wishmaster22

Last night my wife was driving the 4 runner home and noticed the heat gauge in the red. She slowed down and drove a few more feet and heard an explosion and saw steam. We towed it home and It was dark, but I noticed that the upper radiator hose was split. I believe this was the noise. So I went to town and got a new one, and in -10 degree weather changed the hose and added more radiator fluid. I then started in and put it in the garage. It was to dark and way too cold to be screwig with this thing.

SO today, I started it up backed it out the garage and noticed that it was reving at about 2000 rpm, but after reving it a little and letting it warm up it went down to 1000 rpm. But right before that It did kinda rev up and down erratically on its own. The fan was spinning fine and I was just waiting for it to heat up to see if the thermostat kicked in. Well I then noticed that the fan had stopped and was coming to a slow halt and then it started to steam up. I squeezed the upper radiator hose to see if it was full, and it was soft and not full at all.


Sooo could it be the thermostat not letting water get thru?

Is that why the hosed busted in the first place.

Its like 28 degrees outside, not sure how it could heat up.

I checked the oil, it doesn't look milky, it looks fine.


Not sure which way to go from here?


Thanks

eric-the-red

If the fan isn't spinning when it's hot you may need a new fan clutch.

mt_goat

Is this a 22re? If so, its likely the heater is over-cooling the coolant and preventing the thermostat from opening.

See this:
http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

If its not a 22re engine, you have some big issue somewhere with your cooling system to overheat in cold weather. Maybe start with the fan clutch since you say it quit spinning before it steamed up. Also check the thermostat and make sure its working.

js9924

i have horrible luck with cooling systems but have you replaced the water pump ever? alot of times they have plastic impellers and they will break with time. always get a metal one if you can. as for the idle it is not uncommon for the motor to idle at 2000 rpm when its cold out when it warms up it returns to about 850. 1000 is a little high but it should settle back down after a minute or two when it is up to operating temperatures. I have noticed my yota idleing higher in park as opposed to drive as well. also if you do not feel pressure in the upper hose that is a good sign that the water pump is not working correctly. I had a problem on my 94 t100 where it was getting hot because the freeze plug in the back of the motor by the tranny was leaking and dropping the pressure so the water pump was rendered useless so you may want to check all of those as well. check the fan clutch as well

P.S. if you dont have one get a service manual

wishmaster22

its a 3.0 3v

I changed the fan clutch about three years ago. How can I tell if its bad again?

The fan was spinning fine for awhile, its like a fuse blew or something.

I'm getting ready to pull it in, I bet it spins for a while at least.

Could it possibly be just the thermostat?
Thanks

SEAIRESCUE

Start cheap and work your way to expensive.

New thermostat with the little jiggle valve to purge trapped air. See what happens. I would also replace lower radiator hose. Cheap ones tend to collapse and starve the water flow as they age and get soft. Test by revving engine and watch the hose for signs of restriction.

Fan sounds scary. They are why many a 3.0 ends up with a head gasket problem for the reasons you have described. They are silicone fluid coupled and generally die a slow death with eratic performance. I highly recommend you buy a flex fan or get a new fluid coupling from the stealership, now. Evaluate this change.

Radiator? Old? They scale up and become marginal. Get a new one before it kills your automatic transmission from an internal leak.

From hear on, it gets expensive.....

My $0.02

wishmaster22

Thanks...


I'll start cheap. Tommorrow I'll change the Thermostat. See what happens...

I'll be back!

wishmaster22

I was checking out prices online for water pumps, in case I have to change it; and I keep seeing references to false water pumps for a 94 v6 .

Is this correct, and how hard is it to change?

Thanks

mt_goat

There is a fake one and a real one. The fake one is nothing but a bearing in a housing and it supports the fan. The real one is driven by the timing belt and is much harder to get to. You have the remove the timing belt, so most people replace the timing belt and water pump together.

wishmaster22

Wholly Crap!

Man I really don't want to take off the timing belt..

I really hope its something easier!

Thanks

sandboxbully

i had a similar problem with my yota over heating, i bought a radiator with 3 rows instead of 2, and replaced my hoses, a mistake i made was taking off my fan shroud, it made a big difference when i came to the truck over heating, she would stay cool at all! anyway i almost sure its ur fan clutch thats making that fan stop, but remember to start cheap and little by little get the parts u need, but when it come to ur radiator make sure u replace ur hoses with a new radiator

runethechamp

I bet your fan has nothing to do with it. It only comes on in very rare instances. It does however spin for a little while after you start up the engine, so what you observed there should be normal.

wishmaster22

Heres a dumb question. Usually on other vehicles I have always found the thermostat up top at the end of the upper radiator hose. Not this one, It looks like its on the bottom radiator hose coming out of the engine.

I just want to make sure I am not crazy, before I drain the whole system.

Is this correct?

Thanks

mt_goat

Yes, that's it on the return side. That's Toyota's way and probably why they run a 180 deg t-stat instead of a 198 deg like Ford or GM.

wishmaster22

Well this is going to be fun. I drained the radiator, I tried to take the bottom hose loose to drain the rest of the fluid from the engine, but its really stuck on there. I don't want to rip the hose. Whats the best way to tackle this thing? It already looks like its going to be hard to get the nuts or studs off.

I keep telling myself its too cold for things like this to happen.

mt_goat

Yeah it can be hard to remove the hoses sometimes, I usually take a screw driver and work it under the hose and try to get it wet to lubricate it enough to slide off. Going back on, use a little dielectric grease and next time it will slide off much easier. You may be able to change the t-stat without removing the lower hose though, you just need to pull the housing off the studs and the hose could flex enough to do that, at least I was able to on my 5VZFE.

wishmaster22

Thanks Dale

I'd be lost with out ya!

854x4

When you do replace the thermostat make sure you put the jiggle valve at the 12 o clock position so it will let the air pass when you bleed the system.

mt_goat

I like to test the new ones before I put them in:


There are 2 schools of thought on the clocking of the jiggle valve, 12:00 makes it easier to get the air out first try, of course once the t-stat opens its irrelevent, 6:00 makes it easier to drain more of the coolant out of the block without removing the t-stat. Personally I like 6:00, but thats just me.

BLKNBLU

iTrader: (1)

Hopefully it's not the fan bracket. Here is a (kinda long) thread about it. The crux of it shows up late on the 2nd page and is more useful from there on.
https://www.yotatech.com/forums/f116/shop-127893/
Unfortunately with a 94 it is pretty involved which is why I say I hope for you that this is not the problem. The part changes considerably between 88-92 models and 93-95 models.

Also, if you don't already know about this site, it will be really useful to you.
http://personal.utulsa.edu/~nathan-buchanan/93fsm/