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WATERSKI MagazineQ: I recently rebuilt the wheel cylinders on my 1993 Hydrodyne's single-axle trailer to stop a brake fluid leak. The leak stopped, but it doesn't seem as though my trailer stops as well as it used to. I tried adjusting the brakes, but I don't know what the adjustment criteria are.
ACELMOR0@wcc.com
A: You will need to bleed the trailer brake system just as you would an automotive system. Before doing so, make sure the brakes are adjusted. You will need a drum brake adjusting tool, available at any auto supply store. Jack up the trailer one side at a time. While spinning the wheel, turn the adjuster until the wheel stops. Next, back the adjuster off until the wheel spins freely and minimal shoe-to-drum contact is heard.
To bleed the system, you will need another person. Using a pry bar or a similar tool, pump the master cylinder several times to build pressure. Continue to hold pressure on the master cylinder. On the back side of the brake assembly you will find a bleed valve. Open the valve slowly until fluid and air stops. The person pumping up the master cylinder will need to continue to apply pressure until the cylinder bottoms. Do not allow the cylinder to return until the bleeder is closed. Continue to pump up and bleed both sides until a steady stream of fluid is seen (no air).
Take care not to let the master cylinder run dry. You will have to start over if it does. Take care when bleeding the system; brake fluid will melt paint. Catch as much as possible with a rag or container. You may want to put a piece of clear plastic tubing over the end of the bleeder (so you can see the fluid stream) and let the other end drop into a container to salvage the fluid. Brake fluid is water-soluble, so cleanup is easily done with a garden hose.
PROPPING AT ALTITUDE
Q: We ski the summers in Lake Tahoe, elevation 6,200 feet, with a 1988 Ski Centurion with an Indmar/Ford 351 engine. Because of the altitude, we probably lose 20-25 percent of our normal horsepower. Is there a recommended propeller type for our setup that would increase the hole-shot and still deliver decent top-end performance for those long cruises across the lake? Also, is there any economical way to upgrade our current engine to add horsepower that is lost in the higher altitudes?
RMBags@aol.com
A: A standard 351 is designed to have a maximum rpm level of 4,200 to 4,500 rpm. It should be propped to do just that. If at sea level your engine is within this range when using a 13 x 13 prop, try a 13 x 12 light cup propeller at altitude. I recommend decreasing pitch and cup just a little at a time until the desired rpm is achieved. Remember, the engine will not breathe as well at altitude, so the 4,500-rpm level may not be achieved without losing top-end speed. As you decrease pitch, you improve the bottom end and lose top end. So be careful not to go too far. If you wish to increase horsepower, you can purchase a pair of GT-40 heads. While this may not be too economical ($1,500-$2,000), it will give you 30 to 40 more horses and the maximum rpm level can increase to 4,500-4,800 rpm. For more info on engine upgrading, call Discount Inboard Marine at 800-892-4084.
