A 2 HP, 2.6 gal tank? That thing should fill and shut off in a couple minutes. You'll see decent drops in pressure quickly though from using tools because the tank is so small. So the compressor will kick back on constantly.

Sounds defective if it's really taking 20 minutes to fill.

It's defective. No way on earth that should take so long to fill.

Maybe it is broken but with such a small tank you won't have enough cfm of air to do much work.

I'm a bit confused, like air is coming out of the oil cap all the time? Do you have the cap off? Which gauge are you reading the 100psi on when you're adjusting the regulator?

On a different note...a blaster is a seriously air intensive tool, you're going to need a lot more air compressor for that.

If it did run 20min straight due to a leak or other issue, good chance your pump seals are toast. It's not meant for that sort of continuous use.

Or maybe it was bad from the start.

[deleted]

Check valve plate

Return bro, better to be safe and just get a new one

I can't count the amount of times I forget to close the valve on the bottom of my compressor that you open when you are done. Are you sure you checked everything?

Drain valve is slightly open, unless you are saying you can set it to 40 psi and it eventually shuts off and hold pressure for hours. In which case it's just broken.

Edit for all the people downvoting:

Excessive air coming from the oil fill is an obvious sign of a problem with the rings, cylinder, piston, or valves. My guess is broken rings or a fault with the intake valve. Such a defect will also prevent a compressor from intaking as much air as one that does not have such a defect, thus explaining why the air leak is deemed excessive yet assumed to not be the problem.

My bad for being tired and not breaking it down properly the first time. I get that most people lack the mechanical understanding necessary to have reached this obvious conclusion, especially considering how scattered my earlier trail of bread crumbs was.

Feel free to get back to downvoting. I also have a comment below for your downvoting enjoyment.

Original reply:

Get back on that original note, pal. Compressors work like internal combustion engines in that they have a crank shaft, pistons, and rings. Some leak through the rings is acceptable, but bear in mind that any air coming out of the oil cap is air not making it into the tank. Ergo, a lot of air coming out of the oil cap equates to a lot of leak. This is to be expected of a worn out unit, not a new one.

Granted, I do not know @op's gauge of what comprises a lot of air leaking out.

No air should be going through oil so return it and get you money back. Then buy a unit that has separate motor and pulley driven belt to do sand blasting.
https://blog.iseekplant.com.au/blog/air-compressor-sizing-for-sandblasting

I have the same model; great jobsite compressor. I empty the tank after each use and it only requires 2-3 minutes to go from 0 to 90 PSI. Air being discharged through the oil lube port is not normal.

Sounds like there is a couple of issues with the pump. Taking up to twenty minutes to fill the tank sounds like the valve plate has a broken high pressure Reed, but getting pressure out of the oil fill sounds like the rings are shot and pressure is blowing by into the crankcase. You can replace the valve plate fairly easily but if the rings are shot then you’re likely going to be piling money into a repair that isn’t cost effective.

I store mine with the valve open. So I forget about this literally every time I use it.

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Me too

There is a one way valve between the compressor and tank. If you have air leaking back through the compressor, this valve is stuck open. Repair or replace.

Is it oil less pump?

I don’t know why this got downvoted, this is actually a really solid answer for cheap piston compressors. Ring blowby and a lot of pressure behind the oil cap or air / oil shooting out the breather is a sure sign of ring failure. You check used car engines like this too.

You can also check the valves to make sure they are sealing properly.

Ex car mechanic, current industrial mechanic here. I work with big boy compressors.

Not a Makita but my compressor came with a plastic dust cover on the air intake.

I forgot to remove it and it took forever to fill.

Gotta prime it first. Suck from the attachment end with the lever depressed for a couple seconds

See if there's a cold start valve on top of the pump. This could have failed. Or maybe blown head gasket. Check valve wouldn't effect pump up time. Only when it shuts down would the check valve come into play. Cracked discharge tube or unloader line going from pressure switch to check valve might be leaking.

What? I’ve never heard this and can’t tell if you’re joking.

Are you supposed to leave it one way or the other

It doesn't matter that much if you use it frequently, but for infrequence use it's good to keep it open to drain any moisture / prevent corrosion inside.

Thought I was just an idiot. Luckily now I know there are multiple idiots like me

Good thoughts

I live in a humid salty air environment so I drain it each time tipping the compressor as I do it to spray out any moisture that’s built up. You’d be surprised how much water is in it after each day

He joking

This is the way. I also tip it when releasing the air.

it sounds like the check valve is bad, stuck in the open position. The check value is usually screwed into the tank, it may look like a brass adapter fitting. The small ones are not that expensive or hard to replace.

>It doesn't matter that much if you use it frequently

IMO if you use it every day, you drain it every day

Aaah another valve forgeter like me. I resorted to a big sticker at both the wall plug and te regulator switch to remember to close the valve

You took my downvote at pal.

Was going to suggest this exact thing.

When you store it, empty the air and leave the valve opened.

i'm gonna find ya, i'm gonna getcha getcha getcha

Check your air filter… I bet it’s still wrapped in plastic.

No worries, pal. You choose to be a douchebag, and I totally respect that.

I worked on refurbing my backup compressor (oiled twin tank Hitachi) yesterday, due to making air slowly. One of the reed valves was corroded/worn through, the unloader line had a loose connection at the tank exit, and the shutoff diaphragm was leaking. Got that done, but it's not turning on very well - I think the unloader valve is stuck too :/

I'd swap that Makita for a fresh one if you're still within the return period.

do this or rust in place

There should be barelly any air comming out from the oil cap. If any significant amount comes out when new then the unit is faulty.

Also, that unit is very weak. It is about only good for finishing nail gun. It do not have the air flow to power any significant tools, and virtually no reserve capacity.

[deleted]

The more often you use it, the more moisture it will store.

This is the only way. I leave it open until "i make sure all the water blows out" every time too.

The only one who came off as a douchebag was yourself.

Whatever, pal.

2.6gal isn't gonna have enough air capacity to use a powder blaster, IMO

in IT we like to say "there's a defect somewhere...." looks at computer, looks at user.

Yeah that's probably better advice tbh. Don't listen to me!