Bellhousing Plug

Looking under my truck, I saw a threaded hole in the bellhousing. I did a search and looked through the manuals and found out (I think) it is a water fording plug. My (maybe dumb) question is: does the plug belong installed at all times, and take it out to drain water after fording, or leave it out, then install it before fording? I would guess it stays in. Also, I saw in the search that it is a pipe plug (The bellhousing fordng plug is a pipe plug...square head. -brute4C, May 18th, 2007, 02:26 PM)-- does that mean it's just a regular hardware store NPT fitting?

It is intended to be installed prior to fording an removed after, many truck got a stencil or decal on the dash w/ that instruction. I keep mine in the glove box, it is standard thread, however it isnt a typical pipe plug it is flanged.

Thanks! So, in normal circumstances, the drain is just open to the environment? I'll have to look around inside and see if the plug was stashed away somewhere.

That is correct...in to ford...out the rest of the time. The bellhousing vents the oil from the leaky rear main seal on the 230, among other reasons for it being there...in the fording application, the fording valve pressurizes the axles, gearboxes and master cylinder. With the plug out, the pressurization wouldnt work and would leak out this hole. With it in, one will notice the boot on the shifter will actually inflate, thus telling you the fording system is operating as designed.

The reason for the pressure is that when one is going through water there is pressure from inside the axle or gearbox going outward, so if there is a leak it will be from the inside out pushing water away, instead of driving in water and possibly having it leak in to those components.


If you dont have the fording kit with he fording valve to pressurize the stuff, it still keeps water and mud and etc off the clutch...a good thing to protect.

Anybody have a detailed picture of one? I made one but the handle or wings are not right I'm sure.

Quote:

---

Originally Posted by brute4c

That is correct...in to ford...out the rest of the time. The bellhousing vents the oil from the leaky rear main seal on the 230, among other reasons for it being there...in the fording application, the fording valve pressurizes the axles, gearboxes and master cylinder. With the plug out, the pressurization wouldnt work and would leak out this hole. With it in, one will notice the boot on the shifter will actually inflate, thus telling you the fording system is operating as designed.

The reason for the pressure is that when one is going through water there is pressure from inside the axle or gearbox going outward, so if there is a leak it will be from the inside out pushing water away, instead of driving in water and possibly having it leak in to those components.


If you dont have the fording kit with he fording valve to pressurize the stuff, it still keeps water and mud and etc off the clutch...a good thing to protect.

---

And don't forget to switch the valve in the gas cap too.....

If yours has it....some dont..like mine.

Heres an image from Saturn Surplus of the M151 cdrain plug for the bellhousing...M715 is similiar...

http://www.saturnsurplus.com/m151/images/drainplug.jpg

Pipe plug with a flange on the head.

Quote:

---

Originally Posted by brute4c

If yours has it....some dont..like mine.

---

Really? I wasn't aware of that. What did they do in that situation then?

Mine is the non vented variety. The fording caps are vented and non vented by the position of the lever...so mine is like the fording one locked in the fording position...the gas tank would be pressurized through the vent line just like the fording one.

When I first got my truck and drove it a distance, it died and wouldnt start...checked a bunch of stuff, then realized there was no fuel to the carb...took off the gas cap and it sucked in deeply...got home and checked the vent line from the filler neck to the air cleaner...where it gets low between the tank and the air cleaner, it was full of gas...blew out a ton with the compressor...probably had been overfilled enough times over the years and it settled in the low part of the hose blocking off the venting of the tank.

Where is the fording value and what does it look like?
I do not have the bellhousing plug and my cap is non vented.

Actually the vented caps are for M-37,M-38 an other earlier trucks! by the time M-715 an M-151 came along the vented caps were discontinued.(possibly because they often got left open during fording) the correct cap for the 715 is one w/o the vent in it, although since either cap fits any truck many got the incorrect caps some where in their life. Having a fording kit didnt change the type of cap you would have used either.

The fording valve is a ball type shut off valve plumbed in at the PCV valve, and controlled by a cable from the dash, all of this is part of a fording kit.Look in the parts manual for a illiastration

I hate being told when I am looking for information to read the manual. But, the fording stuff is one of those topics where a look through the -20 will help a lot. It also will enlighten you on the "why" for a lot of the plumbing under the hood. Plus, if you try to follow the vent lines to all the drive train parts, I would imagine at least one of yours is broken off and just flapping in the breeze.

If you print out all the manuals, put them in seperate 3 ring binders and then put them next to your tv watching chair. You would be amazed at how much stuff you didn't know just leafing through them while watching something mindless like a football game.