Seeking Air Compressor Knowledge

[gator]

I have an older version (4-5 years old) of this HF compressor (3HP, 21 gal, oil lubed)

http://www.harborfreight.com/3-hp-21-gallon-115-psi-cast-iron-vertical-air-compressor-94667.html

Walked out in the back yard yesterday morning and heard the compressor running in the shop. Went out and it was covered with a light coat of oil, running wide open and no pressure.

Shut it off and haven't been able to get back out to the shop since. The motor (cylinder head) was not really hot so I don't think it was running a long time.

When I get a chance, what should I be looking for? Certainly where ever the problem is, it is spewing an oil film. I have never taken a compressor apart so I need some guidance as to where to start looking and what to look for.

Thanks
George

 

[CDPeters]

George -

Sounds like the problem is in the leaf valves in the cylinder head. To test, unplug the unit, remove the air intake filter and cover the intake port with the palm of your hand. Turn the flywheel through one complete revolution. During 1/2 of the revolution, you should feel the cylinder trying to suck your hand in. During the other your should hear a slight "whoosh" as the air is forced out into the tank. If you feel the air pushing against your hand (rather than sucking) you know the valves are messed up.

If the pump seems to be working OK, then I believe these units have a check valve between the pump and the tank. That check valve might have gone south.

But since it is blowing oil, I really think the problem is the leaf valves.

IF you can get a repair kit (gaskets, valves etc.), it's shouldn't be too hard to fix. The valves are located in under the cylinder head and are just flat, thin strips of metal that allow air to flow one direction but not the other. Kind of like a toilet flapper.

Not sure where you might go about finding the kit, though.

C.

 

[rick7938]

George,

I had the same problem with my HF compressor. The problem - blown head gasket. The head gasket on mine was made of what appeared to be paraffin soaked paper. The gasket had blown between the intake and exhaust chambers, so the compressor was sucking air in, and then blowing it out of the hole in the gasket instead of into the tank.

After cleaning all of the old gasket off the block and head, I fixed mine with a small bead of Form-a-Gasket RTV. Regarding the reed valves, the recess for one of the valves is in the cylinder block and the other is in the head. So, holding the one up into the recess in the head is darn near impossible. What I did was to take some axle grease and "glue" the reed valve to the head while I installed it and got the head bolts started.

Compressor has worked great for two years now. Good Luck.