Zealot

Heres my engine:

Fuel injection and are computer stock. Had the block and head shaved (alot of metal taken off) and completely rebuilt. Oversized valves, head port and polished, 260 grind w/ 420" lift camshaft w/ LCE adjustable cam gear. I also converted over to electric fan, plus installed a header.

Okay heres my problem:

Even after doing a full radiator flush, a new t-stat, adjusting the cam gear as best I could to get the timing right (with a light), it still wants to overheat after about 20 min of driving, plus it has a odd idle. The idle revs up to about 2500 then kicks down over and over again, and when I put my foot on the brake the idle pulses. The idle and the overheating my be related but I dont know. any suggestions? I am open ears. Thank you

norcalsvx

i had a overheating problem that was solved by a new toyota tstat
http://www.4crawler.com/4x4/CheapTri...tml#TstatOrder

Zealot

I have already put in a brand new 180* T-Stat. Thank you for replying though.

norcalsvx

did you use the toyota dual valve t stat? if not it will overheat sometimes

Zealot

Why is that?

norcalsvx

this is off 4crawler's website

"Thermostat:
After everybody looked at me like I was crazy for saying that it ran hotter with the heat on, I went to the dealership and bought t-stat part # 90916-03070. This did the trick. What happens on the 22R and 22RE engine, when the coolant goes through the heater core it gets cooled off enough that when it gets dumped back in on top of the t-stat it shuts it. Therefore the temperature in the engine continues to go up. The t-stat that I have mentioned has two valves in it, one at the regular temp. and one smaller on at a cooler temp. If the cool water shuts the big one, the smaller one stays open. All this happens because of the lack of a by-pass hose, which on other systems, keeps hot coolant running on the t-stat. On the subject of the overheating thread, an engine can run hotter with no t-stat. But it would probably be a system configured differently than the 22re. Mine runs cold when the t-stat is removed.

Another advantage of the 2-stage thermostat is that the thermal "inertia" of a thermostat is greatly affected by the mass of the temperature sensing element (a.k.a. slug) on the thermostat. The normal single-stage t-stat has one big valve with a large spring and a large slug to force the spring open. The 2-stage t-stat, on the other hand, has a tiny valve and a medium sized valve, with tiny and medium sized springs and slugs. This lets the smaller t-stat valve react very fast to engine temperature changes and the medium sized valve, although a bit slower, still operates faster that the one large valve.

A lower-cost version of this can be done by drilling one or more small holes around the edge of the single state t-stat to allow some coolant to flow all the time. This functions like the normal bypass hose on other engine designs.

On the subject of thermostats (or turd-mo-stats for Toy4x4 old-timers:-), I once tried one of those "fail safe" thermostats. A normal t-stat has a spring that holds the valve closed and the slug forces the valve open in response to coolant temperature. The slug has a sealed chamber with a temperature sensitive medium in it that expands when heated. The typical t-stat failure mode is that the chamber leaks or swells, preventing the t-stat from opening. The fail safe thermostat has a catch that is engaged when the t-stat valve opens fully and then the valve is held open. I guess the idea is that if the engine ever does begin to overheat, the t-stat locks open and prevents further damage. Well anyway, I had installed one once, and it worked fine. One day, I lost the silicone oil out of my fan clutch (didn't notice this until later when I popped the hood and saw the results) on a hot (100F) day. I recall seeing a slight temp rise once, but nothing too bad. Some weeks later, on a cool night, I turned on the heater and got almost no heat. This is when I popped the hood, saw the oil sprayed all over and put two and two together. Pulled the t-stat out and sure enough, it was latched open, so I guess it did its job. However, I now had to replace the t-stat, since once it locks open, it can't be reused. But I guess this also shows the engine runs cooler with at least a wide open t-stat in it.

Justin311

The bouncing idle is the ECU thinking you're coming to a stop so it bumps the idle. It will happen if your idle air screw is set too high (idle > 1000 rpm) OR you have another issue. Search "bouncing idle". If you can't fix it thru idle adjustments you can clip the wire going to the ECU, there are diagrams of the ECU etc on this board.

Zealot

Well I dont know if this helps but I know that my engine runs cooler if I have my heater on. I can sometimes maintain temp. if I have my heater on full blast. Gets kinda toasty in that little cab of mine.

motoriderbc

Sounds like your rad is plugged. The entire core should be hot, plugged sections will be much colder.

Zealot

I was thinking that, and yes some of my veins are clogged. Still, my old engine never overheated, (I did an engine swapped).

84sr5yoty

A newer engine is tighter, resulting in more friction, creating more heat. In some American vehicles it isn't uncommon for the motor to run on the hot side until it breaks in. This is why your old motor didn't have an issue with the plugged radiator because the motor was loose. In short, replace the radiator and check your fan clutch.

Zealot

Yeah I was planning on replacing it, I just thought it wasn't the main issue, thanks. Oh But I did switch to a electric fan, no worries about the fan clutch.