The infamous Ford Explorer OHV knock/tap

I have spent time searching and reading on this. I am posting this new thread as I guess I am not really getting anywhere and have basically stopped driving the EX until I can figure this out.

I have done 2 rounds of Seafoam through the intake, my neighbors are questioning. I am sure it helped something, but not this noise.

The sound is not present at startup. It is present after things warm up, the warmer the louder. In order to hear it, I have to drop it into D and rev, while braking. IT DOES cycle with the motor, but does not sound like a rod, not 'heavy' enough. At idle it is about 4 times a second and picks up as I rev up a little while in gear, although I think I can detect it while driving, usually slow on my street where it is quiet. In any event, it is not real loud or real noticeable while driving, but it is very distinct, not the noise of a lifter IMHO, but who knows?

I am told (here) that it also may be in the tranny, perhaps the torque converter? Again, I know and have read plenty of posts on this, and I guess I am thinking 'lifter not pumping up' but I want to eliminate rod knock and be assured that a flat lifter will not hurt me while driving as long as I take it easy?

Ideas?? Thanks in advance and I also looked on you toob to see if I could find a video of my sound, and I could not. Anybody know of one?

Hmm, if you have to put it in gear to hear it than it's not the typical lifter noise. Which would likely means it has something to do with the tranny.

If you can, get an audio clip.

I too just had this probelm arise yesterday. I didn't get it to do it yesterday because I had it in park. But when driving it today I heard it. So I powerbraked it slightly and hear a really soft sound louder than valve noise but quieter than a rod knock.....I'll try to get sound

I might know what sound youre talking about...

Try and get that clip.

I also have a noise that I fear is not a lifter noise.

However mine is present at startup.

i have a tapping sound from the engine and got two opinoins from two different mechanics. one said it was a fuel injector clicking, another said it was a lifter. but both agreed that i shouldn't worry about it with the amoutn of miles i have on the engine.

you might try the stethoscope method. it's like one a doctor uses but it's a little tube you can put against the engine, you might be able to pinpoint about where it's coming from. if it gets louder the warmer it is, then chances are it's making the sound at all times, you just can't hear it. the stethoscope should make it easeir to hear it when parked.

Update NOW WITH VIDEO / AUDIO !!

http://media-mobi.com/en/?play-bk4v5l5g322fcx7kldozxw3kjc07d7nv

and another

http://media-mobi.com/en/?play-7l7qgbls5tszepocpga038ohis2ttjk5

This is with me holding the camera phone while sitting in the drivers seat. I have the brake on and and reving about 1000 or so.


Masterd: I (now have) an audio/video clip of the sound that I can post. I regret that I have yet to do the steth-test ( I use a long piece of wood), but I talked to my wife about helping me today and will check.

This is no fuel injector tap that I have ever heard, but I do know that noise.

Briwayjones: You mention the typical lifter noise as (likely) to be heard at all times, and I agree, although this is my first explorer and I am not real familiar with all the noises.

Anyway, I have the video and will try to post this am.

Thanks!!

Sorry but I have no idea what that noise is. But I can tell you it doesn't sound good.

I've tried the TSB on the carbon knock on acceleration. Cured it. Runs faster than a mechanic from the toolman....lol

Torque Converter Bolt(s) loose?

Let's say the noise is tranny, and it is loose torque converter bolts (one possible diagnosis)

Can I tighten them? Without taking out the tranny (T-case etc. etc.)?

Ideas???

My diagnosis would be either loose torque converter bolts or a cracked flex plate. On the older trannys there was an inspection/access plate, if not then just remove the starter to get at the bolts.

If thats not a cracked flexplate (which is somewhat common, considering its construction), then I'd say bottom end noise.

Hows power? Does it smoke? What RPM is the noise loudest at?

Flex Plate inspection

Allout: I will climb under it this weekend and look for an inspection plate. As I have never actually done anything to a tranny, except some peripheral stuff, I assume I look for anything loose (and tighten it up) or anything that is cracked?? As a shade tree mechanic, my experience only goes to jobs I have done, and while I replaced a T-Case, I did not have to take out the tranny to do it!! And it was on a Jeep, not a Explorer. So, new territory.

masterd: Absolutely no smoke, runs like a champ, plenty of power has been extremely well maintained over the years by the previous (1) owner.

When cold, it absolutely does not make the 'noise' - In any gear, or N. This AM, if I started her, and put her in D with the brake on, engine sounds like it was new.

When she has been driven for awhile, and I THEN stop, put her in D with the brake on, she makes the noise at idle, and if I apply the gas some, the noise picks up and gets more noticeable. :thumbdwn:

Check the oil pressure.

Cold oil is thicker than oil at regukar engine temp. The thicker oil will cushion the noise until it thins out.

Oil pressure, engine hot and at 2k Rpms, should be at least 40 pounds.

I'm thinking a cracked flex plate would be making noise 24/7, to at least some degree.

Just one more idea I had, it's not an exhaust leak/tap is it? After hearing that noise it reminded me of the sound my buddy's Dakota has, and he says it's a leak around the headers/engine.

We can figure this out!

Agreed with Josh. You need to get us some oil pressure numbers so we can rule out the bottom end and focus on it being:

A) Lifters

B) Rocker(s)

C) Exhaust leak

D) Flexplate

Masterd said:

Agreed with Josh. You need to get us some oil pressure numbers so we can rule out the bottom end and focus on it being:
A) Lifters
B) Rocker(s)
C) Exhaust leak
D) Flex plate

Click to expand...

Hmmm, well the idiot guage reads about in the middle, and I am not going to be able to get real oil numbers in the short term, however, it does not run like it has oil pressure low enough to cause this noise (like I would know! )

I am pretty sure I will be able to better sus it out with a sound test when I am underneath. If it is coming from the oil pan area.....:thumbdwn:

I will get back on this and thanks everyone for the notes.

Well I had a 99 explorer sport, which had that little rattle on start up and the tick while in gear. The rattle turned out to be the starter gear hanging up on the ring gear and the tick turned out to be a bad torque converter which shot metal shavings through out my whole tranny.

I have learned that the first gen 4.0L have a bad oiling issue with the upper portion of the push rods and eventually wear out causing play and creates a lifter like tapping. My current explorer xlt 4x4 has the lifter tapping issue, I have already replaced the heads, valve train, lifters and push rods and there was no tapping until about the first couple hours. My oil pressure guage is all over the place, but I have heard it is just an on/off switch and is probably faulty; another mechanic mentioned that I may need a new oil pump which is not providing enough oil pressure to inflate the lifters. I have not replaced it yet because it requires pulling the engine, but the sooner the better because the original heads had about six valves that were pounding the valve seats into the head by at least an inch.

Update, I listened while under the EX!

Got the Ex up on ramps and had my wife put her in gear, parking brake on, while I listened. I could easily hear the clunking.

Remember, it really does NOT make the sound until warmed up.

I listened at the oil pan and heard it, as well as felt it - a slight taping feel in time with the sound. IT seemed to be coming from the rear part of the drive-train, around the bell housing, but I could not be sure. It is real distinct while lying under the ex.

Pull the oil pan?