Air Compresser issue knock knock knock

[4v shane]

Well I have a Delta brand 80 gallon 6.5 horse compressor i guess manufactered by devilbiss Model number # DLKC6580V2-1

http://www.allpartsinc.com/ProductD...2-1---Delta-Type-1-6.5HP-80G-VS-OL-2STG-240V-

The compressor has stated to periodically knock from time to time. I need to make this thing live for atleast a week or two. Currently calls for SAE 30 weight any suggestions or tips ideas anything to keep this thing limping along until I can get the parts? Any suggestions on sites who sell a rebuild kit that isnt $500 mind you the new price of the compressor is like $899.99.


Thanks for any and all input in advance GJ people!

 

[Milton Shaw]

Check to be sure it's not a loose pulley, setscrew or key loose. If it's the crankshaft and rod knocking, maybe a little STP oil additive will make the oil thick enough to last a little while.

 

[Zeke]

Good advice, Milton. I had a compressor that knocked for over 20 years. I gave it away not long ago and it's still going. Typical cast iron twin pump.

 

[e-tek]

Tighten everything down and be sure the oil is at the max level. If it's even a little low it can knock. Mine was getting weak and making noise, it was low oil and a loose belt....

 

[ddawg16]

At least you have a real compressor.....I have one of those 'oilless' units.....takes at least 20 min to fill the 35 gal tank.....I think it's on it's last leg.....makes your 'knock knock' sound good.....

Yea....like everyone said...make sure everything is tight and the oil full....and make sure it's just not banging against something.

FWIW....a 'rod knock' is pretty obvious....about par to smacking two hammers together...the 'tone' of the knock can give you a good clue as to the problem.

Also...I would look into seeing if a rebuild of the actual compressor is an option.

 

[shannonw]

You sure it's a knock from the pump?, a slapping belt can sound somewhat knockish i've noticed when mine got a bit loose.

 

[sublimate]

Who's there?

 

[4v shane]

Well I found some formulated special wizzy oil for my compressor and a new check valve I guess with a faulty check valve and the air flowing back out of the tank back into the pump and can also cause a knock! Well parts purchased tomorrow she gets all torqued to spec,oil change,filter change, full inspection. Back up compressor was found a 10hp quincy with 120 gallon tank for $2600!

 

[OccupantRJ]

Air compressors carbon up on the piston and valves, which can cause one to knock, sometimes just during initial pressure buildup. Cleaning both is part of maintaining one, although most people never do.

 

[JeremyB]

Take off the head and look at the gasket. I have the same pump and it was making the same noise. It turned out that the head gasket had deteriorated. I replaced the gasket and its been running normally ever since. Easy and pretty cheap fix.

 

[shoot summ]

At least you have a real compressor.....I have one of those 'oilless' units.....takes at least 20 min to fill the 35 gal tank.....I think it's on it's last leg.....makes your 'knock knock' sound good.....

Yea....like everyone said...make sure everything is tight and the oil full....and make sure it's just not banging against something.

FWIW....a 'rod knock' is pretty obvious....about par to smacking two hammers together...the 'tone' of the knock can give you a good clue as to the problem.

Also...I would look into seeing if a rebuild of the actual compressor is an option.

I've got a small oil less as a secondary I use for trim work. It is easily over 20 years old. It started taking a long time to fill as well, and actually got to the point it would never fill. I wrote it off thinking I had gotten good service out of it. I was going to buy a cheap portable(bought a Paslode airless nailer instead), couldn't stand to throw the old one away so I decided to check it out. Pulled the head, everything looked OK but I did find that the output pipe(aluminum) had cracked at the ferrule and was leaking. I shortened the pipe, installed a new ferrule, and it works as good as it ever did.

I thought my big compressor was knocking, listened very closely, turns out it is just intake noise on mine.

 

[jsaw]

Take off the head and look at the gasket. I have the same pump and it was making the same noise. It turned out that the head gasket had deteriorated. I replaced the gasket and its been running normally ever since. Easy and pretty cheap fix.

My buddys Ingersoll Rand did this. we were using it one night, and it started knocking. He called them, They said to replace the head gasket. We did, no more knocking.

 

[4v shane]

Now after replacing the check valve i have a strange leak towards the 175 psi cut off.... I did have to drill out the check valve a little to fit in the copper tube with compression fitting on it so it would tighten down on the threads