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I have an old Sears Roto-Spader tiller, something like this one, with a 3.5 or 5 HP B&S engine. (At least I think it's a B&S; there are no surviving labels anywhere on it.)

Recently oil started bubbling out around a bolt on the sheet-metal shroud at the back of the engine. In this picture, I have taken out five long bolts that fasten the shroud and cylinder head to the block, and removed the shroud:

Oil is bubbling out of the bottom middle bolt hole, and it make also be leaking out elsewhere under the engine--a bit hard to tell--but enough oil to smoke on the hot cooling fins.

In this picture, I have taken the head off:

There is oil on the mating surfaces of the cylinder head gasket, and generally around the bottom of the engine. There is also oil visible around the piston. The head gasket itself (not shown) has a small amount of damage to the mounting flange, and the seal has some carbon deposits and wear, but there are no visible breaks or nicks in the seal.

Does that seem like a leaky head gasket? Or does it seem likely that there is another problem, e.g. bad seal around the valves or piston ring?

Many thanks,
bluemower

Definitely shows signs of a blow head gasket. Can you post a pic of the carb? It will allow us to identify the engine manufacturer. Look very carefully at the top and sides of the shroud. Engines that old most times have the identifying numbers stamped into the metal.

No markings or nameplate on the shroud or anywhere else on the engine, that I can find. A picture of the carburetor and air filter is attached. The carburetor has a small "178 B" or "B 178" cast into it, visible in the photograph.



I'm also attaching pictures of both sides of the head gasket. By way of scale, this measures 4.875" side-to-side, measuring between the centers of the two opposite bolt holes. Is this what a blown head gasket looks like?



Many thanks,
bluemower

I've just been told by the previous owner that it's a Tecumseh engine. It is not original to the tiller, but was pulled from something else when the previous engine died. Don't know how to move this to the Tecumseh forum.

You have a Tecumseh engine, my guess is a VH50. Pic of the head gasket shows that the cylinder was leaking through the burned out corner. Is that the corner where you saw oil coming out? Take the head gasket to a good repair shop and they should be able to match it for you. Any other questions post back.

New head gasket appears to have cured it. And I think you are right about the VH50. Many thanks, bluemower