Siphon Spray Gun Won't Suck (or sucks!)

[Fultonius]

Hi,

First post. I'm not a welder but you lot seem to have a lot of good knowledge about bodywork!

I'm in the middle of restoring my Transporter van. I've got a compressor and a basic Clarke 1.4mm siphon gun. I've used it before and got "good enough" results. Last time I used it I ran it through with thinners to clean it, that was around 3 years ago.

Yesterday I filled it with primer, fired it up and....NOTHING. Reading around I found some tips and tried the following:

1. Tipped gun upside down and put some thinners directly into the threaded inlet where the siphon cup connects to the gun. With the gun connected to the air line it happily fired through the thinners in a decent spray.

2. Filled cup with thinners, connected (checked air breather holes and siphon tube clear, they were) and sprayed - again, nothing!

3. Took gun to pieces, cleaned everything. Still nothing.

What I have noticed is that even with the siphon cup disconnected, there is no "suction" at the inlet port of the gun - if you run the gun I would imagine that your finger should get "sucked" into the gun inlet, no? I'm not getting any suction at all, so, of course, there's no way the gun would suck up paint. Any help?

 

[pedrobedro]

Is the breather clear on the top of the plate that seals the cup and the pickup pipe clear? That's the only problem I ever had with mine.

 

[carbon]

Is the gland packing around the needle secure. Any air leak there will affect the ability to suck paint

 

[Fultonius]

Pulled the needle gland and checked, seems ok, tightened it up. Still no suction.

Pedro - I have checked the breather hole, but there's not even any suction from the gun, so even if it's not blocked it's not going to pick anything up. I tried the same thing with the grit blast gun (just to make sure I wasn't going mad) and it has plenty of "suction" from the inlet hole - this is what I expect the gun to do too. I'll phone Clarke in the morning. Cheers anyway.

 

[carbon]

Is there a seal behind the fluid nozzle that's damaged, or any old paint inside the aircap?

 

[Maxakarudy]

I'd agree with Carbon, if this PTFE washers doesn't seal the gun won't work or it splutters constantly.
If you can't get a new seal, get a new gun for £20 on ebay, I like gravity guns

 

[Fultonius]

Everything looks pretty clean. Like I said - if I flip the gun upside down and use like a gravity gun the fluid sprays out nicely, so the air cap etc. all seem to work correctly, it's just not siphoning.

My major issue is that I'm off work for the rest of the week to get this done and need to paint today!

 

[Maxakarudy]

Check the syphon tube, it might not be tight

 

[carbon]

As it works upside down I would have thought that there has to be an air leak between the fluid tip and the syphon tube like a degraded seal. Not a gun I have so not sure on how many seals should be in it but one or more is leaking to stop the suction.

 

[Fultonius]

Cheers for all the replies. I called Clarke and they gave roughly the same advice. Tried everything, nothing worked. Since I was desperate to get the van painted so picked up another Clarke cheapo - this time the PGF14 gravity feed. Happy enough with the finish and no siphon issues! Can't complain at £35.

I'll probably try and get the other one repaired as a backup. Maybe.