Re: The wiper,washer and vacuum leak saga (journey)

Posted by d c On 2014/12/3 20:00:38

Now on to the wiper. It too will be a steady vacuum leak in the stopped (parked) position, the magnitude of which is determined by the condition of the cup seal. This one was cracked and broken to offer little restriction to leakage. Then there is the balance valve. There is little service info on the balance valve though description of normal operation says it should seal the manifold port with the engine under high load and steep throttle angle. After testing, I will assume it was designed to do the opposite also in a pump failure since this valve did seal(separate) the pump port with zero suction from the manifold port and allow the manifold to supply all vacuum to the wiper and washer but would not seal the manifold port when it had no vacuum and suction was coming from the pump port. This would account for slow wipers or stalled blades under heavy acceleration. I suspect that ,just like early Holley carbs with power valves and no blow out protection, the first hard backfire out the carb would destroy this side of the balance valve. If you have weak wipers at idle, connect manifold vacuum directly to the wiper motor bypassing the balance valve. If you have slow wipers only on acceleration, check your balance valve and pump. The service manual only states - up to 20 inches vacuum at 1800 RPM. Would a simple dorman heater/ac vacuum check valve(1/4X1/4) plumbed in solve this? more on that later
There is a rather long winded prefacecoming-sorry for that. I was advised to keep the text short with pictures and captions but there is some good info there for the novice.

This is the balance valve and the park seal on the paddle. Next will be disasembly of the wiper motor and evaluating if it is a candidate for refirb.

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