Tecumseh OHH60 - any good?

[OverKnight]

I recently acquired a Tecumseh OHH60 engine off of a Cyclone Rake. It didn't look like it was used very much. I tore it down and found the exhaust valve was hanging up, and the exhaust rocker arm looked like it had been running hot, with burnt oil caked on it and in that area of the head. I removed the exhaust valve, which except for the seat didn't look bad, cleaned the stem with some steel wool, and with some oil it moved freely. I found a roofing nail in the cylinder, but I think it fell into the spark plug hole after it had stopped running, because it didn't show any signs of being exposed to combustion; I saw no damage to the piston, head or cylinder. The inside of the crankcase and carburetor were both clean.

My questions are, were these decent engines? Would this one be worth cleaning up and replacing all of the gaskets? I have a few implements that could use a fresher engine. I didn't see an oil pump, just splash lubrication; how is the top end lubricated? It appears that rocker arm and valve lubrication was an issue on this engine. Are these engines known for top-end lubrication issues?

Thank you.

[RoyM]

They were good engines in their day but the manufacturer is out of business. Parts may be hard to find.

[OverKnight]

Thanks, RoyM. Except for the exhaust valve, and exhaust rocker arm, everything looks really good. I've studied the Tecumseh Technician's Handbook for this engine, and I can't figure out how a crankcase splash lubrication system can provide sufficient oil to the valve train. The vertical crankshaft engines have an oil pump to lubricate the flywheel end of the crankshaft, but the horizontal engines only have the splash system. All of the gaskets for this engine are available.

Going back to my days with mini-bikes, I always liked Tecumseh engines. It always seemed that the Tecumseh's would outrun an equivalent Briggs.

[bgsengine]

I've studied the Tecumseh Technician's Handbook for this engine, and I can't figure out how a crankcase splash lubrication system can provide sufficient oil to the valve train.

Its an atomized oil mist - which is why the breather is in the valve cover (if it is the one I am thinking of) - crankcase pressure will flow towards the valve box as it flows to the breather to exit, it will carry along with it the atomized droplets of oil (pull a dipstick while engine is running and put your hand over it, you'll quickly collect a handful of oil, no?)

[OverKnight]

Thank you, that makes sense. I'm surprised this wasn't mentioned in the Technician's Handbook. I know that all small engines are supposed to be run at around 3,000 - 3,600 RPM, but I'd imagine if this engine was idled, there wouldn't be as much oil mist. I'm wondering why the exhaust valve was running so hot that it hung up. There was no oil in the engine when I got it, but since there was no other obvious damage, I have to believe that there was some oil present when the problem developed. Maybe this engine is more sensitive than most to running low on oil, especially the exhaust valve.
Thanks again.

[KE4AVB]

OverKnight, I think you may already found the main problem with the valve and that was the engine was very low on oil. If it so that the dipper can't touch the oil enough to create the full mist. I have seen exhaust valves where carbon deposits have cause them to hang up and actually damage the valve guides.

This engine might be an oil burner too. Sorta like the garden tiller I got finished up on. Lightly smoke while running at full throttle but at idle would fog the area. Great if you have a mosquitoe problem. It was going cost more then the one I have for sale similar to it. A rebuild with new head.

As not being mention the SM a lot service manual don't refer a lot the question some us have like the operation the voltage regulator that I was working with on a Kawasaki engine that must have battery voltage applied to it in order to charge the battery.

[OverKnight]

Thank you AVB. "Full mist" is the key phrase, with the emphasis on full. I think it had to have some oil, because I couldn't see any other signs of oil starvation. This engine clearly illustrates how difficult the hot exhaust valve can be to properly lubricate. I'll clean everything up, pick up a set of gaskets and see what happens.

Thanks again, everyone.