Trucks & Trailers - Front Coupler

Has anyone ever had a problem with the Master Cylinder Cap not staying on. I have bought a new Titan 6 Master cylinder with front coupler and the cap seem to be loose when I trailer the boat. I tighten the cap before each trip and when I stop the boat it is as if the cap is just loose on the threads. Almost as if when I apply pressure on the breaks it pops the cap up from the master cylinder. You can just easily pick up the cap. Of course I reported this to where I purchased the product and they called the company, and of course they have never heard of this problem before. I have had 2 other guys tighten the cap before we made a fishing trip. So do we all have no clue how to screw a cap on a master cylinder? Any help would be greatly appreciated!

Contact the retailer again. Tell them that you don't care if there has not been a previous issue before. Your having the issue now and thats what matters. Could be just a small manufacturers defect.

Or, do you have disc brakes or drum? Are your brakes functioning correctly? If not, the master cyclinder could be holding the pressure and pushing out the weakest point. But, that is the worst case scenario. Best bet, contact the retailer again.