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VG4D smoking from crank case


Hello, After my 40 horse vg4d gets warm as I shut it down a ton of smoke comes from the oil fill tube. No noise but it is running a bit rough, several hundred hours sense last rebuild. Any Ideas?


Andrew Mackey

Last Subscription Date
I do not knao who did your rebuild, so I will ask as if you did it your self.

When you did the rebuild, were the rings matched to the cylinders? If you used 3 piece oil control rings, did they install properly? Pull the heads and look carefully at the cylinders - any grooves, shiny spots, indications of galling? Wear on one side of the cylinders?

I have seen Wisconson V-4s with mis-installed parts, that will run, but not well. The piston has to match the cylinder, # and arrow must point to the center of the V. The con rods have to match the location (there are left and rights), if they are installed to the piston wrong, or if they are out of order, they will cause the rod to be off center on the cylinder bore, and will bind the piston to the cylinder wall. The rings have to match bores' diameter, and the oil ring must slide in with out rolling over when it hits the cylinder wall. Personally, I do not like 3 piece rings, I would rather have toe old 1 piece style. No chance of a screw up with those!, and end gaps need to be correct.

Smoke from the block usually means either the engine is getting too hot (binding parts as I have mentioned above), A mechanical defect - too wide a ring gap, mis-sized pistons and rings to piston bore, wear in cylinder walls, physical breakage, or simply that the new rings are not fully worn in yet. Has the engine been run fully loaded?

Also, what oil are you using? Use what is recommended, and use a Diesel rated oil. Have you changed it after the rebuild? Should be changed at 10 hours, and every 25 after that, along with the filter, if it has one. Make sure the oil has no gas in it, if it does, possibility of a bad fuel pump or bad float in carb. Is the oil black, or is it nice and clean? If black, posibility of a lot of blow by - again check the assembly for wear and mis-installation problems. With a fresh and good rebuild, you should not be seeing any smoke!