May want to check your GX CS2 inspection plug.

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JimD

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Mar 27, 2021
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DO NOT BLOCK THIS OR, BLOCK IT WITH SOMETHING FRAGILE. I discovered the hard way that a metal washer was a bad idea. I'm still working on it but I may have ruined my CS2. It appears the metal washer went into the pump somehow (I thought it was too large) and is now stuck in the piston to cylinder gap. The piston will not current move which is preventing disassembly to be completed so I can assess the damage. If I can get it apart it may be recoverable but the best idea is to not block this hole with anything that would damage the compressor if it went into it. Or just do not block it. My original idea was bad.

I was checking the grease in my almost new CS2 and took off the head and pulled the inspection plug. I was surprised the inspection plug had a hole about 1/4 inch in it. So the piston area was open. That doesn't seem right so I made a plug out of a washer and a little Epoxy. I also took the grease out of that area and replaced it with some from Target Forge. Letting air in that area can also admit grit and thus premature wear. I wonder if a part got left out or something. The head bolts were also Very tight. I used an old Ryobi impact. I think my pump is OK but I'm glad I caught this early in it's life.
 
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JimD said:
I was checking the grease in my almost new CS2 and took off the head and pulled the inspection plug. I was surprised the inspection plug had a hole about 1/4 inch in it. So the piston area was open. That doesn't seem right so I made a plug out of a washer and a little Epoxy. I also took the grease out of that area and replaced it with some from Target Forge. Letting air in that area can also admit grit and thus premature wear. I wonder if a part got left out or something. The head bolts were also Very tight. I used an old Ryobi impact. I think my pump is OK but I'm glad I caught this early in it's life.
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Apologies, but I am not clear as to what parts you referenced.

My the "inspection plug", do you mean the black plastic plug that closes off the piston's wrist pin access hole?

I also don't understand, "The head bolts were also Very tight. I used an old Ryobi impact.". IIRC, the head bolt torque is ~110 inch pounds/ 12 Nm, correct?
 
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Yes, the port with the hole is how you remove the wrist pin.

I did not measure the removal force but it was more than I could put on a 5mm Allen wrench. At least three of them were. One was much looser. So I used an impact. I think an impact is less likely to break the bolt. I didn't torque them going back, I just tightened them all I could with a screwdriver. I doubt that's 110 inch lbs. But the dead head test after I got it back together was 15 seconds less.

I added a picture of the as found plug and the underside of it with the washer + Epoxy that is there now.

20250603_150408.jpg


20250603_150431.jpg
 
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JimD said:
Yes, the port with the hole is how you remove the wrist pin.

I did not measure the removal force but it was more than I could put on a 5mm Allen wrench. At least three of them were. One was much looser. So I used an impact. I think an impact is less likely to break the bolt. I didn't torque them going back, I just tightened them all I could with a screwdriver. I doubt that's 110 inch lbs. But the dead head test after I got it back together was 15 seconds less.

I added a picture of the as found plug and the underside of it with the washer + Epoxy that is there now.

View attachment 567278

View attachment 567279
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Thank-you for the explanations. Good call on the plug repair.
 
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My fix is deliberately not permanent. I let the epoxy on the washer set up before I put the washer under the inspection port. The epoxy is to plug the hole in the washer. If I had a circle of plastic the right size I would have just used that. I can remove it if I want or to remove the wrist pin. I didn't and don't think it's appropriate to have the area under the piston open to the atmosphere but one reason I did a dead head test immediately afterwards is I wanted to be sure the pump is working as it did with this area open. The time is, if anything, a few seconds less. So my conclusion is that is best to close off this area unless you are working on the pump. The grease under the plug was also black, not white like it was elsewhere. So it got removed and replaced. I pulled the wrist pin and regreased it but that grease actually looked to be fine.
 
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Definitely a breather, it's made that way for a reason. Earlier ones are vented differently

The cylinder venting on the cs2 and cs3 has changed several times over the years as well as the fan directions.

GX has spent many many hours and dollars in R&D on these compressors.

You can even see the black vent in some of the cs3 cases directly in front of that plug in the cylinder.
 
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PLEASE DO NOT DO WHAT I DID AND RECOMMENDED. My CS2 quit today, I think the overload tripped, while filling my Caiman. It was only at about 150 bar so pressure was not high. It had been working fine. I started taking it apart and that washer I installed to seal the area is missing. It was too big to fall in and was trapped but I am worried I did not anticipate how far towards the piston the washer projected. The piston does not seam damaged except for a slight scratch but somehow that washer went somewhere and I am worried it got chewed on enough it went inside the cylinder. I cannot move the piston and from the position it is in I cannot get the rod off the crankshaft to complete the disassembly. I will continue to mess with it but I may have ruined my CS2. I would hate for anybody else to have a similar experience. I wish now I had left that area open as several of you recommended. Or at least plugged it with a plastic washer that could not do damage. The washer I used was mild steel.
 
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JimD said:
PLEASE DO NOT DO WHAT I DID AND RECOMMENDED. My CS2 quit today, I think the overload tripped, while filling my Caiman. It was only at about 150 bar so pressure was not high. It had been working fine. I started taking it apart and that washer I installed to seal the area is missing. It was too big to fall in and was trapped but I am worried I did not anticipate how far towards the piston the washer projected. The piston does not seam damaged except for a slight scratch but somehow that washer went somewhere and I am worried it got chewed on enough it went inside the cylinder. I cannot move the piston and from the position it is in I cannot get the rod off the crankshaft to complete the disassembly. I will continue to mess with it but I may have ruined my CS2. I would hate for anybody else to have a similar experience. I wish now I had left that area open as several of you recommended. Or at least plugged it with a plastic washer that could not do damage. The washer I used was mild steel.
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Could of just put a piece of tape over it on the outside, and that way it would of blown off if needed as well.

Early plugs are solid, but those are also vented differently than the newer compressors.
 
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