3406B water pump

yeah that is what it means

 

Cat will tell you that a slight amount of seepage is not an issue. They even used to make a standpipe kit for the weep hole to get away from excessive warranty swap outs. Here's the catch, if you're seeing coolant from weep hole, blowing back on oil filter, I'd be changing it. They can go from a "little Cat allowable seepage" to a full blown pour in a short time. Make sure you have correct radiator cap installed, so that you're not adding excessive pressure to system. Back in the days of your truck, it was probably a 7 psi cap and no more than 10.

 

Most trucks use at least a 10 lb cap and without preasure in the system the water pump can leak and also suck in air. Water pump failures are more prevalent in units without a water filter, and units that use DCA4.
Just a thought!

 

DCA4 is a coating not a protectant, it eats or does not stop the eating of aluminum, it does not work very well stopping corrosion on steel parts. when ever you change the WP on a Cat you want to really look at the cover for corrosion, the clearance between the cover and the impeller is very important for effective operation of the pump.
Many units that use DCA4, especially the older Cummins, the steel pipes, for the cooling system corrode away form the inside out.
A water filter gets rid of the sand and very fine particles of corrosion, out of the coolant, those fine particles are what wear out the WP seals, liner "O" rings, and the WP impeller.
I used power cool or power cool plus coolant in every overhaul I did never had a coolant problem with any units after that unless some no mine put on a wrong filter, or added a in-compatable antifreeze.
Just a thought!