Deep Humming Sound (1 Viewer)

[Hokie99]

My daughters 2002 LC with 270k miles is making deep humming sound from where under the car, no vibrations at all. This takes place 50mph and up. I had the tires recently balanced and rotated just to make sure it was not something simple. This Land Cruiser is 100% stock in regard to suspension, wheels, etc…

Any ideas of where to start? Thank you in Advance.

 

[excessive]

check the front, center, and rear diff fluid levels as a first step. also grab and wiggle the driveshafts and yokes to check check for looseness / play

 

[Eyedaho]

My daughters 2002 LC with 270k miles is making deep humming sound from where under the car, no vibrations at all. This takes place 50mph and up. I had the tires recently balanced and rotated just to make sure it was not something simple. This Land Cruiser is 100% stock in regard to suspension, wheels, etc…

Any ideas of where to start? Thank you in Advance.

Possibly the plastic engine cover?

 

[Hokie99]

check the front, center, and rear diff fluid levels as a first step. also grab and wiggle the driveshafts and yokes to check check for looseness / play

Interestingly enough I changed all of the fluids in the summer and the sound is the same before and after, so I don’t think it’s that.

I am wondering if it could be the drive shafts…can I do this without it being on a lift, or does the weight of the vehicle need to be absent to check play in the DS?

Thank you.

 

[Hokie99]

Possibly the plastic engine cover?

I will check when she gets back, thank you.

 

[AlpineAccess]

Going to go with u joints or a dinged driveshaft on this one - a rear DS out of balance exhibits a deep hum and vibration felt in the seat when at high revs. Progressively getting worse.

 

[Mike6158]

Mine does that occasionally. I haven't found the problem. The center bolt that holds the front skid plate on finally gave up. It was stripped out when I bought it and I tapped it to the next larger size. When it started "humming" I was poking around under the car and noticed that the bolt was gone as well as the spacer that I had to install when I installed the lift. My thought is that under some conditions the skid plate is vibrating.

I should add that there is no vibration felt anywhere. Not in any shifter, the seat, steering wheel... nowhere.

 

[jimmyeatsworld]

Wheel bearings?

 

[Hokie99]

Mine does that occasionally. I haven't found the problem. The center bolt that holds the front skid plate on finally gave up. It was stripped out when I bought it and I tapped it to the next larger size. When it started "humming" I was poking around under the car and noticed that the bolt was gone as well as the spacer that I had to install when I installed the lift. My thought is that under some conditions the skid plate is vibrating.

I should add that there is no vibration felt anywhere. Not in any shifter, the seat, steering wheel... nowhere.

Wheel bearings?

Hmmm…didn’t think about that possibility. Thank you. I’m going to try and get it on a lift tomorrow if my mechanic is around, if not it will be next week. Thank you for bringing up this alternative Issue to look at.

 

[Tres Toys]

While you are having the wheel bearings checked, another possible cause could be the front hub flange/drive axle splines being worn. This wear can get accelerated if the proper gap between the hub flange and snap rings has not been maintained over the life of the rig. Best of luck.

 

[Hokie99]

I checked the u joints, bearings, and engine cover this morning and I can’t see anything in need of repair. When she comes back for the summer I’ll get it up to OTRAMM. Thanks everyone for your input!

 

[Eyedaho]

I checked the u joints, bearings, and engine cover this morning and I can’t see anything in need of repair. When she comes back for the summer I’ll get it up to OTRAMM. Thanks everyone for your input!

The engine cover on mine didn't coincide with speed, now that I think about it more. It would do it with vibration at idle as well. I couldn't see any issue, but removed it and the noise stopped. Just noting it for reference for other folks.

 

[abuck99]

Repeatable every time at 50mph and up?

Have you identified if it’s also RPM related? Run in lower gears higher rpm- does the noise occur sooner or still at 50mph?

When you let off the throttle at 50+ does it still make the hum?

On-Throttle hum off throttle no-hum at your target speed would point to rear driveshaft balance issue- worn Ujoints will begin to present at 30-35mph and up.

Engine skid and undercover fastened securely?

 

[2001LC]

Propeller shafts (AKA: drive shafts) aft & forward 4 spiders (AKA: U-joints), will hum if dry! Most often the sound is oscillating. Kind of a WA WA WA. Most bearings will do this when run dry. This is an early warning sound, before they're so damaged one can feel any loosen in them by hand.

She can try this:
One test is to find a long down hill stretch on HWY. Coast at 50 MPH, by shift to N. Coasting helps reduce or eliminated other sounds. WA WA WA heard! Lube spiders and repeat test!

Notes:
Various tire treads, can make many different sounds.
Checking front wheel bearings is done static, wheel off ground. Which only tells if loose, not if bad or improperly lubed.
Rear axle bearings are the hardest to check. As we need to check lateral & radial run-out with dial gauge. But 50% of time, gear lube leak is found.
FDS (AKA: CVC's) also hard to test. But grease loss a good indicator. Clicking in turns, is a sure indicator.

 

[JC w the LC]

I checked the u joints, bearings, and engine cover this morning and I can’t see anything in need of repair. When she comes back for the summer I’ll get it up to OTRAMM. Thanks everyone for your input!

Any update? Mine 100 series is doing something very similar and I’ve already replaced the rear ds and both front wheel bearings. I’ve also lubed the front side of the front ds and spindle. Couldn’t get to the circ fitting on the back side of the front ds so that one is still pretty dry. Weird thing is mine when from perfectly normal to a noticeable but subtle vibration along with the hum.

 

[JC w the LC]

Any update? Mine 100 series is doing something very similar and I’ve already replaced the rear ds and both front wheel bearings. I’ve also lubed the front side of the front ds and spindle. Couldn’t get to the circ fitting on the back side of the front ds so that one is still pretty dry. Weird thing is mine when from perfectly normal to a noticeable but subtle vibration along with the hum.

Btw, the cv axles are also relatively new. Replaced roughly 6 months ago.

 

[Fairgame]

Going to go with u joints or a dinged driveshaft on this one - a rear DS out of balance exhibits a deep hum and vibration felt in the seat when at high revs. Progressively getting worse.

Yep

 

[Hokie99]

never got any worse and it’s not bad in the first place. I’m guessing it’s got to be the driveshaft getting out of balance. I’ll check it again when she gets home for Thanksgiving break.

 

[uHu]

Is the vibration damper removed, maybe? Newbie Question - https://forum.ih8mud.com/threads/newbie-question.1315218/#post-15017059

 

[lexuslandcruiser]

never got any worse and it’s not bad in the first place. I’m guessing it’s got to be the driveshaft getting out of balance. I’ll check it again when she gets home for Thanksgiving break.

Did you ever find anything else out on this? I have a similar issue to what you described and curious if you got it sorted out