Aeroquip Socketless hose

[15w40]

SAE 100R6 hose is an industrial low-pressure hydraulic hose. It is a quality product of synthetic nitril rubber tube and cover, compounded for resistance to oil, heat and cold. The synthetic inner tube is covered with a uniformly braided woven rayon cord and then encased in a synthetic rubber cover. Recommended working temperatures are -40°F to +200°F. This hose should be used with petroleum- and water-based hydraulic fluids.

Well, I am not so sure about the above specification when used with diesel. Several months ago I started an experiment by soaking a piece of hose in diesel. I first measured the hose thickness using a micrometer and repeated the measurement every month. The wall thickness started out at 0.154” and after 3 months grew to 0.205. The hose starts out as a tough piece of rubber as anyone who has tried to push on the socket less fittings knows. After soaking for 3 months it becomes fairly soft and will easily slide onto a fitting and off again if I pull hard enough.

This is beginning to worry me since I recently re-did my fuel system. I wonder how many years before the hoses begin to leak of suck in air.

The photo below shows two cut sections of hose. On the left is one that sat in diesel for three months. On the right is a piece of new hose. It is obvious that the left hose has swollen when compared to the right. It is also much softer.