93 4Runner/V6 will not go into O/D

Just purchased a 93 4Runner with 177K. Looking for some help. It would not go into overdrive unless you drove it for quite awhile. I have read many a post in this forum and I am trying the thermostat route first. Couple things...prior to putting in the new thermostat, the temp ran about midpoint on the gauge. I bought a new one today from Toyota and put it in. When I pulled the old one out, it had 7 holes drilled in it. Why would someone do that? Are they notorious for running hot? I did not drill any holes in the new one. I put close to 2.5 gal of 60/40 antifreeze in it and let it warm up, yada yada. Took it out for a ride and it pegged hot really fast. My first guess is I got a bad thermostat. I know, I know, I should have tested it prior to putting it in. I am going to pull it out tomorrow and test it. Is there something else I should be checking? The antifreeze capacity is something like 2.35 gallons according to the manual. If I got that much in there to begin with, the stat must have opened at some point, no? Any help you can provide would be greatly appreciated.

Did you install it like in this picture?

http://i16.photobucket.com/albums/b8/rogersb/3VZ-EThermostat.jpg

Yes...exactly like that.

I tested the thermostat, it works fine. Could there be some blockage in the system somewhere? It is running with green coolant. Not sure what was in there from the beginning. I have heard the red stuff will crystalize in places. Is a flush in order? Would a flush get rid of any blockage in the system? i.e crystalization deposits?

Maybe....I am not filling it back up right? Am I just supposed to put the stat back in and fill it up from the radiator cap? Is there some reason that maybe it's not getting enough coolant into the engine and it is all sitting in the radiator?

Once it got hot did you recheck the level? (careful)
How did you test the thermostat?
At exactly what temp did it open?

I did add a little more coolant to it....not much though, maybe 1/2 a quart. Didn't seem to make much of a difference. I just boiled a pan of water and stuck the thing in there after the water boiled. It opened up pretty quickly.

Just got off the phone with a tech at my local toyota dealer...he states that it is probably an air pocket in the system somewhere. He said should fill the block up as much as I can through the top radiator hose, all the while have the front end lifted up several feet so the incoming coolant will force the air out. Also ensuring that when I have enough of the coolant in to start it up, make sure that the interior heat is on high as that and the water pump should be the only things restricting the flow through the enigne. He also said to cycle the engine a few times with the coolant jug filled about 3/4 to the top. His reasons for that are if you do have remaining air in the system, if it burps, the level needs to be well above the bottom of the drop down hose in the jug so it doesn't suck any more air in. He did say these are the worst for getting the air out of them. I'll try that tonite and let you know what happens. Thanks for the help so far.

Well...not working...It seems to stay mid-remp range but then as soon as I back it out of the garage and take it for a spin, it gets hot again. I had it idling in there for awhile and it didn't get too hot. Why would it get hot when you drive it? ARGH!!! Side note, it does shift into overdrive now. The tranny seems to shift better all around. Please help!

If you still have the old one put it back in.
Make SURE it is installed correctly. this really sounds like it is installed backwards.
There is a small hole to allow just enough flow to get the hot water to the thermostat to open it.
Have either the top or bottom radiator hose been compromised?
To test properly the thermostat should open at the specified temperature, this will be stamped on the thermostat.
If it only opens at 100 degrees Celsius it will over heat.
Make sure it is the correct temperature thermostat. 80 - 84 degrees Celsius

Sticky post at top of forum:
1993 FSM
http://personal.utulsa.edu/~nathan-buchanan/93fsm/

Thermostat:
http://personal.utulsa.edu/~nathan-buchanan/93fsm/engine/110thermost.pdf

Dropped it off at the dealer today....they said the top of the radiator is HOT when it overheats, yet the bottom of the radiator is cold. Plugged radiator. Stopped at Napa and got one today...will do swap tonite and let you know. Kinda looks like we'll have a fix tonite....stay tuned

If there is no flow because the thermostat is malfunctioning the radiator will do the same thing.
Interesting. Hope it fixes it, what did it cost you?
I paid $9.00 for a 1988 3 row core on ebay it cost me $19 S&H and $50 to have it cleaned and tested.
Good Luck and do let us know.

Well, same thing...new radiator and is still overheating. Bottom radiator hose is cold and top is hot. Flow of water should go from top hose to water pump, what possible obstructions would be between the top hose of the radiator and the thermostat to block flow or quit working? Should I hook up a hose to the top hose and pull the thermostat and see if there is any flow? Not sure what else to do?

Well, same thing...new radiator and is still overheating. Bottom radiator hose is cold and top is hot. Flow of water should go from top hose to water pump, what possible obstructions would be between the top hose of the radiator and the thermostat to block flow or quit working? Should I hook up a hose to the top hose and pull the thermostat and see if there is any flow? Not sure what else to do?

The coolant goes from the bottom radiator hose to the water pump into the engine, then from the thermostat into the radiator through the top radiator hose. Think about it. If the top hose fed the pump, you'd kill your engine everytime you ran even a little low on water.

That's why the top is hot, bottom is cold. It's natural. The engine overheating and the high termperature gradient in the radiator are both signs of insufficient flow through the engine/radiator. Sounds to me like you have either a bad water pump (corroded fins), plugged up cooling jacket, or a bad bottom hose that's collapsing under suction.

Check the bottom hose first and replace if it is not strong to squeezing it. If that doesn't fix it, then flush the engine. Then, last of all, replace the water pump.

it should be your water pump or your fan clutch. the top one is the outlet and the bottom one is the inlet were the cold will start giong inside the block.. you should just change both the water pump and the fan clutch..

Faulty fan clutch is way down on the list. A bad clutch would make the whole radiator hot, not just the top. The problem appears to be poor coolant circulation, not poor airflow through the radiator.

We'll try the flush first, then see about the water pump. Should we just run a hose in through the top radiator hose and see what comes out by the thermostat? Not sure on this...I'd hate to push the blockage any further into the block. Is the water pump an easy replace?

Hey it worked until you fixed it right? Just a shifting problem. Concentrate on what work was done that made it worse!!
Again if you still have the old thermostat, put it back in to try to get it back to just a shifting problem.

Even a BAD stat will open in boiling water.

The new thermostat is bad or it is installed backwards either of these scenarios will produce your symptoms. The more probable is that it is installed incorectly.
You're not listening and it's costing you money.
We are trying to help you, please listen.

^^Test the opening temperature of the new thermostat more carefully and make sure it is installed correctly with the jiggle valve up and the coil sensor inside the block.

The stat is installed properly. Just as in the picture on page 1. Jiggle valve is at the 12:00 position. It says 82 degress Celsius on the stat. I will pull it and test the water prior to testing it again. Haven't had time to work on it yet today. I'm thinking it has to be either blockage somewhere or the water pump is not working. I really do appreciate the help. More to come....

What side is the spring and sensor on?
I HAS TO BE towards the block!
Lets take a look at what has happened, it worked well other than a OD shifting prob. Then the thermostat was replaced and everything went to hell in a hand basket.
So “SOMETHING” happened in the R&R process. If you are damn certain that it is installed correctly then there is another problem that just surfaced after the R&R of the stat.
Inspect the hoses.
Do you have the old thermostat? Put it back in, in other words bake out all the changes made that made this happen.
If you don’t have the old stat just eliminate it for testing purposes, it will tell you if you still have a blockage.
I am sticking to the stat being in backwards or that hose is compromised.

Old stat back in and back to square one. Not shifting into OD. Different "new" stat and overheating. The stat is in the correct way. Coil spring towards block (just as in picture on 1st page). Where is the ECT sensor located on the block? Will I get anywhere if I put the hose in the top hose and see what or how good the flow is out of the block where the stat is located? Might be some blockage in the block somewhere.

ECT sensor is on top rear of engine.

Wait! If you put the old stat back in and the overheating prob goes away look CLOSELY at both stats and find the diference, What is the temp stamp on both? A blockage in the block will cause overheating with BOTH stats.

I'm kind of thinking it may be blockage in the block. How would one clear that out?

I'm kind of thinking it may be blockage in the block. How would one clear that out?

there is a second drain plug that is locate some where around your oil filter if you found it drain it and use a water pressure hose and stick it in there then flush the hell out of it, or you can leave the second plug open and use the hose on top outlet and flush it from there, if you want you can run the engine at idle, did you change the water pump yet? about your fan clutch did it run very fast at first start? then will slow when the engine is warm? and while driving does the fan run as you press the gas? so are you saying it get hot while driving? so like they said blockage... I never got this problem on any of my car... only for my celica that it will get over heat when you idle it to long but as you go it will cool down, if your is not like that then it should be your water pump or blockage or is your head gasket in good condition? no white smoke coming out from the muffler?

The fan does go fast at initial start up, then slows down as engine warms. As far as the white smoke, this is Minnesota, nothing but white smoke coming out of every car here after October 1st...lol...It's hard to tell. The oil looks clean, not milky at all. I had an old 1980 Hilux and blew a head gasket on that, so I'm kind of familiar with that whole deal. I think the head gasket is in good shape..I'll try to flush it out after Christmas and see what happens. It's been warm here the last day or so, and the stat that is in there now, has 4 small holes drilled in it. It seems the warmer it is outside, the better the thing runs. Started it up today and let it warm up for 20 mins or so (it's 35 degrees here today) and it had no problems shifting into OD today. I can't find the ECT sensor....there are 5 sensors at the back of the engine by the firewall. Chiltons book doesn't tell you squat. Anyone have a good schematic of which one it is?

http://personal.utulsa.edu/~nathan-buchanan/93fsm/engine/98engineco.pdf

OR

http://personal.utulsa.edu/~nathan-buchanan/93fsm/engine/82operatio.pdf

[QUOTEBlown head gasket, Sorry.
On these V6s there won’t be much of any other symptoms no oil in the water check your compressions look closely at the #1 and #6 cylinders.
Head design causes excessive wear (from expansion/contraction against alu/iron) on these two cylinders.
Do a search in this forum for head gasket and read on. Many posts here about the problem with Toyota’s V6 head gasket. The service campaign has long since stopped.
when you had the timing cover off you might have noticed seepage at the #1 cylinder head/block interface.QUOTE]
4Wheel,
You posted this response on another post about overheating in the V6, do you think I may have the same problem?