Hello everyone. I just placed another used engine in my 1999 dodge ram 1500 3.9L. Only new things I replaced were the timing chain, both sprockets, and the tensioner, also replaced some of the gaskets. I've only put about roughly 300 miles on it since I got it. The salvage yard told me had 98k on it. After I placed in motor in I forgot to put the two bolts on the transmission at the cross member. So when I went to take a test drive in it pulled over turn around I hit a hard bump and took off again. I started to feel this high vibration or rumble from the transmission all the way to the stick shift. Also I have a 5 speed M/T. The vibration or rumble won't start doing this until I reach 55mph. Other day I bolted up the transmission how it should be, but still have the rumble and vibration cing from the transmission. I know my differential pinion bearing is going out because I hear a clunking noise less than 5 mi but goes away when I speed up and no problems there but could that cause my problem too? Information on how to diagnose this problem would be very helpful.

 

Take a look at U-joints as well...... they may not necessarily be loose, they might be dry, and tight.....

 

Yeah....kinda difficult to diagnose from a distance and with the info provided. I would also recommend a close inspection of u-joints and I'd give the pinion a good shake in every direction to look for any play. Your description doesn't convince me your pinion is on the way out necessarily, but it certainly is possible

After driving carefully feel each u-joint cup for excessive heat. Sometimes they're tight but dry and will tend to run hot(ter than the others)

Is this a 4wd?

 

No it's 2x2 rwd.

 

I’d take a look at the tranny mount too…..mine had a vibration at higher speeds and a clinch when I shifted into gear (auto trans)

my mount came out in three pieces but looked ok just looking at it…..when I took a pry bar did some investigation I found the mount and rubber had completely separated and one of the ears was broken off but looked fine when in the truck….nope….new mount now no issues

 

So I drove around today got it to normal operation. I carefully looked around underneath the cab. The U-joint seem to be okay, but I noticed theirs a rattling noise kind of excessive like taping on something or so. You hear it more near the bell housing and near the middle. I tried up loading a video, but won't let me which sucks. Also this is a manual transmission 5 speed. What might be that problem?

 

You can upload the video to YouTube and provide a link to it in your next post.

Did you have a chance to check the transmission mount as was mentioned earlier as a possible solution to your issue? You might also want to check your exhaust hangers closely, too. Lastly, might also want to have someone rev the motor and listen closely to the catalytic converter - sometimes, the substrate inside of the cat can break off and make a rattling noise.

 

This is the noise I've encountered.

 

I also checked the transmission mount and the rubber mount and their both good and bolted it up and snugged on their good. As far my exhaust goes when under the cab I didn't notice anything wrong with the hangers everything looked solid, but I'll look little more closely tomorrow when I get the chance.

 

Does the noise change or go away when you depress the clutch? If so, it could be the throw-out bearing.