Is it safe to run my B&S petrol mower without the air filter?

[Usjes]

Hi,

I have been having problems with my petrol mower. It seems to be running slowly and unevenly chugging like it is about to stall all the time. From googling one suggestions of the cause of the problem is that the air filter (marked in attached photo ,LawnMower.png, with the red arrow) may be clogged with oil. I opened the filter to inspect it and it does indeed seem to have a lot of oil in it. Before buying a replacement filter I would like to be sure that this is the only problem. So I'm wondering if it is okay to run the mower with the sponge-like insert (see AirFilter(1).jpg attached) in the air-filter removed completely. I assume this insert is to filter out various airborne particles which would clog up the motor over time but that running without it for a short time just to test shouldn't be a problem ? I'm not sure if this is safe though, I know next to nothing about petrol motors. I assume running it without the insert might result in a larger airflow into the engine, could this cause it to malfunction or damage it ? Or is this a safe enough test ?


Thanks,

Usjes.

 

[Fish]

The foam filter is supposed to have a little oil in it to help catch dirt. The filter is washable, just wash it in hot soapy water with Dawn or Ajax detergent, and re-install it. Put a few drops of clean oil in the "cleaned" filter andd give it a squeeze, and re-assemble.
If the mower was turned up on it's side for any reason, the air filter can get oil sogged.

 

[Fish]

If it still runs slow, take a pic of the top of the carb/tank with the air filter assembly off, the governor setup could just be bent a little, and is easily adjusted.

 

[bertsmobile1]

I found shampoo to work better and be easier on the foam.
As for oiling them, don't
dip your finger in some oil then wipe it across the top of the filter.
'Scrunch the filter a bit to distribute the oil so the entire top has changed colour showing it is oiled.

You can do this a couple of times if you like.
The idea is to have the bottom where the air enters unoiled so it does not slog so easily and the top oily so it will catch all of the rest of the diry before entering the engine.

Running without the air filter when mowing will cause drastic wear in your engine and can destroy the engine in a single season.

 

[tom3]

Wouldn't hurt to run it for a few minutes without the filter. Put the mounting screw back in place a couple turns while testing. That carburetor has a diaphragm that controls the fuel/air mixture, noted for going bad after several years and will make the motor run rich, run rough, and you may see some black smoke from the exhaust.

 

[Usjes]

Thanks for the replies. I tried running the mower for a few minutes without the foam insert in the air filter because to me it looks like it has way too much oil in it. The results were inconclusive, the problem is that the behaviour is intermittent. There was only a little petrol in the tank and the lawn didn't need moving but I pushed it up and down a few times without the filter a few times until the tank was empty and it seemed like it was running at bit better. I then refilled the tank and restarted but it ran very badly, slow uneven and with the odd plume of visible emission from the exhaust and a petroly smell. Whatever is wrong seems to be intermittent and is usually more noticeable when the mower is in motion. So if I start it and it starts well I suspect that if I don't move it at all it will spin fine on the spot but if start mowing I find that when I come to the end of the lawn and stop to turn around it is particularly at this point that the engine will chug like it is struggling and maybe emit a plume of visible/smelly smoke. The only difference I can think of here is that the petrol will be sloshing from one end of the tank to the other as the mower comes to a halt.

> If it still runs slow, take a pic of the top of the carb/tank with the air filter assembly off, the governor setup could just be bent a little, and is easily adjusted.
See the attached photos AirFilterRemoved(1/2).jpg, maybe these show what you are interested in ?

> That carburetor has a diaphragm that controls the fuel/air mixture, noted for going bad after several years and will make the motor run rich, run rough, and you may see some black smoke
As noted above I do see some dark smoke when it is struggling. See the attached photo Exhaust.jpg, note the black dicoloration on the silver guard. I assume this is due to black smoke ?

Finally, it is worth mentioning that these problems all started near the end of last season and I left the mower in to the local repair shop to be serviced with a description of the problem. It was only used once after the service and then put into storage. The photo below shows the spot on the ground beneath the engine, clearly something is leaking out, is this just excess oil or could it explain the problems I am experiencing ?


Thanks,

Usjes,

 

[Fish]

Sounds like you have some bubbles of water in the bottom of your gas tank.

 

[bertsmobile1]

Pull the breather tube off the side of the carb and run the engine ffor a few minutes.
Watch for a lot of smoke &/or liquid oil coming out of the breather.