Some maintenance questions for 1994 LC (1 Viewer)

[NY2NC]

After bleeding the brakes and seeing how dark it was, I'm looking to replace all fluids. I've already done a coolant flush. I was looking into the differential/transfer case gear oil change. Is it recommended to do those? I saw one YouTube video where the guy says he does it every 3k. A bit excessive?

I also get a whining noise that starts around 30mph, and it's particularly noticeable (loud) around 40-50mph. It only happens when I press on the gas. If I let the pedal off, the whining disappears. Common 80 series issue? Or should I have it checked out.

 

[JohnVee]

1. Change the diff oil. Change the transfer case oil. Make sure you unscrew the FILL plugs first or you'll hate yourself if it doesn't come loose after draining all the fluid. Every 3000 miles is a fool's waste of money unless you frequently drive through deep water.

1(b). Unscrew the square bolt on the knuckles and stick something in there to see if they're about 3/4 full of grease.

1(c). Start the transmission flush process and follow up at every oil change. Look this up in the 80 FAQ's. You'll need to put in exactly how much comes out, and it won't be the entire capacity of the transmission.

2. I think they all have some degree of whine like that.

 

[NY2NC]

Awesome! Thank you so much John! Sucks about the whine though. I didn't hear it initially because my exhaust leak was loud. After I got that fixed, I started noticing the whine. Oh well.

 

[fourtrax]

+1 like the Vee said.

use some mobile 1 or Valvoline gear oil for the diffs about 3.4 qt for the front and 3.8 qt for the rear i think and about 1.4 qt for the t-case. Any GL-5 rated 75w-90 or 80w-90 is fine. you can use conventional or synthetic, it wont care which you use. maybe change the fluid every 50-60k unless making deep water crossings. also check you vent hose caps ( axle breathers) they can get clogged up.

## it is a good idea to replace the washers on the drain plugs every couple changes they are a wear item. ##

i usually remove the transmission plug, let it drain then reinstall plug and add 4qts.

check your u joints for wear and grease them as well.

 

[roadstr6]

What JohnVee said and also this: Whining noise / vibration when on/off the throttle can be a u-joint going bad. Typically the front ones are the first to bite the dust. At least that has been my experience. In addition, check both differentials where the driveshaft attaches for any play in the pinions. Could be a bad pinion bearing. I was hoping you'd come out to the Charlotte meeting yesterday to introduce yourself. We had a great turnout. Check us out some time.

 

[sogafarm]

Check brake caliper bolts for torque as well as driveshaft bolts, they come loose and fall out sometimes. The whine may be coming from u-joints, check for excessive play and lube with grease.

 

[jfz80]

Everyone is pretty on point with the recommendations

I know you just did calipers but wont hurt to check for 90 ft/lb on each of them now that you have added some miles.

Whining as described to me would point to pinion but best to start with the easy stuff as said. Lube u joints, check for play at flange while your are there. Mine has had a whine for quite a while I suspect is pinion and it will likely let you know before it gets worse without risk of catastrophic failure.

50k is a good and easy to remember interval for the 3 diff's fluid swap. Definately check the breather. If they clog it can cause the diff to suck in moly grease from the knuckles when it cools. If you find grease has entered the housing contaminating the gear oil maybe buy some cheap 90w and do a few more frequent swaps to flush it out. thats the only reason id do the 3k mile interval.

 

[NY2NC]

What JohnVee said and also this: Whining noise / vibration when on/off the throttle can be a u-joint going bad. Typically the front ones are the first to bite the dust. At least that has been my experience. In addition, check both differentials where the driveshaft attaches for any play in the pinions. Could be a bad pinion bearing. I was hoping you'd come out to the Charlotte meeting yesterday to introduce yourself. We had a great turnout. Check us out some time.

I saw the meeting invite, but I couldn't come out. I had previous plans. Is it a monthly meet?

 

[SFROMAN]

What JohnVee said and also this: Whining noise / vibration when on/off the throttle can be a u-joint going bad. Typically the front ones are the first to bite the dust. At least that has been my experience. In addition, check both differentials where the driveshaft attaches for any play in the pinions. Could be a bad pinion bearing. I was hoping you'd come out to the Charlotte meeting yesterday to introduce yourself. We had a great turnout. Check us out some time.

The drive shaft u joints are the one thing I didn’t inspect, grease or replace when I bought mine and my front drive shaft failed on one of our road trips. So don’t overlook this.

 

[forrest5000]

I saw the meeting invite, but I couldn't come out. I had previous plans. Is it a monthly meet?

Yes , ill send you an invite next month also.

 

[NY2NC]

+1 like the Vee said.

use some mobile 1 or Valvoline gear oil for the diffs about 3.4 qt for the front and 3.8 qt for the rear i think and about 1.4 qt for the t-case. Any GL-5 rated 75w-90 or 80w-90 is fine. you can use conventional or synthetic, it wont care which you use. maybe change the fluid every 50-60k unless making deep water crossings. also check you vent hose caps ( axle breathers) they can get clogged up.

## it is a good idea to replace the washers on the drain plugs every couple changes they are a wear item. ##

i usually remove the transmission plug, let it drain then reinstall plug and add 4qts.

check your u joints for wear and grease them as well.

So not having ever done this before, since most of my previous cars have been FWD or RWD...

The front/rear diff and transfer case all use gear oil? And then the transmission uses transmission fluid?

 

[jfz80]

Correct.

 

[NY2NC]

What size sockets are required? You guys just use a generic pump to fill fluid?

 

[fourtrax]

24mm for the diffs and the transfer case.
I think the drain plug on the transmission is either 14 or 17 mm I don't remember.

Do you have access to a factory service manual?

 

[NY2NC]

24mm for the diffs and the transfer case.
I think the drain plug on the transmission is either 14 or 17 mm I don't remember.

Do you have access to a factory service manual?

Nope, but it's something on "my want list".

 

[forrest5000]

Over on upstate ,Marshall has the download for the 94 .for free .Its under FSMs

 

[forrest5000]

FSM's

[update: these are no longer available at the links below] MUD now has a Resource tab at the top of the Navigation bar: Resources - https://forum.ih8mud.com/resources/ You may find what you are looking for there. Manuals Chassis and Body 1958-1970 1971 Chassis & Body manual 1975...

forum.ih8mud.com

 

[NY2NC]

FSM's

[update: these are no longer available at the links below] MUD now has a Resource tab at the top of the Navigation bar: Resources - https://forum.ih8mud.com/resources/ You may find what you are looking for there. Manuals Chassis and Body 1958-1970 1971 Chassis & Body manual 1975...

forum.ih8mud.com

Thank you!

 

[NY2NC]

i usually remove the transmission plug, let it drain then reinstall plug and add 4qts.

So, I could do that? Every YouTube video I'm finding, the guy is pulling off the pan, replacing the filter, and then doing a flush. My transmission is very smooth. So, I figure if it ain't broke, don't fix it.

 

[fourtrax]

Don't pull the pan off if it's not leaking around the gasket. These transmissions are way over built. Just pull the plug, drop the oil, replace the plug, add 4 qts of ATF, roll on. I usually do this every 3 or 4 oil changes. This way you replace 1/3 of your transmission oil every 15-20k