I took the FToy to Moab for the weekend to give it a nice break-in test on some of the easier trails. However, I was not able to run any of them because I have a serious over heating issue. I was not even able to make it onto the trail from town without the temp climbing into the high 200's (250). This was just driving it down the highway.

It is running a stock (and well used) 22r out of an 85 truck. I ran this engine in my other rig for about 5 years with no issues, but swapped it for a EFI engine. The radiator is out of a 83, with the stock metal shroud. I was able to get a electric fan that fits nicely inside the shroud. I am also running the gotpropane kit on it, 5sp, duals, and 40's. I am currently running the 4.10 thirds.

While in Moab, we replaced the thermostat with a 180, and added a 2nd 12" fan to the front of the radiator (as a pusher). We also flushed the engine, but it still builds excessive heat. It takes about 5 minutes to push the 250 mark. It can idle for 15-20 minutes without overheating, but not while driving it.

We adjusted the timing, and it helped a little, but it still overheats.
The radiator was flushed prior to installation, and the upper and lower hoses are new. The mechanical temp gauge is routed to the top of the block after the thermostat.

Does anyone have any other ideas as to why this may be happening?

Just throwing this out, is the radiator cap the highest part in the system?
if not that will allow a bubble of air to stay in the system.

And my truck did that, found out I had a crack in the top tank of the radiator. After I changed radiators it stayed cool. I did the same with changing the thermostat, even pulled it out. But not till I changed radiators was it fine.

Just couple ideas for you I could think of.

Radiator had a crack in it. Had it repaired and flushed. Yes, the cap is the highest point, and the engine is slanting down from the rear to the front (t-case is higher than normal - flat belly, engine is at 1" down, 8" back).

I had a 22r with an air pocket ?somewhere? before the thermostat. This was not allowing the coolant to flow properly and the guage to read crazy hot in 5-10 minutes at idle.. I had to remove the thermostat run the truck then re-install the thermostat later.

Please explain how what you did with the heater circuit. Did you plug off the lines or did you hook them together? Also, the little 3/8 hoses that run coolant through a thermostatic valve and the throttle body, what did you do with those?
One other thing, did you experience temperatures that vary up and down quickly (up to 250 deg and then drops fast to 180, then back up).

I pulled the thermostat out and am running it without it now. I was able to trailer it to the trail on Mon and run a few obstacles, but it still is running hot. About 15 min of crawling at an idle, and it was pushing 225.

At least I got to wheel it for a few minutes. Going to need new springs for it now. Guess I should have finished the wrap bar before making the trip.
http://i284.photobucket.com/albums/ll10/fire_201/Image085.jpg

It seems to work good otherwise.:)
http://i284.photobucket.com/albums/ll10/fire_201/Image084.jpg

Please explain how what you did with the heater circuit. Did you plug off the lines or did you hook them together? Also, the little 3/8 hoses that run coolant through a thermostatic valve and the throttle body, what did you do with those?
One other thing, did you experience temperatures that vary up and down quickly (up to 250 deg and then drops fast to 180, then back up).

I ran the 2 lines for the heater directly to the propane regulator (where the directions stated to put them).
I am running the 22r carb base. I don't remember any 3/8 hoses on the throttle body.

The temperature rose rapidly, but not erratically. When it got hot (since the fan wasn't cooling it fast enough with engine running) I would shut the engine off and run just the fan. When I would start the engine again to circulate the coolant, it would instantly drop 10 - 20 deg. I did this repeatedly until it cooled down enough to try driving again.

Fan going the right way and are the blades going the right direction?

Yes, fan in the shroud is set up to pull and the fan in front of the rad is set up to push. Not sure the size on the puller fan, but the pusher is about 850 CFM. The only thing in front of the rad to restrict airflow is the winch, but it is a lay-down style that is dropped behind the front x-member. I had a trans cooler up there before, but thought that was part of problem. I moved it when I added the second fan.

...with the stock metal shroud. I was able to get a electric fan that fits nicely inside the shroud.

If you have mounted the fan close to the radiator core, which is where it should be, then the one you have is definitely way too small. It should cover the entire core, and if it fits inside the the shroud, it isn't doing that.

You either need to reinstall the stock fan in conjunction with the shroud, or get a proper electric fan / shroud setup, such as the Taurus/Mark VIII. However, with the Taurus/Mark VIII, you would need to get a V6 radiator for it to fit properly.

With the fan filling the entire hole (where the OEM mechanical fan fit), would it not cool as well as the stock one? That is the point of a shroud (I think), is to direct the air flow created by the fanthrough the entire radiator surface.
I can understand if the CFM is not enough, but with 2 fans, 1 pushing and 1 pulling, there is a lot of air moving through the radiator. Also, with a stock fan setup, which has a clutch, doesn't it allow the fan to disengage at highway speeds? This is when I build heat most, not so much when I am at idle.

BTW, the fan is mounted to the shroud, with the fan size being about a 1/2" smaller than the hole in the shroud. There is not a gap around the fan and shroud. The fan assy completely fills the hole.

Here is what I know. toyota's suffer from a thermostat problem that makes them overheat in the first 5 minutes of driving. It has to do with the heater circuit and the returning coolant dumping on top of the thermostat, keeping it closed. On a stock toyota, it is only a problem when you have the heater on and the coolant is circulating through the heater loop. I would guess that since you are using a propane system, this is the same as having the heater on.
There are 2 fixes for this. The first is to go to toyota and purchase a thermostat that is specifically made to fix this problem. It cost about $25 and I havent seen a dealer that stocked it yet.
The second is way easier. Look at your thermostat and you will see that there is a small hole in the flat area with a little piece of brass crimped so that it loosely blocks the hole. REMOVE THE PIECE OF BRASS. Then take a 1/8" drill bit and drill a hole opposite the hole you removed the brass from.
Problem fixed! What this does is allow the thermostat to bypass enough coolant so it doesn't get confused on what the actual temperature is.
I have had this problem with 2 different trucks and this fixed both of them. the only difference is, both these trucks were fuel injected.

Hope this long ass post helps.

I found this in the toyota FAQ section.

Thermostat Problem

Question: “Why does my engine temp go all the way up to the red before it comes back down to the middle of the gauge after I start it up in the morning. It only does this when the engine is cold and once it warms up it seems to operate normally. Could it be as simple as a stuck thermostat?”

Answer: (From Roger Brown’s Web Site - http://4crawler.cruiserpages.com/4x4...tml#Thermostat)

“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.”

You can get the two-stage thermostat mentioned above from your local Toyota Dealer.
Part Number: #90916-03070

We pulled the old thermostat out to replace it with a new one. The new one didn't help the problem, so we took the old one apart (completely gutted it, so all that is left is the ring for the o-ring) and put it in. This should by-pass the thermostat all together, since there is nothing there, but it still got hot. It should circulate all the time now, and would make it run colder. Am I wrong in thinking this way?

BTW, I will drill the new one when I put it back in.

I gutted a thermostat when I was trying to figure out the above problem and found that the coolant circulates too fast resulting in an overheating problem also.

sounds like the radiator isnt doing its heat transfer job, is it new or used? what happens when you hose the radiator off when its hot?

sounds like the radiator isnt doing its heat transfer job, is it new or used? what happens when you hose the radiator off when its hot?

Did you try running water thru the radiator? make sure its flowing good? I have had rads that were rodded and solder plugged it slowing the flow down. After the trucks been running a while is the top and bottom of the rad hot? if the tops hot and the bottoms cold theres your problem

I was not even able to make it onto the trail from town without the temp climbing into the high 200's (250). This was just driving it down the highway.

If it over heats at highway speeds that tells you it isnt a electric fan problem.....

....as long as the radatior face is "open" to the air flow its getting all the air it needs to stay cool at highway speeds.

The radiator is used, but I pulled it from a 83 that is running. I drove it for a few hours before I pulled the front axle and radiator. It never over heated.

As to running water through the rad, yes, we ran water through it for about 5 minutes with the cpa off and the thermostat housing off the block, so it is flowing through the radiator and block. The temp at the top of the radiator and the bottom were both hot to the touch (couldn't hold hand on either end when it was hot). We didn't try putting water on the outside of the rad while it was hot to see if it changed the temp.

I was thinking the same way about the highway speeds and being able to cool the engine.

if you cant touch either hose going to the radiator then the radiator isnt doing its job, there should be a significant change in temps between the two. Doesnt sound like air flow is your issue but instead just clogged core in the radiator-or posible bad radiator cap. I would buy and new 3 row radiator and put it in-i got mine from autozone w/ cap for $115-cured my overheat problem. just my $.02-let us know what you find