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The technical manual says to remove the plug at the bottom of the steering knuckle then shoot grease in from the top. I can find the top zerk fitting but the bottom plug is a mystery. If the plug is that bump among the four bolts securing the plate (see photo), there is no way to remove it. I'm stumped and/or confused as to the location of the plug. Help please.
Terry

That one gets grease via the Zerk in the axle housing bell via gravity. Essentially pump that baby full till it oozes a bit out the felt seals.

The internal shaft seal always leaks a bit of gear oil in there, too. Messy, but it keeps things from wearing out.

PoW

If that photo is a picture from the bottom looking up, then the nice shiny grease zerk near the top of the photo is actually in the hole where the plug should go. The plug should be in that hole when driving, not the zerk.

The lube order says to remove that plug and grease from the top until grease comes out the hole in the bottom (TM 9-8030 pg 62, figure 34, Note 6, also appearing in the newer LO 9-2320-212-12 in note 6). While the lube order is clear about greasing from the top, I've had a couple of knowledgeable people say to remove the zerk from the top and screw it in where the plug normally goes, greasing from the bottom until it comes out the top. When done, remove the zerk from the bottom, replace the plug there, and put the zerk back in the top. (Basically, they use the top hole as a convenient place to store the zerk until needed, then remove it when greasing to give an indication of grease level.)

I'm not an expert on these trucks, so don't take my word for it. I've been greasing from the bottom with good results. Hopefully someone more knowledgeable will chime in.

I'll post a picture later today. Nam Vet had one out here but it now errors off.
Gary

Here you go:

Gary - your plug looks a little different than I remember mine. Now I'm curious: I'll have to go look.

Thank you for the assistance. I'm going to climb under the axle after a three week vacation (with no grease) and see what's what.

Hi John,
Yep, that's the NOS slotted-head access plug;
Terry, happy to help-please keep us posted!
Thanks,
Gary

Hello from the UK ..
Novice Looking to buy blue M37 , .. very good condition but !!! ....

Front axle both sides has a lot of gunky grease around bit where the joint / hub is , is this normal ? or does it sound like the seal has gone?
Appreciate difficult to say but am I over stressing ? .. ... as can see there is a lot of grease goes into this part ... back axle is fine ..

just a bit anxious as getting spares / repairs probably hard over here and don't want to buy a whole lot of trouble .. though I do love it already }:> thanks
Mel

Wheel bearings get the grease, any good grease other than moly.

The Tractra joints in the knuckle live in a big wad of it, too. Normal there.

PoW

My knuckles have healed, I am back to work on my M37. I left off at getting some very helpful advice. Thank you all. Now my question is: Wouldn't a zerk fitting work well as a zerk plug in the steering knuckle? And while on the topic of lubrication, I've changed the lube in the rear differential, installed a new crush washer, but I have a leak from the drain plug. I tightened the drain plug snug. Still got a leak. I tightened it more firmly. Still got a leak. Tightened it again, this time using a breaker bar. Don't think I can get it much tighter. Still got a leak. Suggestions?

shrinx wrote: ↑Wed Aug 20, 2025 12:30 pmSuggestions?

Suspect the crush washer isn't doing its job. Try another type?

I use all copper, fits good, no leaks.
M22 Flat Washer Copper Sealing... https://www.amazon.com/dp/B09H4GDD14?re ... b_ap_share

Anneal the copper washer.
Use torch to heat it cherry red and drop it in water.
Now it will conform to any imperfections in the sealing surface.

Heating and rapidly cooling metal in water hardens it.

Heating and allowing it to cool naturally achieves annealing.

PoW

Copper is not a ferrous metal. Water (or oil) quench does not harden it. It does make it useable instantly and help reduce scale formation.