Compressor playing up.

[chunkolini]

About a year ago I thought my SIP compressor had croaked.
hanks to advice here I bought a new capacitor and it was sorted.
Samke thing happened about a week back, new capacitor and sorted.
Today it happened again.
Turn it on, a loud buzz, the motor attempts to turn then the overheat switch pops.
Any ideas?
Where is the Tigler when you need him?

 

[jonjoe]

did you try to turn the pump over when it buzzen

 

[Badger1bear]

is it a belt drive compressor ? if it is take the belt off and try the motor also see if there is much resistance in the compressor pump turning it by hand ? just a guess

 

[normspanners]

The Check valve in the tank leaking and causing back pressure which overloads the pump, the check valve should hold the pressure in the tank, then the pressure switch should vent the line from the head to the check valve, so that when the pump kicks in it working on an empty pipe giving the motor chance to get to speed before any serious pumping,
Next, is it in a cold enviroment coz the oil thickens over time /cold and gives the motor a lot of stick till it warms the oil I have had the same issues, with mine, I got some thinner oil and its working fine.
It didnt do the cap in it was just stalling on start but up that will do the start cap in !

 

[chunkolini]

I am busy tomorrow off site, on Monday will look into all of these suggestions.
My theory is it must be something simple.
It is in a room that stays above 8c ov er the recent cold snap.
Oil has never been changed. Looked at it ages ago and it looked 'clean'.
Will try the belt off and see what it does. is it belt drive? think so.
Here it is in all it's splendour.

 

[Badger1bear]

I think thats direct drive, our friend could well be on the right lines with the non return valve.....I remember my one some years back had the same symptoms and it was the non return valve

 

[shenion]

That is not belt drive but direct drive.

Could be cheap Chinese caps, i have had them not last at all.

I had a similar compressor, the start cap was minimal. Even new it had a hard time starting. I increased to a bit larger value and it ran fine from then on.

 

[chunkolini]

See how knowledgable I am in these matters.
ow would I check the non return valve.
It does sound as though the motor is struggling to turn over against a load.
This is the original capacitor
How would I upgrade it?

 

[shenion]

Pic is real blurry; cant see if it is 4.0 or 40uf.

Looks like the same one as on my chinese junk compressor that was deafening and vibrated so bad it walked across the room

If it is 4.0 the 4.7 to 6uf would work.
If it is 40 then 47-60uf would work
Should be 300V or higher.

On mine, I paralleled another 4uf on the 40.

 

[Badger1bear]

it will look like this, the big nut on the end you can undo and there will be a spring and a rubber washer in there, if the washer is not seating correctly it will allow air to feed back to the pump which will then be under load when trying to start, as quick check unscrew the big nut off of your one, take the spring and washer out and see if the motor spins up freely with no load or buzzing

 

[the repair man]

Is that the original cap ? or at least identical ?
Starter caps normally have more of a range, yours is 38-42 microfarad, not much at all.
Try a bigger cap, and all other suggestions, good oil, return valve etc. A bigger cap wont do you any harm and will give the motor a good boot up the bum..

 

[chunkolini]

The picture is of the original cap'.
How do I vent the tank? literlaly dont have a clue about these things

 

[Badger1bear]

this link is great for compressor info, you can drain down your tank just by attaching an airline and letting the air out, once its out there is usually a drain plug or bolt that you can unscrew to let any water out,



http://www.about-air-compressors.com/portable-compressors.html

 

[eil]

That is a direct drive,PSC motor (permanent split capacitor) 40uf is correct don't go upping the cap more than 5% as its a run cap and 40uf is what is its designed spec . Do clean and check the non return valve on the tank though, when it switches off does it hiss when unloading and then stop or carry on hissing letting air through. Is the air filter clean.

 

[chunkolini]

Hi guys, thanks for the advice.
Yet again the workshop monkey gets a good result fro this forum.
I had a look at it today, pulled the springy thingy that looks like a decompression device, made me jump out of my skin, but vented the tank.
Then as I moved the compressor I noticed a brass tgingy touch a dangling hose and release air, It was happy to be switched back on and pump.
Looks like it a release valve problem.
While playing up.

While not playing up. below
is it just dismantle the valve, lose tiny springs and seals, spend two hours crawling about in the dust and reassemble?

 

[normspanners]

Thats not the check/nonereturn valve that looks like a pressure release valve
if you emptied the tank and it ran up ( that is because it was pumping against little /no pressure to begin with this could very well be an oil issue as I said only the other day I had exactly the same problem I had replaced my oil because the compressor had fallen over and lost its oil I put 5w 30 synthetic motor oil in because thats all I could get from a service stn near to the boat yard I was working at miles from anywhere and it ran fine ( you are not supposed to use detergent oil in a compressor).
Anyway I thought now I will put some 'proper compressor' oil in but was using it outside during all the snow poss -5c ish and I was having starting problems when it was starting from cold,it would start then become tighter , then stop, drain air out, start it empty, let it warm and it would start all day as long as it stayed slightly warm but if it didnt run for an hour or so same thing, would stall out.
But i was then using it +5c for the last few days with no problem, I think the oil is for european weather,
When the motor is restricted, by pressure and heavy oil it really gives the cap some stick during starting.
That is why vehicles have thinner oil in cold conditions to assist starting
Chunkolini, Did the first cap fail, in the cold weather?

 

[chunkolini]

It never gets that old in my shack, I am lucky eough to have heating, rarely gets below 8c.
it seems okish today.
The button in the picture above seesm to be the ptoblem.
When the pip is up the motor wont turn over, pop it down and all is fine.
I took the valve thingy off and it seems ok.
I will keep an eye on it and maybe vent it off a few times and see how it behaves refilling itself.

 

[droopsnoot]

Hijacking for a moment, I've had trouble with my Sealey compressor blowing fuses either when it first starts, or when it kicks back in after a bit of use, last time it blew the fuse in the RCD plug on the extension lead. Sealey offered a few options, cheapest seemed to be a new capacitor which I have got from eBay and need to fit spade terminals to, then will test out.

However, when I took the old one off, I didn't note which way around it connected. As both wires in the compressor "loom" are black, is it safe to assume that it doesn't actually matter which way I connect the blue and brown wires on my new cap, when I re-fit it?

 

[madkayaker]

It's an AC capacitor so doesn't matter

 

[normspanners]

t's an AC capacitor so doesn't matter

yep +1