i have a 93 pickup 22re street rv cam and head lc header exhaust k&n filter. electrec fan. 160degree stat

When am at idle the the engine stays cool just fine. its when i'm driving on a hot day 80 and above about 3k on the ttach my engine coolant temp rises to imbeteen quarter and half way then half and and a little past. i have to have the engine at rest like at a stop light for the temp to finally cool down and it drops fast. there is no fluid comimg from the weep whole on the pump. there is fluid in the resevoir. and it has been burped sinsce the last coolant change. about two months ago. i also can not use the aircandition cause it rises the temp a quarter bar more.
this all happens driveing on hwy. the hoses replaced with toyota hoses a year ago. wgat are ya'lls thoughts

Have you had your radiator checked ?, it could be plugged inside. you might also consider replacing your radiator with a 3 core unit for a 4 Runner.

I got a 3 core for my 89' pickup at orielly auto parts for $130. Very good price. Its a good quality unit and bolts right up. It is actually about 1 longer in the bottom as it comes with a tranny cooler as well. If used in a manual tranny, just leave the plugs on the tubes for the cooler.

Sounds exactly like the overheating symptoms I had with my '85 about 9 years ago. Turned out to be a partly clogged radiator, put in a new 3-row radiator and it now runs nice and cool:
- http://www.4crawler.com/4Runner.shtml#Engine

I think the 160f t-stat is too low and it may not be allowing emough coolant residence time in the radiator for proper cooling. Try going back to the stock t-stat.
Thumbs up on the 3 core rad too, i just installed 1 about a month ago, working really well in the south eastern 100f heat. $130 with lifetime warranty for a brand new (not reconditioned) rad from advance auto parts.

Another vote for the rad being partially clogged. You can have it rebuilt with a 3rd row added, may be cheaper than buying a new one. A 3.0 radiator is also a direct bolt in.

well i replaced the rad 2yrs ago with a 3 row from rad barn.
this problem has been here for a while. i thought that maybe when i did my eng overhaul earler this year that the problem would go away. <img src="/forums/images/graemlins/frown.gif" alt="" />
but it still presist. what psi is the cap? i'll try to go back with the 180 stat if ya'll think that would be better.
any other suggestions?

Radiator condition was not mentioned in the original post.

I run a 13 psi cap on mine, I think that is what the stock cap is. I also run an OEM 88C/190F thermostat in my 22RE and it runs fine. Might also see if the radiator hoses are in good shape. Have heard of a soft lower hose collapsing at high RPMs from the suction of the water pump. Also how old is the pump?

I just got through solving my "running too hot" issue. I'm not really sure it was ever running hotter than "normal"...but it was hotter than I ever want it to run. The solution was a 160-degree TRD thermostat (the little [email]bast@rd[/email] costed me $80 too).

My issue started when I installed a real temp gauge (actually put it in the gauge cluster....it's pretty trick) and installed a 2-speed ford taurus radiator fan. After I finally resolved some wiring issues with the control (needed to add a few relays), I found that my truck was running around 205 - 210 when I'm just cruising around town....which is too hot for my tastes. So.....and after messing with the fan temp settings relentlessly, I gave up and started talking to those who know far more than me. Aside from a few posts on here, I harrassed every toyota service tech and manager and every toyota specialist who'd answer the phone. What I came up with is that a stock 3.4L motor (and probably true for the 2.2 and 3.0L) will run around 205 - 210 under normal conditions on a hot day....and that is too hot. Ideally they should run around 185 - 195.

According to all the experts I talked too even 210 really isn't that bad, provided you aren't beating on it, and you change the oil regularly. But, that's a problem for most of us since we are wheeling our trucks. They all also said, the best solution is a 160-degree thermostat. A couple guys mentioned bigger radiators and electric water pumps too....but those were for severe, extreme use scenerios.

I put in the 160-degree thermostat this evening and just got back from about a 30 mile start/stop around town drive. The highest my temp went too was 190 and it spent most of the time around 180-185....perfect as far as I'm concerned.

And...I also "experiemented" with the stock toyota temp gauge on my bench and found out that it's really tunned for a certain temp range. My experiment was pretty crude but, I found that for a range of 140 - 210 degrees my factory temp gauge would stick in the same position (right at the mid point)...anything over 210 and the gauge would move quickly to the high side and peg at around 225.....which tells me that if the factory gauge is going beyond the mid point, you are probably already in the danger zone.

So...all that being said....check to make sure you're water pump belt isn't slipping (which would happen more at high RPM's, replace your thermostat (just to be safe) and check your radiator for plugging. My vote goes to a plugged radiator...if you don;t use distilled water in there, they can plug very quickly depending on the minerals in the water.