Hello

[bertsmobile1]

It sounds like a leaking head gasket, loose inlet guide or broken flywheel key .

However to be double sure take the plug out and poke a long screwdriver down the plug hole till it touches the top of the piston.
put a little pressure on the piston and with your other hand turn the engine over 2 full revolutions.

The piston should move smoothly from the top to the bottom of the stroke.
Now if the piston clicks or suddenly drops as the motion changed from in to out then the rod is gone.
The two valves you just adjusted should sit at identical heights when the rockers are not pressing on them.
If not then one of the valve guides has slipped.

These engines generally blow the head gasket between the bore & the pushrod tube but occasionally they go between the bore & one of the valves

 

[Rotoblade]

How can I tell if the head gasket is blown? It seems like when you start it it sounds like a loud exhaust noise coming out of the intake. Also loud the last few rpms of the engine. Kind of sounds like a engine without a muffler at the times it makes this noise.

 

[Rotoblade]

How can I tell if the head gasket is blown? It seems like when you start it it sounds like a loud exhaust noise coming out of the intake. Also loud the last few rpms of the engine. Kind of sounds like a engine without a muffler at the times it makes this noise.

Good morning,
Tore into the noisy engine yesterday. Found the noise was coming from the plastic cooling fan on top of the flywheel. There are two allenhead bolts on the flywheel that the fan and two holes in the fan. The fan just sits on top of the flywheel and is supposed to be held down by the bolt that holds the flywheel on. It is just sandwiched in there and the flywheel bolt didn’t put enough pressure on it, so it was loose in there and the holes in the plastic egged out, resulting in the noise. Not a very good design. Finally got it fixed. A poor diagnosis by me. Should have found this a lot sooner. Thanks again to all who replied

 

[bertsmobile1]

More important is you came back with the final solution.
For which you are to be thanked.
Describing a problem in words is never easy particularly when you do not have the trade jargon at hand.
Could have been worse.
usually the blades all break off.