Hello all, I recently found a pretty significant coolant leak in my 05 4runner 2UZFE with 249,500 Miles on it. I've attached some photos below of where I'm seeing coolant leak out, but I'm wondering if its a more serious area like the water pump based on how much I'm losing.


I fully filled up the coolant reservoir (from empty) around 3PM yesterday, drove 2 mins then sat for a 8 hours then drove 2 mins back and I go out today around noon to check it and completely empty.

For reference ive done the timing belt and water pump whole kit around 3 years ago (228,500 miles) and had no issues since, radiator was replaced last year and my main suspect right now is this upper thermostat housing combination leakage of both the o ring circular outlet and RTV gasketed water pump square part.

In a perfect world id much prefer that than to tear down the entire front end just to find out I gotta do the water pump again. Is there a way to rule out any possible leak spots. I considered taking the timing cover off for a better view at the pump itself.

Any help on this would be great.

P.s. The car has never overheated while under my ownership and never goes above 190F even on the hottest summer days.

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Do you see the coolant on the ground under your car?

I mostly park in grass/sand area, but when I do park under concrete there is a medium sized pooling of coolant, more than a few drops but less than it all coming out at once

IMO, whatever you have to do, you have to do! Yes, I'd pull the timing cover off to get a better look and then make whatever repair deemed necessary, you can't be losing that much coolant and feel comfortable.

I had a replaced water pump& timing belt on my Pilot start leaking at 20,000 miles because I let a shop select the brand! Obviously lower quality.
Had a premier shop redo belt & water pump with top brand (forgot names of brands).
Your pink deposits are surely coolant escaping. I would do the easy stuff first and keep a close eye on your engine oil for signs of dreaded coolant intrusion.

The teardown has begun.


Went out today and there was a pretty significant puddle underneath the front engine cross member. I drained radiator and began trying to take off as little as possible to rule out possible areas of leakage.

I attached some more photos below if anyone with more expertise would like to chime in. I see patches of crusty pink coolant residue but nothing that makes me say yeah thats the spot for sure.

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Realizing now that I'm not 100% confident in a leak area I should have pressure tested the system using distilled water first... Would that help eliminate a majority of concern areas?

Current solution so I can drive and hopefully diagnose further over weekend is
Putting everything back together
Resealing upper thermostat housing with new FIPG and OEM O-ring (Part #16323C)
Refilling coolant with Peak Asian vehicles coolant and watching overflow reservoir meticulously over the next few days, multiple times a day.