93 4.0X rattle

93 4.0X oddball rattle

I'm sure a thousand people have brought up the subject that every ohv 4.0 owner eventually faces - valvetrain rattle, thinking theirs is unique. I'm not beating them over the head mind you... I'm no stranger to it, but this 'new' problem (maybe problem(s) ) is stumping me.

Facts are as follows:
engine has 112.6K documented miles
previous owner had WAY too heavy of oil in it (20w50 AND lucas additive)
it had badly worn rockers and pushrods when I got it (sounded very much diesel-like and horrible slop in the valvetrain components)
oil pump IS good (+/- 30 psi warm idle)
I ordered brand new hardened pushrods (melling I think, memory fails me sometimes) but I did confirm they're heat treated.
I ordered the "better" rockers on rails with the hardened pushrod seats (term may be incorrect of course)
I have changed both the filter, oil (twice oil, 3x filter) in 1k miles, found no metallic particulates even after inspecting the filter directly, and even the filter mount to a remote mount kit although I find that last bit irrelevant. It is now running the recommended 5w30 oil, with yet another fresh filter as of 2 hours before typing out this post.
The rattle is still there, though not as bad as it once was.
It is verified to be upper end rattle, nothing in the crankcase.
It does not necessarily get louder/deeper/etc when warm, or cold.
Oil is not contaminated that I can tell, with inspection of the oil drained, with limited to no sludge ever coming out of the pan.

My problem is this:
While the rattle is nowhere near as bad as it was, it's still very much there as I said, and the symptoms seem to have reversed in how to reproduce them. Instead of the rattle increasing under load, there is NO rattle under load unless between 2k rpm and 3k.
In fact, there is no rattle PERIOD above or below that number, except at a warm idle where it's consistent... but only on the back passenger side. It is also, when throttle is applied under no load condition, intermittent (although once in a while it stops) within that 2k-3k range.

I have no doubt that there's something I've been missing here. The only components that I feel could cause this which I have NOT replaced are the lifters and the oil pump. I saw no need to change the pump with the pressures being so good. I don't see how the lifters, being rollers, could go bad with so few miles on them unless somewhat plugged up (though it does run VERY smooth) unless running that heavy oil did more damage than good.

But then begs the question, why put the heavy oil in in the first place?

This truck is only a part time driver, so while I don't much care so long as it runs, I know it can and should be better than this. My 91 Explorer has almost if not 3x the miles on the clock and DOES run better than this is right now, with nowhere near the rattle/knock/ this one has, and has never had the valve covers off let alone any valvetrain work done.

Any help, advice or even reference to some sticky/thread here would be great, and I'd be happy to answer any relevant questions about this to help me diagnose as I am able. Thanks!

Ford fuel injectors can be quite noisy, and exactly the same "tick, tick, tick" timing as valve train noise.

As you increase RPMs the injectors have less closed time, so can actually get quieter
I use a longer vacuum hose as stethoscope to ID noisy injectors

Just a thought

4.0l OHV really didn't have the valve train noises like earlier Ford V6s did, not to say it didn't happen, just not that common
You do need to pull the heads to change all the lifters

RonD said:

Ford fuel injectors can be quite noisy, and exactly the same "tick, tick, tick" timing as valve train noise.

As you increase RPMs the injectors have less closed time, so can actually get quieter
I use a longer vacuum hose as stethoscope to ID a noisy injectors

Just a thought

4.0l OHV really didn't have the valve train noises like earlier Ford V6s did, not to say it didn't happen, just not that common

Click to expand...

Oh, I thought of that myself and did in fact check, but... I don't believe it's the injectors. It comes from the head itself, using a similar stethoscope method. Perhaps I should have added that as being tested, but I did forget. Sorry Yeah it's really stumping me. I've had vehicles with each of the common engines in this 'family', ie the 2.8 (74 mustang II), the later 2.8 from an early 80's baby bronco, a 2.9 in an earlier ranger (HATED that thing) and now this being my second 4.0. I do agree that they're not nearly as noisy as their older siblings... which is why this concerns me most

Then lifters are all thats left, and if rockers and push rods were worn lifter cups will be as well

RonD said:

Then lifters are all thats left, and if rockers and push rods were worn lifter cups will be as well

Click to expand...

Alright, I'll definitely start hunting for some. I was afraid that was the case, though I had hoped otherwise of course. Would it still explain the intermittent nature of the noise, under certain conditions only?

Also, now that I think of it - would it cause more damage to continue the occasional drive with it? I'd think so myself, but it never hurts to ask another person...

A few Lifters could have been bad from sitting long periods, which would explain the 50w oil to try and quiet them down

Older lower mile engines/vehicles are fine if you don't use them much, but from my experience parts will dry out and smaller openings clog up, seals will tear and gaskets dry out and leak, when start ups and use are few and far between.

113,000 miles in 25 years is 4,500/year, or 350 a month, so it sat for long periods, because I doubt it was driven 350 miles a month.

Low milers can be good finds but they often do need some repairs not needed with average miles

RonD gave good info. Off the wall idea, if you do not like his, could be worn cam lobes having caused poor valve train geometry and therefore some ticking-needed longer pushrods(but a bad solution). Yes, those lifters do get junked up.

I had this exact same rattle. Always on Cold startup, and then once hot only under light load from 2-3k rpms. Heavy or no load would not induce the rattle. Bought the motor this way (unknowingly of course).

Ran for 10k miles before I pulled it due to cracked heads. Sure glad I did because every single rod journal was scored beyond machining. Rebuilt it and the Rattles been gone ever since.

Gotta say these motors are tanks because you can bet your ass I wasn’t easy on it during that time haha

Post a video of the rattle if you can and I’ll confirm if it sounds the same as mine did


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cp2295 said:

I had this exact same rattle. Always on Cold startup, and then once hot only under light load from 2-3k rpms. Heavy or no load would not induce the rattle. Bought the motor this way (unknowingly of course).

Ran for 10k miles before I pulled it due to cracked heads. Sure glad I did because every single rod journal was scored beyond machining. Rebuilt it and the Rattles been gone ever since.

Gotta say these motors are tanks because you can bet your ass I wasn’t easy on it during that time haha

Post a video of the rattle if you can and I’ll confirm if it sounds the same as mine did


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Click to expand...

Sorry that I've not updated lately - I've been consistently working on the truck with my spare time. I had the heads off and apart, surprisingly things look fine. Lifters were a little gummy but I cleaned them up as best I could and put the engine back together. Still has the rattle, now only when warm. I suspected at that point that I had in fact an oil pressure issue all along, and after installing an aftermarket gauge set (water temp and oil pressure specifically) to monitor everything. Engine doesn't heat up past factory spec (thank the maker) so I know there's not excessive friction... but oil pressure IS low enough to make me nervous. running 5w30 synthetic now after a thorough cleaning of the engine both by flushing and elbow grease... and as the temperature comes up from cold, pressure goes down. just less than 20psi at 2000 rpm warm, under load or not. when cold, pressure is up around 40-45 but doesn't stay there long. based on that, I have to assume the noise left is primarily caused by the low oil pressure.

Have an M328, intermediate shaft, pickup/screen and set of gaskets on the way as I type this. If it continues to rattle after all that, I'm running it till it blows itself apart and then getting another engine.

**Edit - I realize now that my original figures of +/- 30psi was in error, based solely on poor diagnosis on my part. Sorry! In general I realize most mechanics go from 'most likely to least likely', or perhaps if a bit shady 'most expensive to least expensive' (lol)... but I go by a slightly different route - least difficult to most difficult. *shrugs* I suppose that doesn't always work

Things being as they are I did miss the most basic of indicators too - oil pressure goes down, rattle comes up... though it's not pronounced and still not in the crankcase itself so I can likely rule out lower end bearings etc. However, the main thing that made me go back and really look was that the rattle being in that RPM range under very certain conditions makes me think that the oil pump being weak making the lifters work, but not necessarily keep up with engine load/rpm for the very moment until they pressurize enough to remove the slop. My theory could be entirely wrong, though I guess time, a few more skinned knuckles, some grease stains and a LOT of cuss words will tell...