I'm thinking of buying a 2004 F-150 XLT 4wd super cab with an auto trans and 5.4 but it's making a couple of peculiar noises and I haven't been able to find much out with searches.

The first is a rattle that comes from somewhere in the torque converter/starter area. It doesn't happen all the time. When I first started it, it was there. It seems to go away when you rev it but comes back when it idles down in park or neutral. I drove the truck around for a while and every time I stopped it came back whether I shut the truck off or not. The weird thing is that just a little bit ago I took it for another ride after it sat for a few hours and the noise isn't there!

The next noise is almost like a misfire. I once had a Dodge Ram that would misfire when I was lugging up a hill in OD but was fine on flat roads and going down hill. This Ford is almost the opposite! When I'm cruising at a steady speed the engine gets louder, but the speed and rpms stay the same. If I ease into the gas it quiets down and sounds normal. It also seems to make the same noise when I'm gently accelerating. If I put the hammer down the engine sounds great. It doesn't seem like the loudness corresponds to any particular speed, gear, or rpm range. It's just there when I hold steady at highway speeds and is sometimes worse when speeding up slowly from a stop.
I used a cheap scanner on it and it didn't come up with any codes from the past or present. There is no check engine light. The truck has 130,000 miles on it.

Any tips or advice would be great! I would love for these two noises to be related and have an easy fix, but what are the chances of that?

 

How many miles are there on the truck? The first noise you describe, sounds like the timing chain rattle.

Is the second noise like a loud "hum" when you apply throttle to the truck?

 

130,000 miles. I read about the timing chain, but wouldn't that noise come from the front of the engine? I crawled all around under the truck and the noise was loudest where the engine and transmission bolt together.

The noise is kind of like that, but it happens when i'm holding steady throttle on flat roads but goes away when I give it a little more gas and speed up.

 

Yes it would be predominantly in the front area. At first i thought it was a loose converter bolt. Mine occurs at startup, and when I let off the throttle. I notice it much more when I'm in a drive through.

Your second noise could be an attribute of the intake foam deterioration. Upon removing the intake filter, it fits in a little tray. That tray has a foam around it that helps it seal when it's latched in. If that foam starts to come apart, it can cause what you are describing.

 

You might want to think twice about buying a high mileage first year 5.4 3 valve, especially if it's making noises.

 

This makes sense to me. On that old dodge the engine noise got much louder when I replaced the stock air box with a 10" round open element filter and that is exactly what this noise reminds me of. Would it be safe to pull the air filter out and take it for a short ride to see if that makes the noise go away? I know it would be noisier, but if it is the issue the noise would be different but steady.

When yours made this noise, was it there on every single startup and drive or was it there sometimes and other times you couldn't hear it at all?

I'm taking it into careful consideration, that's why I'm here asking questions. I know they can be hit or miss.

My stepdad has a mechanically identical truck and has had 230,000 relatively trouble free mile (spark plug snapped off in the head when he brought it in for its first tune up, and that's it as far as I know). With this I know that these trucks have potential.

If I buy it I'll be paying the guys loan off. He hardly uses the truck and just bought a car for commuting, so he really can't afford two car payments. He doesn't owe much on it, I'd get it for less than half of clean book value. Because of this I'm willing to buy it if I can figure out that the noises aren't caused by a failing engine or transmission.

 

Without the air filter in there, something could get lodged in the maf and cause bigger issues. I would check it and see how the foam and filter looks. If the foam is in bad shape, maybe the guy will replace it at your request. It's not expensive from the dealer.


Its intermittent on the startup. But there every time I let off the throttle.

 

The foam is almost completely gone! I think I might try to put some weather stripping or something on it just to see if the sound goes away. If it does I know that's that noise! I imagine that without the foam there, as I'm cruising there is less air drawn through, so it can rattle, but when i hammer it the tray is sucked tighter, making the noise go away.

 

Could the rattle near the engine be a heat shield on the exhaust?

 

The foam I put on didn't seem to make a difference. I'm not sure how thick it should be but I tried it at .020" and .040" and the sound was still the same.

I did figure out a couple of interesting things though. The engine noise seems loudest around 2000 rpms and when i'm coasting down my road at any rpm without giving it any gas, bumps seems to trigger the noise.

There may be a small change in throttle response and a slight loss in power when the noise happens, but I can't really tell one way or another. The sounds also kind of reminds me of a semi jake brake, but not nearly as loud. There is also a bit of a tin rattle with it, I think, otherwise that might just be the original marbles in a soup can rattle, just at speed.

 

I did some more looking underneath and found the heat shield on the passenger side was only held on by one bolt. Took it off but unfortunately the noises are still there. Before I took it off there was sometimes a rattle at idle when It was put into gear and that's gone.

I used a hose to stethoscope the engine and the only place it seemed a little noisier at idle was at the back of the oil pan on the block, but I'm not sure if that really means anything.

 

Today I tried wetting down the coils hoping one would short and be the cause of the noise that happens when cruising down the road, but they all did fine while wet. Just to be sure I took it for a ride and disconnected the coils one at a time and was able to duplicate the noise with each coil unplugged. I don't think I have a problem with a misfire, so now what?

I also pulled the starter off. It seems to engage just fine outside of the truck, but I'm going to bring it in tomorrow to get it tested while I have it out.

I noticed a few things regarding the starter that I hope might have to do with some of the noises. On the flexplate teeth, they all seem to be shiney on the side facing the starter. Also, the teeth on the starter gear don't seem to come to as much of a point when compared to pictures I've found online. From what I know, it's the original starter but it was rebuilt either this past winter or the winter before. How likely is it that the starter isn't fully retracting and the teeth are riding on the flexplate and catch every once and awhile. The third thing is that the lower passenger side bolt is broken off in the transmission bell housing. Could only having 2 of 3 bolts holding it in place be a problem?

 

Started a new thread, I think I found the problem. https://www.f150online.com/forums/20...ml#post4989997