PCV for MF 135

[ltolson]

Got a Mf 135 with a Perkins gas engine. I have being restoring and replacing for a month. Looking over the engine I got to wondering about replacing the vent tube with a pcv and routing to the air box. When the engine was built in 1973 gas was 25 cents and dumping excess down the front of the engine was no big deal. But at 3.29 a gallon can a significant improvement be had in routing the unburned fuel back through the intake? Would better ventilation make oil changes less frequent?

Larry

 

[Anonymous-0]

A 3 cylinder Perkins is very fuel efficient whether it's a diesel or a gas. I don't think gas comes out of the crankcase vent unless there is some kind of problem that is causing gas to get into the crankcase. Any gas coming out could catch on fire. A diesel returns unused fuel to the fuel tank but is a totally different system than a gas engine. Changing the oil at the recommended intervals is cheap insurance for longer engine life. It's only a 3 cylinder. It doesn't hold 10 gallons of oil. Dave

 

[Anonymous-0]

The "gasses" that are vented from the crankcase AREN'T gasoline. They are unburnt hydrocarbons, but not anything that is a re-usable "fuel". On an engine with a PCV system, those gasses are reburnt to lessen pollution, but they sure don't do anything to extend fuel economy, engine life, oil life, or engine power output. As was mentioned, the good ol' Perkins, be it gas or diesel, is one of the most efficient little engines ever built. Personally, I think your attempt to install a PCV system would be counterproductive.

 

[Jerry/MT]

PCV systems take blowby gases and route them to the intake manifold for combustion in the cylinders. Don"t know what you mean by "...dumping the excess down the front of the engine...". I know of no gas engine that operates normally in this fashion.

The draft tube on most tractor engines takes these same gases and vents them overboard to the atmosphere. The products of combustion are ideally CO2 & water vapor but some other compounds are also produced,some of which are combustible and some of which aren"t. Oil particles are among the constiuents of typical blow by gases. Very little if any raw gas is contained in blowby gas unless the carb is misadjusted and/or the engine is badly worn. I don"t see why there would be any appreciable effect on the oil change interval since it doesn"t make much difference whether you pass the blowby gas from the crankcase to the manifold or from the crankcase to the atmosphere.
I don"t know what you mean by the "air box" but if that is up stream of the carb then you"ll risk fouling up the inside of the carb with blowby gas. If I were going to do this I"d tap the intake manifold downstream of the carb but I don"t understand what you hope to gain by doing this.

 

[ltolson]

I did some research online and found a number of references that suggest ventilating the crankcase prolongs engine oil by removing water and other corrosive byproducts as well as reduce hydrocarbon (gas) emissions. I am not an expert on internal combustion engines but since just about all automotive gas engines since 1964 have pcv valves it sounded like a good idea. I guess I will let that idea die.

 

[Jerry/MT]

Why doesn"t a crankcase vent tube do the same thing? The only difference is that one is hooked to the intake manifold and the other is vented to the atmosphere. The reason PCV valves were added was for smog prevention. They didn"t want blow by gases in the atmosphere.