Fan Won't Come On

courtenay · Post by **courtenay** » Wed Feb 02, 2011 7:05 pm

My fan doesn't seem to want to start on its own. I've replaced the temperature unit in the bottom of the radiator. My temp guage gets well over 190 - almost to the red and the fan doesn't come on. I have a dash switch installed that allows me to get the fan going manually. The switch is wired to the ground leads just above the connector to the rad temp unit. Because the fan works through the switch I know it is getting power.
I'm pretty sure I've burped the cooling system properly as the bottom of the rad feels every bit as hot as the top. As do the hoses on either side of the t-stat.
I'd welcome any suggestions re-something I might have missed.

narfire · Post by **narfire** » Wed Feb 02, 2011 8:33 pm

I re-burped mine a number of weeks ago as my fan was not comming on. Put it up on ramps on the sloped driveway and just let it idle for about 10 minutes or more with the rad cap off. Air came out for several minutes and then I could look in the rad and see the coolant flowing and then.... THE FAN CAME ON..... smiled and popped a Guiness.
Get the front up Bruce and let it idle for a while with the cap off. I'd put a tray underneith for any spillage and let it do its thing for several minutes or more once the temp is up. Do you have the thermostat mod with a hole drilled in it? Check IAP tech bulletin for the mod. Helps prevent an air bubble staying at the thermostat and buggering things up.
Chris

courtenay · Post by **courtenay** » Wed Feb 02, 2011 9:06 pm

Thanks, Chris. I'll try re-burping tomorrow. I do have the car up on ramps, but not on a sloped driveway. Hopefully the ramps will be sufficient. I haven't drilled out the t-stat, but will give that a shot if the burping doesn't work.

azruss · Post by **azruss** » Wed Feb 02, 2011 11:55 pm

secret is to have the radiator filler neck to be higher than any other coolant component included the heater hoses. a lot of hose massaging helps. if you think the fan should be coming on, feel how hot the bottom of the radiator is. That is the water matters. I've always got mine to work without drilling a hole in the stadt. I drilled a hole in my new stadt from recommendations by others.

SouthSwedeSpider · Post by **SouthSwedeSpider** » Thu Feb 03, 2011 4:25 am

Have you checked the true temerature of the water? I had a problem which began last summer, one day the temp gauge suddenly started to rise into the red area while driving at about 50 mph. I stopped immediately but couldn't see any signs of overheating. Then I tapped at the gauge and it just popped back to about 190 F, then when starting driving again it rose once more and stayed close to the red. It's been like that since then, usually it behaves, but sometimes it goes up and stays in the red area, but the fan does not come on. By knocking (not brutally though) at the gauge glass it sometimes goes back to normal in a second. Guess it's something locally in the gauge, had it been a trapped air bubble it hadn't gone back to normal. While truly hot the fan does comes on.

courtenay · Post by **courtenay** » Thu Feb 03, 2011 12:04 pm

So how do you test the true temp of the water without scalding yourself taking the rad cap off when it's hot?

SouthSwedeSpider · Post by **SouthSwedeSpider** » Thu Feb 03, 2011 4:44 pm

Haven't thought about that...

But seriously I guess the best way is to remove the radiator cap and let it idle until it reaches the right temp, and then put a probe in the water (I use an oven thermometer, the same that goes into my Xmas steak). You might also try to burp and measure through the bolt located at the highest point in the systen, the one that sits on the T just in front of the cam belt. Don't forget to use protective gloves (oven software...).

mdrburchette · Post by **mdrburchette** » Thu Feb 03, 2011 5:34 pm

When burping mine, I have the front end up on jackstands, and with the car running and the radiator cap off, I slowly squeeze the hoses. You can tell if the t-stat opens with the cap off too. It's possible your temp gauge sender or wire is faulty. I had this happen on my 71. It slowly goes to red like it's overheating, but I checked the temp of the head and radiator with an infared thermometer and when the car got up to the proper reading the fan came on.

courtenay · Post by **courtenay** » Thu Feb 03, 2011 6:50 pm

Thanks, guys. Tomorrow will be burp and water temp test day...with the cap off.

SouthSwedeSpider · Post by **SouthSwedeSpider** » Fri Feb 04, 2011 3:28 am

Good luck, don't forget to bring some beer, they'll significantly raise the burp factor.

And - have you noticed the similarities between the Fiat cooling system and small babies? Just fill it up, raise the front end, some gentle rocking and squeezing and there goes the BURP.

courtenay · Post by **courtenay** » Fri Feb 04, 2011 11:46 am

I have a rule to never do anything to the car without an ample supply of installation fluid on hand. Hopefully I will be able to distinguish between Fiat burps and Bruce burps.

It's been a long time since I've had to burp a baby - although that's about to change as grandchild number one is due soon!!

Anyhoo - just finished burping (the car) and testing (the water). I ran the car with the rad cap off. Tested the water temp at the top of the rad a few times. It appeared as though the actual temp at the top of the rad was about 25-30 deg lower than what the dash gauge was reading. The fan did come on just before the gauge needle hit the warning range and the actual temp read just over 200 deg. So, it appears that the fan does work and the gauge is off a bit. I assume I'm OK with all this????

narfire · Post by **narfire** » Fri Feb 04, 2011 9:44 pm

I'd say yes but send me your address and I'll mail up another gauge, see if that is any more accurate. If the weather is decent I'll try on my car first. Think I somehow have several of the things kicking about.
Chris

fiat2000 · Post by **fiat2000** » Mon Feb 07, 2011 3:31 pm

I had a similar situation and had to resort to an extention cord and light switch to get me home. Turned out that the actuall connectors between the power source, fan and fan switch at the bottom of the rad would get so hot that they would loosen up and lose the connection. Run the car and when the fan should kick on around the 190 mark try squeezing the connectors, just a thought, ang.

divace73 · Post by **divace73** » Tue Feb 08, 2011 12:32 am

Does sound like a faulty gauge or sender unit if the fan did turn on, however check is against another gauge. Veglia gauges were't the best at being accurate.....
Assuming your thermostat is good and the system is burped.
Also check the sender units on the top of your head. One (usually the front one closest to the radiator) is the sender for the temp gauge and the one closest to the fire wall is a switch for when the head gets really hot and puts your needle in the hot zone.
If one of these is faulty you will get some issues as well, ensure they are all secure.
If pulling out the gauge also check the return ground is sound.

I actually leave of the sender closest to the fire wall as it makes my needle wander toward the hot region when all is really okay. Makes me panic for no reason. I will get around to fixing that one day.....on day......

SpiderJim · Post by **SpiderJim** » Thu Feb 10, 2011 6:24 pm

Hi Bruce. FYI..... I did install a new fan temp sensor prior to you buying Kermit. Got it from NAPA.

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