Melex 412G rebuild

[mginwyo]

Okay so the Melex I bought a year and half earlier was smoking and buring oil fast so after none of the "mechanic in a bottle/can" solutions helped, I had to do the teardown and rebuild on the engine.

Its a Vanguard 9hp black engine and once I got the parts, it was pretty easy. To get the right parts, the engine ID info is on the Briggs plate on the right hand side behind and under the air cleaner assembly. No one will get you parts unless you have this info...
Blue smoke and low compression was the giveaway it needed rings but one other thing to note is your motor oil will turn black in just a short time of use. Like 3-4 miles for me... This cart looked like it was fogging for mosquitos!

Parts are available online at briggs and stratton or Nagy Golf and Turf has them also.
I bought a set of rings and all the gaskets needed.

Removal from the cart is a bit tricky but mark the electrical and that is the main thing

1. Disconnect battery neg cable, Remove upper covers, shields and cables and linkages to carb (carb can stay on engine but need to remove the other items like cables and linkages.
2. remove the generator/starter taking care to mark each electrical connection
3. Loosen the crank bolt so it is easier later. the bolt cannot be removed in the engine compartment.
4. remove the air cleaner and brackets
5. Remove anything else that will get in the way of lifting the engine straight up out of the engine compartment
6. remove the 4 bolts/nuts holding the engine from underneath the cart . 24 corners of the engine. Mine had double nuts that were not visible so be sure when the first nut comes out, the bolt pushes back up through the engine mounting plate or there may be a 2nd nut on the bolt you cannot see.
7. Remove the wide drive belt now that the engine is unbolted. slip off the belt from the clutch assembly.
8. Remove the engine carefully. Weight is about 50lbs on the 9hp so its not a killer lift.
9. Remove the clutch assembly. use the belt to hold the pulley as you remove the crank bolt.
10. clean the engine and drain the oil. There are a couple plugs you can drain from so pick you poison.
11. remove the rocker cover (new gasket needed)
12. remove the head bolts and the cyl head
13. remove brackets and other items followed by the front (side) cover - no need to remove the fan side, just the driver side cover
14. remove the timing gears paying attention to the marks for re-assembly
15. Remove the piston connecting rod bolts
16. Remove the piston assembly
17. clean and inspect all parts - Use care to remove all fragments of old gaskets. verify size on piston (if marked) and if bearings / crankshaft, valves etc are re-useable.
18. Gaskets needed will include timing cover or case gasket, head, exhaust, rocker, and intake to carb and valve guides if you choose.
19. after all parts were cleaned, reassembly with new parts making sure to test fit as you go.

The whole process was a 2 weekender during free time on saturdays. I spent a whole day cleaning before removing as I had oil leaks big time! In the end IF I had found the double nuts quicker. With info above a novice with only hand tools should be able to do the engine removal in an hour, the engine teardown clean up in 2 hours or less and reassembly in about the same. Then re-install the engine in another 90 minutes so it could be a one day job.

This was the first small engine I have done a teardown on but I definitely will do others if the need arises. easy and the total part cost for rings, gaskets was under 80.00.


Oh yeah, After the rebuild it ran fine after a bit of starting fluid to get the gas back in the carb. No smoke, but alas, Winter is here so it is sitting in the garage until the thaw comes. But it is going to be ready to run in March!