1862 oil usage

Ian181 · #1 09-13-2025, 07:00 PM

My niece has a Cub 1862 with the Magnum 18 h. p. engine, it was worked on on the one head because of blowing oil out the breather. The shop installed new valves and seats of that head and said to run it wide open for an hour or two so the new valves seated properly. The guy stated it could take some time for it to completely seat, but would eventually. He said it would use a little oil until they fully seated but would stop over time. Well it's been over a year and she advised me it uses almost a 3/4 of a quart of oil every time she mows her 3/4 acre yard, WTH?

ol'George · #2 09-13-2025, 08:14 PM

She was snookered, if valves don't seat from the git go, they did something wrong.
New rings in a new bore will sometimes consume a bit of oil, till they seat, but nothing like you describe.

johnwd98 · #3 09-14-2025, 08:20 AM

Unbelievable! "Run it wide open for an hour or two so the new valves seated properly". I agree with ol'George 100%

Ian181 · #4 09-14-2025, 09:41 AM

Thanks guys, just what I was thinking.

Ozcub · #5 09-14-2025, 06:39 PM

I thought valves were seated by hand using lapping paste , not at 3600 rpm
Oz

Ian181 · #6 09-15-2025, 09:06 AM

How hard is it to rebuild an M18?

ol'George · #7 09-15-2025, 02:14 PM

You might as well ask is it going to rain 5 weeks from today.
Rebuilding for me is a piece of cake. I have been rebuilding engines since I was 7 with my dad.
To do it right,ain;t for someone without experience and machining abilities or access to them.
As we here, have no clue as to your abilities we cannot answer that question with any accuracy.

I will say parts are not as easily obtained today, as old as those engines have gotten.
A lot of Factory parts are NLA and the aftermarket has dried up a bit also.
Then there is the cost.

All that said a number of ppl have successfully retrofitted with newer engines.
I personally have a liking for the M-18, prolly because it is old like me, and it is a good engine ,but fails miserably
the newer emission requirements and admittingly its thirsty when running at full song.
Someone will chime in with what they retrofitted with, and the approx. cost when they did it.

ironman · #8 09-15-2025, 04:48 PM

Quote:

Originally Posted by Ian181

My niece has a Cub 1862 with the Magnum 18 h. p. engine, it was worked on on the one head because of blowing oil out the breather. The shop installed new valves and seats of that head and said to run it wide open for an hour or two so the new valves seated properly. The guy stated it could take some time for it to completely seat, but would eventually. He said it would use a little oil until they fully seated but would stop over time. Well it's been over a year and she advised me it uses almost a 3/4 of a quart of oil every time she mows her 3/4 acre yard, WTH?

Blowing oil out the breather sounds more something like compression leaking past the piston rings would cause than bad valves and valves seats.
Additionally, suggesting to run the engine an hour or two to seat new piston rings would not be out of the ordinary.
Is it possible your niece has some confusion as to what work was actually done?
And if she's using 3/4 quart of oil, is it still blowing out the breather or smoke out the exhaust, or a leak such as a crank seal.

Ian181 · #9 09-16-2025, 09:58 PM

Thanks George, I completely understand everything you touched on. Good replacement parts are definitely hard to come by, and ridiculously expensive when you do, also a qualified machinist to true up cylinders, I'm not that person! I also know that switching to a Command Pro would require a drive shaft adaptor, fabrication of a new muffler mount/adaptor, and probably tweaking some wiring. It's a lot to consider, not to mention the expense of everything, and I probably wouldn't wish that expense on my (single mom) niece.

Ironman, I believe it may be a bad breather issue as I'm sure it has the old umbrella style installed and probably failed. I ordered the updated type today to see if that would possibly help with this, seemed like the easiest and cheapest route to try at the moment, might get lucky and solve the problem.

ol'George · #10 09-16-2025, 10:46 PM

The breather is a good place to start, be careful with the rubber breather hose they are hard to get and at that age, they are easily damaged.
Don't forget the paper gaskets.
and the little red rubber seal that looks like a piece of fuel hose it goes on the stud that holds the valve access cover on.

Look for external oil leaks like around the flywheel crank seal and other end of the crankshaft, pto end.
Using that amount of oil, if its rings it should be fouling plugs.
if you haven't already, the service manual is available FREE here on our site.
Luck!