Chirping noise upon acceleration from stop coming from under truck bed


#1

I have an 87 longbed Dakota that I bought new. It’s my work truck. Lately it has developed a chirping noise that I hear best with the rear slider window open. I think it is safe to say that it is not coming from under the hood. When I accelerate from a stop the chirping noise increases in pitch and frequency. The frequency does not change when the auto trans up shifts. There has been no noticeable out-of-the-ordinary vibrations, even at freeway speeds. I have stopped driving on the freeway since the chirping became impossible to ignore. The chirping becomes less and less audible the faster I go as the pitch and frequency increases. When just starting from a dead stop, it sounds like a metallic scraping noise. Whenever I take my foot off the gas the chirping stops, even when still coasting, so it only occurs under load. It does not occur when the truck is stopped and the engine is revved. Does anyone have a clue?

Thanks,
Jack


#2

Sounds like a bad universal joint.


#3

Check to see if there’s a hanger bearing for the drive shafts between the transmission and rear differential.

If there is, that bearing could be bad.

Tester


#4

There is a hanger bearing. It’s a two-section drive shaft with three u-joints. I too suspect the u-joints and hanger bearing, given all the symptoms. I have been debating taking it to a shop versus doing it myself. Ebay has ball joint/u-joint clamps for sale for $40. I’ve done more difficult repairs on this truck, including replacing the head gaskets.


#5

I can’t speak to your make/model, but I’ve replace u-joints on my Ford 4x4 truck without much difficulty. I used to take a 3 hour auto shop class at a local high school and I could drive my truck into the bay, remove the drive shaft, replace the u-joint, re-install the drive shaft, and be done with plenty of time for a cup of coffee and gabbing with the other class members before the class ended. I didn’t even use a press, just a socket and a hammer.

If you do it yourself, the key thing to remember is to place witness marks on all the parts involved, so you can get it back in exactly the same orientation as when you took it off. Otherwise you may battle out of balance driveshaft vibrations.


#6

Thanks for the heads-up on the orientation marks, George. I had come across that when reading up on the process but it sure doesn’t hurt to drive that point home. As to the hammer and socket method, some recommend against it and some do it no other way. I’m leaning toward dropping $40 for the clamp/press on eBay at this point.


#7

Let us know what you find. It does sound like a dried out u-joint.


#8

I will definitely post the results. When I get all the parts assembled and the u-joint clamp I will get right on it.


#9

It was the u-joints, at least one of them. I got all the new parts assembled, yanked the two-part drive shaft, took the front shaft to the driveline shop to get the old carrier bearing pressed off and the new one press on, came back and pressed off the rear u-joint near the differential. The needle bearings under one cap had turned to rust and dust, the others were on their way there. Then the sun went down. I’ll finish up tomorrow.


#10

I know this is an old thread but maybe this will help someone reading this. To quiet my bad u joint I would get the oil squirt can and either squirt some oil all over it or pour some right out of the container. Just drench the hole joint. I had a lift kit on my 1977 Blazer so all I had to do was slide under to do it. This was a yearly ordeal with the angles on mine. The oil would give me a couple or three days of silence until I had time to put a new one in.