Hi all! Long time lurker, first time poster here.

Here's a shortened version of my question: Truck has symptoms of water pump failure and/ or head gasket/ cracked block. Need advice for next steps.

Backstory:

I bought a 96 xlt 4.0L V6 four months ago. Ran sluggish and started shooting misfire codes soon after on the highway (shaking at >45mph). Most of my driving is in town so I watched engine temp and minimized loads.

First, when addressing the misfire issue: changed out plugs, wires, oil/ filter and cleaned MAFS. The two hardest to reach plugs on passenger side (closest to firewall) were different brands and seized, so I don't know the last time they've been changed out. Had them soak with PB blaster to get them out. Runs like a dream when warm.

However, I run through a TON of coolant. There's never anything in the overflow tank and I top off the radiator every few days now. I don't have puddles..yet, but there is white smoke at start up. I was concerned it was a blown head gasket, but the test was negative when I used a uview combustive gases test on the radiator.

I'm thinking it may be a failing water pump since I do have a bit of a squealing noise at start up too. I'm curious if there's anything else I can do to rule out an issue with the block/ head gasket before throwing more money and parts at it.

I'm not a mechanic, but know I can fix the problem with the right direction.

I've also attached a pic showing the extent of the leak underneath the truck.

Anything else I should check to rule out a bigger engine block problem?

Thanks!

Ant in Oakland

Attached Images

under radiator.jpg (91.6 KB, 32 views)