Discovered Coolant Leak

Like the title says, while working on my truck today, I found bright pink liquid dripping from under my truck. Freaked out for a minute thinking it was transmission fluid. Then I remembered Toyota uses the pink antifreeze.

So, what's the most common culprit on these 4.0s for coolant leaks? Though I don't KNOW... I'm betting it's the water pump. It's the stock pump that came from the factory when the truck was built, and I've got over 250K miles. Is there any good way to diagnose where the leak is without tearing the whole engine bay apart? Where do I start on this?

 

Should be able to see the water pump while it's running with a decent flashlight and top cover removed. Check out the weep hole and see if anything's coming outta there, and/or around the gasket. A leak big enough to see dripping from the bottom should be pretty easy to spot. Check the hoses and rad too of course

 

Get a UV dye kit. Makes it much easier to trace

 

Ok haven't had a lot of time to look at this leak, but.. from what I found from a Google search that got me to this thread...
https://www.tacomaworld.com/threads/losing-coolant-cant-find-the-leak.478074/page-2

The first pic with the pink build up on the water pump... remember that.

After more browsing Google and possible leak locations I decided to go look at it tonight with a flash light, thinking if something gets wet I could see wet "reflection" better with a flash light. While looking around I noticed my thermostat housing covered in pink build up, just like in that pic before. So, I think I've found my leak... of course I'm going to look deeper and check the water pump weep hole. But I think im on to something here.

 

The amount of locations for a possible coolant leak are endless.

Occasionally a vehicle will have a weak link, or a spot known to leak, or if there’s a coolant leak you should look here first. That’s when search the internet will be helpful.

That picture with the reddish stuff coming out could be excess rtv gasket glue.

If you don’t own a cooling system pressure tester you can rent one from an auto parts store.

Or you can try this. After driving around enough to get it fully warmed up, turn the engine off. Be ready to look with a flashlight and mirror if you have one. I’ve found sometimes immediately after turning it off, a leak will show itself.

If that didn’t help find a leak you might need to pressure test it. If the leak is in the reservoir or reservoir hose, pressure testing won’t cause it to show.

Another trick. Since you say dripping. Mark the ground where your tires are. Move it away from the marks. Note where the puddle is. Then you have an idea where to look.

In case you’re a novice & don’t know. DO NOT open the radiator cap if the engine is hot or warm, it’s pressurized and will squirt hot coolant as soon as you open it.

The recommended interval is 100k miles to replace the coolant, I think. If it’s over due or almost due or you don’t know, I’d replace it.

 

Not complete novice but know the basics
I inclined to believe that the pink crud isn't RTV of some sort. From what I've read, these are put together with none of that from the factory. Since I've been the only owner of this truck and know that the thermostat housing hasn't been touched at all for the life of this truck, im betting on the leak being there.
I've only had to add a few ounces of coolant, so I'm still driving it for now. I'll get it broke down next week on my days off and fix that particular spot, and probably go ahead and do a flush and refill while I'm at it.

 

Just a suggestion - wipe off the old crust on the housing with a damp rag and see if the crust re/appears.
If it does = you found your leak