Automatic Transmission, No Overdrive

[NickMiller]

I have an 88 4Runner 3.0/AT.

I have no overdrive unless the temp gauge reads 1/2 through. The second it drops below that mark, it kicks out of OD. When I first got the vehicle it would shift into OD when the gauge read about 1/4" the Low mark. When I get on the freeway it cools down significantly, so it won't stay in OD. I've resorted to cardboard in front of the radiator....still doesn't work right.

I understand the temperature/OD minimum that Toyota has done.

I've put in 2 different thermostats, replaced the temp sensor, and flushed the system.

It also doesn't blow warm air at idle, I have to rev it up to about 2000 rpms to get warm air from the heater.

I've run out of ideas, and hope someone might have a fix for it....

 

[podzhopnik]

i experienced same problems AFTER replacing the head gasket because it was installed backwards. When the mechanic re-installed the head gasket correctly all issues disappeared.

btw, i own a '95 4runner SR5 V6 2W AT 235K

 

[fourwd1]

You may have an air pocket in the cooling system, try burping it.

Get the front end up in the air a bit.
Take the rad cap off.
Set the heater control to HOT.
Start the engine.

As the engine warms up it may start spitting coolant, that's normal.
When it stops you're done, top it off and put the cap on.

 

[the_dingman]

It also doesn't blow warm air at idle, I have to rev it up to about 2000 rpms to get warm air from the heater.

This is where you need to focus your effort. Fix this, and all will be good.

Try the air bubble idea first. Fourwd1 recommends this often, and his ideas are usually gold.

After that, if you've flushed and don't find blockage, check the water pump. It may be bad.

I am not familiar with how the water pump works on the 3VZE, but the 22RE has it on the same belt as the fan, it can sometimes come loose.

Another issue I've heard of is that some cheap water pumps have had the coolant eat away at the cheap metal the pump blades were made of.

Lastly, remember that even though the temp gauge isn't going up, you still could be overheating. I drove my '86 for a few months in the winter with no coolant thinking everything was find because the temp gauge didn't go up. The gauge didn't move because there was no water at the sensor to transfer the heat.

 

[NickMiller]

You may have an air pocket in the cooling system, try burping it.

Get the front end up in the air a bit.
Take the rad cap off.
Set the heater control to HOT.
Start the engine.

As the engine warms up it may start spitting coolant, that's normal.
When it stops you're done, top it off and put the cap on.

Thanks for the help... I'm gonna try doing that and I'll post the results!

 

[projectX4runner]

So did anything ever happen with this???

 

[caloot]

raising the front end and burping the coolant is a great idea. the location of the coolant sensor for the computer, (as well as the coolant sendor for that matter, as well as the cold start sensor too) is such that it is very easy for an air bubble to form. I think ( after this problem driving me absolutly nuts) that properly burping this vehicle is essential. Ive heard that a seized fan clutch can over cool the engine. I replaced mine. Also, the sensors get majorly corroded and are an easy replacement. One other thing Ive noticed that could be problematic, believe it or not, is the radiator cap. If the rubber seal is not set right, or even if it is not the right pressure (cause its not the right cap or its broke) it will allow coolant to escape into the coolant blowback tank. Youd notice that your blowback tank is always full, and youd notice a small coolant leak under the car (maybe just smell it even).. this small loss of coolant will create those pesky bubbles at the sensors. As far as replacing the head gasket, Id surmise that it was more a matter of the mechanic properly adding coolant than the gasket. Pss.. Ive heard of mechanics actually adding coolant at the sensor.... shrug.... ANYWAY I cant stress enough that I think the problem will boil down to there not being enough coolant in the engine.. for whatever reason.