Compressor Refurb

[rodw]

Well, I have been meaning to buy a belt driven compressor for a while and I spied this one on Grays Online Auctions recently and because it was not far from home to pick up, I thought I would take a punt on it sight unseen based on this photo that was in the listing

Pilot is a very good Aussie brand and this compressor retails for around AUD $1,000 and I knew you could still get parts for them locally otherwise I would not have bothered. This mode has only just been discontinued and you can still buy it.

I figured that either the motor or the pump was seized and hoped that it would not be both.

Anyway, I was quite surprised that I won it for well under my maximum bid so I allocated a day to collect it, clean it up and sort out what parts I needed.

When I got it home, I was a bit disappointed to see that the motor would only just turn the thing over so I pulled it off and to my surprise the motor ran like a train with no load. Anyway, I put it aside and tackled the first stage cleanup with my Stihl Pressure washer and copies quantities of degreaser, I got it to this stage and saw that it was built in 1995.



I was quite surprised that there was still air (and a lot of sludge) in the tank. I did not see any evidence of shale or rust though.

I rang an electric motor repair place to see if it was worth getting the motor repaired and they said they hated to see old motors like this Brook Crompton Betts thrown out as you simply could not buy motors of that quality anywhere today (even if you bought the same brand). Anyway, they talked me into bringing it in for an assessment and said they would test it and quote on repairs.

So in the afternoon, I headed off to Pilot and picked up an air filter, a new oil filler/breather to replace the broken one and a set of head gaskets so I could see what was going on inside. I also decided I would get an air pressure gauge so I could check that the pressure switch was cutting out at a safe pressure. All up I spent $100 or so on parts.

The pump is a two cylinder Italian made one and the valves are riveted to a plate that is sandwiched between the cylinder and the head. The guy at Pilot reckoned that the rings probably would not need replacing and said if it was pumping air, there was no need to worry about buying a new set of valves which he had in stock at a price of $115. Off I went to drop the motor off to be assessed for repair. I was not too concerned about the motor being shot as I know I can grab a new Chinese on for $200 that would do the job for home use but if the repair not too bad I will stick to the original. I asked the guy what oil to use and he said just use 15W/40 diesel engine oil. I had some of this on hand so I changed the oil once I got home.

We went away for the weekend but after we got home I pulled the head off to see what was going on. I am pleased I did as it was very dirty around the valves and it took a long time to clean it all up.

The head



The valve plate which I stamped and scribed so I would not forget which way is up



And the pistons




One piston has quite a scorched look and I found this hard to clean off and I don't think I will worry too much about it as I did not want to get too much dirt down onto the rings.

By the look of it, somebody had been in here before me as the arrows look to be engraved by the same hand that had engraved the belt code on the motor housing. I figured this is not a bad thing as it meant that the rings are not 20 years old! There is heaps of compression. I turned the thing over for a while and noticed there was a thin film of oil on one cylinder wall but none getting last the rings on the other one. Not ideal but I don't think it is worth stripping it down further at this stage to fix this. If it does need reboring, I think I will be able to swing the cylinder on my 13" lathe and do it myself but for now I don't want the expense of new pistons, rings and bearings unless I really have to.

The reed valves seem to be fine now they are cleaned up.

The next stage is to strip the fittings off the tank and clean out the sludge. and put the pump back together. The tank will probably get a coat of paint.

Anyway, there did not seem to be much about compressors on this site so I thought I would document this project so you can see what a compressor looks like on the inside as I had never seen one opened up either. Sorry, I did not take any photos before I cleaned it up.

For the record, this has a 15 cubic foot a minute displacement pump with free air delivery of 243 litres per minute (8.3 cubic foot) and a 58 litre air tank. The motor is a 2 kW single phase which draws 12.5 amps so it officially needs a 15 amp power point but of course the lead on it has a 10 amp plug on it.

I can't wait to get it up and running so I can retire the cr@ppy $150 noisy as anything direct drive compressor that only delivers half the air of this unit.

 

[fishingboat]

Rod W,
It looks like you have this project under control. The only comment I have is to do with rewinding an old motor. The only down side is that you loose the efficiency that can be had with a new motor but where as it is for home use you more than likely would not have wanted to pay the price of a high efficiency motor. As for the scorching on one cylinder. If it is a 2 stage that would account for it otherwise it is more than likely from a burnt or stuck valve or possible a ring issue. It you should know more when you fire it up, either issue will effect the output. One last thing, you should check to make sure that the unloader is working. The compressor will not be able to start with air pressure against the valves or pistons. The unloader is probably incorporated into the pressure switch. Good luck!!

 

[ZipSnipe]

Rod looks like a great project. I don't think you will regret taking the motor to an electric motor place.

For my lathe I should have done that but instead tried to put another motor on which I did but was a huge pain to get it close to being right. Better to use an original.

 

[rodw]

Rod W,
It looks like you have this project under control. The only comment I have is to do with rewinding an old motor. The only down side is that you loose the efficiency that can be had with a new motor but where as it is for home use you more than likely would not have wanted to pay the price of a high efficiency motor. As for the scorching on one cylinder. If it is a 2 stage that would account for it otherwise it is more than likely from a burnt or stuck valve or possible a ring issue. It you should know more when you fire it up, either issue will effect the output. One last thing, you should check to make sure that the unloader is working. The compressor will not be able to start with air pressure against the valves or pistons. The unloader is probably incorporated into the pressure switch. Good luck!!

Fishingboat, thanks for your thoughts.

I am not so sure if I am in control of this project, maybe it's just that I have not got stuck yet!

I don't think it is a two stage pump by the look of the valve and head arrangement but I don't know enough to say for sure. I will have a bit more of a look at the valves and maybe the rings. There was an awful lot of muck built up around the valve, which might have had something to do with the scorch marks. A bit of oil dieseling perhaps?

I think the unloader is working OK but I will revisit this once I get the motor back.

As far as the motor efficiency goes, I noticed that new compressors of this size today seem to run a 2.2 kW motor and this one is only 2.0 kW which I thought might have been an indicator of the efficiency of this old motor, but yes you are right, I don't think additional money for an efficient motor is necessary for home use.

Rod looks like a great project. I don't think you will regret taking the motor to an electric motor place.

For my lathe I should have done that but instead tried to put another motor on which I did but was a huge pain to get it close to being right. Better to use an original.

ZipSnipe, thanks for that feedback, ease of mounting the old one back was a point not lost on me.

 

[Charles Lamont]

If it were 2-stage the bores would be different sizes.
Perhaps it would be wise to test the receiver?

 

[rodw]

If it were 2-stage the bores would be different sizes.
Perhaps it would be wise to test the receiver?

Charles, I pulled out the end bungs and flushed out the tank this afternoon. This compressor serviced agricultural machinery and had obviously lived in very dusty conditions as most of the goop that came out was mud and there was no evidence of rust or shale. I sloshed ome heavy duty truck wash inside and left it sit for an hour or so to soften the residue. once flushed out clean, I was able to shine a torch inside and visually inspect it with my carefully calibrated eyeometer. I am satisfied it is still sound. It is a very solid tank, not like your average Chinese one.

I made up a tool to remove the bungs with a couple of high tensile bolts and a steel offcut but all I managed to do was bend the bolts so I resorted to a Stilson wrench and they both came out. Sometimes you over think things when rough and ready gets the job done straight away.

 

[rodw]

Yesterday, I picked up the motor from the repairer and it cost me $100 to fit a set of 2 new capacitors. They said they were not happy with the torque after this repair and that if it did not work out for me to bring it back so they could recover the parts and they would give me my money back as it was not worth rewinding a motor of this size as they could sell me a new Australian made motor for less than the cost of a rewind.

Last night, I had a rush trip to Tradetools before they closed at 6:00pm because I realised I would need a 1/2" drive Allen key to torque up the head bolts and of course the one I bought 30 years ago was the wrong size. I came back with a complete set for $35 which I thought was pretty good value.

I found time to put the compressor back together today and torqued the head bolts to 34 foot pound as per the advice from Pilot. There were six bolts so I tightened up the centre pair then went diagonally around the head in two passes with the first pass at about 20 foot pound.

Well I had a bit of a setback after that though. I mounted up the motor and found it was not much better than it was and I did not have the outlet connected to anything.

So anyway, I have pulled the motor off again and will go looking for a new motor.

I knew everything was going too smoothly.

 

[rodw]

Well, I better put some more pics up.

I got it back together and the new motor fitted and tested everything. The pressure switch is fine and the blowoff valve seems set just above it.

Here is my cheap arsed torque wrench and the $35 set of allen keys I needed to tackle the head bolts.










I decided I could not complete the job without painting it and I found an old tin of Killrust black enamel paint in the garden shed. I Hit the stickers with a hot air gun and got them off without too many dramas. I masked off a couple of rmeaining fittings and painted it with a brush.



And did a final assembly including the guards



So now it was time to plumb in the air. Before we start, let me share a couple of things with you.

First, don't use thread seal tape for air fittings. You will be forever chasing down leaks. Use a liquid sealant.


This is some stuff I got from a plumbing supply place that I had on hand. Locktite also have it They make 2 types. This one which is rated for low pressure and stays soft. Its rated to 2600 kPa (3-4 times what we need here) so there is no need to get the high pressure sealant that dries hard and is harder to undo.

This cheap tool cost me < $10 from a plumbing supply place and I have used it so much that I had to turn the blade round to the second cutting edge. It is great for cutting irrigation pipe and hoses like air line.



And finally, I used these clamp on connectors for the first time which somebody said you can clamp with a blunt pair of pincers. I am a convert. They are great and much better than hose clamps for this sort of thing. And the guy at the air shop gave them to me for free!



So with the tutorial over, lets get some air in this shed, note the plastic electrical grommet the hose passes through.



And the crimp on clamps


And a hole in the wall with a step drill, a squirt of metal primer from the inside so there are no unpainted edges



And a rubber grommet after wiping off the excess paint dribble



A male Nitto fitting, a couple of conduit clips screwed to the post for the storage rack and we are all good to go



Park it on the slab I poured about 2 years ago and stick some rubber pads under the wheels which don't have much padding left on them



And as soon as the electrical is complete we are done!



I better get the roof over my materials rack now.

I had thought of using hard air lines for this install but decided for the short length of the run, air hose would be fine and once I get a power point outside, I will be able to unplug it and wheel it away for some other job if required.

Awesome to have air in my shop. Even without power, a full tank lasts a long time and I have wound the regulator back to about 60 psi as it was pretty strong at higher pressures.

 

[Philjoe5]

Nice restoration work Rodw. Always nice to see good old machinery put back into workThm:

Cheers,
Phil

 

[fishingboat]

Hi Rod W,
It's good to see that the project is done, and with minimal issues. A fresh coat of paint always makes a restoration look better and the new motor doesn't look out of place now. I know that compressed are seems like a luxury until you have it. My compressor is the most used tool in my shop. I use it for everything from carpentry to painting with sanding seeming to be the most prevalent. I restored a 21' fiberglass boat and now a 1956 MGA. I am sure that you will enjoy and use it often!

 

[gabby]

Very nice, is the new motor a 2.2kw ?
I have recently got a donated compressor going, but never went as far as you have with the new paint and all, I simply repaired the reeds and reassembled then test run ok :hDe: I am hoping the tank is still ok, there was no gunk in it when i opened the drain valve at 60psi so I'm happy.

 

[rodw]

Very nice, is the new motor a 2.2kw ?
I have recently got a donated compressor going, but never went as far as you have with the new paint and all, I simply repaired the reeds and reassembled then test run ok :hDe: I am hoping the tank is still ok, there was no gunk in it when i opened the drain valve at 60psi so I'm happy.

Gabby, yes the motor is 2.2 kW v's the old one being 2.0 kW.

I bought the motor from Hare and Forbes who are over your way too. It had the correct frame size so all the dimensions made it a simple bolt on swap. They also had a Chinese motor for about half the price that would have required some work to sort out fitting the shaft and the motor mounts. I did not really want to spend any more time on it so took the easy way out.

This old thing had lived in a dusty transport yard and the tank was full of mud that oozed out of the drain cock after it got shaken up on the way home so I had to flush it out. With the thickness of the steel used in these old compressors, I reckon the tank is the least of your worries. This one will outlast the Titanic!