brand new air compressor taking forever to fill

Submitted by kattaganist t3_11di7bq in DIY

I got a Makita Mac700 and it will not fill quickly at all it takes at least 20 minutes i broke it in for 30 minutes it has oil. There is a lot of air coming out of the the oil cap but that doesn't seem to be the issue. Is this normal or is this defective. I've checked everywhere for leaks and can't find any. And when I attach the tool it decreases by 20 and everyime I use the tool another 10. It's hooked up to a powder blaster and is set to 100 psi. And even when I lower the regulator it doesn't change.

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javeryh t1_ja8zx4g wrote

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?

163

nalybuites t1_ja9se71 wrote

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

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misterflappypants t1_jaaxvyc wrote

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

9

zRobertez t1_jaawugw wrote

Are you supposed to leave it one way or the other

2

Zealouslybored t1_jaaytr3 wrote

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

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danpluso t1_jab04gb wrote

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

1

vernZeeFern t1_jaaxlbr wrote

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.

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cardcomm t1_jab57rn wrote

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

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

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vernZeeFern t1_jaduibm wrote

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

1

Space-Square t1_jabnyhq wrote

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

2

Dylsnick t1_jabb5ir wrote

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

1

toastfighter2 t1_jabvh7g wrote

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

0

The_Jeffniss t1_jab6xz8 wrote

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

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alr126 t1_jabavw9 wrote

Was going to suggest this exact thing.

1

cptnamr7 t1_ja8t6o7 wrote

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.

51

OldMotoxed t1_ja8u0pb wrote

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.

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its8up t1_ja90xuh wrote

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.

−69

DCOutlaw620 t1_jab7pnd wrote

You took my downvote at pal.

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its8up t1_jabe7uq wrote

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

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SatanLifeProTips t1_jaamgzm wrote

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.

5

gunfighter01 t1_jaap37c wrote

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.

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derphurr t1_ja90u0n wrote

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.

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LittleJohnStone t1_ja8tc6x wrote

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

16

freecain t1_jado0yk wrote

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

3

keylo-92 t1_ja8zli4 wrote

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

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NagromYargTrebloc t1_ja9jovk wrote

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.

4

SamBrico246 t1_ja8v8fn wrote

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.

2

Architect_of_Sanity t1_jabbjpl wrote

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

2

wiresmoke t1_ja8tceo wrote

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

1

LazloHollifeld t1_ja9o412 wrote

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.

1

HomeAutomationCowboy t1_jaagjek wrote

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.

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ShattersHd t1_jaahatl wrote

Is it oil less pump?

1

penguinpower81 t1_jaaqb4y wrote

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.

1

bassboat1 t1_jabgvcf wrote

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.

1

thephantom1492 t1_jabk08m wrote

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.

1

Born-Work2089 t1_jab2i2l wrote

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.

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steve_glynn t1_jaapubw wrote

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

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