Running with no air filter - how bad?

Post by **JimK** » Sat Feb 17, 2007 9:35 pm

Just hypothetically, how bad would it be to run for a thousand miles or so without an air filter?

Post by **Onne** » Sat Feb 17, 2007 9:41 pm

Might be bad, the do clean out the dust/sand/water you donb't want to have in there. Also take away a lot of noise.

I wouldn't run without.

Post by **JimK** » Sat Feb 17, 2007 9:49 pm

I went to change the filter yesterday afternoon as part of the service, and found I couldn't strictly change it as there wasn't one in there

Rather alarming, to say the least. I assume the only way I can check for damage is to look? I'll keep an eye on oil and water levels but I don't really want to take the engine apart.

When I bought the car I greased it and checked stuff like the level and condition of the oil, but it didn't occur to me that there might not be an air filter. I mean, why would it?

Post by **Onne** » Sat Feb 17, 2007 9:55 pm

You put one in now? Does it still breath well enough?

Post by **JimK** » Sat Feb 17, 2007 9:59 pm

Haven't tried - got interrupted by a small person halfway through an oil change (after draining but before refilling).

I'll try it tomorrow. Actually, just thought: I've seen mention of priming the oil pump. Do I need to do that if it's been sat draining for 18 hours? Or is it just with a new pump?

Post by **Onne** » Sat Feb 17, 2007 10:02 pm

I think that is just with new pump.

what you can do, when you fill her back up with oil, take the plugs out, ignition on, and use starter motor until the oil light goes out. The you can be sure that there is pressure.

Post by **JimK** » Sat Feb 17, 2007 10:09 pm

Good plan. I've filled with oil, after finding out how much to put in...

I'm going to change the plugs anyway. Leads are already marked so I can detach them all instead of one by one as I usually do.

Post by **Packedup** » Sun Feb 18, 2007 12:59 am

Running without an air filter is only bad when dusty/ gritty particles can find their way into the engine. On wet roads that's highly unlikely as any normally airborne crud is nicely held on the floor by water, but there's still a chance of some making it in, causing accelerated bore wear.

Personally I wouldn't worry about running without a filter in this weather for a few days or so, but it's always better to ahve one just in case - Knowing my luck a bit of gravel would somehow bounce into the carb and find its way into either jamming a valve or smacking around in the cylinder...

As for priming the pump - I think a far bigger deal is made of this than is usually necessary. I fired up an A series (Mini) that had been in a barn for approx 15 years, and after taking the right precautions (bit of oil down the plug holes, spin it over with the plugs out to build up pressure etc) it fired and held pressure no problems. It's a very good idea to prime the pump by (packing it with Vaseline when fitting a new one or doing an engine rebuild as they're quite poor at pulling air through so tend to take forever to pick up oil (or sometimes fail to manage at all). But when simply draining and refilling the oil I don't see a problem. The A series pump will always retain a little oil in the bottom due to orientation, which so far as I can tell will seal the vanes and provide enough suction for it to prime itself perfectly well if you spin the engine with the plugs out for a few seconds.

I've had the pumps off the hateful 1500 Triumph engines when doing the bearings and refitted them without priming (I try not to, but sometimes I forget or can't find the Vaseline) and still managed to get pressure - And they're much worse IMO for building up pressure after a total emptying.

Post by **JimK** » Sun Feb 18, 2007 9:36 am

Packedup wrote:Personally I wouldn't worry about running without a filter in this weather for a few days or so, but it's always better to ahve one just in case - Knowing my luck a bit of gravel would somehow bounce into the carb and find its way into either jamming a valve or smacking around in the cylinder...

It wasn't a few days, it was two months. And I wonder if the misfiring last week was because a bit of gack got in? It's pretty much gone now.

The A series pump will always retain a little oil in the bottom due to orientation, which so far as I can tell will seal the vanes and provide enough suction for it to prime itself perfectly well if you spin the engine with the plugs out for a few seconds.

I'll do that.

Post by **Packedup** » Sun Feb 18, 2007 2:02 pm

JimK wrote:It wasn't a few days, it was two months. And I wonder if the misfiring last week was because a bit of gack got in? It's pretty much gone now.

So not exactly hypothetical after all? ;)

If you run without a filter the airborne small gritty dusty particles get in and cause increased wear in the bores and upper engine (valve guides mainly IIRC). This won't go away, once there's wear there's wear. But as the airborne particles are far more common on dry summer days than generally wet miserable winter ones I doubt you've done a great deal of damage. Chances are you had a bit of damp in your dizzy cap or suchlike causing the misfire - Even my "modern" Rhonda plays up on wet days sometimes.

Post by **Kevin** » Mon Feb 19, 2007 3:36 pm

Even my "modern" Rhonda plays up on wet days sometimes.

Hmmm is that the type of car the Beach Boys used to drive

Post by **bmcecosse** » Mon Feb 19, 2007 7:08 pm

Don't worry about the airfilter unless driving on dry dusty roads. It's not ideal - but it's not fatal either! Oil pump will be fine.

Post by **RogerRust** » Mon Feb 19, 2007 7:31 pm

30 years ago I remember seeing a mechanic at a race shake Vim down the ram pipe to "deglaze" the bores and get the compression up. But only good for one race I suspect! The very thought makes me shudder

.

Post by **Kevin** » Mon Feb 19, 2007 9:59 pm

shake Vim down the ram pipe to "deglaze" the bores and get the compression up.

Bet there are a few on here that dont know what VIM is Roger.

Post by **bigginger** » Mon Feb 19, 2007 10:19 pm

Ooh, me, me, I don't. Honest...

Post by **alex_holden** » Mon Feb 19, 2007 10:27 pm

I know what it is/was but don't think I've ever used it.

Vim is also my favourite text editor... http://www.vim.org/

Post by **RogerRust** » Tue Feb 20, 2007 5:37 am

Vim and Ajax were scouring powders before the days of cream cleaners with stupid names like "cif"

Post by **wibble_puppy** » Tue Feb 20, 2007 12:15 pm

Post by **bigginger** » Tue Feb 20, 2007 1:37 pm

And, as a complete aside, while it was called Cif everywhere else in the world, it was called 'Vim' in Britain because Cif might have been mistaken for an abbreviation for a sexually transmitted infection. That's the urban myth, anyway, but the difference in the names isn't. I think, btw, that that's acceptable for a family audience, but delete it if not - it's a favourite story of mine

Post by **Willie** » Tue Feb 20, 2007 1:38 pm

It will not mean much to you youngsters! but,in my silly youth I used to clean my teeth with Vim to removed tobacco stains! (I've still got them and no, they are not in a jar).