This may be a dumb question, but I'm asking it anyway. I purchased my 79 250 4x4 np435,np205 with 80k original miles. It was only used to go camping with a huge overhead camper twice a year. When I bought the truck, it had a very quiet muffler, so I immediatley noticed when I would start off from a dead stop you would hear a clang, now there is no slack, no play anywhere, I replaced the U-joints anyway, and the mechanic said It was nothing to worry about.

What do you guys think?
Also;

I changed the tranny oil shortly after purchase, with 90w, about 15k down the road I was reading a shop manual and it said to place 140w. I couldnt find a shop to change the oil out with 140 since I lost my shop and most of my tools, and the mechanics all said it was no big deal as well. They said they hadnt ever heard of using 140w.

Well now its starting to get hard to shift (especially down) I am at 125k now, What do you guys think?

 

hmmm no help eh guys???

 

If the mechanic said it was nothing you should probably stick to his judgement or take it to another mechanic. A mechanic can hear the noise and see how it is produced, we can't.

Many vehicles have a clunk or clang as tolerances are taken up when starting out. You may not be able to feel the slop but it has to be there in order to operate.

 

phew! I was hoping I wouldnt have a list of probs, I really wanted to trust his judgement as I have been Taking my cars to him for over six years. Thanks for the relief!

 

Does this sound like a real Clang.. Clank..
Like hitting a piece of metal pipe with a ball peen hammer?

If so it is probably the slack in the driveshaft.
I had this problem right from the time the truck was new.
Ford say they could do anything because everything was in order.
What I did is, take a handful high temp wheel-bearing grease and put it in the front receiver of the driveshaft.

Voila ! No more Clangggg !

 

Well Yeah, mi1lion that really is what it sounds like, thanks for the great suggestion!

 

I had the same problame, only i had a humming sound it ended up being my gears in the rear end, give that a check..

 

jack up the back of the truck and turn the tire, watch the driveshaft, turn the driveshaft back and forth, hear any weird noises or clunking sounds?

the transmission: i would not put 140w oil in there, that will be very hard to shift in the cold months, stick with the 90w oil