My F350, V10 has just broken the second discharge hose at the compressor within a two month time span. The break is at the aluminum block that goes into the compressor as it was described to me.
I obviously have something else going. The guys have looked to see if I have a broken engine mount and have side to side movement, but there wasn't any. They did notice the engine and transmission seemed to move forward a little when they would accelerate with the brake depressed, but other than that, are at a loss as to what could be causing this.
Both times this happened, I have been on the interstate for at least the past hour, pulling a 12', single axle enclosed trailer, with no more than 3000lbs max in the trailer.
OK, no takers here so far on this one, so I'll spin something up...
I looked up your truck's compressor & discharge tube/hose assembly on rockauto.
It looks like the discharge tube assembly (motorcraft YF3568) when mounted on the compressor, goes radially outward from the compressor. The length of the tube end mounting to the compressor, with its muffler section, before it does a 90 degree turn forward and switches to hose, looks rather spindly. Long and narrow.
If the engine torqued CW/CCW on its mounts, the compressor-end of the hose would go up/down or left/right as mounted. Which means the hose would probably flex enough in those directions to avoid stressing the tube at its weakest point, which is where it goes into its mounting block.
However, if the engine is moving fore/aft, that movement would tend to try to compress/extend the hose in-line with the hose, not a direction that there is give in an A/C hose. That would be like having the hose disconnected and grabbing the 90 degree tubing turn with your hands, and working it forward/backward as mounted in the truck. That could fatigue the aluminum tube at the compressor block-joint.
A look at the failed tube may help verify this. If it broke at the front or the back (or both) the most where the tubing goes into the mounting block, that would show that it was forward/backward flexing of the tube that broke it.
If the engine is moving appreciably forward/backward, why?
As the rear axle goes up/down, or rear spring axle-wrap (axle housing rotating some on its axis, leaf spring ahead and behind the axle bend opposite ways), the driveline length changes. There is always a splined slip-joint to compensate for the changing length. If it is bound-up/very sticky, then the dynamic changing of effective driveline-length could push/pull the engine forward/backward via the transmission case.
Thanks Torky. I am going to stop by and talk with them today a bit more. We have had a hot muggy week and they have been slammed. We discussed doing a little CSI investigation on the end that broke to see if we can tell how it broke, because he said that line has a loop so certain directional strains/stresses should be absorbed by it.
Whatever it is, has to be fairly consistent or occasionally violent, because I have probably driven the truck once a week, 10 miles or so each time since it happened in June.
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