Poorly compressor

[Paint munky]

Probably best if i start right from the start with this. I have a Fiac 2.5HP 100L compressor which i brought 2nd hand, its in great shape and was told by the previous owner he overhauled the motor not long prior to me buying it.
Anyway all was well for a few months bearing in mind i dont use it everyday, once a week sometimes more, then one day i noticed it had been running a while and when i opened the garage door air was ******* out of somewhere and it wasnt holding much presure. I was told it could be the reed valves so stripped the motor down to the point where i could get the cylinder off the piston. Everything looked ok, gaskets like new and reed valves seemed to do what there meant to so ****** off that i hadnt found anything wrong put it all back together, fired it up and it worked a treat.
Went on for another few months and it may just be in my head but im sure its now taking longer to build presure but worse of all its burning oil. At first it didnt seem like much, id open the garage door and there would be a whiff of burning oil and a tiny bit of smoke, today i went in to drain it after spraying for a few hours and there was that much smoke i had to let it clear before i could get in.

I now dont wanna use it through risk of burning my garage and house down so it needs sorting, can anyone point me in the right direction as to what maybe wrong.

 

[rtbcomp]

Did you use the correct oil

http://www.mig-welding.co.uk/forum/showthread.php?t=31690

 

[Paint munky]

This is what i ended up getting http://www.ebay.co.uk/itm/290355603...WNX:IT&_trksid=p3984.m1439.l2649#ht_961wt_932

I first noticed the smoking before i changed the oil so id kinda ruled that out

 

[tigler]

Is the airfilter choked up ?

 

[the snooper]

there is really only 2 things to cause this
1 wrong oil
2 overheating

if it was burning oil as you put it then the smoke would be coming from the air line

one other thought check the piston rings they could be allowing hot air past making the oil smoke

 

[eil]

I presume the compressor is running the right way ie cooling fan sucking air over the compressor.

 

[brightspark]

is it direct drive??

 

[shenion]

Is the cut off pressure right?

Could be it is running up to to high a pressure. Above a certain PSI, it really drops airflow and gets hot.

 

[Paint munky]

there is really only 2 things to cause this
1 wrong oil
2 overheating

if it was burning oil as you put it then the smoke would be coming from the air line

one other thought check the piston rings they could be allowing hot air past making the oil smoke

Your right it would be wouldnt it, it was a bitch to get the rings compressed to get the cylinder back on so that could be worth checking.

I presume the compressor is running the right way ie cooling fan sucking air over the compressor.

Mmmmm this is how its sitting

is it direct drive??

Belt driven i belive

Is the cut off pressure right?

Could be it is running up to to high a pressure. Above a certain PSI, it really drops airflow and gets hot.

The cut off point hasnt changed since day one so doubt its that.

 

[eil]

I know that pump quite well from experience. Before delving into major surgery check the air filter for blockage and the air outlet pipe from the compressor to receiver which I've known to block with carboned oil.. The cooling fan can't be wrong, it's part of the drive pulley.

But didn't the previous owner replace the motor?, I did not suggest that the cooling fan was wrong, I merely asked if it was spinning the right way round, if it doesn't then it wont cool will it, especially under the bench and up against the wall.

 

[eil]

Motor to me means electric motor, the bit that it turns is the compressor, why is it doubtful that the motor could be rotating in the wrong direction. Don't know what difference it makes that the pulley is on a tapered shaft though, I did not suggest that the pulley had been put on wrong or **** about face at all.

 

[Paint munky]

Nothing was replaced i was just told it had been overhauled, what had be done exactly i dont know but the guy seem pretty clued up as far as these things go.

I pulled the outlet pipe off and although there was some oily crap in there there was nothing i could see that would cause a problem but ive left it to soak overnight anyway.

The air filter doesnt look mint but again it didnt look dirty enough to cause issues. What material should the filter be made off? mine looks a bit like paintroom filter material.

 

[eil]

Stand in front of the compressor the side furthest away from the crank pulley and switch on if it blows air over your face then its turning the right way, or even hold a sheet of bog roll near the pulley fan outlet and note the airflow like that.

 

[eil]

In your opening post you stated that the previous owner had overhauled the motor. I took that as overhauled the electric motor as opposed to overhauled the motor in the American stylee.

 

[Cobbler]

Some motors will start in reverse if the start capacitor is faulty. I found this out looking at a friends garden shredder that would not cut. The capacitor was open circuit but the motor would start and run ok but would go in reverse. New capacitor from the motor rewind people was about £6, from the shredder makers dearer than a new shredder. I was of the opinion that it was only required for starting, but apparently this is not so.

Cobbler

 

[eil]

Conventional approach to fault finding is to rule out the simplest and most obvious first.

What can be simpler than to check correct airflow over the compressor, can be done in seconds, and if its OK then move on to the next possibility.

The fact that the pulley is mounted on a tapered shaft means it can not be incorrectly installed.

That frankly is quite obvious, but at no time did I suggest I such a thing.

The motor turning in the wrong direction is quite unlikely in your experience.

Then your experience is different to mine through my dealings with various motor rewind company's.

It has been working OK up to now though.

Has it though, this by the OP`s admission is the second breakdown now. Has it been spinning the right way since he got it ?.
If it was rotating the wrong way it would still get to pressure no problem, but when worked harder and in higher ambients ....

 

[tigler]

You obviously know what the fault is then so no need for my contribution.

 

[the snooper]

original problem air escaping and pressure not building
air escaping not really a symptom of the valves

also somewhere you mentioned that it was hard to get the rings back into the cylinder, i think you should remove the cylinder head and check for damage to the cylinder just incase you broke a ring getting the cylinder back on, usually cylinders that are meant to be replaced that way have tapers on the bottom for that reason if yours didnt then it should have gone in from the top with a ring compressor.

 

[eil]

You obviously know what the fault is then so no need for my contribution.

Not at all, you discounted my contribution as not possible, neither of us can say what the problem is outright as were not on site to properly make the right diagnosis. No need for you to take umbrage.

 

[Paint munky]

Ok i can confirm the fan is blowing in the right direction, away from the wall and over the compressor. And this is what the filter looks like

I just timed the compressor filling from empty and it takes 11 minutes to reach 9 bar with the last couple of bar seems to take forever. Bit odd as the sticker on the tank states safety cut off is 11 bar.

Also this may seem like a lame question but i take it the red dot in the middle of the sight glass is the correct level for the oil and not the minimum level?