Got a '95 f150 5.0 with 205,000 on it. I work it hard pulling trailers and stuff. I've had the truck since 165,000.

In the last year I've been more aware of a slight knocking sound from the lower end. It's very possible the knocking has been there the whole time I've had the rig, but now I'm more aware of it.

Anyway, it knocks the worse on cold startup. I can barely hear it when standing beside the truck, and can't really hear it inside the cab. I can hear it plainly if I get under the truck closer to the oil pan.

After the truck has warmed up or been driven a bit, I have to crawl under it to hear the knocking at all.

This isn't loud knocking by any means. I can't hear it at all with the additional noise of the engine being revved up.

Oil pressure is good and has been verified with a mechanical gauge.

The truck runs great and produces decent power. Mileage is still reasonably good.

My question is, are these 302's known for this, and do I have a mild case that will result in good longevity still; or is this known to get worse quick?

I'm thinking it should last for a good while yet considering its performance so far (which is good) and that I haven't been able to tell that the knocking has gotten any worse in recent times.

Any thoughts and/or experiences that I can hopefully draw from to better gauge what to expect out of my rig?

Thanks.

 

I'm no expert, but my understanding of a knocking sound means a bad crank/piston rod. In your case, it seems to me the more likely cause is that a crank bearing has broken, and fallen out, so you're getting the knocking sound but not as bad as a normally "thrown" rod.

Again, not an expert, but what I do know is that any knocking sound from an engine can't be good, and the more you drive it, towing or not, the worse it's gonna get....

 

I can't tell you what the noise is without hearing it for myself. That being said...

Get a second opinion. If you have to get under the truck and listen near the pan to hear it... then it isn't even close to a knock that I would describe as a thrown rod, spun bearing, piston slap, or anything of the like. Those are all really obvious with or without the hood up imo.

Run it by a known, reputable mechanic and let him give a listen. Go from there and be happy because then you can quit speculating. And, you don't have to shoot for an internet diagnosis! Yay. That means you won't have to take the advice of guys telling you all kinds of things, I mean after all they can't hear the noise either. Or you could post up some video, audio of the noise.

 

Put a little Lucas in it & run it. 5.0 are built in a manner that it amazes me that they last as long as they do. A buddy had 5 running 5.0s. A friend of his wanted one rebuilt for a vehicle he had. out of the 5 everyone was so bad that a complete machining & crank kits would of been required. Its cheaper to buy a new short block than to try & rebuild a 5.0.
So my point run it till it blows.
I had a 5.0 in an 88 T-Bird that had a piston knock that went 300,000 miles & was still running when the guy I sold it to junked the car.

 

More than likely its just main bearing wear. And if you have to get under the truck and put your ear to the oil pan to hear it, there's plenty of life left in it. Just use quality oil, a Wix, Napa, or Motorcraft FL1A oil filter. You got many more miles to go before that engine gives you problems.

 

Also check your header bolts and where the flanges that bolt into the ends of the headers, mine was loose on the right side and I heard a similar sound when the engine was cold until it warmed up and expanded to fill and seal most of the gap.

 

If you had a thrown rod you'd know it. The large hole in the side of the block that the rod was thrown through usually gives it away. A thrown rod is no longer connected to the crankshaft and that always happens under load, so really bad things happen before the engine gets stopped. I've had three different single cylinder engines throw rods (1 on a go kart and a couple of lawn mowers) as well as seeing a Pontiac 2.0L turbo engine on a dyno that had recently thrown a rod. None of the engines was salvageable.

Low end knock that you hear but might consider still using the engine, as others have said here, is usually slightly worn rod or main bearings. If you still have good oil pressure they probably aren't that bad and you probably can still borrow a fair amount of time with the engine. But you are on borrowed time.

 

Sorry I couldn't get back to this thread sooner. I appreciate the replies.

The knocking is loud enough to hear it while standing next to the truck at cold idle, and it is quiet enough at warm idle that I have to crawl underneath to hear it. It doesn't seem to be getting worse in a way that I can detect.

I think I will continue to run it and most likely expect to get some good use out of it still.

Is Lucas the go-to additive?

 

While you can run it, just know that the more you drive it, the more it will likely cost to fix when you finially do fix it.

 

Turn the radio up and drive it till it blows!

 

Not always true. When my cousin was 17, the 350 in his chevy threw a rod. It was obviously a thrown rod by the knock - I can't recall what the cause was (meaning whether it was the crankshaft or piston end that broke loose) but it didn't punch a hole in the block.

 

I for sure don't have a thrown rod, and I don't get the impression it's anywhere near that bad yet.

 

My brothers truck once had a sound that started out of the blue one day and it turned out to be a bad lifter. Same symptom you describe.

Here's a link to the video of it. Just click on the photo and it will show a video

 

You can buy a cheap 302 anywhere. I'd pick one up and put it in the corner and have it ready to go and just drive what you've got till it let's go.

 

The way you describe it is that Your crank/ piston bearings are basically starving for oil when you start the truck. The oil is cold so it cannot flow well. Once the engine starts to warm the oil is able to flow and it gets quiet. At 200K+ miles and you stated that you work the snot out of this motor, I'd say it's getting time to rebuild it. My 95 F250 with the 5.8L Has a tick in it when it's cold, let the engine run for about a minute and it all quiets down. I have 130K on my engine but it has also been used as a work horse. Keep the oil changed regularly, Don't Hammer on the gas pedal and it should last you a good bit longer. You could try dropping the oil pan and changing the the bearings but I bet once you get in there and MIC the crank, you'll see it's wore down and probably will either have to have a new crank or go with over sized bearings.