1995 Avalon overheating! Please Help! - Toyota Nation Forum : Toyota Car and Truck Forums

Vernon29RW · 05-06-2011, 11:49 AM

Hey everybody,
I have a 1995 Avalon with 181K on it. Bought it used with around 120K. Everything has been running great on it. I keep up with the regular maintenance, just recently put new brakes all around with new rear calipers. Just a few weeks ago I noticed the cars temp would start to spike if I sat at idle for any given amount of time. After doing a litle experimenting I realized that the cooling fans are not turning on. However I did confirm they are working because they turn on when the A/C cycles. Is there just a temperature switch that I could replace? If so where is it and is there any electrical tests I can do on it to confirm that it is in fact faulty?

I don't believe the thermostat is bad because if I crank the heat up I can keep the gauge in the middle and the car warms up normally. I also noticed that if I turn the A/C on forcing the fans to cycle I can slow down the temperature increase but it will still get way too hot.

If anyone has anything that I can try please don't hesitate to reply. I'm pretty handy and have done all repairs on the car myself so I'm confident I can do the work. I'm just trying to avoid having to bring it to someone and them trying to railroad me.

Thanks,
Steve

***HATEnFATE*** · 05-06-2011, 03:35 PM

There are three temp sensors on the water neck going into the engine on the transmission side. One of those three kicks on the cooling fan for the engine but I can't remember which one. Two are called temp detect switches and one is the EFI temp sensor.

Vernon29RW · 05-07-2011, 06:12 PM

So no one really knows which temp switch controls the fans? Or how I could go about testing that with to confirm it is in fact the part that really is broken? Hope someone can chime in and at least point me in the right direction. Maybe someone has a Haynes manual they could look it up for me.

Thanks!
Steve

bob2 · 05-08-2011, 05:00 AM

remove the wires from the 3 sensors. ground the caps. one of them should make a fan start. if not, it's the fan relay. i would think 2 of those sensors would start a fan - one the primary (left) and the other the secondary (right) when the engine got even hotter.

Vernon29RW · 05-08-2011, 11:22 PM

Thanks for the reply! So you're saying pull the connector off and ground out one of the pins on the connector until it starts the fan? Right? That's sounds pretty simply. I am still a little confused by the other post. He said the water neck is on the transmission side. My inlet pipe is right above the timing belt. I'm almost positive all 3.0V6s are all the same. Unless he is referring to the lower Rad hose but I would have just assumed those sensors would be on the upper hose near the thermostat. Any input on that?

Thanks,
Steve

bob2 · 05-09-2011, 07:47 AM

Quote:

Originally Posted by Vernon29RW

Thanks for the reply! So you're saying pull the connector off and ground out one of the pins on the connector until it starts the fan? Right? That's sounds pretty simply. I am still a little confused by the other post. He said the water neck is on the transmission side. My inlet pipe is right above the timing belt.

Thanks,
Steve

should be only one pin on the connecter. it should be a simple carbon temp resistor that allows more current (becomes less resistive) as the engine temp increases. when the current becomes sufficient to fire the fan relay's electromagnetic coil, the fan turns on.

i have not had to do any of this to the avy. i'm talking from general experience with cars. the water pump is on the timing side of the engine with the thermostat. you're right - it seems that having the sensors where they are would measure the temp of the water from the radiator, as opposed to the engine temp.

now i'm confused - lol

N3M3S1S357 · 05-14-2011, 02:49 AM

This is my first post on this forum but I've got the same problem. I've got a '95 XLS that the fans won't turn on by themselves but I can kick them on by turning on the AC. That worked for a while to stave off almost overheating but now it doesn't seem to be enough. I've also noticed that I'm losing a good amount of coolant from somewhere(I haven't been able to track it down).

Just wondering of any ideas of common areas of leaks or what could be causing it. This is my first experience with a Japanese car, I'm used to American. Currently it's my girlfriend's daily driver so fixing it is high priority if I don't want to get a beating.

My daily driver is an '88 Fiero Formula.

Vernon29RW · 05-14-2011, 10:54 AM

I forgot to write back on here the other day in response to the help I got. So what I did was I located the sensors which are in fact on a water neck going into the motor on the transmission side. However there were only two. One is a one wire, the other a two wire. I took the one wire connector off, grounded it out and the fans came on. I put that back on and took off the two wire connector. As soon as I disconnected that the fans turned on the high setting. Plug it back on and they go off. I'm not sure what that one does.

Anyways so I sprayed both connectors with electrical contact cleaner put them back on and now the fans DO come on when the cars gets hot, but only on the low setting. I'm still confused as to why they won't turn on on the high setting. The sensor that I was talking about in earlier posts on the inlet pipe near the tstat isn't a sensor at all. It's the sending unit for the temp gauge on the dash.

I also think I have another problem. I think ky tstat is getting stuck half closed because the car will get really really hot, the fans do come on but like I said only low. Not enough to do the job. But if I rev the piss out of the engine the temp falls sharply real quick. Which makes me think the coolant is being obstructed and not circulating. Anyone have any thoughts on that?

N3M3SIS, it sounds like you have more problems than me, as I'm not losing coolant anywhere. You need to locate the point of the leak first. But try to clean off those connectors and see if that does the trick with the fans. Also don't rule out the thermostat. It may be completely stuck closed and no coolant is getting circulated through the radiator. Also the leak may just be the overflow tank spilling over when the car does overheat. If the coolant leak is along the pass frame rail it may just be the tank spilling. But like I said before you gotta locate the area of that leak. Let us know what you find.

Steve

bob2 · 05-14-2011, 03:56 PM

i would stop using the car until i got this fixed. aluminum engined do NOT like being overheated. they can warp so that not a single bolt will turn in the aluminum - it will quite literally break off before it will budge. changing head gaskets and milling the heads will cost a lot more than the car would sell for...

change the thermostat and the sensor with 2 wires on it.

steve550 · 05-17-2011, 08:11 AM

I am having the same problem. I did replace the thermostat and the water outlet cap. With the old cap the system dumps the built up pressure into the reservior and it bubbles vigoressly. Witht he new cap it doesn't do that but the hoses get so tight with pressure. i have noticed when i turn my heater/defrost on the temp falls to normal but as soon as i turn it off it climbs back up. any suggestions?????

Vernon29RW · 05-17-2011, 10:43 AM

Well I'm not sure if you know but the engine fans are supposed to turn on when you activate the defroster (assuming you mean front defroster). So first make sure the fans are turning on. If theyre not trying checking those sensors mentioned earlier. If they are then its possible that the tstat could have been faulty but I know you just said that you replaced it. Do you have sufficient heat? It's possible you could have a blockage somewhere or your water pump isn't circulating. Just a lot of possibilities. Gotta start eliminating things.
Hope this helps you out some.

Steve