# Smoke from 8N OilCap/Vent



## FordmanUGA

I've noticed that my '52 8N is smoking a little from the oil cap/vent at start-up. It goes away quickly and the only other times I see any smoke is if the motor is under a heavy load like pulling up a steep hill while mowing. Is this something I should be concerned about or is this somewhat normal? There is never smoke from the tail pipe, only the oil fill cap.

Thanks,
FordmanUGA


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## RC Wells

Smoke on start up is usually from worn valve guides, and not something to worry about. Smoke on lugging is piston and ring blow by, and when the tractor starts consuming excessive oil is when to consider a rebuild. 

If the smoke on hill climbing occurs as you break over a grade and the engine unloads, that will be valve guides too. 

I would not worry about it unless you are fouling spark plugs or consuming enough oil to present a problem in use of the tractor.


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## FordmanUGA

RC Wells said:


> Smoke on start up is usually from worn valve guides, and not something to worry about. Smoke on lugging is piston and ring blow by, and when the tractor starts consuming excessive oil is when to consider a rebuild.
> 
> If the smoke on hill climbing occurs as you break over a grade and the engine unloads, that will be valve guides too.
> 
> I would not worry about it unless you are fouling spark plugs or consuming enough oil to present a problem in use of the tractor.


Good to know. The plugs aren't fouled and I only have to add some oil every 3-4 weeks to keep it in the good range on the dip stick. I'll save the rebuild for when I get ready to completely restore this wonderful machine.

They sure don't build farm machinery like this anymore. 

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## RC Wells

The Japanese and Koreans are building durable tractors, but not like the old US built tractors. The philosophy of engineering was not not driven by marketing types trying to keep their service departments full back when your tractor was built.


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## FordmanUGA

All right, a little update. I'm almost embarrassed to admit this, but I talked to my wife's uncle about it (he has an 8N) and he asked if I had checked the element in the breather cap on the oil fill. I said no, it was saturarted with oil, so I cleaned it off real good with gasoline, let it dry out real good, put it back on, and no more smoke when I start it. I haven't put it under load recently, the finish mower is down for now, but as soon as I can put it under load I'll update again. But it's good to not see any smoke at start up.

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## Ultradog

That cap is vented to allow the crankcase to breathe.
If it could not breathe it would build pressure in the crankcase and blow your crankshaft oil seals out.
Since about the 1970s all automobiles captured that smoke by means of the PCV (positive crankcase ventilation) system and all that smoke was sucked back into the intake manifold where it was mixed with the other combustion gasses and burned - thus preventing significant amounts of air pollution.
As to the valve guides being worn and causing it to smoke; That might be the case on an OHV engine but is highly unlikely on a flathead engine like a Ford N has.
Ultimately, you have a bit of blow-by.
No big deal.


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## FordmanUGA

Ultradog said:


> That cap is vented to allow the crankcase to breathe.
> If it could not breathe it would build pressure in the crankcase and blow your crankshaft oil seals out.
> Since about the 1970s all automobiles captured that smoke by means of the PCV (positive crankcase ventilation) system and all that smoke was sucked back into the intake manifold where it was mixed with the other combustion gasses and burned - thus preventing significant amounts of air pollution.
> As to the valve guides being worn and causing it to smoke; That might be the case on an OHV engine but is highly unlikely on a flathead engine like a Ford N has.
> Ultimately, you have a bit of blow-by.
> No big deal.


Yeah, I think it wasn't venting well because of the excess buildup on the element inside the cap. Once I cleaned it real good no more smoke at start up. Thanks for the info. I'm not used to these older motors. The more I'm learning the more I love this old tractor. It seems pretty simple and straight forward to maintain and fix.

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