MDS engine.

Remove the carb and check for metal flashing (left over metal after machining). Sometimes fuel nipples (screw in) are blocked by flashing in the carb body at the seat of the hole where the fuel inlet nipple is threaded in place. Check for particles blocking the fuel passages. Also ensure that the muffler pressure nipple is drilled all the way through, as it should be.

Ensure that the carburetor is seated and leak free upon reinstallation. A little bead of silicone rubber glue around the base of the carb would prove beneficial.

Check the backplate for a proper seal. Again, if in doubt, a small bead of silicone rubber around the engine's backplate opening couldn't hurt. Use the silicone sparingly. You don't want silicone extending into the crankcase and running afoul of the crankshaft while in rotation.

Check that the cylinder head bolts are uniformly snug.

MDS engines can be finicky regarding fuel nitro content (lower is better) and glow plug selection. Try different glow plugs if the problem persists. Choose a prop toward the low end of the selection range while breaking-in the engine. Yes, even ABC engines can need some break-in time.

Don't take a hammer to it. It is still worth something to someone else who needs parts, or who is accustomed to MDS engines and their quirks.

Good luck and let us know how you fare.


Ed Cregger