5.4 noise that's not a usual suspect
 

Hi all. I've got a 97 5.4 with about 175k on it with an odd noise. It's not a Triton so no cam phasers, no exhaust leaks, no bad plug holes. The noise comes and goes, mostly when cold and mostly at idle, follows engine revs to a point where I can't hear it any more. It will subside after a highway run sometimes. I change the oil regularly, have used full synthetic always. Most is highway driving. Video:
The vid is after only a couple of minutes running on a cold day.

It's been doing it for a months now, getting only slightly worse. I have changed out the alternator that went dead (that's when the noise appeared but it's not the new alt) and found a bad a/c clutch a few weeks later that's been removed. Power is fine, gas mileage is fine, no other symptoms. Unfortunately I learned late not to use Fram filters but I have been using the NAPA ones for about a year now.

I've tried finding it with a stethoscope but can't seem to. For sure it's louder on the passenger side, I can't decide if it's top or bottom end. Appears to be loudest in the right wheel arch.

It sounds like a rotating part to me, perhaps lifter(s) or something else valve train, expensive and/or internal. I'd rather not get rid of it. I'm thinking of doing a long block as it doesn't have body rust, needs some bushings but the rest is all good and I've spent a bit on accessories for it.

I'd appreciate educated guesses or input from others with the same noise.

Its a marginally loose rod bearing I suspect....it almost sounds to me like a piston is making contact with the cylinder head as a result. I have seen this many times - yours is in a phase where it hasn't gotten bad yet - but it will get much worse. If I had to guess that noise is probably most pronounced during unloaded deceleration. It comes and goes like that at idle as the rpms change in minute increments. I'd be willing to bet that if you did a compression test that you'd find one cylinder on that bank with lower numbers than the others - because the piston isn't coming as far up in the bore as a result of the worn rod bearing.

This is just my opinion - however it is fairly educated...lol.

Also - you may not notice a significant loss of a oil pressure at this point either.

Something I hadn't considered. I'll have a read through my workshop manual, I haven't done any motor work on Fords. Can the journals be checked and the bearings replaced if the crank is good with the motor in the truck?

It is possible that you can get away with simply putting new bearings in it, however I'm doubtful you can do that without removing the engine. I don't think you can get the pan off with it in the frame.

On another note - if this is in fact what's going on here and the piston is making contact with the head - the piston really should be replaced also. It may or may not be cracked or broken. Would suck to do all that work and get it back together and be driving it somewhere days or months later and have it scatter when that cracked/broken piston finally decides to **** the bed.

It's possible it's a con rod bearing but I don't think piston(s) are contacting the head. I've been around lots of motors in my days and I think it would a) be a lot more consistent noise than it is if there were contact and b) if there was contact it would be either a lot louder or instant junk and c) it wouldn't run as well as it does once it's off idle. It does sound like slop in something. I wish it would just break and put me out of my misery.

I asked about putting bearings in with the motor installed because I've done mains in a motor that way, push out the old shells with the new, check end float, put in new thrust bearing half-moon shells etc. If the pan won't come off then that's not an easy option.

Forgot to mention, the noise isn't on overrun either. It only shows up at idle or just slightly above. It sounds like a lifter and low oil pressure except that it is like 10 'ticks' then stops, 10 more, stops. Maybe timing chain?

It might be time to start a tear-down.

J

Could be the chain - it's kinda hard to tell listening to your video. If I was standing in front of it with my stethoscope then I might be able to get a better idea.

.....throw a heavy weight oil in it, if the noise stays it's likely the chain, if it goes away or lessens....bearing

^^ good idea.

Before you dig too deep into the engine, try taking the belt off and starting it. Could be an idler bearing, or even a dirty belt. The way it tunes in and out is not typical rod bearing noise.

I think we've solved it and no long block required...

It was making the noise regularly the other day after my drive home from work. I stuck my head under the hood to find the a/c compressor pulley turning in an odd oval-shaped way - hardly noticeable but every time I get the noise, the pulley is moving around a bit.

The a/c clutch had come apart earlier in the winter so I pulled off the outer plate, looks like a new compressor is in order. Way better than a rebuild.

Thanks all for the suggestions.

Jamie

Update
 

Hi all. I hadn't had an a/c clutch off before so decided to buy a clutch kit, pull the thing apart and see if it was in fact the clutch or if it needed a replacement compressor. If just the clutch, I had one. I didn't realize how easy it was. I know why it was loud...

https://www.ford-trucks.com/forums/p...ctureid=130622
https://www.ford-trucks.com/forums/m...22-130622.html