Vague air horn question

[oceanjake]

My air horn stopped working suddenly. The system appears to consist of an engine driven compressor that feeds a small manifold which supplies a 3 gallon air tank in the engine room. Air line then runs to the bridge and stops at a solenoid just before the actual horns. There is only ~15lbs of pressure in the tank. I have plans of troubleshooting, but are there any common points of failure I should look at?

[Briankinley2004]

The relay went out on mine. It was 32 volt and hard to find a replacement but finally did. You need more pressure than 15# Once you get that fixed and its still not working check electrical or blown out diaphrams in the actual horn. You should have a gauge on the valve that the relay activates. crack the out going side of it and press the button. If no air comes out its in the valve itself or the electrical side. If air comes out its in the horns or the lines feeding them

[oceanjake]

The switch and relay are working properly. When activated, the 15psi run through them and produce a muffled sound from the horns that resembles an injured animal. When I open the drain valve on the tank there is constant air being produced but very little. I’m suspecting either a bad line going to the bridge or a bad compressor but hoping for something more simple. There is a small manifold after the compressor and before the tank that I don’t understand. Yet.

[kingsley_oasis]

If tank pressure is low, and assuming no leaks then it is likely in the compressor assembly. Good news is that usually it is a stuck poppet valve or the compressor unloading valve assembly. Stripping and cleaning has revived a few for me in past. Mind you they are reasonably priced due to the truck industry.

[oceanjake]

Thank you for the info. To dismantle the compressor must the whole thing come off the engine? It looks like there is coolant running through it. I’d rather not drain the whole system

[oceanjake]

Does anyone have further info on these compressors? How do I check for a stuck valve? Do I need to remove the whole unit from the engine or can I get away with something less invasive?

[SEVEN]

I’m not at my boat and can’t remember the name of the horns. Does any have that name? I spoke to that company 3 years ago and found they rebuild and re-chrome the horns at a very reasonable price.

[oceanjake]

Pretty sure the compressor is a Bendix compressor. Engine mounted and I believe gear driven. As mentioned, it's only building about 10psi in the air tank despite there being no obvious leaks in the system.

[Glory]

On the side of the compressor is an air filter check to see if it is clogged, likely on the left side of compressor or the side away from the trans pump. The filter just clips on, in most cases.

If not,

The air governor might be something to check, its aluminum, mounted on the compressor and has a line going to the tank. If the governor, a D2 governor about $20, is bad and and you released the 2 5/16 bolts holding the governor to the air compressor then start the engine it will build pressure.

If no change, the compressor might be in trouble. To access the poppets as suggested above you will need to drain the coolant, most compressors are water cooled, and remove the compressor head. I'd be replacing the compressor.

Of you shop around you should be able to get one for about $300 depending on model, mine is a part Bendix # 286581( $290).

[oceanjake]

Glory, thanks for the detailed reply. I ordered a new governor just because they are cheap and a spare wouldn’t be a bad thing anyhow. If mine is bad, would it be evident by blowing off air pressure all the time? I’m not seeing that.