The Stovebolt Site Forums The Shop Area Driveline Steering Gear Box Fill Plug-Vented or Not?

The other day I replaced the sector shaft seal on my '47 3100. When refilling the gear box I noticed a small hole in the fill plug (about an 1/8"), drilled vertically from the top to the bottom. This seems like an easy route for moisture to enter the gear box. It doesn't look like it would have come from the factory this way and likely is the handy work of a PO. There's no mention of a vent in the shop manual either. Are these steering gear boxes supposed to be vented? I may get a new plug and drill a 90 degree or tee vent hole configuration, if needed.

Thanks,

Ive never seen that either. Dont get the fill and drain plug mixed up.

Mine does not have a hole in it.

Doesn't that fill plug have a simple pipe thread? I believe a vent might be a good idea to prevent pressure buildup inside the box from pushing lubricant past the seals when the under hood temperature gets high, but I'd suggest drilling intersecting holes at right angles, with the hole to the atmosphere coming in from the side.
Jerry

There doesn't need to be a vent at the fill plug. My '41 steering gear box is not sealed where the steering shaft exits the gear box so that is all the vent it needs. The steering column tube keeps trash from entering the steering gear box. So it really vents to inside the cab right under the steering wheel!

I have seen a number of drilled plugs, mainly 41-46 boxes.
I am with Joe though, there is plenty of venting up the steering shaft/ column.

Thanks fellas, I appreciate all of the feedback. I've included some pics of the seal I removed. I found it interesting that the lip of the seal was faced into the gear box; however, maybe the old seal had a lip on each side and the outer one wore/rotted away? The old seal certainly looks different than the new on. The new seal was purchased from NAPA, SKF 11055 or the new part number 27SS2251. Looking at the 1947 Truck Shop Manual, I also wondered if the gear box could vent up through the steering column, which you have confirmed.

I'll get a new NPT plug and give it a try. If I run into problems down the road it can always be modified with a vent hole.

Thanks again,

I believe the seal shown is the original, or at least and original replacement. The center was felt type material and could be replaced ( packing is what they called it ), similar to a water valve. It was held in place by the small outer steel and the housing.

In the process of cleaning up my 38 saginaw box for rebuild I noticed that the top bolt on the side cover is drilled for venting. As far as the venting up the steering shaft tube, if the bushings are tight fitting and lubed there won't be much of a pathway. Personelly I don't see much of an issue either way, as its not realy going to generate a lot of heat like a trans or rear end.