Coolant leak[possible location of leak]

Hello, new to this place[but I lurk],

I drive a 2010 Prerunner 2WD 4.0 V6 Tacoma.
I recently found out my coolant has been disappearing somewhere. No puddles were visible where I parked. Nor were there any other white or pink powdery stains anywhere else[thankfully], except around the water inlet piece. I’ve tightened the bolts a little more to see if that would help. Only a little as now there is a lot more powdery pink and white stains all over the water pump, belt and pulleys. There is even build up at the three corners of the water outlet.
I have provided two pics of what I’m referring to. Is this an easy fix? Replacing the gasket between both parts[is there even one?]? Or replace the thermostat?

I would like to tackle this fix myself as it looks simple enough of just draining the coolant and removing the part. Thank you in advance!

 

Should be pretty straight forward; grab a new thermostat, gasket, and coolant. Drain, flush, replace.... maybe an hour tops.

 

Thanks for replying. I’m going OEM and the Toyota Parts shop displays the thermostat as the plastic piece, thermostat inside and O-ring. O-ring being the gasket? Autozone shows another gasket [similar to what you’d use on a valve cover, as an example] but Toyota shows no type of gasket like that.
As for flushing the system. Can I not just refill the radiator with the special 50/50 pink coolant until it’s at full and do the whole start engine and let engine fan run to see if I need to add more? I’ve had a coolant flush before where I get my oil changed.

 

Most of the plastic fittings do use an o-ring vice a traditional paper gasket. You don't actually need to do anything other than drain off a quart or two of coolant to get the level in the system low enough to remove the cover. The drain, flush & fill is just (IMO) best practice; if you're going to open up the system to do part of the job, why not go the extra mile? Sort of like pulling a manual trans; if it's out, throw a new clutch in it just because it's out.

 

How many miles? If you are doing coolant and thermostat, why not put a new water pump on as well?

 

Be careful removing the bolts. When i replaced my tstat, one of the bolt heads broke off

 

I’m grateful for the tip but I think I’ll be fine just replacing the thermostat and topping it off. [famous last words lol]

I’m sitting at 241,950 miles. It’s the whole process...unless you’re going to say it’s fine at this mileage. “Maybe change it at 400k”.

Oh gee thanks for reminding me of the time I broke one of the bolt heads holding the coil while changing the spark plugs. To this day I have NO IDEA how it happened. It’s one of the easiest jobs to do! Was finished with the rest and then just as I’m tightening the bolt on the coil that’s closest to the driver side, I felt it get loose. I could feel the blood drain from my face as I realized what had happened. That is literally my biggest fear. Breaking a bolt head or stripping a thread when doing mechanical work. I don’t have assorted tools to get that fixed or own another vehicle so yeah...I’m rambling now.

 

pb blaster and a soft hand