I replaced my timing belt and water pump at 140k miles and at 160k I started getting a small coolant leak at the water inlet joint that gets RTV (not the location that gets an o-ring). The water inlet I am talking about is the little housing that the thermostat housing bolts to on the 4.7L V8. When replacing the tb/wp I was careful to use hi-temp RTV just like the manual describes. I am thinking the RTV is breaking down over time because it took 20k miles for this leak to show up. I haven't taken it apart yet since it is not leaking much yet and I want to get the right RTV before resealing it. So far it's just red crust, no drops to speak of.

Has anyone had this leak happen before, or replaced a tb/wp and not had this happen and if so what kind of RTV did you use? I used VersaChem Hi Temp Red Type 650. I won't be reusing it again but I would like to see if anyone has a suggestion for the best RTV for this application. Any input is appreciated.

I used Toyota seal packaging 102 (FIPG), 82G from Toyota part number 00295-00103 in a 3 oz. tube. No problems after 4 years. This is what toyota used from the factory. It is not that expensive either.

wolf4runner,

The pic attached is from the service manual showing the rectangular face that gets RTV. The manual calls it seal packing, I assume that is RTV.


03_4x4Runner,

You gave me a different P/N than what the manual calls for. Any idea if there is a difference?

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The part number I gave you came right off the tube. The part number they have may be for a bulk container.

Here is a link to the sealer I have. Toyota Seal Packaging (FIPG), Twos R Us I did not buy mine there. Search around and you can find it for around $10.

I've recently had a similar problem and I want to post this to help other people. My 02 3.4L 4runner was leaking coolant from the center part of the engine coming down and dripping where the frame goes across the two front tires. It would leak in the mornings mainly when I would come out I also did smell the sweet smell of coolant burning a few times. Every morning it would be underneath the truck it got to the point where it was leaking pretty heavy. To make a long story short I fix the water pump and I still have a leak from my Lower water Inlet . The first big mistake that I made was I did not fix the thermostat while doing the water pump. (This makes no sense) When you do the water pump always do the thermostat because it literally is a component of the system. Always do the thermostat because it has a gasket/ Oring that tends to be problematic for alot of folks. It mainly makes water leak were the Lower Water Inlet meets the Thermastat Housing. I could see moisture just looking at the top of the Thermastat though . It seems to be a very problematic thing for a lot of people. I would also advise to use Toyota Lube or some form of lube or seal. My mechanic looked at it and also said that I eventually may have to replace the lower water inlet to get a better fit especially with 4runners with higher mileage that have had several water pumps put on. My last and final you may have to grind the surface where the Lower water Inlet the meets the thermostat housing. My mechanic did it to mine to get a good flush smooth fit where they meet. It on 3-t or 3 somthing the the Manuel. Good luck. Keep in mind the Lower Water Inlet directly connects into your lower radiator hose that's how you find the thermostat.