Radiator Fans Not Coming On

[Krayzie Se7en]

Hello All!!

I've been reading this forum for a while and this is my first post. So YAY YAY. I have a Lexus Gs300 1998 with 108k miles on it. It was in an accident before and they had to replace the radiator and I don't know what else since it wasn't disclosed to me, this was the previous owner.

My radiator was leaking from the top tank causing it to leak over the engine and creating lost off steam. I pressure tested to find the leak.

So I went and got a new radiator and put it in, filled it up and thought I was good to go. But as I went to pick up my GF, it was steaming again... I opened the hood up and heard the water boiling in the reservoir and spitting the coolant our the drain tube in the reservoir tank that goes straight down. At this time I noticed the fans weren't coming on and the car wasn't overheating. The needle wanted to climb up but it never did... Its been about 15 to 20 degrees here in Chicago.

So I did some research and called a few friends and they told me to check the fans. I hooked them up directly to the car battery and they turned right on. So they work. Then I went and got a new Cooling Fan Switch and installed it. Again drove my GF home (3 miles away) and the car was throwing hot air with the heater on and after about 5 minutes it was just cold air. When we go to her house, the Fans weren't on and the car was steaming a little again from the reservoir. By the time I got home, it was boiling and spitting it out the again from the reservoir hose.

So I did some more research and thought that maybe the thermostat was stuck closed. So I went and bought that. To my surprise, the one in the car was installed backwards!! So I removed it, and put the new one in. Hooked everything, filled it with coolant and turned on the car.. It sat for about 20 minutes at idle with the heat on with out the radiator cap on to burp the system but all it did was slowly begin to steam from the top or the radiator. The fans never kicked on. So I shut of the car and came inside for the night.

I'm hoping that its not the water pump but what else could it be? I was going to remove the serpentine belt and see if there is any play on the water pump. Would tat help determine if something is wrong? There is no leaking from the water pump as far as I can see, and I don't hear nothing crazy coming from the area.

Other Notes:

1. I checked the fan 3 relay switch by placing it on the Horn relay and honking the horn. It work.

2. I Checked the fan 1 relay by hooking it up to the battery, terminal 1 and 2 and then checking for NO continuity in ports 3 and 4... and it worked fine. also felt the click once it was connected to the battery.

3. Don't really know how to check fan relay switch number 2 because it has and extra prong.

4. The coolant doesn't move like a river like I've been told it would if you take the cap off. It doesn't go down when the car is running, it releases a few air bubbles but that's it. This is while trying to burp the system. (This makes me think that it's the water pump)

5. If I remove the connection to the Cooling Fan Switch, the fans kick on. I don't know why or what the deal is with that (minimal mechanic skills) but makes me feel like the relays and fuses are working correctly.

6. No Blown fuses anywhere...

7. Top hose gets hot like its supposed to but the bottom hose was just a tad bit warm...

8. And lastly the top tank gets hot but the bottom one stays cool. I read somewhere that it may be an indication of a bad water pump.....

9. I didn't rev the engine at all after I replaced the last part, the thermostat and just let the car idle. I want to see if i keep the revs up and see if the fans kick on.

Any help in the matter would be greatly appreciated as I really don't have the money to take the car to someone to even diagnose it or to pay for them to repair it. That means I have to do it all myself. I don't mind but I have never worked with the timing belt and well, it looks a little complicated especially removing the crankshaft pulley bolt I believe. I know i have to do that if it is the water pump.....

Thank you

Jorge

[ivnnln]

Hello All!!

I've been reading this forum for a while and this is my first post. So YAY YAY. I have a Lexus Gs300 1998 with 108k miles on it. It was in an accident before and they had to replace the radiator and I don't know what else since it wasn't disclosed to me, this was the previous owner.

My radiator was leaking from the top tank causing it to leak over the engine and creating lost off steam. I pressure tested to find the leak.

So I went and got a new radiator and put it in, filled it up and thought I was good to go. But as I went to pick up my GF, it was steaming again... I opened the hood up and heard the water boiling in the reservoir and spitting the coolant our the drain tube in the reservoir tank that goes straight down. At this time I noticed the fans weren't coming on and the car wasn't overheating. The needle wanted to climb up but it never did... Its been about 15 to 20 degrees here in Chicago.

So I did some research and called a few friends and they told me to check the fans. I hooked them up directly to the car battery and they turned right on. So they work. Then I went and got a new Cooling Fan Switch and installed it. Again drove my GF home (3 miles away) and the car was throwing hot air with the heater on and after about 5 minutes it was just cold air. When we go to her house, the Fans weren't on and the car was steaming a little again from the reservoir. By the time I got home, it was boiling and spitting it out the again from the reservoir hose.

So I did some more research and thought that maybe the thermostat was stuck closed. So I went and bought that. To my surprise, the one in the car was installed backwards!! So I removed it, and put the new one in. Hooked everything, filled it with coolant and turned on the car.. It sat for about 20 minutes at idle with the heat on with out the radiator cap on to burp the system but all it did was slowly begin to steam from the top or the radiator. The fans never kicked on. So I shut of the car and came inside for the night.

I'm hoping that its not the water pump but what else could it be? I was going to remove the serpentine belt and see if there is any play on the water pump. Would tat help determine if something is wrong? There is no leaking from the water pump as far as I can see, and I don't hear nothing crazy coming from the area.

Other Notes:

1. I checked the fan 3 relay switch by placing it on the Horn relay and honking the horn. It work.

2. I Checked the fan 1 relay by hooking it up to the battery, terminal 1 and 2 and then checking for NO continuity in ports 3 and 4... and it worked fine. also felt the click once it was connected to the battery.

3. Don't really know how to check fan relay switch number 2 because it has and extra prong.

4. The coolant doesn't move like a river like I've been told it would if you take the cap off. It doesn't go down when the car is running, it releases a few air bubbles but that's it. This is while trying to burp the system. (This makes me think that it's the water pump)

5. If I remove the connection to the Cooling Fan Switch, the fans kick on. I don't know why or what the deal is with that (minimal mechanic skills) but makes me feel like the relays and fuses are working correctly.

6. No Blown fuses anywhere...

7. Top hose gets hot like its supposed to but the bottom hose was just a tad bit warm...

8. And lastly the top tank gets hot but the bottom one stays cool. I read somewhere that it may be an indication of a bad water pump.....

9. I didn't rev the engine at all after I replaced the last part, the thermostat and just let the car idle. I want to see if i keep the revs up and see if the fans kick on.

Any help in the matter would be greatly appreciated as I really don't have the money to take the car to someone to even diagnose it or to pay for them to repair it. That means I have to do it all myself. I don't mind but I have never worked with the timing belt and well, it looks a little complicated especially removing the crankshaft pulley bolt I believe. I know i have to do that if it is the water pump.....

Thank you

Jorge

I can help with the pics for the timing belt and water pump procedure. I just replaced my uncle with timing belt, water pump, idler, cam & crank seals while you are at it. If that is what you want to tackle yourself. I believe there two cooling sensor on that GS300, one is on the engine and the other is under the radiator tank. I presume that you changed the one under the tank, right? Are you due for a timing belt change soon or later? I am not a mechanic so I can't recommend to change the cooling senor on the engine. I would go to clublexus.com and ask folks in that forum for more advise for your issue. If you know that is the water pump is the cause, then it's simple to swap it out. I can help with that and timing belt. Good luck.