1995 Explorer with interesting engine noise

[Tedybear]

Well my day went from good-bad-worse.

Did the basic maintenance. Oil change to a motorcraft filter, and went with 10w30 oil. (The P/O mentioned he only used 5w30 and this truck has well over 200k on it. So it's warm enough, let's go with 10w30....)

Had it running for about 20 seconds before shutting down to recheck level. No issues.

Did the cooling service--New thermostat and purged out the air. (This thing had pure 100% coolant that drained out)

Okay. Did the purge, no leaks. Then I noted a very pronounced engine noise starting to surface the longer it runs. Oil pressure gauge of course is a dummy gauge, but it's not reading "0", so it has at least 7lbs.

https://youtu.be/UTfto1dtgQk

That's a link to my video I did of the noise from under the SUV.

I'm still pricing out the rest of the stuff it needs. 4 tires and brakes all around. Yeah I expected brake's and tires. This engine noise? Really not what I'm used to or expecting....

Ideas welcome. This isn't going on the road anytime soon, so there's not a huge rush.

S-

 

[lobo411]

Sounds like mine. I put a stethoscope on it and I had a few louder than average lifters, but it's been that way for 40000 miles and doesn't appear to have hurt anything. I'd chalk it up to having an old engine.

 

[Tedybear]

I think all things considered just for fun?

Install a "Real" oil pressure gauge for a start.

If it holds pressure fairly well, and I believe the standard is 10PSI per 1,000 RPM. (roughly of course)

Maybe finish up the rest of the repairs and see how it does.

Rock Auto has the brake parts needed for about 130ish. Tires are expected and that will run about 300plus depending on what I locate.

Worse case? If the engine gives out, save the wheels and tires for a similar SUV.

I'll hang loose and see what others have to say as well. It was hard to hear that noise over the exhaust.

On that same subject: It will need the flange replaced coming off the converter. Anyone happen to know the size?

Thanks again!!

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[manimal]

Not really sure how loud the noise really is, could be any number of things. Does not sound like the loud hollow banging of a bottom end noise.

It sounds similar to both my 91 and 95 when they're cold. The 91 is almost at 300k miles and does have some bottom end rattle when started cold, which does NOT sound like your video.

IMO.. The likelihood of the OHV 4.0 eating a bottom end and dying is pretty unlikely if regular maintenance is done.

I think the only reason my 91 makes any noise at all is that I WAY over-revved it several years back in a severe snow/ice storm, sliding down a hill in 4-Low, barely avoided hitting an abandoned car at the bottom of the hill. The noise began shortly after that.

The thing to remember about the Cologne OHV V6 engines, is that they are a nearly 50 year old design, and even by the time the OHV 4.0 was produced they were nowhere near the NVH standards of many newer engines of the time. Some misc. running noise is to be expected of them.

 

[Robman]

Sounds good for a diesel
So this all started after changing the oil/coolant? Strange.
You'd think a slightly heavier oil would dampen noises.
All I could suggest it try a different oil filter? I'm baffled.

 

[J_C]

Sounds good for a diesel
So this all started after changing the oil/coolant? Strange.
You'd think a slightly heavier oil would dampen noises.
All I could suggest it try a different oil filter? I'm baffled.

Hmm, noisier as it warms up... It makes me wonder if this is the first oil change after it was bought and the seller wasn't quite honest about 5W30, dumped some oil thickener in to quiet the engine, make it seem healthier for resale.

 

[Tedybear]

Sorry for not getting back here sooner. Oddly enough I do work on a ranger forum, and eric the car guy. I posted this issue there as well.

Now those forums I get notified of responses in real time.

Didn't get anything from here until I physically came in. That's why I went to the other forums with this.. I figured no one was able to respond to this.

Okay, lesson learned. Stop in and check personally.

Here's what I posted for the updates:

Did an oil pressure check. Stone cold we get about 65psi. All warmed up and at low idle we get about 28-32. Highly responsive to throttle position.

https://youtu.be/9ba2-bFCZ1o

We did a couple more videos of that noise.

https://youtu.be/c1U0dEQuZqs

https://youtu.be/khX22OePZfg

Here's where things get interesting. You can clearly hear the 'knock'. Upon giving it some gas, the knock diminishes to the point it's pretty well gone. Last time I had an issue with rod knock, it got louder and more pronounced when the engine RPM was raised.

Now where this blows my mind away....

I used a mechanics Stethoscope. I had that probe end all over the engine and transmission...and bell housing. NOTHING to report!! With that knocking sound? No place I touched the probe reported anything. The oil pan? I could hear rotational sounds, and even the 'Wshoosssssh' sound (best way to describe it) of the oil pickup! But no knocking sound.

Then I touched the probe to the exhaust pipes.

Bingo...... not as loud as I expected, but it's clear as day. I then probed higher up to the manifolds. The noise isn't "Loud" or as loud as what I'm hearing, but it's very pronounced and the only place I could pick up that noise was when I had the probe of that stethoscope touching the manifolds and exhaust pipes.

Possible burnt exhaust valve? I'm guessing on this. I've heard rod knocks before, and they always get much worse with acceleration and they are clearly able to be heard with the stethoscope through the oil pan. The fact when it's making this noise, I can hear all the "Rotational" sounds within the oil pan---and no knocking noise when I have that stethoscope touching various parts of that oil pan.

This isn't a rod knock that I know of....

Any ideas? Am I totally off base with the idea of a burnt exhaust valve?

Looks like an oddball issue. I'll be doing more checks on Tuesday (going to pick and pull looking for parts today for this)

next up:

Compression test
Probe upper half of engine with the mechanics 'ear'.
Use test light to ground out each spark for the cyc's. Attempt to pin point 1-6 which cyc is the root cause of this.
Possible leak down test depending on compression test results.

Again, Sorry for not stopping in sooner. I'll be doing another post about trying to get the keyfobs programmed. (That's one oddball electrical issue in the making. But in a different thread)

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[Tedybear]

Any more suggestions on this noise please let me know. I've had people suggest a lot of things from carbon build up to the tension pulley on the front of the engine.

The more suggestions I have the better I can dive into the correct areas to check. I will also report back with the compression testing numbers once I have a dry enough day. (went from mild and partly cloudy...to yuck cold and rain. NOTHING is worse then that cold steady rain shower)


The brake parts have been ordered in, so that's also coming up. (120 from RockAuto for pads, rotors, and shoes. Napa will get a sale on the hardware kit for the parking brake shoes)

Thanks again for all the help!

S-