Hello all, yes, I'm still here and kickin! Finally was "forced" to work on my 1998 SR5-Limited. Been busy getting things and still contemplating the switch over from radiator cooled tranny to an external tranny cooler. Things being such, I have decided to shelf that project in favor of doing some other needed repairs (and because my wife told me to get it back together or move it on) so I will hook up the tranny lines to the radiator cooling system.

I ordered a replacement radiator and when it arrived, I started taking the rest of the front end apart. I got the old radiator and the cooling fan mod out of the truck, drained the coolant, capped off the tranny lines and then started to prepare the new radiator. I have an issue, the radiator cap that came on my 98 won't fir the new radiator, even though it was a "guaranteed to fit", well the cap did not. Seems the distance in the neck of the newer radiator is shallower than the OEM 1998. I went back out to my local bone yard as I needed the brackets for the rear bumper replacement (another story) while there I noted that the 2000 I had gotten the bumper and passenger seat out of still had its engine installed(shock) and the radiator as well. I took the cap off and it is a bit different then my 98's. Got it home and it does fit the new radiator.

My question is, has anyone else had any issues with replacement radiators (96-99) and when they got them if the OEM caps did not fit? I will investgate further with Toyota, but wanted to come here first to see if I am the only one that has had this issue.

 

I replaced the oe radiator cap on the original radiator with some piece of junk from Autozone (out of town) which fit fine.
Then I replaced the radiator itself with a Spectra, the Autozone cap fit fine.
Next I replaced the failed Autozone cap with a Toyota cap (also out of town, heh), fit fine on the Spectra.
Now I've replaced the radiator with a Denso for a Tacoma, cap doesn't fit that one because different part number, so new Stant cap.

 

Interesting path. I discovered a potential problem so not sure if the cap that I got off a 2000 radiator is bad too, but it did fit the replacement radiator. I did a bad thing with my Runner, I forgot to tighten a clamp on the radiator hose, and it blew the hose, fortunately I was able to catch it in time and nothing more than loss of coolant. Interesting thing is after assembling everything back and double checking, I topped off the coolant and let it cool down over night. The upper hose was collapsed and the overflow tank was still pretty full. I released the cap and pressure went back into the system and I topped off the coolant again just to be sure it was full. I am going to go out and get a new cap but not sure which one to get. Toyota does show two different caps now and I am going to check with parts department to see if there is a real difference. The OEM cap from my original radiator is longer as the neck of the radiator was deeper. The replacement radiator neck is swallower. This is supposed to be the OEM replacement for 96-02 4runners. Well I'm not sure about that now. So I will investigate this further and determine the deal with the different caps. My understanding on the overflow tank is when the coolant cools, it takes a vacuum on the overflow tank to pull in coolant from expansion during operation and then when the system cools pulls the coolant back. So I am wondering if the cap is another issue. Either way I will just replace the cap so I have a good start point with this radiator replacement. Comments and opinions welcome.