Question out of curiosity. About 10 seconds after I start my truck in the morning there is a huge mechanical type SNAP that comes from the front of the truck. Anybody within about 20 feet jumps. Sometimes it will do this a couple of times. What causes this and is it normal to be this loud? My wife refuses to walk in front of the truck when I start it up as it has startled her once too often. She says it sounds like it wants to eat her.<br>Seem to remember reading something about this somewhere but can't find it now.

 

It is the relay for the heating grid cycling on and off.<br><br>No biggie.

 

I suppose it could be the clutch on the AC compressor. Mine makes a snapping noise sometimes. Not as consistent as your sounds though, and not as loud either. Hmmm... <br>-Dave

 

Thanks guys. Had a suspicion it was the heater grid but this sounds too loud and mechanical. One morning after the snap there seemed to be a slight burnt electrical smell but I could not find nothing burning.<br>My A/C is never off. Will try and remember tomorrow to shut it off before I start and see if this quiets things down. I did wonder about this but the temps are normally cool enough for the first hour or two that the A/C should not cycle. Specially this morning as we have had an unusual cold front go thru. If it is the A/C clutch, I have never heard one as loud as this on any of the many A/C equipt vehicles I have owned.

 

If you had an electrical burn smell maybe there is a loose connection at the heater grid. Snap may be an arc when the grid cycles...these things draw about 130 amps. The connections are on the intake manifold on the back side of the air inlet duct from the intercooler. Also check the ground connection on the front side of the air inlet. They are easy to get at.<br><br>-Vic

 

Mine makes a slight snap noise when the grid heaters (and wait to start light) turn off. Nothing as loud as what you're talking about, though. Does your light go off a the same time as when you hear the noise?

 

The light turns off before I start it. The noise is after it starts and just sitting idling.

 

maybe it is a normal noise never heard before over the sound of the old style motor? <br><br>Just an idle thought from a 'noisey' diesel truck owner<br>DuaneWKKC

 

No, I don't think this is normal. This morning I started the engine with the A/C switched off. No noise! Will try again tomorrow with the A/C switched off and see what happens.

 

[quote author=Mexstan link=board=17;threadid=12985;start=0#122924 date=1049186391]
The light turns off before I start it. The noise is after it starts and just sitting idling.
[/quote]

But if the 03's operate like a 2nd genner, the grid heater continues to cycle after the engine is started and up to speeds of 15 mph. I would be intreresting to start it, get it up about 15mph while the engine is still cold, stop, then observe it to see if the snapping sound occurs.

 

Yes, I believe that the '03's are the same. Have never heard any noise once I start driving. I know what the grid relay sound is like and this morning I could hear that, but that noise is not very loud. Also it does not make a snapping sound and is quite muted. For what I am hearing, take the grid relay noise and multiply it by say, 50 or amybe even more. This noise is more like the mechanical sound of the A/C clutch but VERY loud. If it is the A/C clutch why would I hear it in the morning when it is cool? It is presumed that the clutch would not cycle at cool temps. I never hear it during the day.

 

It could be an electrical problem if it is loud enough to startle people. Have your wife start the truck with the hood open while you look around and see if you can find the source of the noise. The heater grids make a small thunk. A snap would be an electrical arc of some type. Check battery cables and any large visable wires for being loose from their connectors.<br>Jeff

 

[quote author=Mexstan link=board=17;threadid=12985;start=0#123023 date=1049213817]<br>This noise is more like the mechanical sound of the A/C clutch but VERY loud. If it is the A/C clutch why would I hear it in the morning when it is cool? It is presumed that the clutch would not cycle at cool temps. I never hear it during the day.<br>[/quote]<br><br>If you have the climate control on Defrost or Defrost/Floor the AC cycles.<br>It does this to defrost faster by removing the moisture from the air. (How AC works, partly)<br>It will do this in the dead of winter, or the heat of summer.<br><br>If you're not hearing it later in the day, not sure though.<br><br>Unless it's a combination AC clutch and grid heaters snapping at the same time, there by making it sound louder?<br><br><br>phox

 

Don't have the climate control and know what you mean about it working in winter. This option is also good to keep the compressor working during the winter months.<br>Good guess about both the grid heater and the clutch working together and making the noise but that would be too much of a repeat coincidence. Specially as it happens EVERY day, except today.<br>As soon as I get a chance I will check the underhood HD electrics.

 

Another way to locate if it is an electrical 'ark' would be to open hood and have your wife start truck after DARK. That way you dont have to listen, just look for the blue flash. (ps take your underhood lightbulb out first)<br><br>DuaneWKKC