OK guys, be gentle. I hate to ask a dumb question, but here goes. Let me first say that I have worked on 2 and 4 cycle motorcycle engines for 30 years, but have only recently started fooling around with glow engines. Other than blow by passed the piston, what lubricates the bottom end of a 4 cycle glow engine? Is that it? If so, how can these little engines hold up like most of them do? What lubricates the valve train? Is there anything that can be done from a preventative maintenance standpoint that will be beneficial to the bottom end and valve train? Thanks for your help.

....periodically flood the crankcase with oil through the
breather nipple....and remove the valve cover and oil the
rockers as well. Thin some oil a little bit, and run it down
the pushrod tubes, and flood the cambox as well.

After you run the 4-strokes for awhile, you will find out that
they really don't lube from the "blow-by" worth a hoot. In fact
no oil gets to the cambox and rockers at all. They rely on the
hardness of the metal surfaces to make them last.

Dave.

I can't argue about other brands or models but I take exception to this when it comes to the OS Surpass .91's (I & II). I've run a number of these for about five years now and usually check the engines at least once or twice during the season for valve clearance, cam and cam follower wear, etc. The parts always show a reasonable amount of lubrication when I pull the covers and I never see "dry" parts. The valve clearance doesn't seem to change at all indicating no wear in the valve train.

On the other hand, I don't run my engines leaned for every last RPM either so there's always a slight smoke trail. I also use fuel that has at least 18% oil in it (but no castor), as recommended by OS.

I really doubt that the better manufacturers (OS, YS, etc.) design their engines without ensuring proper lubrication to all the parts that need it. That to me would seem to be asking for it, liability-wise.

i run my saito 72 with 22% synth oil heli fuel, 15% nitro. Runs great and also the valves always show plenty of lubrication when the covers are off... (although squirting more in never hurts!)

Anytime I've pulled the backplate off of a Saito after running it there is more than a teaspoon of clean, and in this case red oil in the crankcase, and in the 100 and 150 more than a tablespoon. A lot of people have the idea that the blow by oil should be grungy and dirty when in fact it is perfectly clean.

Been running 4-strokes since the 80's & have always filled the rocker arm cover with white lithium grease, put it back on & washed off the overage with solvent . Change it once a year when I check the valves. Have used it in cam housing on OS engines but seemed unnecessary so quit. MAX H.
.

I've yet to find the innards of a 4C engine "dry" after a day of flying.

Yep...I always hose 'em down good with oil before the first break in run, and THOROUGHLY after a day of flying. Never had a problem.

For what it's worth, my newest OS .70's breather is located right next to the cam bearing. ALL the breather goo passes over the cam/bearings before it get's routed back to the intake for recirculation.

No castor? Shameful.

'Race

The problem with putting grease in the rocker arm housing is that the rocker arm movement moves the grease out of the way where it is totally useless.

Hobbsy :The grease moves around quite a bit when it gets warm & at the end of the year a good bit is gone so it must be doing something. Many of your old real aircraft engines had a grease Zerk on the rocker shafts to lube that area . Seems better than a sharp stick in the eye! MAX H.

I run several brands of 4 strokes, Enya, OS, Magnum and Saito and ALL have enough oil in the blow by to keep the cam and rocker arms well lubricated.

My old OS FS 120 that I bought used had rust in the valve area in both rocker covers . Cleaned it all out & ran it for a summer & by fall the rust was back, that's when I filled them with grease. They should have run the crankcase vent out the rocker cover that would have given the oil a better chance to circulate. My thoughts . MAX H.

....the crankcase drain on the bottom or back of the engine
(Saitos) allows all the pressue....blow-by....oil....and
anything else gets blown out of the engine on every stroke.

I just serviced my Magnum .91FS....and the rocker area was
deviod of any fluid, what so ever. The motor was mounted sideways.
Whatever oil, or grease that was in the rockers
had been flung off, and collected on the sides of the
rocker box, and had hardened.

It was dry as a popcorn fart. The cam box had some grease
in it.....but was devoid of oil, or any liquids as well....

I have an OS .90FS mounted inverted in a plane with several
flights on it. I'm gonna check it and see if oil runs out of
the cambox.....I don't think it will, however I would certainly
be delighted if it did.... ....even if it does, it doesn't
necessarily mean that any oil got onto any moving parts.

Dave.

Isn't it funny....

That there are dozens (if not hundreds) of posts in this very forum poo-pooing the use of after-run oil.....dismissing the need to dry-run the engine (dry-run does not mean strip the lubrication from the motor) and extolling the virtues of "synthetic only" fuels.

THEN....

We see the wailing and gnashing of teeth over "dry" engines and rust.

Hmmmm.....

heh heh.....

'Race

Thanks guys. I appreciate your input.

Dirt Dauber, you best listen to us . Combined you got a million dollars of information. We don't come cheap. MAX H, & the rest of the experts on this thread