Whine after crossing river

So I was out duck hunting this last season and drove my truck across a river crossing (once to get in and once to get out). The water was up just at the top of the tires, so I would imagine the water was up around at least the bottom part of the motor.

Ever since I crossed that river my truck makes this loud whining sound when I start it and drive it. The noise gets louder as the RPMs go up. I have since changed the oil in the truck at least 2 times and each time I've checked it for water and found none. I've swapped out the air filter at least 2 times as well and have never seen any signs of water getting anywhere near the filter.

It almost sounds like its coming from the belts and so I did a belt change and I still get the noise. I flushed the front of the engine area down with fresh water from my garden hose for about 20 mins with it running and with it off. Still have the noise. It almost sounds like the bearings in the belt tensioner might have some gunk in it from crossing the river but I can't imagine it would still make that sound after flushing the entire front of the engine and well now that Its been so long since I've crossed that river.

I thought it might be the front diff but when I shift the truck into N while crusing down the road, the noise drops as soon as the RPMs drop.

Just curious if anyone has come across this same kind of thing, if crossing a river and if so, where was the noise coming from and what did you do to get rid of it..? I haven't had time to tear down the front of the truck yet so I can get a better look but I'm about to do that i na few weeks. I have an idea that it's the bearings in the belt tensioner and the fly wheels that the belt rides on or something. Maybe the altenator or something?

Any ideas?

 

thanks, adding that to the list of things to check.. Hopefully its something simple to replace or repair.

 

well im thinking if the whine went down with the rpms, it wouldn't be the diff becasue thats constant with road speed, not engine speed. but i agree with you on changing the fluid nonetheless, and doing the mod to prevent it from happening either again or in the future if you have a habit of fording rivers

 

Isn't the front diff breather already extended?

Yes check your rear gear oil for milkyness.

 

Changed out the front and rear diff oils tonight (had a hour to kill before work) and it all looked fine. Will take a look at the Idler Pulley this weekend.

 

Free supercharger with every crossing?

 

Well unfortunately it wasn't a free super charger but I did have someone ask me if I had one under the hood. I replaced the 3 pulleys this weekend and the whine went away... I still have a quiet whine when the engine revs but I'm sure it has something to do with the fact that I've got 150K miles on it..

 

Could possibly be the water pump b/c of the high mileage and cause it also makes a whining sound if the bearing goes before it leaks bad. Not sure if you have a first or second gen but if first might be timing belt if it's really old and dryinout. Or power steering pump.