o_man_76

First off let me give my thanks to all members who are taking their time to read about my problem. I'm just glad there is a common place for us to share our knowledge in something we are passionate about.

My problem is the car keeps over heating. It's a 98'GS300. I've already replaced the thermostat, radiator and coolant fluid. I changed the radiator because it developed a leak. I thought this would fix the problem. The temperature gauge in the dash rises and stays right about the middle. Although the gauge indicates normal operating temperature, the coolant fluid is vaporizing sending smoke out of the hood. One thing that I noticed is that the fans don't come on. I double checked the connections and they are fine. I'm pretty certain the fans not operating is my problem. Does anyone have scematics of the fans. I'm no stranger to electrical work, but I don't know where all the components are located. Any input would be greatly appreciated. Thanks again for your time!

kevs98GS4

iTrader: (1)

When you had a cracked radiator did you run it hot?? If so, how hot? I would check and see if the fans are getting fire. Turn your ac on. Does the fan kick on now? It should! If you are getting fir to the fans and they still don't work, need to replace the fans. If your not getting fire at the fans check on the other side of the fan relay. If your getting fire there and not on the other side it should be your fan relay. But the main question is the first one! When you say the the coolant is vaporizing, is it boiling in the coolant tank? Do you see any condensation(white smoke) coming out of the tail pipes? Is the oil milky? check all these and get back to me. I'll have some more answers for you then! GL and pray you don't have condensation coming out your tail pipe!!!!

o_man_76

Thanks for your promt response! I really appreciate it. I haven't got around to testing the fans yet, but thety don't come on even when I turn on the a/c.
I could hear the coolant boiling in the tank. I didn't check the tail pipes yet, but I will. Where do I find the relay? I don't have time to check today, but i will tomorow. I'll post more info then. Thanks again for your time!

kevs98GS4

iTrader: (1)

I chrenge when you say the fluid was boiling in the tank...........waiting for more answers.........

marshun

^ *cringe

anywho. if yer fans dont come on wiht the AC on then theres something wrong with the fan system. find out asap and i wouldnt suggest driving the car till its fixed.

kit cat

iTrader: (6)

I dunno if they do, but check the fuse for the fans if they have a fuse. I hope your problem's something simple like that.

BCP43002

There are two relays, one for each fan located in a box with a cover. You have to take off the cover to get at them. They look like big somewhat square fuses.

o_man_76

Thanks for all the input. I've been really busy and haven't gotten around to checking the relays yet. I plan on working on the car tomorrow, so I'll have an update then.

o_man_76

I got a little free time and I found the relays to the fans. Looks like there are three, one large and two smaller. I turned the ignition switch to the "ON" position and turned on the A/C. The fans didn't turn on. What would be the best approach to test which relay is bad? I'm thinking I'll disconnect the harness that goes to the fans and check for 12 volts, right? I'll update everyone again tomorrow with my results.

kevs98GS4

iTrader: (1)

These are the most important things to answer before you spend too much time on the fans. If you come up with the wrong answers here it doesn't matter if the fans work or not! You have one sign already of a blown headgasket(boiling coolant in the tank) Get back to me on the others first before you start to worry!

LexusIV

Are the relays your a talking about approx. .5"x.5" squares with clear tops? If they are then if you pull one out and look at it there should be something that looks like a T inside it. If it is broken then you know its bad. I think the onwers manual actually has a picture of it.

o_man_76

Alright guys, I have an update. I got the fans to work, but only after disconnecting the sensor that is right below the fan harness. If I leave that sensor plugged in the fans turn off. Looks like I'll need to replace that sensor. Another observation is that the upper hose get's hot, while the lower one stays cool. Is this normal?

<To clear things up my oil is not milky nor do I have condensation coming from the tail pipes.>

LexusIV

Yes, the top hose would be hot because it is the coolent comeing from the engine, where the bottom is the cooled coolent thats past through the radiator already.

o_man_76

Good to hear! What about that sensor that goes in the radiator. I'm assuming that it's a temperature sensor that activates the fans when the coolant reaches a certain temperature. Is this something that I need to replace before I begin to drive my car again?

To sum things up, it appears that my cooling system is working properly with the exception of that sensor, which for now causes the fans not to operate when plugged in. If I unplug it then the fans power on. I even let the car tempterature reach normal operating level, plugged in the sensor and instantly the fans shut off.

DASHOCKER

iTrader: (2)

Go to Autozone to see if any codes pop up on the OBD2 scanner.