Vintage Mustang Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
3,179 Posts
Discussion Starter #1
Crappy siphon feed Harbor Frieght spray gun with PPG Epoxy. Usually it goes Psssst! when I shoot paint (amazingly enough) but yesterday it stuttered no matter how I twiddled the two adjusting knobs.

I ran the paint through a filter and the gun's not clogged and I think 60 lbs pressure at the compressor is adequate (50 ft of hose). Did I do some stupid rookie move? I'd use my gravity fed Binks but I'm trying to spray under the dash and the cup gets in the way.

Thanks in advance,

Dean T
 

·
Registered
Joined
·
630 Posts
how many CFM's is your compressor putting out?
 

·
Registered
Joined
·
3,179 Posts
Discussion Starter #3
A very good question - why didn't I think of that?

Here's the compressor's specs:

7.7 cfm @ 40psi
6 cfm @ 90 psi

6HP peak, 27 gallon tank, 155 psi capacity.

Yes, this is a crappy oiless compressor I bought at COSTCO. *G*

It worked fine before, in fact it works great with my gravity fed Binks but yesterday it sputtered so I gave up rather than waste more epoxy primer.

Regards,

Dean T
 

·
Registered
Joined
·
75 Posts
Check to see if yours has a vent tube that runs from the cup to the latch for the cup. When those get clogged it spits and sputters like you describe.
 

·
Registered
Joined
·
3,179 Posts
Discussion Starter #5
Thanks,

I'll have to check that!

Dean T
 

·
Gone but never forgetten
Joined
·
25,239 Posts
I have the same Harbor Freight gravity fed HVLP gun. Does it actually make the noise like that? If so, it sounds like an air restriction. If it sounds ok, and just splatters, instead of spraying a smooth coat, check the little filter in the bottom of the cup. My clogged yesterday shooting primer on my daughter's car, and started really shooting crappy. Then to rub salt in the wound, I f&#@ked around with it long enough that the primer started to set up inside the gun. Took me forever to get the gun all cleaned out again.

Just a tip ... if in fact that is the HVLP gun, you shouldn't be shooting it at 60 PSI. You should have about 40 PSI at the gun (I have a regulator on the tank and another at the gun when I'm using my paint gun).

Actually that Harbor Freight cheap HVLP gravity feed is a great little gun for the money.
 

·
Registered
Joined
·
3,179 Posts
Discussion Starter #7
Hi John,

Unfortunately, I have the siphon feed crappy Harbor Freight spray gun - the $13.99 on sale Special. But it seemed to work okay for primer and Zero-Rust/POR-15/Encapsulator duty.

Between your post and ellis569 I think I may have spotted the problem - you've mentioned air restriction and ellis569 a clogged vent tube. One thing I've done was use a small plastic lidded jar which to use a smaller batch of paint and confine it in a smaller area to conserve paint. Yup, the lid was tightly pressed against the siphon tube and probably not allowing enough air into the inner jar to siphon out the paint.

I'll open up the hole some more and see if that works. Thanks all for the inspiration!

Oh, that regulator/gauge at the gun sounds like a good idea - I'll get one for the gravity fed Binks (HVLP). I definitely run lower pressure with it but with the 50 ft hose I'm always guessing at the compressor's regulator setting.

Thanks again everyone!

Dean T
 

·
Registered
Joined
·
4,926 Posts
John, I have 4 paint guns now. If you need to borrow one, stop on by. They are all HVLP - one is a touch up gun. The fittings are 3/8ths, but that can be swapped. I have regulators on 3 of the 4 guns. plus at the tank and one at the buddy tank. I have 3 different lengths of 3/8ths hose also.
 

·
Registered
Joined
·
4,926 Posts
Sounds like either 1) primer in the gun was starting to set up - if you are painting in 90 plus degree temp, the pot life for the primer is probably something like 15-20 minutes before it starts setting up, unless you thin it with reducer. 2) dirty gun, including vent on the cap to the paint cup, filter in the paint cup, air cap tip, air cap. Merely running lacquer thinner through the gun doesn't clean it. Disassemble and soak the air cap and nozzle in lacquer thinner while you scrub out the reservoir with a bristle brush (.30 cal. gun bore brushworks well) and lacquer thinner. Blow out all of the passages with compressed air, blow out the tip with compressed air - you get the picture. I use a fireplace wooden matchstick wrapped in a cotton rag, soaked in lacquer thinner then worked down inside the nozzle to clean that out. good luck.
 

·
Registered
Joined
·
3,595 Posts
With a siphon feed gun, the container must be vented. Some are actually siphon/pressure feed, where there is a little allen screw that plugs the hole in the lid when you switch from siphon to pressure. Your lid may not be venting, and the gun is starving for paint like your Mustang would starve for fuel if a vented gas cap weren't used.
 

·
Gone but never forgetten
Joined
·
25,239 Posts
Woops. When I read your post, my eyes saw siphon feed, but my brain saw gravity feed *LOL*. I used to have that same gun, which I used for years ... until it fell off of my workbench and broke in 2 :eek:

With the siphon feed, you can probably run 60 PSI at the gun. It's still a great idea to have a regulator at the gun (~$10 from Harbor Freight).
 

·
Registered
Joined
·
3,179 Posts
Discussion Starter #13
Tomorrow I'm going to have a spray gun cleaning party. I've soaked the gun parts but haven't really blasted out the passages with compressed air afterwards.

Hope I'm not too late!

I'll have to pay more attention to paint thickness too, next time.

Thanks a bunch! I'd be lost without Y'all.

Dean T
 

·
Gone but never forgetten
Joined
·
25,239 Posts
Ken, we're hoping to have Steph's car back together by the weekend and ready for the paint shop. As soon as that's done, I'm ready to trade work on your car for work on the sportsroof. I'm going to get serious here REAL soon about getting the body work and paint done.
 

·
Registered
Joined
·
1,043 Posts
Super CJ's exactly right. all the above suggestions are good, and i recommend that you give them all a try but the packing in the gun has probably gone bad. If you take the gun apart, there is a long rod that goes through the gun. where this rod enters the body of the gun in front of the handle, there is a seal. if this seal leaks, even the most tiny amount, the gun will spit like that. In my binks the seal was made out of graphite... mine had hardened so hard that it would not make the seal anymore... i got a new one at the local auto body supply store for $.30. There are seals elsewhere in the gun that can go bad too, but this is the only one I've ever delt with, and it was causing problems exactly like you described. I hope i explained this well enough, i can send pictures if you like.

- Jason
 

·
Registered
Joined
·
913 Posts
John you actually had a good experiance with the harbor frieght gun? I've tried three and still could never get it to spray w/o some orange peel on my 72. But in under 5 minutes of adjusting a finishline III gun I was able to spray mirror finishes that required no color sanding to have a deep shine.

I wish i would've spent the extra $150 in the first place for the FLIII :) I replaced the 3 crappy HF HVLP with hopefully another one (under warranty) that'll work well enough for primer.
 
1 - 17 of 17 Posts
Top