Coolant leak, 1994 B2300

[Nater]

This one just popped up on me the other day. Stopped to get gas, filled up, paid, and getting back into the truck, I noticed a coolant leak....very slow, but enough I would consider it a Class II leak. Look under the truck and notice it is running down the front of the oil pan and down. Check fluid level and a little below cold line. Drive it the 20 miles home, and check to see if there is coolant where I park it..(easy to tell since there is snow on the ground)....Nada. Park it, and check the fluid level again....Same level. Engine is not running hot or anything. Wake up the next morning and check under it before leaving for work....No sign of coolant anywhere. Drive it to work and check again....Nothing....Leave work after 7 hours and start it up....Had to get out again for something I left in the office and as I come back out, notice it is leaking again... Water pump gasket would come to mind, but I would think if the gasket was leaking it would always leak...not on or off as it is..

 

[srteach]

Notice a pattern? Sitting still, idling makes it leak. Turned off, no leak.

This pattern indicates water pump seal problems, which means new water pump is needed. It will get worse, and is probably caused by wear in the pump bearings.
If you check the weep hole on the pump, it will confirm it.