Rhythmic rumble

[markp2]

Hi Folks,
Wondering if anyone can help track down a rumbling sound coming from under the body of my Gen 3?
It occurs at all speeds and increases in frequency with road speed - transmission related I assume.
The noise stops when you brake but is still there if you coast in neutral. It doesn't seem to be coming from any one corner of the car but can sometimes be felt through the throttle pedal.
I have checked all the transmission oil levels, greased the props and checked the wheel bearings for play. All the wheels turn freely without any noticable noise.
Any ideas?
Thanks,
Mark

[muddle]

You need to jack all 4 an listen for noise, could be tyre noise. Is it fron or rear

[markp2]

Thanks for the suggestion. The tyres have been changed recently but it was there before (which is one reason why the tyres were changed).
I have jacked both ends and spun the wheels - all run quietly. The noise isn't coming from anywhere specific - sometimes I think it might be at the front and other times it appears to be behind me.
Cheers,
Mark

[BarraSSRX]

More rattles than rumbles... but the fan shroud that bolts against the radiator sometimes noisy if bottom bolts are missing, you could check if it's loose anywhere, or one of the bash guards missing a bolt or two could cause rattling underbody

[markp2]

Thanks Barra.
It is definately a low tone rumble which rises and falls in volume - sounds rather like a washing machine doing it's 'wash' bit.
Mark

[benjo]

the rumble that rises with speed would suggest to me a wheel bearing or possible prop shaft carrier? this is what i would be looking at on other cars but as a mechanic but new to surfs so i stand to be corrected. have you tried jacking each wheel and check for side to side/up down movementand check for play in your prop

[TonyN]

Noises that stop with the brakes being used are usually wheel bearings as the pads/shoes help support the bearing so the noise changes as the brakes are applied.

You can ease the handbrake on gently to see if its the rears.

Assuming its isn't just worn/loose brakes themselves.

Check the UJ's too though.

[markp2]

Update on this.
I couldn't isolate the corner the noise was coming from - thought it was OS front but couldn't be sure - so bought bearing kits for front and rear from RT.
Village garage identified (guessed?) NS rear and were right. They fitted the new bearing kit. Glad I didn't try it myself because the various collars and bearing races were very tight.
All quiet now (and some spare bearings in the shed for next time).

But........ wife's Gen 3 has started leaking oil from the front transfer case seal. Oh, the joys of running older vehicles!!
cheers,
Mark