Bogged-down compressor

[spavined]

Thanks for the thoughts, I appreciate it.

For the time being, I'm inclined to agree with the mechanical arguments. I've been talking to a compressor mechanic on a different board, and his best guess is a cracked ring allowing compression below the cylinder or, less likely, a cracked piston.

In any case, it looks like I'll be taking this apart in the next few days - I'll keep you posted. In the meanwhile, I welcome any further thoughts.

As an aside the model # is 919.175960. It's interesting - sears parts.com brings up the correct diagram, as you'd suspect, but the their site for manuals brings up an oil-free unit's manual. Annoying.

 

[shenion]

Their parts list shows a 240V motor on that model.

 

[spavined]

Quick note: I said it's wired for 110. It is. I still agree with it being a mechanical issue, but I'll let you know if I turn out to be wrong.

 

[spavined]

I tore down the compressor, and I expected more parts. In any case, here is where I am:

Exhibit A
Exhibit B
Exhibit C

Several findings:

Of note: gaskets were blown. Wired for 110, but probably should be 220, as has been covered.

Good news: no broken rings or piston. Cylinder walls look good.

Bad news
#1: I'm fairly positive this is not the original compressor. When I got to taking it off, I only then realized it didn't fit the original mounts. It has no features I can find to tell me its make or model.

#2: Due to the above, it looks like I'm going to have to make all my new gaskets, which is not my preference. They differ from those seen on the sears parts site.

#3: Am I correct in thinking this is a piston short?(!)

Assuming "yes" to #3, is this my issue? Why would it run fine for a while before, though? I can't make the logic work there. If not the issue, is it simply the loss of pressure from very bad gaskets? Can I safely run this on one cylinder? If I need two pistons, I have no clue where to get the right hardware for this replacement compressor.

The reason I'm not positive about the # of pistons is the sears diagram for the original compressor shows two cylinders but only one piston. This makes no sense to me, but I'm new to this technology...

I appreciate any further thoughts, thanks.

 

[eil]

Its a twin cylinder and you only have one piston/ con-rod then you are a piston short, what state is there on the crank and thrust washers, any idea as to how the splash lube is supposed to work, as someone has clearly been in there before you perhaps they forgot to re-fit the splash lube bits, It certainly sounded a mechanical fault type of noise to me in your video, did it have any oil in when you took it apart, any swarf or bits in the crankcase ?
It will work on one cylinder if its not missing the discharge valve in the empty cylinder, if that is left out also it will just pressurise the crankcase and blow out the oil/gaskets.

 

[shenion]

You want a new pump; that has been mucked with.

There are sellers on ebay that sell these exact pumps. About $170 IIRC. Horror Freight has one for $140 that will work with probably some mounting changes.

Rebuild kits are available but you would also need the second crank and piston. Will cost more than a new pump.

As to why it ran fine before. Try emptying the tank and I bet it runs for several minutes. Sounds like the seller pulled a real fast one on you. Never changed the oil, broke a rod and kludged it up. Made shure the tank was empty when he ran it.

Mine is over 20 years old and still runs fine. I keep hoping the compressor blows so I can have a real reason to put a big Eaton 2-stage pump on it

 

[the snooper]

id be back at the guy that sold it to you .

we all had ideas and theorys as to the cause of the machine failing
nobody saw that one one coming did they

 

[spavined]

I figured as much - looking around in there last night I was able to pretty much figure out the situation, but you've all confirmed it for me.

If there's an upside, expensive lessons are usually the ones I learn the most from...

Thanks, all.

 

[eil]

Seeing as he was a chiropractor go and treat him to a taste of your big toe, make sure its in your steel toecap boot first though.

 

[spavined]

Update:

Things are progressing. After a few conversations, the prior owner of the compressor and I have come to an understanding about a few things. The result is he's sending me back 75% of what I paid him and I'm keeping the unit.

I've rewired it to 240V (13A), which is a return to its original set-up. Seeing as the cylinders are in fine shape, I'd planned rebuild the compressor; however, seeing as I have no sense as to the original manufacturer (there's no identifying marks or numbers), this has proven challenging. This morning I called a couple of commercial compressor shops to see if they had any ideas for aftermarket rods and pistons that could match what I've got, but both told me I was out of luck.

This leaves me with a couple of questions for you all:

1. There are serials on the piston and rod I have (VS-1-A and VT-1-B, respectively). Does this mean anything to anyone? An internet search unsurprisingly didn't find anything. Any other ideas for finding aftermarket pistons?

2. Unless something turns up for (1), I'll probably just buy a new compressor unit with the money I'm getting back from the prior owner. To this end, I've been looking around and have found both 3hp and 5hp options--the latter generally being considerably more expensive. If the only difference between the two is air delivery levels (i.e. max PSI and max RPMs are otherwise the same), is there a reason the 3hp compressor couldn't/wouldn't/shouldn't be put to work connected to a 5hp motor?


Thanks,
-s

 

[shenion]

The 3HP compressor will run fine on the 5HP motor. The main difference is the CFM.

Which pumps are you looking at?

 

[tigler]

Speed compatibilty is an issue.