Guys,

I have been having an issue with my 2002 4Runner with about 64,000 miles overheating. This first happened over a year ago and at that time I suspected the thermostat and replaced it and the fluid. That seemed to do the trick for about a year until it happened again about 4 months ago. I went ahead and replaced the thermostat again, but now I am back where I started. I am not sure if the issue is the water pump (I don't hear it making any noise) or maybe the clutch fan? I was thinking of just going ahead and covering all my bases and replacing the clutch fan, water pump, hoses, and t-stat this weekend. I am curious to know what you guys think and also IF I replace the waterpump will I have to remove the timing belt? Thanks for the help!!

 

Yes you should do the timing belt along with the waterpump. Once your in that far you may as well do it all.

 

Let me ask you this. In order to replace the water pump do you have to remove the timing belt or mess with it at all? While I agree it may be a good idea to replace while you have easy access to it, I am not sure how big or complicated of a task that is?

 

Yes, you will have to remove the timing belt to get at the water pump. There is a good thread about changing the t-belt and water pump but I can't find it right now.

 

http://www.lieblweb.com/tacoma/Mecha...cans/index.htm

Its for a tacoma but it should be the same for your 4runner

 

Does the truck overheat while it's sitting and running or does it overheat while you're moving? This will help determine if it's the fan or something else.

 

Well, the 2 times I noticed it I was driving for a while. At that point the fluid had all boiled/evaporated away. The thing is if I filled it back up with water it was fine for the 30 minute drive home. It's been sitting in place ever since. I never see any fluid on the ground so didn't really thnik anything was leaking etc. I guess the plan is just to replace it all to just get it over with and running reliably again.

 

Well, if it's overheating when you're moving, the fan clutch is probably fine because the wind alone should normally be enough to cool it. If it overheats while sitting, that means there's probably a problem w/ the fan. Diagnose the problem before you start replacing everything, otherwise you will spend a lot more $$ and still might not find the problem. It would suck to replace the w.p., timing belt, thermo, fan clutch, etc...only to find out it's a head gasket or something.

 

Ewww, don't even say head gasket. After reading through some replies and threads on this and other forums I am now wondering if it might be a clogged up radiator not flowing as well as it should be.

 

Could be a clogged radiator or a water passage. Do yourself a favor and have a shop just diagnose it if you're not comfortable yourself and then you know where you stand. A half hour of labor is better than hours of labor and expensive parts that may not even be the root of the problem. A pressure test might help you figure it out.

 

I am going to replace the upper and lower hoses this weekend and flush out the radiator with the hose. Then really watch for any kind of leaks or see if the overflow reservoir changes. The fluid has to be going someplace and I sure hope its not a head gasket. I will also check the oil to make sure it's not discolored or anything like that. I really don't think it is a head gasket. I am hoping its a small hose leak that maybe only happens once everything heats up?? We'll see if I can't figure it out I will take it someplace. This really isn't my daily driver and doesn't get driven much or I would have really tried to get this done sooner.

 

Didn't mean to scare you about the HG, hopefully it's not. When you check the oil, it will look like milkshake if it has water (coolant) in it. Also make sure there's no oil in the radiator cuz it can go both ways. Check for water out the tailpipe too- some dripping when the engine is warming up is normal, but if it continues to drip water after several minutes, it's a sign of HG failure. So is white smoke out the tailpipe or a sweet exhaust smell.

BTW, when working properly, the reservoir will go up an inch or 2 once it gets hot and back down when it cools off, so don't let that throw you off. If you can't find any noticeable leaks or other problems, do a cooling system pressure test and a cylinder compression test.

 

Just wanted to post an update to this thread. I dropped the 4Runner off at a local fixer up shop and had them diagnose. Turns out there was a leak in the radiator which they are going to replace. They will also be filling it back up with the Toyota red coolant. I didn't even have to mention to use that so I am happy that they are paying attention to detail. I will be picking it back up this evening. I will have them point out the area of the leak on the old unit when I pick it up. Thanks for all the posts, I just wanted to let everyone know the outcome. Only 69,000 miles on the truck so we should be good to go. Thanks

 

It's a good thing you didn't spend a bunch of $$ on the w.p./t.b, fan clutch, etc. Glad to hear you figured it out.