Good Evening. First off let me say I'm not a professional mechanic but I do like to understand whats going on.
My 4R overheats and has for a long time. Has had water pump replaced, new thermostat, flushed system, etc, etc. Hard to find a decent mechanic here on the island. As soon as you mention overheating they start talking water pump
I recently had the transmission fluid/filter changed and the fluid was quite burnt looking. Looked good afterwards but within a couple weeks it looked as bad as before. I don't know if that's because the guy didn't flush it thoroughly or what but its pointing me to the electric fan in front of the radiator.
I'm looking for an explanation of exactly how this fan works. Could its failing could it cause both of my symptoms?
Thanks for your advice.

 

I am assuming your truck is stock and there is no aftermarket parts. The fan between the radiator and grille will not cool the truck. Its there for the AC condenser to keep the AC cold when the truck is not moving. A couple of things I would start with is grab the radiator fan that is bolted to the motor and see if it spins freely or is there resistance? If it spins freely then it needs to be serviced. You can go to Toyota and get a tube of fluid for the clutch on the fan. Its very easy to remove it, open it up, clean it out and empty the fluid into the clutch. Put it all back together. I would also buy a radiator pressure tester or have someone do it. Also pressure check the cap. These items need to be working properly or you don't stand a chance.

Jake

 

Thanks for the reply. Fan shows resistance. I've been thru radiator caps of various pressure ratings. I guess I'll buy a radiator pressure kit and test the pressure. That's never been checked as far as I know.
The radiator itself is aftermarket. The car had a minor accident back before I got it and the top seam on the radiator had broken and been resoldered. That solder fix gave way and it was replaced. That's been about 12 years ago. Head gaskets (both) were replaced about 10 years ago. Water pump was replaced but not the tensioner.
Everything else is original.

 

When I say original I mean no aftermarket. From what you have described I would call that original. Buying a radiator pressure kit will be a great investment. You can build pressure and see if it drops while you are staring at it or leave it overnight to see if it drops. Pressure testing the cap will be a big deal also. Do you have a radiator overflow tank? Does the level run between the lines on the tank as it should? Another inexpensive test is something like this ( ). They are not fool proof but its a quick inexpensive way just to take out of suspicion. Are you sure the truck is running a thermostat? Its another inexpensive part you can change. They do go bad.

Jake

 

Yes, the overflow tank is in place. Hard to say about the level because all I can do is drive a few blocks to the store every now and then.
Yes, thermostat is in place and new. It was running without one before.

 

Sounds like you are on the way. Once you can verify the cooling system will stay pressurized and not leak down that will start to narrow it down.

Jake

 

Thanks

 

That block test would be a good thing to do early on. Takes a lot off the table if it passes.
Regarding the trans, unless you do a complete flush on a transmission you probably only get half the fluid out doing a drain and refill. That why the new fluid discolors so quickly. Dropping the pan doesn't really get any more out than if you just pull the drain plug. Most techs do a drain and refill on the atm, as opposed to a complete flush. Flushing an automatic transmission requires special equipment, and you use a lot more fluid. So it gets pricey.

 

Hi. I don't have a lot of confidence in this fella's work and I'll leave it at that. This was a 'buddy system' referral.