Front end "grumble" when coasting between 25....35MPH...??

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GregLCA

GregLCA

10 Year
Joined
Jan 19, 2015
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Hey Guys,

I'm dropping my LC off for a couple small repairs on Thursday and I'll try to have this one diagnosed as well, but wanted to get some feedback in case anyone recognizes this symptom.

I'm running the stock Michelin LTX M/S tires (stock 16" size) and the truck has always been whisper quiet on surface roads and on the highway. Lately though I am picking up a noise from the front end that sounds very similar to the "tire hum" that you'd get if you were running a more aggressive M/T-type tire on the highway...... kind of a steady-state "Wom...wom...wom..wom...." droning sound.

What is weird is that it's only noticeable at low speeds around town. I can most easily replicate it by letting off the gas between 25-35MPH and just letting the truck coast down under load. I've tried putting the truck into neutral just to see if the sound changes at all (thinking maybe it's the diff or a bad driveline?) but it doesn't make any difference.

Could this be something like the front CV's starting to go bad? or maybe front wheel bearings?

I'm sure over the next few months, this truck will give me AMPLE opportunity to spend money fixing all the little things I'm noticing are "odd". I'm not the kind of person that can drive a car/truck that isn't running 100% perfect.... so I'm just putting my plan of attack and priority list together now! :)


Thanks!

-G
 
Well, start with the free and easy things first. I'd make sure your front drive shaft and u-joints are lubed up good (same for the rear while you've got the grease gun out). With full-time 4WD your drive shaft is still turning when in N from the wheels rolling.

My experience with CV's is they sound worse under any kind of load (especially when turning under load) when they're going bad, and the noise disappeared when coasting. Visually check the boots for leakage.

It also could be bearings, along with a million other things. I had the small shield that protects the tie-rod boot crack, and flap in the wind at low speeds. Very annoying. Good luck, and start with just looking underneath and poking around. Jack up front end, and push-pull tires at 12 and 6 o'clock to check for loose bearings.
 
Will do! Thanks for the tips.....

I'm not too familiar with full-time 4WD systems, and I guess it makes sense that even with the truck in "N" and coasting all of those front-end components are still going to be spinning all the time (CVs, front driveshaft, transfercase gears)...

Maybe I'll get lucky and the tech will diagnose it cheaply for me, and I can then decide if I want to DIY it myself or just pay them to do it.

This truck is a lot more "approachable" than other cars I've owned in terms of repairs, so I might be willing to try a few simply things myself. The only risk is that since it's my DD.... if I screw up a repair, break bolts or do anything that requires extra parts I didn't buy ahead of time... I'm walking to work the next day!!!


-G
 
ton504 said:
You can grease the driveshafts and u joints. Its not hard at all. If the hum is still there after then bring it to the tech.
Click to expand...

When I see service described as "lube prop shaft"... is that typically referring to greasing the slip joint of the driveshaft / the u-joints at the ends....or both???

It seems weird that in my time searching and reading here, there doesn't seem to be much talk about swapping out u-joints as part of routine maintenance. Either they just last forever, or maybe it's described in different terms in the Toyota realm???

In Chevy land, u-joints go bad frequently and guys are always swapping them out pro-actively (and carrying spares on the trail) to prevent getting stranded either offroad or on the side of the highway.


-G
 
I'm on OEM u-joints on both rigs, combined over 400K miles. They're beefy, plus we're not running 6"-8" lifts that stress them out, and we get CV issues up front instead of u-joint issues since the front shaft moves very little...
 
I can't really provide much help here, but I would be inclined to think it's not U-joints based on how long they seem to last in most cases. I see you're in NH, where are you taking your rig to get worked on? I'm in Boston and looking to find a good indy mechanic that knows LC's reasonably well.
 
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