Mysterious Engine Noise (not idlers)

[eburrows]

I have a noise on my D2 that sounds exactly like a bad idler bearing, but isn't, because I just put in new ones this morning, plus tensioner, and it's still there.

It starts after a few minutes of driving (after things are warm), and can only be heard above 2k RPM. It gets louder and higher pitch with higher engine RPM. It sounds like it's coming from the right side of the engine, maybe around the rear end, or near the trans/TC. It has a remarkably similar tone to the HVAC fan rubbing on it's housing, but it keeps going after turning off the HVAC/radio.

It's slowly getting worse, but it's been a couple hundred miles already. Any guesses while I wait for it to get obvious enough to find?

 

[eburrows]

I should also say that I can't feel or hear anything odd manually spinning the alternator, water pump, or AC pulley. The main crankshaft pulley, PS pulley and everything else feels solid when I push/pull on them.

 

[rovercanus]

How does the power steering pump feel when you turn it? This is my guess for a whining noise.

 

[eburrows]

How does the power steering pump feel when you turn it? This is my guess for a whining noise.

Thanks for your suggestion! It feels smooth, and using a mechanic's stethoscope, it sounds smooth. No crunchy bearing, scraping-piston, etc. I don't feel much resistance or chunky-feeling like piston movement, though I'm not sure if I should. It's got fluid, the fluid isn't foamy, and steering feel is normal.

 

[special ed]

Get it warmed up so to replicate the noise and remove the belt and run it. If it still makes noise check that the oil pressure sender is plugged in. If the noise subsides without the belt it is probably an alternator but you can use the stethescope to isolate it. if the noise is still present then something internal has failed.

 

[boxster]

Like Ed says does it make same noise with belt removed engine running while your parked? You might put it up on jack stands run it in place to duplicate the location of the noise. You mentioned noise at TC/trans area maybe loose flex plate?

 

[eburrows]

I haven't been able to replicate the sound while in the driveway. Might have to wait for it to get worse in order to do that.

I was thinking about the alternator bearings too, but as of yet I can't hear anything in the driveway.

The flex plate is an interesting thought. I've cracked them before, and they're easy enough to check, even though my current one is only a couple of years old. I'll peek in there.

 

[discostew]

I had a whining noise in my Disco. Ended up being my wife.

 

[rovercanus]

I had a whining noise in my Disco. Ended up being my wife.

What did you end up replacing her with?

 

[discostew]

What did you end up replacing her with?

I just throw money at her till she stops.

 

[rovercanus]

I just throw money at her till she stops.

Advanced trouble shooting.

 

[discostew]

Kicking the can down the road more like

 

[eburrows]

I just throw money at her till she stops.

Pretty sure that's what this whole website about discos is about.

Anyway, don't think it's the flex plate. No change in general pitch when running the engine and open the bell housing inspection cover. Not certain, but unlikely.

I did find a few loose exhaust manifold bolts, one of which is stripped out... That's a problem for another day, maybe.

 

[discostew]

It might be the water pump. They sometimes make a high pitched noise and can be kind of intermittent.

 

[eburrows]

I finally got it to do the squeal while in the driveway, so I immediately removed the fan and belt, and revved it... Still squeals. Sounds like it's from near the front, top, right. Definitely not an accessory, and doesn't sound like it's from the rear or transmission. :-(

 

[discostew]

It’s probably your intake gasket leaking.

 

[eburrows]

It’s probably your intake gasket leaking.

Interesting idea. Do you mean the upper intake gasket (small) or the large lower intake gasket? Both/either I suppose.

 

[discostew]

Probably the lower.Get a good spray bottle and spray lots of water at the lower gasket. It will stop whistling when you fill that leak.
It’s not real common but I’ve seen it a few times.

 

[eburrows]

Thanks for your advice @discostew. I choose to believe that your explanation is most likely, so I can keep driving it for a little while. This engine is ~300k miles old, and rattles/leaks like crazy, so I'm planning to swap it with an AB remanufactured long-block. If the wait time is long, I might dig into the current engine and tighten up the intake bolts a bit. Probably not though, I'm lazy.

 

[boxster]

I would try propane to isolate that intake air leak if that’s what it is, as to reman engine replacement maybe check with IE Rovers Lake Elsinore Ca.