Odd noise

[billpac4u]

My 95 4x4 Ranger XLT w/4.0 V-6 makes an odd high pitched humming noise when it gets really warm. The ambient daytime temps here now are in the high 90's, and after driving for about 15 miles or so, the humming begins. it's most noticeable when I stop, idling at traffic lights or such, and does not seem to change with engine speed. In trying to isolate where it's coming from, it seems to be loudest directly in front of the engine/radiator. Any ideas?

 

[--weezl--]

you're going to need to post a video with sound for us to properly identify it...

infront of the rad though? not much that would make a noise up there... possibly your fan clutch, or a slipping belt, though those are typically RPM dependant

 

[doorgunner]

Hmmmmmmmmmmmmmmmmmmmmmmmm......I got the same sound between my ears.......I was gonna suggest a bad electric cooler fan on the transmission oil cooler.....but neither one of us got one of those.....

 

[billpac4u]

Thanks, guys

I have no way to post a video with sound, so . . .

At least it doesn't seem to cause any problems - no overheating or anything - so, I'll just watch it until something else happens. Keep on truckin'

 

[baddis]

have you checked the coolant level? just because the gauge reads normal doesn't mean it is right. when the noise starts pull over to a safe area and open the hood and see if the top radiator hose is solid as a rock. sounds like it might be overheating.

 

[billpac4u]

Forgot to mention . . .

The noise stops when the engine is off. Idling in driveway (after running at least 15-20 min) and humming noise is there; turn off engine, noise stops; turn on key, nothing; restart engine, humming resumes. ???

All fluids are up to proper levels, no leaks apparent.

 

[naford]

Check the air intake and air filter. I remember that there used to be a hose that went to the exhaust manifold that would allow warm air in when the motor was cold. It went from the air cleaner box to the top of the exhaust manifold. These are just guesses. The only thing that doesn't fit is that it doesn't change with engine rpm.

 

[Duane867]

Check your ac compressor clutch.

 

[billpac4u]

Thanks, Duane

I can't tell if it's the AC clutch or not; the hum seems constant, whether or not the AC is running or turned off. I am leaning toward something to do with the tranny cooler, but I haven't a clue. Don't want to waste any more of you guys' time with it. I'll let you know if and when something changes. Thanks for your expertise!

 

[Duane867]

Well, any pulley driven equipment ( AC, water pump, power steering, timing set, alternator,)
with a squeak or a hum would certainly change with high or low RPM.
You have no electric fan on the radiator cooler. Dude was kidding. The trans cooler is built into the radiator and cooled via clutch fan on the water pump driven by the crank.
At this point I would lean towards a vacuum leak, or pressure leak.

 

[billpac4u]

Thanks, Duane

Yeah . . . I know he was kidding; still, it seems to be coming from the general area where the radiator mounted trans cooler is located, and I have no way of knowing how it is performing, though I assume if it were boiling (?) it would effect the radiator, and show up on my temp gage, which remains in normal range, or cause the tranny to shift funny, or leak or something. Like I say, lets wait it out and see what develops. Thanks again for all the input!

 

[Duane867]

Check the trans lines from the trans to the cooler right up against the cor support where the hold down clamps attach lines to the core support. They could possibly be loose and vibrating with the engine ?

 

[--weezl--]

Well, any pulley driven equipment ( AC, water pump, power steering, timing set, alternator,)
with a squeak or a hum would certainly change with high or low RPM.
You have no electric fan on the radiator cooler. Dude was kidding. The trans cooler is built into the radiator and cooled via clutch fan on the water pump driven by the crank.
At this point I would lean towards a vacuum leak, or pressure leak.

wrong, a lot of RBV's come with external transmission coolers, both with, and without the tow package

 

[Duane867]

With electric cooling fans on them, and in 95' ? That was more or less what I was talking about. Not that they didn't exist. Should have stated it more clearly I guess.
Towing packages did then but they had no electric fan, and you were more likely to find them in Bronco II's and Explorers then in a Ranger unless specially ordered. Special option only that I was aware of. But they did and do exist so your right about that. but today they come in the form of an HD aluminum radiator trans cooler still all in one. Or so I thought.
I assumed the owner already knew he did or did not have an external.

 

[--weezl--]

most trucks with a trans cooler, the trans cooler is an auxiliary trans cooler, the fluid still typically runs through the rad, it's in addition to the normal cooling to keep the trans extra cool, not just a different style... the radiator on your truck will do more than the normal trans cooler, but if you bring it down to say 120* celcius, from what ever it was, then put it through another cooler, which is infront of the rad, it will bring it down even farther... this aids for long hills, towing, or someone who drives hard, it's cheap insurance to help your transmission last a little longer... it can be done on a manual too, though it is a lot of work... i have thought about putting one on my mustang before, but it's honestly more work than it's worth, being that the fluid is only there for lubrication in a manual (and for the syncros to work properly) though the warmer the parts are, the softer the metal becomes, and the faster it wears...