A-702 leak

[Mogman]

I just wondered if anyone else has ever seen this problem.
I built this A-702 (Chicago) about 6-7 years ago, and it has always leaked around the helmet, I of course have inspected the casting for flaws or cracks and this is the third helmet (this was a new one from San Angelo on the mill now) In fact one of the helmets that leaked was swapped from a mill that did not leak,
This picture was taken on a very windy day so it is flowing pretty well and had just been serviced, I service this mill every quarter and even then it has been dangerously low on oil a couple times.
I have several Chicago cores and plan on building one to replace this motor this winter but still thought I would ask.

[windybob]

It's probably the helmet. The inner lip HAS TO flow oil off it inside the case edge. Also, where the inner lip and outer lip of the helmet meet, it MUST be sealed, soldered, or whatever. If you are sure the inner lip drips inside the case top, take the helmet, and clean it really good at the bottom of the inside, and seal it with some kind of caulking that will stick to the inside. The oil will run down the side, and inside the case then.

I have had multiple problems with these helmets fitting good.

[Mogman]

This is the third helmet, I have swapped them between two mills and the problem stayed with this mill, this particular helmet was purchased new.

[Ron Stauffer]

Same case and 3 helmets and the leakage is always puddled at that same place? So after higher winds, pull the helmet and see how far up from the helmet base you have oil on the inside. If you have not much oil on the inside up high in the helmet, it is probably not a fitment or an inner lip seal issue. I would look at how close the inner lip is to the pitman arm on that side or the end play of the top shaft. If anything is touching or close, it will pick up oil.

The bevel washer under the mast nut will pick up oil if not centered and touching the large gears. But with this you get oil down the mast.

Oil on the pump rod is more prevalent with the heavier green weenie Aermotor era pump rods. Or the pump rods that Randy Stubbs used to promote of making them out of a worn out next larger size mill. If the pump rod doesnt touch the mast nut it is less likely to pick up oil.

Used mast pipes and cases are more prone to leakage. We use wheel bearing grease on the stem at install.

Non pumpers will sling oil more on the inside of the helmet. A good seal and fit is really important.

Windmill ownership is much easier if you have some tolerance for noise and oil seepage.

Ron Stauffer
Montrose CO

[Mogman]

I did look at the pitman arm and the helmet and they are definitely not hitting but I did not think about if they were close enough it could "push" the oil up under the lip, that would be exactly where it would leak.
I did machine a replacement main shaft for this mill but that would only affect the pinion gears not the large gears, but it is definitely something to look at for sure.
Every mill I have works for a living no decorations here!

[Ron Stauffer]

Some pitman arm pins in the main gears allow a lot of end play and should be shimmed on the inside to hold the arm close to the main gear boss.

So you have unimogs?

Ron

[Mogman]

I used to import them 25 years ago or so, have had lots of them from the 404 up to the 424, I have only one 404 with a hard cab, radio box and a 5 cyl 3.0L turbo diesel now.
I ran one in the 1995 4wheeler top truck challenge, it had a 2.8L 280S engine in it.

[Ron Stauffer]

I hauled a radio truck for a friend out of Baltimore port to western PA. Nice trucks but I like something that you dont get older just getting to a job.

I have another friend in southern NM that is retiring and his truck is for sale. Would be a perfect fit for you...

unimog 40' wide spread 001.JPG

unimog 40' wide spread 002.JPG

Goes anywhere but dont traverse the steep stuff

Ron

[Mogman]

Nice rig, I have a knuckle truck with a winch on the boom that I can use that works great for erecting towers and working over cylinders, but usually I just hang some pulleys on the top and bottom and have a wife run the skid loader, I also have a 40' JLG lift that makes life MUCH easier.
The 404 with the 2.8L would hum along at 65 or so even with my M422 Mighty Mite in the back, really wish I had not sold that little gem (the M422)

[LoTec]

602 Aermotors with the old style single stroke big gears had a steel boss pin cast into the casting. These pins have a distressing tendency to loosen up in the gear. And, the clearance between the end of the pin and the helmet drip rim is almost non-existent. If the big gear bearing is a tiny bit off center, these pins can hit the drip rim. When rebuilding one of these mills, I like to put a bit of paint on the end of these pins and install the helmet and turn the hub a few turns and then remove the helmet and see if there are any paint marks on the rim indicating the pitman pins are rubbing. If so, I grind the ends of the pins until no paint shows.

You have a 702, which should have a more reasonable amount of clearance between the pitmen and the drip rim. But if you have this persistent leak problem, maybe it would be a good idea to drain the oil, clean the pitmen and helmet, put some paint on the pitmen, and run this little test to see if your problem is due to pitmen scraping on the rim.