Rear Main Bearing Cap Oil Drain Pipe?

[Daves43GPW]

I am in the middle of tearing my L134 engine down for a complete rebuild. This engine came out of a �49 (I think) CJ3A that had been sitting outside without a distributor or spark plugs for several years and is pretty well seized. In doing some Google searches I noticed alot of L134 have an �oil drain pipe� that is attached to the rear main bearing cap. I am finding no such part in my engine. Was this something that was only on the original chain drive engines?

It looks like somebody had previously been inside this engine as the crankshaft was turned down to accept 0.020� undersized bearings. I also discovered the oil pump float and support bracket are damaged so I�m pretty sure if who ever was inside this engine before didn�t know what he/she was doing.

Thanks and Best Regards,
Dave

[athawk11]

Hi Dave,
Welcome.

I Took part in the same question a few years back.  My first L-134 was a GPW engine with the drain tube.  I opened up a 3A engine.  It has a drain tube.  I opened up a 2A engine.  Same thing...drain tube.  Here is that discussion.

http://www.thecj2apage.com/forums/rear-main-bearing-cap_topic28141.html

 It's not very definitive...at least from my point of view.  If true why does this engine have a drain tube?






Again, this is just one 3A engine that, according to the posted conversation, doesn't exist. 

Others here may offer some additional information.

Tim

[1955CJ-5]

The model A engine has a similar tube.

It is an oil drain tube for the rear main bearing.

It's purpose is to allow the oil to drain into the pan, but it drains it below the surface of the pan's oil reservoir.

This prevents the positive pressure in the crankcase from forcing the oil out through the main bearing and onto the garage floor....as it would if the rear main were simply vented into the crankcase cavity

I believe that with the addition of PCV valves the pressure in the crankcase is reduced so it was no longer a problem...

Here is a picture of the Model A engine drain tube...the model A has no rear main seal, just an oil recovery trough so it's a necessary part...

[Daves43GPW]

Very Interesting, I'm glad other people have wondered this also.

I could see no practical purpose for this pipe, but did not think of the crankcase pressure forcing oil out through the seal.

Didn't Willys change the rear seal design from rope to a rubber type in the early 50's? If so I wonder if the engineers decided the oil return pipe is no longer needed with the new seal design. (I did remove a rubber type seal from this engine)

Thanks,
Dave

[athawk11]

Dave,
Yes the rubber/neoprene seal started to show up about the same time the government wanted a Willys that could ford through fairly deep water...the M-38.

Tim