Nice truck with one prob

[trailbreaker]

I just got an 87 blazer and i got a prob. when ever it is really cold out the speedometer jumps aound 5 -10 mph at a whatever speed i am tring to drive at. I was hoping that someone could shed some light to my prob.

Also if i run my heater until the inside of the truck is warm it stops. could this mean the speedometer is messing up? where can i get a new one at?

any help would be great. thanks for looking at my thread

 

[AkMudr]

You mean the needle bobs back n forth? Mine does the same..I have heard its the speedo cable but it never bothered me enough to change it, lol.

 

[Russell]

Easy to fix

Simply pull the cable out with a pair of pliers ( out it's housing) coat it with white lithium grease, and send it back in Whats happening is when it is cold, the speedo cable is dragging in it's housing

 

[jac6695]

Thats an easy one. The speedo in my 97 does the same thing at idle, truck not moving, when I start the truck if it is cold. Remember, in 97 the trucks have speed sensors and full electronic speedometers. I really cannot figure it out, and it goes away by the time the glow plugs cycle a couple of times, so I think it is some kind of electrical interference from the glow plug controller.


BTW, did you get your lines yet?

 

[diesel4me]

My speedo sucks too!

Your lucky it just jumps around!--The speedo on my 79 C10 makes a variety of weird noises,depending on speed and temparature--sometimes it sounds like a bird singing,or a bearing knock(had me worried,right after I swapped in another motor!),or it also can make a grinding noise--I've tried pulling the cable and lubing it up,and even took the dash cluster apart and tried applying some graphite type heat riser penatrating oil lube to the oddometer and speedometer head unit,it stopped for a day or two,and now its louder than ever--it usually goes away or at least quiets down after the cab warms to room temparature..,and does not do it every day..

I guess I will have to replace the speedometer someday--the truck has 114,000 original miles,so I hate to swap in a dash with different oddometer readings,but for the sake of my sanity,I might have too!- -I'm hoping too find one in the junkyard with mileage close to mine....

 

[3 on the tree]

If I am thinking right, the speed drive is a friction drum. When its cold, they slip and grab erratically, then they warm up and work properly.If you can get it apart, look inside the drum for wear marks, smooth out gently with 150 sandpaper