Seems Fine, But......

[rbbailey]

OK, so I have finally got my truck running after nearly 3 years. But all of my work was very basic: Just Get It Running.

So I took it to the local Rover guru, and he dialed it in really well. Finally got the new dual brake system working. nailed down the timing, tweaked the carb, fixed the choke, etc, etc.... It runs so nice and quiet now, right at start up even, no coughing and such till it warms. Then when it warms up, I can push the choke in all the way, and the idle is just perfect. I have never been able to run it with the choke all the way in in 10 years!

Anyway... It runs and drives well, except!...

When it gets to higher RPM's, there is a deep growl that develops. And if I am, for instance, putting along at 50 mph, in 4th gear, then begin a hill climb, it will start to slow, so the RPM's also slow. The truck has no problem going up normal country road hills, as long as I don't demand too much of it. But when those RPM's drop, so they are in the lower half of the band for that gear/speed, there is a distinct knocking that develops. This is under load, but not torture.

The other thing is that I cannot replicate this in the garage in neutral, it only happens when under load when driving. It is almost certainly coming from the back of the engine some place. I do not have the front drive shaft engaged, and the hubs are disconnected.

Any ideas?

[SafeAirOne]

Are you sure of the location that the sound is coming from?

My first instinct would be to examine the universal joints on the rear driveshaft.

Does it do it in every gear under heavy load?

[rbbailey]

I know my front shaft is bad, and I have to say that the last time I drove it I did not notice the sound it usually makes --- maybe that is changing? (I keep the hubs free.)

However, I noticed this sound along with drive shaft sound before....?

First gear it is impossible to tell. Too short, too loud.
Second gear I have not been able to tell because that is pretty much never used under the same type of circumstances long enough to discern -- I will test more closely.
Third gear, yes. Same thing. Lower end of RPMs like when torquing up a hill at driving speed -- 25-30 MPH.
Fourth gear yes, as described above.

Thanks.