For many years I ran an ex hire SIP 2HP Compressor for my air needs, mainly because it was what I could afford at the time.
Recently I started looking for something with a bit more oomph to run an air Grinder etc. Like most domestic workshops I was limited in how big I could go by the single phase supply into the house.
I concluded the ideal no expense spared option would be a Tandem machine but really couldn't justify the £££ so ended up buying a Wolf Dakota 3HP machine for a very reasonable £280 when there was a discount coupon on EBay. I've been quite happy with it, seems a decent machine with good after sales support, it did start tripping it's thermal trip and a new pair of capacitors were sent out next day delivery which sorted things out. However despite a significant increase in power I do still have to occasionally stop grinding to let it catch up, not a big drama but indicative that a bit more wouldn't be a terrible thing.
Then up popped a used Tandem machine on Marketplace, sold with some issues as spares or repair.
My Brother In Law kindly collected it for me in his Van and it arrived home on what appeared to be the Pallet it was originally delivered on. We removed it and manhandled it into the garage. First job was to buy a set of temporary Castors to make it manageable.
So what had I bought? The seller said one pair was slow (I took that to mean it turned slowly) and the other was tripping. I didn't attempt to run either side initially but tested the capacitors and found that the start capacitor on the slow pair was well out of spec so obtained and fitted a replacement. That done a temporary plug was fitted to each motor and I started with trying the slow unit, first trying the motor uncoupled. It seemed to run sweetly and quietly. One thing to note was that this motor was clearly a replacement, it differed from the other and had a later date of manufacture. It was also badly fitted as the belt run misaligned. A brief attempt to realign the pulley indicated it was stuck so I simply elongated the mounting holes to get it aligned. I then tried everything coupled up and it ran OK, but took rather longer to fill the tank than I felt it should as pressure built it did slow a little bit but I suspected what the seller may have meant about it being slow may have referred to the time taken to fill. One other observation was that cut-off pressure was set as 100PSI, odd for a Professional machine.
Time to test the other pair. It span up fine and ran OK, impressions were it filled more quickly but things changed at around 50 PSI where it started to sound really laboured and the belt started chirping. It didn't trip, mechanical empathy wouldn't allow me to let it run long enough. As soon as switched off at the unloader I span the pump by hand and it rotated easily so we don't appear to have some kind of overheat seize going on. Next potential culprit was the check valve sticking preventing air entering the receiver. As I have two, one per pump I simply swapped them to see if the symptoms changed, they didn't, so probably not that. Next I ran the machine again to the point it started to struggle and as it did I loosened the delivery pipe as it attached the check valve, it immediately picked up to normal running speed.
That brings me up to date. I've withdrawn to consider potential issues and I think the issue must be with the valves in the pump. The way I see it the pump delivers air in a series of high pressure slugs. Each delivery has to be higher than the tank pressure or the check valve will not move to admit the charge into the tank, if the pump can't make enough pressure to do that the air stays in the pump and discharge pipe getting hot (pump gets very hot quickly) and eventually a point comes where the pump can't turn and the motor objects.
So next step it to take off the Cylinder head and have a look at the Valve plates. The Pumps are Chinook K17s, which don't seem to be as common. I've found a UK supplier that wants £200 for a service kit!! Don't think so. There are suppliers in the US who have them for a much more reasonable $65 so that's probably where I'll be getting them from assuming investigations indicate that's where the issues are.
I'll close with a pic of the machine after it had a thorough clean.
![IMG_1624[1].JPG](https://www.mig-welding.co.uk/forum/attachments/img_1624-1-jpg.402876/ "IMG_1624[1].JPG")
Recently I started looking for something with a bit more oomph to run an air Grinder etc. Like most domestic workshops I was limited in how big I could go by the single phase supply into the house.
I concluded the ideal no expense spared option would be a Tandem machine but really couldn't justify the £££ so ended up buying a Wolf Dakota 3HP machine for a very reasonable £280 when there was a discount coupon on EBay. I've been quite happy with it, seems a decent machine with good after sales support, it did start tripping it's thermal trip and a new pair of capacitors were sent out next day delivery which sorted things out. However despite a significant increase in power I do still have to occasionally stop grinding to let it catch up, not a big drama but indicative that a bit more wouldn't be a terrible thing.
Then up popped a used Tandem machine on Marketplace, sold with some issues as spares or repair.
My Brother In Law kindly collected it for me in his Van and it arrived home on what appeared to be the Pallet it was originally delivered on. We removed it and manhandled it into the garage. First job was to buy a set of temporary Castors to make it manageable.
So what had I bought? The seller said one pair was slow (I took that to mean it turned slowly) and the other was tripping. I didn't attempt to run either side initially but tested the capacitors and found that the start capacitor on the slow pair was well out of spec so obtained and fitted a replacement. That done a temporary plug was fitted to each motor and I started with trying the slow unit, first trying the motor uncoupled. It seemed to run sweetly and quietly. One thing to note was that this motor was clearly a replacement, it differed from the other and had a later date of manufacture. It was also badly fitted as the belt run misaligned. A brief attempt to realign the pulley indicated it was stuck so I simply elongated the mounting holes to get it aligned. I then tried everything coupled up and it ran OK, but took rather longer to fill the tank than I felt it should as pressure built it did slow a little bit but I suspected what the seller may have meant about it being slow may have referred to the time taken to fill. One other observation was that cut-off pressure was set as 100PSI, odd for a Professional machine.
Time to test the other pair. It span up fine and ran OK, impressions were it filled more quickly but things changed at around 50 PSI where it started to sound really laboured and the belt started chirping. It didn't trip, mechanical empathy wouldn't allow me to let it run long enough. As soon as switched off at the unloader I span the pump by hand and it rotated easily so we don't appear to have some kind of overheat seize going on. Next potential culprit was the check valve sticking preventing air entering the receiver. As I have two, one per pump I simply swapped them to see if the symptoms changed, they didn't, so probably not that. Next I ran the machine again to the point it started to struggle and as it did I loosened the delivery pipe as it attached the check valve, it immediately picked up to normal running speed.
That brings me up to date. I've withdrawn to consider potential issues and I think the issue must be with the valves in the pump. The way I see it the pump delivers air in a series of high pressure slugs. Each delivery has to be higher than the tank pressure or the check valve will not move to admit the charge into the tank, if the pump can't make enough pressure to do that the air stays in the pump and discharge pipe getting hot (pump gets very hot quickly) and eventually a point comes where the pump can't turn and the motor objects.
So next step it to take off the Cylinder head and have a look at the Valve plates. The Pumps are Chinook K17s, which don't seem to be as common. I've found a UK supplier that wants £200 for a service kit!! Don't think so. There are suppliers in the US who have them for a much more reasonable $65 so that's probably where I'll be getting them from assuming investigations indicate that's where the issues are.
I'll close with a pic of the machine after it had a thorough clean.
