by Dave Krueger
(Sussex, Wi. U.S. )

I have a GX5 that keeps overheating.

I’m running a CNC machine shop, that has 5 machines in it. I run this place myself so most of the time I run one machine, and have no problems. As soon as I try to run two machines at once, the compressor has overheating issues. A couple years ago, I had a crew of 3, and we would run 4 machines at the same time, had no issues with the compressor, so I know running 2 machines should not be overworking this compressor.

New Atlas Copco GX5 air compressor
New Atlas Copco GX5 air compressor

Called service a few times on this, and this is what has happened. Oil, oil filter, and oil seperator has been changed. Thermostat has been changed. Intake air filter has been changed. The oil cooling radiator has been taken off and completely power washed so it’s clean as new, and also blew air through it to make sure it’s not plugged.

I checked with a temperature gun when it overheats, and it’s definitely reaching 213 degrees, so I know it’s getting hot. I don’t know what else to do with this thing. Could the pump itself have a bad bearing that’s getting everything too hot? It’s turning on about every 6-7 minutes.


by: Carl

Well, there’s only a few things that can cause overheating and looks like you’ve covered most of them!

So the cooler is clear and has full flow through it, is it actually getting hot though? It does sound like an oil flow issue as it’s only overheating when working hard, possibly one of the oil pipes/hoses blocked up? Try removing then all one by one and clearing them.

Does your machine have an electric fan or is it connected to the motor? If electric, is it turning?

Is the compressor close to a wall? I mean is there enough air flow getting to it or letting the hot air out properly?

You are right, if the bearings on the air end are dry or not enough flow to them then that could be an issue.

One last thing to check, sometimes there is a little gauze filter going to the airend, in the pipe/hose, have a close look, maybe take that hose/pipe off and see if there is anything in there, if there is any kind of blockage going to the air end then it will overheat.

Please let us know your findings.


GX5 overheating
by: Doug in

Is this a tank mounted model with no dryer?

You’ve been draining the tank?

Is the radiator getting hot?
If not the bypass valve isn’t working.

When you say ” It’s turning on about every 6-7 minutes. ” do you mean motor starts, or loading?

Anything else changed since you became one-man shop? Piping, etc.

How many hours on it?

And yes, it *could* be the air end, but let’s hope not.


GX5 Atlas copco keeps overheating –  Fixed!!
by: Dave

Ok to answer some questions, yes it’s tank mounted, and no I do not have a dryer on this unit. It is near a wall, but had plenty of open air around all sides of it.

I had a different repair person in yesterday on it, and believe it or not, it appears someone put the thermal couple in backwards. That was the whole problem with it. He flipped it over and it’s staying about 30-50 degrees cooler. Good lord, the time I spent chasing this issue. But, glad it’s all fixed now. Thanks to everyone in helping search for the problem.


Great that it’s fixed!
by: Carl

Fantastic, glad you got it fixed! I thought it sounded like an oil flow issue.

Anyway pleased it’s done now.



by: Doug in

So this was already happening, and when whoever changed the thermostat, broke it good?

Wow. This is why history is good to know.

I trust you’re getting at least a partial refund from the company that messed it up.


by: Dave

Doug–yes, the whole fix was free of charge. As for the past guy who put it in wrong, well, he did other maintenance on the machine besides this, so I doubt I’ll see any refunds on that work.


GX5 Atlas copco fixed update
by: Dave

The original work was done for overheating, but their remedy was to do a full maintenance on it. Which they did, and seemed to remedy the overheating, but then the problem returned about 4 months later.

The only thing they didn’t do was change the seperator because they didn’t have one on the truck.

So when the problem returned 4 months later, they then had a seperator and swapped that out.

Problem went away again for about 2 months, then returned again.

Then they said the regulator might be bad. It’s cheap, so let’s replace it. Which they did.

Problem went away again for about 2 months, then returned again. It wasn’t until now that a different repair person came out to discover the regulator was put in backwards.

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