My Willys 3A and 3B Community
TECH FAQ SECTIONS => Gearboxes and axles => Topic started by: Andrew on September 20, 2025, 10:14:09 PM
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On a late 1949 CJ3A with 3 spd. tranny , how much G-4 oil is needed for each the Tranny and Tr.Case, which have individual filler and drain plugs? These cases are reconditioned units, completely empty.
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Andrew,
Have you checked your Service Manual (SM)?
In Section B, there are lubrication charts that list capacities. The 2-A/3-A list 3.5 pts. The 3-B/ 5/ 6 list 6.5 pts. Seems like a big difference (wondering if the 2A/3A listing is meant for each). Nearly every vehicle I've topped off (or the only one I filled from empty) I've verified watching the filler hole and using my finger.
I purchased a pump for outboard engines that screw on to any quart bottle:
https://www.cabelas.com/p/bass-pro-shops-fluid-pump-and-lower-unit-gear-lube-combo?ds_e=MICROSOFT&ds_c=Cabelas%7CShopping%7CPMax%7CProprietary%7CGeneral%7CNAud%7CMSFT%7CNMT&msclkid=aa877b34aa831cb3187113fb57deedb5&gclid=aa877b34aa831cb3187113fb57deedb5&gclsrc=3p.ds&gad_source=7&gad_campaignid=22483857013
https://www.walmart.com/ip/Quicksilver-8M0072133-Gear-Lube-Pump-Fits-One-Qt-or-One-Liter-Bottles/17165291
And I just repurposed an empty engine oil bottle to transfer my gear oil into. I jamb and twist the plastic end so it will sit inside the filler port and pump until I see oil come out of the hole (I'm not really concerned with how much, just that it's full - which is what every garage will do too).
I know you wanted a quick answer but not knowing if you're adding from the top (shifter removed on transmission) or crawling under to add, I thought I'd turn this into a novel to add technique - in case. If you do overfill, the transfer case will spew out the breather on top, when you go for a drive, and give your jeep a good coating. I think I understand correctly that the early gear boxes did not share the lube. The later versions had a flow-through port where the lubricant would move between the transmission and transfer case. Here's a handy link from the CJ3A Info Page to explain the later version:
https://cj3a.info/tech/fluid.html
I'd recommend, since empty, filling both individually up to the fill plugs. I've consolidated using GL-4 in axles, gearboxes, steering box (per the SM) to simplify my storage. You'll want more than you need to top off later anyways.
Another handy reference is this Universal Check Chart:
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Ron: Many thanks for your write-up on this. I've filled both, first Tr.Case and then Tranns, both up to overflow level on the respective filler plugs. Tr.Case at 55 oz. and Tranny 40oz.Thats just an ounce short of 6 pints total.
I've lost my notes on how to place a new forum question:give me the steps to follow to do this,please.
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I've lost my notes on how to place a new forum question:give me the steps to follow to do this,please.
Dang Andrew! Looks like you figured out how to post a new topic/question (referencing all your new posts)! Well done.
Now that your gear boxes are filled, it will be easier to keep them topped off. My technique is to use a "marine" pump that screws into a qt. sized bottle. I keep an empty bottle from an oil change and just keep using that. When needed I fill it up from the gal. jug of gear oil.
This is the pump I bought and is real easy for me.
https://www.walmart.com/ip/Quicksilver-8M0072133-Gear-Lube-Pump-Fits-One-Qt-or-One-Liter-Bottles/17165291?wmlspartner=wlpa&selectedSellerId=101229190&adid=22222222222000000000&wmlspartner=wmtlabs&wl0=e&wl1=o&wl2=c&wl3=10352200394&wl4=pla-1103028060075&wl5=78545&wl6=&wl7=&wl10=Walmart&wl11=Online&wl12=17165291_10001248550&wl14=quicksilver%20marine%20pump%20walmart&veh=sem&msclkid=c83ee6f4fe24165e5d458e11f99faf10&gclid=c83ee6f4fe24165e5d458e11f99faf10&gclsrc=3p.ds
(https://www.walmart.com/ip/Quicksilver-8M0072133-Gear-Lube-Pump-Fits-One-Qt-or-One-Liter-Bottles/17165291?wmlspartner=wlpa&selectedSellerId=101229190&adid=22222222222000000000&wmlspartner=wmtlabs&wl0=e&wl1=o&wl2=c&wl3=10352200394&wl4=pla-1103028060075&wl5=78545&wl6=&wl7=&wl10=Walmart&wl11=Online&wl12=17165291_10001248550&wl14=quicksilver%20marine%20pump%20walmart&veh=sem&msclkid=c83ee6f4fe24165e5d458e11f99faf10&gclid=c83ee6f4fe24165e5d458e11f99faf10&gclsrc=3p.ds)
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i cheat i buy the gallon, remove the trans shifter tower an fill it up, and let it sit over nite. my t case and trans share oil