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1998 4Runner Timing Belt & Water Pump Replacement

My water pump was leaking coolant at an alarming rate (you could say pouring coolant). I first noticed when my car overheated during my commute to work. I had to pull off the side of the highway to take a look around but found nothing. I continued driving to work with the car overheating. If this was a newer and more valuable car, I probably would have called for a tow. I drove the car back home (overheating) and then found that the coolant was empty (oops!). Even after driving overheated for approximately one hour, this freaking champ of a Toyota (with 200k miles I'll add) runs like a charm. I'm sold, Toyotas are hands down the best car. I filler her up cold, and drove to work the next day. After the car heated up on the way to work, it leaked about one liter of coolant in the parking lot! Knowing that glycerol is toxic, I would have filled her up with water only, but it was winter time in Boston so I dished out about $50 in coolant before I got around to replacing the water pump (identified as the source of the leak) in my buddies garage (thanks Ben!). For some awful reason, the water pump on this engine is timing belt driven, so it is best practice to replace the timing belt while you are at it.

Setup in Ben's garage to replace the water pump. It was below freezing out and this garage is not heated. Living in Boston, my fingers would go completely numb working on my motorcycle and truck. The cold is something you just have to embrace!

Timelapse of the job! I added general instructions in the bottom left that should provide enough guidance to the handy type to do the same.

I do most of the work on my vehicles because it saves some money but also I have fun with it! Through the process of repairing these amazing machines I get the opportunity to learn about the design and manufacturing engineering that went into every detail. The revolutionary Toyota Production System (TPS) has been the driving force that makes Toyota the best car manufacturer in the world, in my opinion. Toyota prides itself on reliability, and this water pump replacement project gave me some insight as to why.

Timing belt removed with the new Aisin water pump. At the bottom you see the crank shaft with the timing belt pulley still mounted. The timing belt snakes past the water pump and both cam shafts (two larger pulleys at the top) to provide the timing for the valves. To note - the engine block is cast iron. Toyota switched to aluminum in the 2000s, but some believe iron is more robust.

Custom pulley holder and puller. This tool was CRITICAL in this process. In the video you will see that the crank pulley bolt is extremely tight (spec is 180 ft-lbs / 245 Nm). This also served to pull the pulley off the crank (some say you can wiggle it off by hand, but I definitely needed the pulley puller action with this tool).

New timing belt on the left, old on the right. You can see that the old belt is worn smooth and is starting to form some cracks. I would not have replaced this pulley on its own (looks OK), but since I already had the water pump off, it was definitely worth replacing to get another 100k miles or whatever.

Thank you for reading. I hope this was informative if you are trying to work on your 4runner, or enjoyable if you are just browsing!

Car: 1998 Toyota 4runner 3.4L V6 (5VZ-FE)
Parts: Aisin TKT-025 Timing Belt Kit
Tools: Custom made pulley holder and puller (see picture above)
Purchase option (pulley holder) - note that I have not used this so idk if it works
Repair Guide Shoutout: eCuration IFIXIT


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