strange noise what could it be??

[84 400]

I know It could be alot of things but thought some of you 4x4 guys might be able to point me in the right direction....

Truck
1977 K10 Big 10 350 Th350 Np203 10 bolt font 12 bolt G80 rear. Still full time 4x4. 28,000 miles all fluids where changed by me in the last 2 months and no leakage. Also checked levels yesterday, greased all points and drive shaft slip yokes.

Strange piece of plastic
While greasing the zerk fittings on the front and rear drive shafts I was wiping off some of the grease and a large half circle shape plastic chunk was inside my paper towl. I could not figure where it had come from but did notice the only plastic injectod area in the drive line was the CV joint on the front drive shaft right before the transfer case.

The Problem
when driving down the road I get a large humming noise and possible a slight vibration. Feels like it is coming from the T case or Front end but it is hard to tell. Kinda sounds like a louder version of tire hum but the pitch changes with speed. it starts around 30 MPH.

A few Questions...

1) How do you inspect / check U joints. I have replaced them before but Don't know How to spot a bad one.

2) I have heard NAPA sells a rebuild kit for the CV joint on the font shaft. Can it be rebuilt or should I be looking for a new shaft if it is infact the problem?

3) On an NP 203 where do you drain the case from? I have it full of 30 w motor oil as recommended in the manual but would like to change the fluid. there is no plug so do I remove the rear inspection cover??


Thanks for any info

[Mudder]

Wheel bearing???? Hard to tell without being able to hear it. TC has to be drained from the bottom inspection cover. Good time to check out the chain.

[mudmizer]

Was the plastic about 1/4 inch across and about 1 and 1/2 inch in cercumfrence and white? If you were wiping off the slip yoke then I suspect the piece of plastic came from the plastic washer that acts a wiper/shield from the screw on collar that fits inside the cap. It is just where the yolk and spline slide in and out. U-joints? block the truck from rolling and put it in neutral. get under the truck and twist the drive shafts back and forth and watch and listen for and slop in the joints. This should tell you if you have a BAD joint but you could still have a bad or dry joint, listen for any sqeak at slow,slow speed 2-3 mph. Being full time everything is always turning check all joints. As Mudder said go over your bearings. Jack it up and spin the tires, try the play in and out from the top of the tire. Might be a good time to pull them apart and at least repack them, if they are bad it's fairly cheep to install new bearings, don't forget the new seals. You can get rebuild kits a many locations, NAPA is where I would go. All these jobs are fairly easy to do IF you know how to do them. Find a buddy who knows and work with him otherwise get it done proper.

[84 400]

I have done u joints and bearings before. I was just unsure on the right way to check u joints.

[DirtyLarry]

You might want to give the front drive shaft constant velocity joint a good look over. It almost sounds like the inner ball socket on the CV died and a piece of the nylon bushing was pushed out when you greased it. Being that it is still a virgin 203 case running full time 4x4 that front shaft gets a lot of wear spinning all the time which would be why you now feel a vibration running down the road.

If it is a CV joint….you don’t want to do that yourself IMHO. I always send CV jobs to the driveline shop to be redone. It is well worth the money to pay someone for that job.

Just an idea.

Oh, get a 203 part time kit while you are at it and save on front drive shaft wear and gas. It won’t take long for the conversion kit to pay for itself. Mile Marker still sells the 203 conversion kit. I put a few in but can’t remember exactly how to do it off hand. I don’t recall it being hard.

Good luck!

[Mudder]

Another thought is maybe the way one of your tires is wearing. Front ends being out of alignment can cause cupping and uneven tire wear.

[84 400]

Okay a little background here it think might help.

This truck was a farm truck and was only really used on the farm. Then it was given to the farmers grandson who I don't think had much knowledge on mainbrace and what not. I think the fact that it eats the gas saved the drive line from being blown apat by him. It had sat since 2000 before I traded a garden tractor for it and have been fixing it up. It does not get driven much but this noise is definatly new. the half circle peice I found was a bittle plastic. I can't ember where I was wiping when I found it as it was stuck in the paper towel and I did not notice it right away. It is about the size of a half quarter and maybe an 1/8 of an inch wide.

Both front tires are new and tread wear looks fine. The font end is nice and tight with no play at all as it should be for the millage.

once home again I am going to take a good look at the front bearings and at least repack them. I have a feeling it is the constant velocity joint and if so I will have a drive line shop do that. Or at least have them take a look at it

On the part time kit
Any info on it would be great. Would I really save that much on fuel? I know of a junk yard where I could get a set of warn hubs from and I know mile marker offers two kits. I read a wite up on it on CK5 and it seems straight forward enough. Will I really notice a difference in millage. IT IS HORRIBLE. Of course I expect bad millage but it really seems to eat the gas. I have done a fresh tune up and rebuilt the carb. It runs well and all but it gets worse millage then my 84 which has a built motor. I know the 84 gets around 14 MPG but this truck is getting far less.

Anybody have other opinions on the part time kit and how millage was effected. Logically it makes sence I should get better millage not powering the front end all the time but the CK5 write up said that millage was not really increased. Of course he could of been turning 35's and what not.

[LONGHAIR]

You will notice a HUGE difference in how the truck drives (accelerates, steers,etc.) You mileage will probably increase, but not right away....you will be driving it harder in the begining...LOL. You will also notice that you have to actually use the brakes to stop....there is a LOT less engine braking effect when you convert. It is the first thing anyone should do if they get ahold of one of these trucks. It's hard to belive that they are still out there un-converted, but they are.
The conversion is very easy for a guy with average mechanical abilities. It is straight-foreward and the directions are easy to follow.

I would also agree with DirtyLarry about having the front C/V joint rebuilt, professionally. It is very likely to be the source of your noise.

I would not be surprized to see axle joint issues either.

[Mudder]

I have changed all of my 203's with part time kits. Myself have never had any problems with the 203's. I abused them pretty good. Once had a chain come apart and replaced it for about $60 bucks. Yep you can buy 203's all day for that price around here. probably find some free ones if you look around.

[84 400]

guys which kit did you use to convert? Mile marker offers two. One you have to pull the T case and the other u can do it with the case still attached just removing the tail shaft housing for access i believe.

[Mudder]

I didn't have to remove the TC.

[LONGHAIR]

I have never had to remove one the do the conversion.
Removing a 203 is no easy task.....heavy, awkward and off balanced.