Oil filler cap breather

[jenevers]

I've noticed that some LWs have a breather/ filter on the oil filler cap. Mine doesn't. I presume it's there to reduce the air pressure in the crankcase (?). So I leave my filler cap slightly loose. I notice that the air seems to blow out through the loose fitting and not suck in, like the normal air filter. Am I risk sucking unfiltered air into the engine?

[steamraiser2]

The air blowing out is compression loss past the piston rings. Unless there is a lot of air/fumes there is nothing to worry about. There is no need to run with the filler cap slackened as you are drawing in air as you thought. There is no such thing as an air tight Gardner.

[jenevers]

The air blowing out is compression loss past the piston rings. Unless there is a lot of air/fumes there is nothing to worry about. There is no need to run with the filler cap slackened as you are drawing in air as you thought. There is no such thing as an air tight Gardner.

Thanks. I slackened the cap off a bit cos I thought a build up of pressure in the crankcase might be the reason why I get a fair amount of oil seeping from various places.

[steamraiser2]

Sounds like your engine is , indeed, blowing past the rings. Has it done many hours? Alternatively is it run on light loads a lot? I would suspect worn rings or glazed bores as either can cause your symptoms. What grade and specification of oil are you using?

[Timleech]

Thanks. I slackened the cap off a bit cos I thought a build up of pressure in the crankcase might be the reason why I get a fair amount of oil seeping from various places.

 

It might be worth trying the fitting of a breather/filler.

 

When we had a 4LW which leaked a little bit of smoke (also no breather), rather than oil, when the engine was working hard, we just fitted a small extractor fan

 

 

Tim

[jenevers]

Sounds like your engine is , indeed, blowing past the rings. Has it done many hours? Alternatively is it run on light loads a lot? I would suspect worn rings or glazed bores as either can cause your symptoms. What grade and specification of oil are you using?

Gulp!

My engine was originally an emergency power supply aboard a ship, so I presume it had very little use. When the ship was scrapped the previous owner acquired the engine and installed in my boat. When I bought the boat I discovered that there was no thermostat on the engine! How many years it had been like that I don't know. It had been used by him for river work mainly, so would have worked pretty hard although only for pleasure not commercial.

It is now almost entirely used on canals so only on low revs. When I get on a river I give it some "stick". The engine doesn't smoke at all after 10 mins and hardly even during warm up. It runs like a dream on SAE 30 API CC.

 

So I wonder what other LWs are like if the oil filler cap is loose. Do they blow, suck or both?

Let's have a poll amongst owners!

[steamraiser2]

As a rule an engine that does not blow by will have little crankcase pressure and will not seriously vent through the filler cap. If it is worn or blowing it can be a different story.Do you get fumes when running it with the rocker cover off? From what you have said about smoke I can't imagine there is very much wrong with it. You are certainly using the correct oil. Is the oil pressure normal?

[LEO]

Gulp!

My engine was originally an emergency power supply aboard a ship, so I presume it had very little use. When the ship was scrapped the previous owner acquired the engine and installed in my boat. When I bought the boat I discovered that there was no thermostat on the engine! How many years it had been like that I don't know. It had been used by him for river work mainly, so would have worked pretty hard although only for pleasure not commercial.

It is now almost entirely used on canals so only on low revs. When I get on a river I give it some "stick". The engine doesn't smoke at all after 10 mins and hardly even during warm up. It runs like a dream on SAE 30 API CC.

 

So I wonder what other LWs are like if the oil filler cap is loose. Do they blow, suck or both?

Let's have a poll amongst owners!

 

Hi,

 

2LW No112695 - Filter on top of spin on/off oil cap. Regret I am too polite to ask if it 'blows or sucks'.............

 

L

Edited June 3, 2015 by LEO

[jenevers]

As a rule an engine that does not blow by will have little crankcase pressure and will not seriously vent through the filler cap. If it is worn or blowing it can be a different story.Do you get fumes when running it with the rocker cover off? From what you have said about smoke I can't imagine there is very much wrong with it. You are certainly using the correct oil. Is the oil pressure normal?

I'll try taking the rocker covers off next time I'm aboard. I certainly don't get fumes with them in place.

 

Oil pressure runs at 45 lbs all the time, although the top of the pressure regulating valve has "35 lbs" engraved on the top.

[steamraiser2]

all good then