...but I'm not sure how bad. I'm looking at a junkyard truck with a clean title. It's something on the upper end of the beater truck price range, but I'm not afraid of putting a little sweat and blood into a truck.

I posted this in the 5.4L subforum, but thought maybe you Super Duty guys would have some ideas for me, too:

I'm looking at picking up a Super Duty with a 5.4 in it from a local salvage yard. It's got a clean title, and doesn't need much work, but it's got an engine noise that has me a bit concerned. At idle, it has an occasional knock, as well as a tapping sound. The tapping sound could easily be the injectors and what appears to be a little exhaust leak. Never had a truck that didn't make some kind of noise like that. The more pronounced knock concerns me, though. If I hold the engine at 1,000 RPM, it goes away, but if I let it idle down from that, it comes back, fairly quietly but distinctly, and not consistent at all. If I rev it past 1,000 RPM, it gets louder, but still doesn't have the rhythm I'd expect from rod knock. You can hear it clearly from inside the cab, under the truck, or with the hood open looking in from above. Can't quite tell exactly where it's coming from, but it's definitely engine noise. I've heard noises like that before, but only in engines that were on their way out, but it's usually a consistent noise.

I've seen posts about cam phasers and timing chain slap, but usually it seems that those noises have a fixed range of RPM you'd hear them at, usually low end. What confuses me is that it apparently goes away if I hold the needle on 1k. I can get a used engine for a decent price, but I've torn a few of these trucks apart for scrap now, and don't look forward to having to do an engine swap.

We've had some older trucks and tractors that made all manner of nasty noises and ran for years, but I don't know anything about the modular engines. My newest engine block up til now has been a Windsor from the early '90's. Any thoughts?

 

What year is the truck?

The exhaust leak is common. The exhaust manifold studs are probably rotted.

As for the knock, it could be piston slap, which is fairly common on the Triton engines (not to mention most modern V-8 engines) because of the short piston skirts favored by engine designers. If you get the oil analyzed you may have a better picture on what is causing the knock.

 

It sounds like a piston slap. My V10 had a piston slap only when it was cold. As soon as it warmed up it smoothed out but is still noticeable at idle. If the truck is in good shape I say go for it! Id drive it untill it stops. Used 5.4s are very cheap and easy to get. But I have read here that broken exhaust manifold studs can make all sorts of strange sounds! First I would check for those! How many miles on it?

 

It's a 2000. This sound is a lot more pronounced than I'd expect piston slap to be, and it didn't go away when it warmed up. It seems too regular for piston slap, and too irregular for rod knock. Kind of stumped. The same yard has 100k 5.4's going for around 650, but I honestly don't look forward to doing an engine swap when I look at buying a truck.

 

Maybe check to see if the noise is the timing chain slaping against the cover?

 

Is that fairly common? The engine seems to run fine, just makes this noise. Starts reasonably well considering it's a salvage yard truck that's been sitting for quite a while and usually needs jumped due to a dead battery.

 

Iv heard of the chain tensioners wearing and breaking. Then fall into the oil pan.
Then the chain will just start slapping. Might even break things inside such as the cover might have a hole in it.
Is the noise comming from the front of the engine?

 

It seems to be more toward the front when I listen from underneath. I've got to go back and take another listen sometime, for sure. What are the odds that a bad chain tensioner has done other damage to the engine?

 

Go to get a cheap stethoscope and listen around the front cover with the truck running. If it is something timing related its easy to replace the stuff. Do you see any small metal pieces in the oil on the dipstick?

 

i hate to say this, might have some people i know on here that would love to know this. My 2004 F350 with the 5.4 has a ticking noise for the past four months i checked the header bolts and it isn't them, checked the y-pipe flanges and they are tight and not leaking. Mine seems to be on both sides of the motor, just a ticking at idle, anything over idle it goes away. But i don't care i change the oil ever 4k with full synthetic oil since i bought it brand new and im gonna run her till see either blows up, or seizes shut

 

If you find that the noise is from the front of the motor, it is hard to say what else is broken. Probably just needs a new timing chain kit.

 

I'm leaning real heavily towards just buying the thing. For the condition of the rest of the truck, the price isn't bad, and I really like the color. It's not red, and it's not white, and most of the ones I've looked at have been one or the other. I prefer my Ford's blue, but I can't be too picky.

 

Didn't see any metal in the oil, and the oil was surprisingly not excessively black for a truck that's been sitting in junkyards for the better part of a year and making the noises it makes. A couple small air bubbles on the stick that looked like shavings at first, but I wiped it down with a clean white cloth and it didn't show any filings or such.

 

If the motor pops soon after you buy it you could always just put a new one in if you have the cash. Mainly just make sure the rest of the truck checks out.

 

It's not mint by any means. Bed is starting to get cancer, but I won't be paying much for it, and I plan on building a flatbed anyway. My big issue is that my current vehicle is out of inspection, and pretty much can't be made to pass, so I'm trying to get something together as soon as possible, so it's got me a bit nervous.