My 4Runner overheated a few weeks ago.

Turns out the water pump is leaking below the thermostat housing.

I rebuilt the engine last year, and have had it on the road for about 10 months now.
This truck is also Lemon Flavoured...

Anyhow, when I rebuilt the motor, I reused the water pump. I used the Toyota FIPG on it. Lasted pretty well until last week.

Now it leaks about a gallon of coolant every other week....


Last week, I pulled the water pump, cleaned it up, used a toyota gasket, painted the block and one side of the gasket with Permatex Form-a-Gasket and the waterpump with toyota FIPG.
Then torqued the water pump bolts to the factory specs...

Still leaking....

could it be that the water pump has warped somehow?
When I rebuild the engine, I used a gasket specific surface prep pad on my cookie buffer to take off all the old gasket material. I used new gaskets and new thermostat when I put it all together...

I hate this 4Runner.....

 

Try just using the gasket dry:

https://www.yotatech.com/forums/f116...efresh-103166/

Rob

 

go ahead & replace the water pump. IF you overheat the engine much you run the risk of warping a head, which you DO NOT want to do....

 

This is on a 3.0 3VZ-E

 

He said he replaced the water pump but is still having the same problem.

Are you 100% sure the leak is coming from where you think it is?
I'd pull the waterpump and check the mating surface of the block to see if it's cracked/warped. Use a straight level and a feeler gauge. I'm not too familiar with the 3.0 engine, but it water could be coming from the bolts if they go into the water passage. You could put some thread sealer/water blocker on the bolts when you reinstall. Good luck.

 

Actually, it sounds like the wp wasn't replaced, but merely r&r and re-used after a re-seal.

+1 for getting another waterpump. OE, OEM, NPW, etc all are fine, some of the others, I dunno. Definately don't use a reman

 

I ordered a new OEM water pump today.
Checker, Autozone, and Napa's prices on Toytoa stuff is actually more expensive than OEM these days...

 

I believe there are 2 different styles of water pump gaskets. One has the FIPG built into it and goes on DRY, and the other one needs to have FIPG added. Is it possible you had the one that already has it and you added some to it? The one that goes on dry has a black bead going around it. This is the one that I used, dry, and it works just fine. Just a thought....

 

Im of the belief that if the gasket doesnt say to use anything with it then dont.. Dry is fine.. Overcompensating can cause problems sumtimes

 

I just re-read your post. I see that you put gasket material to BOTH sides. That's a no-no for sure. If the gasket calls for FIPG, then apply it to ONE side. I usually apply it to the water pump, so that you don't have to scrape it off the engine side down the road.

 

I too am having a water leak from around the thermostat housing, I cant see where it comes from exactly but the water pours down on to a componant just below the housing. I once tried to use RTV around the hosing but didnt fix my leak, over time the leak has gradually gotten worce. Where are the water pump weeping holes and would they leak around the thermostat housing? Currently working on removing the housing inspecting for cracks or damage. Did not find any. Removed the thermostat and water was released after removing it from the block. Good seal right? So I am down to re sealing the housing the correct way, ie no RTV, or removing the water pump.Oh the motor is the 3.0 v-6 if that helps anyone. Also the leak occurs when the motor is not running and cold. When I fill the radiator with water I can see the water leaking out from where seems to be the thermostat housing