If it’s not one thing.... it’s the other. (Leaky RMS)

[MikeEyre74]

So after splitting the tractor (1975 185) to change transmission gears and shifter forks, I get it all back together and go for a test drive. It’s a little noisy, but things seem to work well. Once I get it back in the garage I wake up the next morning to find a nice puddle of oil coming from what appears to be the rear main seal area.

<sigh>

I knew when I purchased this tractor that it was going to be a little bit of a project… But I did not know that it was going to be several projects all in a row!

[mozer71]

That seems to be a lot of oil when the crank case isn't even pressurized. The fuel cut-off below the tank can leak if open and no draw to it. The fuel drips ( on mine) traveled a route of oily surfaces to around the RMS. Now I shut it off after use but I know the RMS is in the future.

[outdoors4evr]

Since you are already there...
When you get your rear main back from machining, use a punch and stake beside the seal so it can't move. The seals seem to spin in the retainer when the metals get warm. (Aluminum and Steel expand at different rates) If you stake it in, it won't spin, wander, and create a cup for oil to drain out.

Buy an oil pan gasket and a rear main seal retainer gasket. Use RTV at the corners (between oil pan and rear main retainer). This is a good chance to clean out the sludge in the bottom of the oil pan and get a good look at the bottom end of the engine.

Before reinstalling the oil pan, flatten the rim of the pan near the bolt holes. The pan edge tends to pooch upward at the holes making the pan gasket not seal well and can seep oil. Make the pan edge very flat and don't over-tighten the bolts.

[outdoors4evr]

At least this is one job that nearly every numbered series needs to have done. We are very fortunate to have talented guys around who figured out how to improve on the design!

[MikeEyre74]

Thanks for the advise, fellows. Mozer, unfortunately for me, I know this is an oil leak. I also have to shut my fuel off after use or she’ll leak as well, but this is clearly oil. No such luck on a leaky fuel bowl for me this time.

[mozer71]

We have this great guy who just posted. I can elaborate on his advise to flatten the bolt holes to level. It is just garage stuff at hand. Stack a 12 point socket upon a length of socket extensions so that the pan lip height is even. The socket is just a bit wider than "pooched" area of the hole/s. Find a machine or socket head cap screw which fits the hole. Now you can pound on the screw head while the extensions provide support.

[mozer71]

I'm surprised nobody mentioned a hardwood slat. I've used that method before. Using stacked sockets is more precise as to what I was getting to. Again, it has been used a jillion times but worth mention. Some areas are more "pooched" than others. The SHCS is used as a screw press. It fits through the required socket diameter and continues to another- holding the nut. More precise than pounding.

[MikeEyre74]

So I cleaned up all the oil and junk around the oil pan and underneath in the rear main seal area and then fired it up and let it run for a bit while I set up my clutch brake… It ran for 15 minutes with Mary a drop in sight. I turned it off, and about 10 minutes later I got a couple of drops starting to form on the floor. I can’t tell for certain if it’s actually the rear main seal, or maybe just an oil pan leak? It seems to be coming from the corner bolt area only, closest to the left rear tire. I tightened up the oil pan bolts, and I guess we’ll see what happens.