I went for a ride and for the first time ended up in some water/mud - not too deep - maybe 18" or so. But I noticed after that when going back home I could hear a whining sound from my front diff (I think). This trip was one of the few times that I've run it up to full speed in 5th gear (mid-range) for a good distance, so I don't know if that is a normal sound or not! It's not very loud, but I am always listening for something new so I can head off any problems.

Suggestions? Thanks!

 

I will be honest I have never heard this noise on my 300. I have heard it on other cats though. When you have been riding for a while and the diff is hot and you splash a puddle (doesnt matter how deep or shallow) the water or mud if the case may be turns to steam and that means alot of pressure. Water expands over 1700 times its normal size when it turnes to steam. Most seals cant hold up to this type of pressure and water will enter through gaskets etc. The thing to do right now is drain your diff and run a synthetic (will repell water better) diff lube. I run the valveoline synthetic I got at auto zone works great. If you suspect water did enter the diff, drain fill, ride for a while drain fill you get the idea. Water in the diff isnt un -heard of and could be the casue of your noise, just one of the more simple things to check. I would start with this and see what it does for your noise.

 

Thanks. I'll pick up some syn gear lube. What weight for syn? Is it the same?

 

ok. I know this is old, but I haven't been riding much.

I changed the differential fluid twice. It didn't look like there was any water in it, but I changed it twice for good measure. Made sure that I topped it off to the fill plug level, which is not to completely fill the diff. The noise is still there. It seems to go away if I hold my heel down (clutch in) and then start again when I put it back into gear.

I'm wondering something now. I know that I can get a lever that will disengage the front diff from the driveshaft - is there a way that I can disengage it without buying and installing the lever? I'd like to disengage it (2x4 mode) and see if there's still the sound.

 

If you have a 2002 or newer 250 the whining sound is normal due to cat using a straight cut gear- the old cats didn't wine or at least as much because they used a bevel cut gear. The reason that cat told me is that they went to a straight cut gear is that it costs half as much to manufacture and it allows you a physically smaller gear with the same gear radio as a bevel cut which gives you a little more ground clearance. As for disengageing the front diff, there is a lever on the top towards the back- give it a crank (I am not sure which way off the top of my head) and you should have 2wd. Be careful not to overfill the front dif- it should be 1" below the fill hole if you have a 02 or newer model........

 

That's good info about 2002 and newer. I didn't know that.

Why 1" below the filler hole?

 

I believe its so the oil doesn't leak out past the axle seals.