I'm replacing my water pump currently and I see sludge above the water pump under the bypass hose. What do you think? coolant and oil both look good inside the car so... what do you think is the cause while I have her cracked open? I can replace the hose but why would it be sludgey up there... must be leaking oil too no?

 

Probably the bypass hose has degraded.... Won't hurt to replace it., if you are doing the water pump anyway, now is the time.

 

I agree, most likely the hose itself is causing the "sludge", I've seen it on my own truck in the past while replacing the water pump. I just cleaned everything up, replaced the hose, and never had an issue.

 

Small holes in the metal tube. They are like $15-$20 with a gasket since you're down there too.

 

Probably leakage from the hose. That hose is designed to fail in the winter when it's 25 degrees or colder and freezing rain is falling while the wind blows up the back of your coat while you are out in the middle of nowhere. Seriously, replace it when you replace the water pump. I'd pull the upper hose if you haven't already, and look to see what the thermostat looks like. If it look a bit iffy, replace it with a 195 unit as a matter of course. Absolutely DO NOT use a Failsafe unit. Every single one of those I've dealt with were either failed or failed soon after installation. I installed one when they first came out and it failed after ONE heat cycle.

There is some grey RTV for water pumps and thermostats. I add a film of it on the gaskets. I also put a little film around the O ring on the pipe on the side of the pump and if I have enough, on the bolts that go into the block. These are the really long ones that go into the water jacket. If you run out of the grey, black RTV will work there. Just look on the package to make sure it works with coolant. These bolts can give you a pesky leak that is a stinker to find at times.

 

Thanks for the advice, it's all running again. Watching for leaks.