Air leak problem on compressor

[Southernsorrow]

I have a craftsman compressor. had it for years no problems. I noticed a little over a week ago that it was leaking around the aluminum hardline at the tube seal that goes into the head/manifold. so Okay $2 part changed that out along with valve plate + new upper head gasket and lower valve plate gasket No more leaks from that spot anymore.....

But now I go to use it and no air in the tank.... filled the mofo up to 150lbs... and 10 minutes later lost 20+lbs... got out some soap and water and traced the leak to the 5/16 compression nut holding the main aluminum line from the compressor to the tank. The air is seeping out the top of the compression nut around the diameter of the tube. I tightened it down hard and still leaks like a sob.

So do you think the problem would be solved if I just replace the compression nut for $5-6? or do you think I need a new outlet tube which is around $35-$50.FD "friggin dollars" and/or or could it be the $20 check valve ? or all of the above ?

 

[The Cobbler]

with the compressor off, there should not be any air leaking from the unloader line or the line from the head to the tank ( after it has unloaded) but it shouldn't leak at the fittings in any event. sounds like your check valve is bad as well as a few connections

 

[md21722]

The check valve is the only part that would cause air to leak backwards from the tank. They can be had for $10-15 using a common parts supplier, but then you need to figure out exactly what thread sizes you need. If the compression nut fittings use rubber/teflon seals on the aluminum or copper pipe you may consider replacing them as well while its off.

 

[59 wagon man]

if you tightened the line and it didnt help try draining the tank completely and loosen the nut completely. now take about a 2ft piece of teflon tape and fold it together. now take the long piece you have and roll it between your hands. you should now have about 12" of teflon packing. wrap this around the shaft and tighten the nut back again. now build air and check for leaks

 

[md21722]

if you tightened the line and it didnt help try draining the tank completely and loosen the nut completely. now take about a 2ft piece of teflon tape and fold it together. now take the long piece you have and roll it between your hands. you should now have about 12" of teflon packing. wrap this around the shaft and tighten the nut back again. now build air and check for leaks

This won't help if the tank is leaking backwards from the tank towards the pump when the compressor is not running. If it does at all, then its just loading the head/valves and expecting them to do the job of the check valve. It should only be expected to help when the compressor itself is running, building pressure slowly because the discharge tube/fittings are leaking.

 

[Southernsorrow]

was kinda figuring it to be the check valve, the whole point of that valve is to keep air from coming back out once it's put in... I'll grab a valve and a nut and save buying the hardline unless I need it. Check valve part# is A19718 , the Compression fitting is SSP-473

 

[Marctrees]

Southernsorrow - SLOW down.

Why is this so complicated??????

Use spray soap solution as you said.

If the leak is a piping joint of any kind, redo it w pipe dope or teflon, or change the fitting if necessary.

If its a component, like the relief valve, clean and /or swap that out.

Why are you jumping to a "check valve" if you already found the leak???

I don't understand otherwise. Marc

 

[Marctrees]

So, is this check valve leaking externally, or internally?? Marc

 

[Southernsorrow]

it's leaking air around where the compression fitting/nut bolts the hard line "aluminum hose" from the compressor to the check valve on the tank.

I Tried dope, thread tape "the good tape not the cheap 99 cent white garbage" and still leaking there. I don't see any cracks in the hard line so either it's the check valve it bolts to, or simply the nut that holds it down "see pics below". When I took everything apart to change the leaking tube seal and head gaskets on the opposite end of the hardline I made damn sure to baby it like it was made out of glass so as to not bend or break the aluminum tube supposedly to make something like this wouldn't happen

Random pics "I'll take my own tomorrow if needed"

This compression nut "pic1" slides over the red line end of the aluminum hardline "pic 2" and holds that end of the aluminum hard line down onto the check valve "pic 3"

 

[MDK22]

Get a new compression nut with brass compression insert. As they stated above the check valve also should not be leaking air back into the line anyway so that is bad also.

IE replace both..... If I was you I would just put an inline coupler in and install a brass ball on spring check valve rated for 300psi. Then reduce it down to whatever line size you use. Will it cost like 30-40 bucks ya but, that pile of garbage check valve is an engineers ********* instead of just doing it tried and true.

 

[bsaint]

You never told us if air is leaking out while its running or off (or you did and I missed it.) If its ******* air while off, its a bad check valve and most likely cracked discharge tube. Aluminum work hardens with vibrations, as does copper. It happens over time. Most likely the ferule is not bad. If it only leaks while running, its probably just a cracked discharge tube. Easy fix. Cut off the old crimped ferule and replace it with home depot 1/4" brass ferule. You can get like a 10 pack for 5 dollars.