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by Bill Webb
(Alachua, Florida)
Makita 700
4 years old
Will run continuously but only build 40 psi.
Used in Florida garage shop, light use with a pin nailer.
Just got a framing nailer to build a 20 foot fence and it just wouldn’t work a few days into the project.
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Makita mac700 won’t build pressure
by: Bill
Howdy Bill… that’s a pain, isn’t it, when you go to use your compressor and it won’t work properly.
Any air huffing back out of the intake port when the compressor is running?
If so, that suggests the intake valve is compromised. There are a number of valve plates for this compressor, so you might as well change them all if you are changing one. Replacing the valve plate should help stop air from backing back out and improve pressure build. Make sure if you do you replace the gaskets too.
Any air coming out of the oil fill tube when the compressor is running? That’s pointing to piston seals if there is, and you’ll need to tear down the pump to check the condition of the piston, the seals, and the cylinder wall.
Give us some idea if any of this helps, K?
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Thanks
I will definitely check both of those.
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I found this same compressor that a neighbor was throwing out. It won’t build pressure either. Mine has air coming out of the oil fill tube which points to your suspicion of bad compression rings. I’ve tore down part of the pump partially to where I can see the cylinder wall.There is no scoring. The connecting rod does have play. Not Up, Down, Right, Left. But it does have play along the crankshaft (about 1/4″ each way) if I pull/push it. Not sure if that is normal for these Makitas. From what I saw from the parts breakdown I got… Read more »
(Not directly answering your question)
“Mine has air coming out of the oil fill tube which points to your suspicion of bad compression rings.” Is there an actual flow of air, or is it just puffing in and out? Normal piston motion will cause pressure changes.
The rod play does seem a bit much, but absent a bunch of loose metal in the crankcase, it’s likely OK.
As to the pressure, are you pretty sure you don’t just have a bad head gasket?
Good luck.
There’s significant air flow. both out of relief valve and the oil filler cap when it was on. I ordered a replacement gasket kit for the compressor. I’ll get the gaskets replaced and I’ll go from there if the symptoms still persist.
OK, thanks. Keep us posted on how it’s going, please.
Wait – you have flow from the relief valve? That should not be happening. Maybe pull and push it in a couple times to see if it stops? Or do you mean some other valve?