Hey guys and gals! I have a 2003 Discovery 2. When it's at idle, it runs perfectly fine. However, after I drove it for 5-10 minutes at 25 mph, it will spring a massive leak. The leak is under the coolant reservoir. It seems to be coming from the hose, but I couldn't find a split when I inspected it earlier. The coolant reservoir itself is split at the seam. I tried filling in the gap with epoxy, and it worked for a few minutes. However, after driving, the epoxy popped and the seam was opened again. The epoxy was dry. What would cause this increase in pressure? Am I just incompetent with epoxy? Any help is much appreciated. Thanks!

 

Your epoxy abilities unknown to me.

May just be incompetent to attempt repair. Get a replacement reservoir, cost about $35 on-line.
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Once new tank is installed, and the motor is up to temp, check the upper hose for hardness or pregnant look. You may have an overpressurized system due to air or exhaust gases in the cooling system.