Coolant Evidence - Water Pump Leak?

[CalEngineer]

Doing a “standard” oil change and noticed some evidence of coolant leaking. Tracing the leak up, I’m thinking it’s the water pump. Some info - the LX is about to hit 120k, not sure if the water pump has been done yet. Went for a weekend of off roading last week over Memorial Day weekend + 500 miles back home, no overheating or otherwise issues. The coolant reservoir indicates a bit below the L.

At this point, my plan is to order some coolant to fill up the reservoir and see if the off roading was what caused the leak or if it’s persistently sucking down coolant. Reading through the other posts, I don’t think (hope!) that it’s not a valley leak. Am I on the right track?

 

[1world1love]

Have you had your radiator swapped? Any signs around the top of the radiator? Did you check all of your hoses?

 

[CharlieS]

Sure looks like the water pump to me.

 

[CalEngineer]

I did some more digging. Looks fairly certain that it is the water pump based on the coolant leakage around the gasket when viewed from the top. Radiator has not been replaced, but looks to be in good shape for now, although I’m guessing this is probably coming soon.

 

[TXMeatball]

Personally I'd go ahead and replace the radiator while you're doing the water pump. It's not necessary to remove it but makes the job a lot easier. Updated radiator part # is 16400-50384. OEM water pump # is 16100-09491 and the OE is Aisin is a bit cheaper.
These 2 pics were taken exactly 3 months apart (3.4k miles).

 

[CalEngineer]

That is great advice. Ordered the OE Aisin water pump. Definitely worth going with the Toyota radiator I assume?

 

[TXMeatball]

That is great advice. Ordered the OE Aisin water pump. Definitely worth going with the Toyota radiator I assume?

That's what I did. TRAD is the OE, not sure where to get that. Believe the other popular replacement are the denso ones. Some good information in here. 2008-2010 Radiator Failure and Public Service Announcement - https://forum.ih8mud.com/threads/2008-2010-radiator-failure-and-public-service-announcement.917447/

 

[CalEngineer]

Also, any other items to swap while I’m down there? Thermostat? I bought the car at about 90k and has been an absolute champ for the 30k miles, wanna do what I need to to keep it running smoothly.

 

[TXMeatball]

Also, any other items to swap while I’m down there? Thermostat? I bought the car at about 90k and has been an absolute champ for the 30k miles, wanna do what I need to to keep it running smoothly.

Mostly how pragmatic you want to be. I'd replace the serpentine belt (Bando 8PK2410, OE) and tensioner/pulley (16620-0S012/16603-38012, believe Dayco is the OE for these) while in there because mine starter chirping 7 months later. I believe the 120k service calls for new coolant and plugs too if you want to get everything done in one big swoop.

 

[CalEngineer]

Welp, looks like 120 is gonna be the big one. I was already planning on swapping the AHC fluid and doing the brakes. My wallet is not gonna be happy, but I guess doing it yourself means one can buy a lot of tools, right?

 

[CharlieS]

Water pump
Thermostat
Thermostat housing
Tensioner
Idler pulley
Radiator
Serpentine belt
Hoses
Some people do the fan bracket
The reverse thread bolt on the idler just in case (I’ve had them seize, and it puts the job on hold)
Factory red coolant
Distilled water

I like to use tools to pinch off the transmission cooler lines so you don’t lose much atf.

 

[bloc]

There is a strong case to be made for not flushing the old coolant with straight water, as you will never get all of it out and it will dilute your new coolant. As long as you don’t go ridiculously past the original coolant life expectancy I wouldn’t have a problem leaving the small portion of it remaining when doing a thorough drain and fill.

 

[kcjaz]

That is great advice. Ordered the OE Aisin water pump. Definitely worth going with the Toyota radiator I assume?

FWIW, I had a non OEM radiator installed as part of a front end collision (deer) repair. It only made it two years before it leaked in the aluminum the core (not the plastic). I’ve replaced with OEM.

Also, if you replace the radiator, pinch off the tranny cooler hoses to minimize tranny fluid loss and catch and measure the fluid you do loose so you know if you need to add fluid back to the tranny.

 

[CalEngineer]

So took the whole thing apart yesterday, and outside of a few stubborn nuts on the cooling fan, the process was fairly straightforward. That being said, I’m having a hard time figuring out if the water pump was actually bad. The bearing seems to spin freely and is mostly clear of obstruction. Maybe it was just the gasket?

 

[bloc]

The bearing is usually fine, it’s the shaft seal that allows coolant past. Often out of the weep hole, but sometimes along the back of the pulley flange, then into the pulley where it gets slung everywhere.

 

[CalEngineer]

I was able to replace the water pump/radiator + thermostat and pulleys last weekend, more or less without issue. I did notice, when I put everything back together that I was getting some coolant spraying around the engine - almost as though it was hitting the fan during driving.

The coolant expansion tank was also emptied out. I put on my old radiator cap, thinking the new one might be the issue. Checking the coolant level under the cap, it looks like it’s more or less full. I drove a few days with the expansion tank empty to see if the coolant level dropped at all in the radiator, which it did not. So I refilled the expansion tank, drove it a couple days and it emptied out again. I’m stumped on what the cause might be - thinking my next step is to replace the hoses going to the expansion tank and then maybe the tank itself. Any other diagnostic ideas as to what might be the issue?

 

[CalEngineer]

Chasing it down a bit further - looks like it’s one of the hoses connected to the thermostat housing or something in that vicinity based on the concentration of coolant in the area.
Looks like a job for next weekend :/

 

[bloc]

Hose from the rad cap goes to the bottom of the reservoir. Make sure that is on tight and not damaged?

 

[CalEngineer]

So the leak was in one of the hoses feeding the thermostat body (the short hose nearest the engine). I replaced this hose when I was changing the water pump, but was a bit too aggressive with the pliers trying to get it on (it’s in a very awkward position). Rather than have to take the whole thing apart again, I opted to seal the leak with some silicone tape and throw some hose clamps on it. Let’s hope it holds - given that it’s such a short hose length that’s exposed, hopefully it won’t be a problem.

 

[CharlieS]

Is that a limp along until you get a new hose fix or permanent repair? I’d replace the hose. Also, you can get padded curved jaw pliers made specifically for hoses that come in handy for things like this.