Bad Noises

[76BigheadFJ40]

As I was driving home today on the freeway, my truck sounded fine, but when I let off the gas, a grinding noise seemed to be coming from the front right-ish area of underneath the body, but also right underneath, like the transmission is grinding against itself or something? Then, on the same drive, it started doing it more and more, so whenever I shift, it makes the noise, but while accelerating it does it, and when I lay off the gas, or brake, but once the truck has stopped, the noise stops. Please Help! It's a 76 FJ40, stock parts underneath, and I don't know what to do.

 

[rgentry]

Check the driveshaft bolts first. They come loose and cause
all sorts of bad noises.

If not that, then:

U-Joint (grab the driveshaft an shake it)
Ring and Pinion (grab the pinion flange and shake it)
Transfer case (not sure how to diagnose)

 

[nhfj40]

I had similar problem and it turned out to be the output spline on my 4 speed was worn where the t-case drive gear sits.

 

[Vitesse_6]

I second the DS bolt's, Happend to me, Now I check them every time I go wheelin
Never hurts to start small and work your way up.
Good luck

 

[sherwood]

'Very thing happened to me tonight. Half way to work..... let off gas..... roar/grind. After a little head scratching.... turns out the T-Case lever had been knocked slightly out of 4Hi when I tossed my gear in to go to work. You might check the linkages.

John

 

[IDave]

The sound you describe also reminds me of the front drive shift, as John Sherwood submits. That is definitely a "grinding" sound, whereas the loose driveshaft bolts cause more of rapid clunking vibrating sensation. That said, common things are common, and loose ds bolts are that for sure.

 

[65swb45]

Ditto on everything said. Pretty much covers the most likely suspects. You're in good hands here.

 

[RUfj40crazy]

Linkage check for sure... May want to give the hubs the once over. A friends nissan xterr was making some killer noise, turns out it was a linkage of some sort in the front right hub. I know the 40 dosent have one but it was causing the auto lock to grab the line and twist it in the axle. Just a thought