First gear growl

[meatshieldchris]

I've got some growling happening in a new-to-me '92 4x4, coming away from a stop. I initially thought it was clutch chatter, but I quickly realized I could make it happen with the clutch fully engaged, simply by being rolling, clutch fully engaged, rpm at about 1500, then just giving it some gas. I can't make it happen by doing the same in 4rth or 5th at low speed, so I don't think the clutch is slipping. I can put it into 5th at about 30km/h, hammer on the gas, and the rpm doesn't increase like a slipping clutch would, and it doesn't sound anything different than just lugging it in the wrong gear (I can't really hear the growl, but maybe the lugging is masking it). Also, I can make the noise lessen over about 2000 rpm and dissapear completely over 2500 rpm.

The more I drive it, the more I think it's limited to just first gear. After a long highway trip, there's a slight knocking or ticking sound. It seems to quieten down and fade away if I hold the clutch pedal in. Release bearing noise? Could this be causing clutch chatter? Could glazing due to chatter cause continuing chatter even with the pedal fully out? Or do you think this is a first gear transmission problem since I can't duplicate it in other gears?

Any other tests I can do to narrow it down?

 

[meatshieldchris]

hmm, driving in to work today, I'm starting to think output shaft bearing...it might be speed sensitive rather than gear sensitive, I'm just blowing past the first gear speed so fast. How can I confirm that before I dig in? Remove the transfercase and check for play? I do have a little bit of ATF leaking from between the tranny and transfercase, might be related?

 

[creepinjeepster]

You say first gear growl, I'm assuming you have a manual tranny, correct? In your second post you say you have a little bit of ATF leaking from between the tranny and transfercase.

If you have a manual tranny, it doesn't use ATF. It should have 90W gear oil in it. ATF (Automatic Transmission Fluid).

 

[meatshieldchris]

Yes, manual transmission. I have the Mazda M50D-R1 transmisison, which according to http://www.therangerstation.com/tech_library/ManualTransmission.html says it requires Mercron ATF.

 

[racsan]

yes, the M5OD manual trans does take a.t.f. have you listened close while in nuetral with the clutch both in and out, could also be a input shaft bearing, if the fluid has gotton low i think thats the first thing that gets the damage. mine has a slight noise while idleing in neutral, when i push the clutch in the noise slows then stops.

 

[meatshieldchris]

yes, the M5OD manual trans does take a.t.f. have you listened close while in nuetral with the clutch both in and out, could also be a input shaft bearing, if the fluid has gotton low i think thats the first thing that gets the damage. mine has a slight noise while idleing in neutral, when i push the clutch in the noise slows then stops.

Hmm, yes, that's exactly what I'm hearing for the "ticking at idle in neutral". when I push the clutch in, it gets quieter then stops. When I got the truck, it was almost 1.5L low on ATF, so I would totally believe your diagnosis. Wouldn't it growl at similar rpm's through all gears if it was an input shaft bearing?

 

[racsan]

it probly does, but the other noises mask it. i have a hurst shifter and i get a bit of noise from it vs the original stock setup. theres also tire noise, noise from the engine as its it different r.p.m's. you may have leaking shift rail plugs, its a common problem. if it is indeed leaking at the output shaft between the trans/transfer case its leaking into the adaptor between them, there is a drian hole at the bottom of the spacer/adaptor where it would be leaking atf from. heres a link describing the shift rail issue and possible fixes. i went with the r.t.v. fix myself.link-> http://www.therangerstation.com/tech_library/shift_rail_plug_maintenance.htm

 

[meatshieldchris]

Thanks for the response. If it was the shift rail plug leak, wouldn't I be getting fluid down the side of the transmission near where the shifter connects?

 

[racsan]

possibly, there are a few varibles, such as airflow under the truck while moving. its a common issue, so i thought id mention it. mine had oil and dirt all over the back half of the trans.

 

[holyford86]

could be a bad inner boot causing leaking down the back half of the trans as well

 

[meatshieldchris]

hmm, could this be the hangar bearing making that noise and vibration? I just noticed the rubber surrounding the bearing is cracked and I've got a lot of vertical and side to side motion if I push and pull on the driveshaft in that area...

 

[meatshieldchris]

just an update: started replacing the center driveshaft bearing...ooohhh that's probably what the noise is. THe rubber is pretty well missing from the bearing, and the U joint that's right next to the bearing is seized completely in one axis.

I didn't think to check this first, because I thought a driveshaft problem should increase with speed. The final U-joint will go back in tonight and I suspect my problem will be gone.