about the V-8, but I know that on the V-6, a loose engine lifting bracket can cause noises like that.

 

The engine lifting brackets appear to be solid; I couldn't budge the nuts whatsoever.

 

Could be a number of things still. Wrist pin would be a guess, giving how it acts at certain rpms. But could be a number of other things. You can remove the pan and check the mains and rod bearings. You can remove the belt and put a wrench on the crank pulley. See what you can feel by hand. Should be able to feel a bad rod bearing or main that way. Always helps to have someone on the under side watching with the pan off though. You can also remove the cam cover and give the guides a visual check. Check the slack in the chain. You may be able to pinpoint a rotating noise per cylinder by use of the mechanics stethoscope. Check right at the exhaust ports on each cylinder. Go from there.

 

Thanks for the thoughts, Toyz. What would a bad rod or main bearing feel like when you crank the pulley by hand? Will you actually feel the knock through your ratchet? Or is it more like a rough spot?

I'll listen again with a stethoscope tomorrow.

 

Yours may not be significant enough. It didnt seem that loud to me, but then again you didnt really rev it high. A flattened rod bearing or worn wrist pin can be felt as a bump or click as your slowing rotating the crank pulley. As the pistons passes tdc, the slack can be felt. It can definitely be seen if someone is underneath as well. Nobody likes dropping the pan, and is a pain with a 4x4 but if that is where the sound seems to be coming from (back of the engine, or lower engine) then that would be the stet to determine what it is.

Check around a bit more.

 

I've been tied up with work hardcore since last Wednesday and haven't had a chance to drop the oil pan yet. I will today. Last night I had a few minutes so I removed the belt and turned the crank slowly by hand. You definitely can feel a couple of spots where the resistance increases then lets go. Is that the kind of thing you're talking about? I would imagine the resistance should feel pretty even and smooth, shouldn't it?

 

Man, dropping that oil pan is a be-atch. What all do you guys disconnect from the engine before you raise it? My exhaust manifolds could use replaced anyway, but I wasn't planning on doing that right now; there's pretty much nothing with my exhaust that I can probably take apart and expect to go back together.

 

You can lift the motor but.... Man, I wish you got those DVD's to work dangit.

Did you give me your email ? I can't recall. I'll send it to you as a web page if you want the diagrams. Yea, you'll want the diagrams. Well, PM your email and I'll send the service procedure for dropping the pan. Here it is without the diagrams.

SECTION 303-01B: Engine — 4.6L 1999 F150/250 Workshop Manual

IN-VEHICLE REPAIR

--------------------------------------------------------------------------------

Oil Pan —4x4 Removal

1. Raise the vehicle on the hoist
2. Drain the engine oil.
3. Support the front axle housing with a jack stand.
4. Remove front axle housing support.
---a.) Remove the front axle mount bolt.
---b.) Remove the axle support bolts.
---c.) Remove the axle support.

5. CAUTION: Use care when lowering the front axle housing, or the vacuum lines to the axle solenoid may become disconnected or damaged. So, disconnect the pink and blue vac lines. Definitely make sure you know how to reconnect properly. Ford has it backwards with some of their diagrams. Write it down or draw yourself a picture lol.
6. Remove the right and front axle housing mount bolts and lower the axle to allow clearance for the oil pan to be removed.
7. Remove the oil pan.

8. CAUTION: Do not use metal scrapers, wire brushes, power abrasive discs, or other abrasive means to clean the sealing surfaces. These may cause scratches and gouges resulting in leak paths. Use a plastic scraper to clean the sealing surfaces.
9. Remove and discard the oil pan gasket. Clean the sealing surfaces.
---a.)Use Metal Surface Cleaner F4AZ-19A536-RA or equivalent meeting Ford specification WSE-M5B392-A.
---Allow the surfaces to dry for four minutes or until there is no sign of wetness, whichever is longest.
---Failure to do so can cause future oil leaks.

 

Hey Brew, man, thank you. I just PM'd you my email. Oh yeah, my truck's 2WD. It's five o'clock somewhere.

 

No problem, - sent you the 2WD instructions. It'll open with exploder automatically. - I meant explorer.

 

I wanted to post a quick update for those who were following this thread. My one neighbor is an old mechanic who used to work on vintage cars for some rich guy; he stopped over and asked me to bring the truck back to his shop so he could check it out up on his lift. To do that I needed to replace my front brake calipers. I'd tried to reuse the old ones when redoing my brake lines, but they just aren't cutting it any longer. They had so much corrosion, once you got down to something paintable, there wasn't enough meat left to properly seat the hardware that holds the new pads. So they did nothing but grab and cause problems.

I just finished replacing the calipers and will see what my neighbor thinks about that noise. I'm pretty sure it's the engine, but I suppose I have a shadow of doubt in my mind about the exhaust, as it is so corroded; I'd like to at least confirm with this guy that it's coming from the block and not the exhaust somehow. I would like to at least know that much before I drop the pan.

More to follow. I'll be sure to post to let anyone interested know what this turns out to be. I really can't thank you guys enough for your help.