getting electric fan going
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
getting electric fan going
Ok, so i have been working on this a little bit at a time. I finally have my mk8 fan installed. its wired and clicks on if i touch the ground wire to the frame but when i connect it to the temp sensor for some reason it wont go on. the temp sensor is attached to a thermostat housing that has a hole in it for the sensor.
i am thinking that the water going through the housing isnt getting to the sensor.
my thinking is that i switch out the coolant sensor for the gauge with the sensor for the fan relay. does this sound logical?
there are no places on my 427 heads that i can find to plug directly into them.
i am thinking that the water going through the housing isnt getting to the sensor.
my thinking is that i switch out the coolant sensor for the gauge with the sensor for the fan relay. does this sound logical?
there are no places on my 427 heads that i can find to plug directly into them.
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
could be but the thermostat is a 185 and i know it is opening up because both radiator hoses are getting hot. it is a 200 on sensor.
i cant look through the radiator cap because it is on the expansion tank.
the temp gauge is getting to 210 straight up. i guess i could hook up my continuity gauge to the engine and the sensor and see if it connects when the engine gets hot. if i check the engine to the outside of the sensor i get a signal so i know i have ground to the sensor itself. it just needs to click on.
i cant look through the radiator cap because it is on the expansion tank.
the temp gauge is getting to 210 straight up. i guess i could hook up my continuity gauge to the engine and the sensor and see if it connects when the engine gets hot. if i check the engine to the outside of the sensor i get a signal so i know i have ground to the sensor itself. it just needs to click on.
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Are you certain you're hooking up to a switch?
....and not a variable resistance sending unit?
Not being a wise-acre; but I spent half a day working on a friends pickup because his gauge wouldn't work....turned out he'd bought a sending unit for an idiot light, instead of a sending unit for a gauge.
Not being a wise-acre; but I spent half a day working on a friends pickup because his gauge wouldn't work....turned out he'd bought a sending unit for an idiot light, instead of a sending unit for a gauge.
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
test light came on at 200 degrees
turned off at 185.
exactly at the advertised temps.
so this leads me to believe that my actual coolant temp gauge is way off. it is getting to 210 and no fan on but in a controlled environment the sender is clicking on as soon as it is rated for.
i guess i should let it run longer and see what happens. i need to go buy an IR thermometer and test the engine temp that way.
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
Update
well apparently the sending unit to my water temp gauge is way off or mounted wrong or something.
after the boiling water test making sure that fan sensor turns on right at 200 degrees i decided to just go for broke and let it run.
temp temp gauge on the dash hit 250 and the fan kicked on.
i moved the gauge sending unit to the thermostat housing.
the sensor for the fan is in the oem location to make sure it is always submerged in coolant.
i saw a post about ohms resistance on the oem sensor. could it be possible i just have one that doesnt give the right resistance.
if anyone could answer his question that might answer mine too.
i wonder if its safe to drive now. the fan kicked on, ran for about 10 minutes and turned off so the coolant around that sensor is only hitting 200 degrees according to my tests.
after the boiling water test making sure that fan sensor turns on right at 200 degrees i decided to just go for broke and let it run.
temp temp gauge on the dash hit 250 and the fan kicked on.
i moved the gauge sending unit to the thermostat housing.
the sensor for the fan is in the oem location to make sure it is always submerged in coolant.
i saw a post about ohms resistance on the oem sensor. could it be possible i just have one that doesnt give the right resistance.
if anyone could answer his question that might answer mine too.
i wonder if its safe to drive now. the fan kicked on, ran for about 10 minutes and turned off so the coolant around that sensor is only hitting 200 degrees according to my tests.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
The way you talk about 'thermostat housing' makes me wonder...is that a divorced thermostat housing like I have from Offenhauser, with two hoses from the heads leading into it, then the stat and hose to the rad??? that includes the sensor and rad hose?? IF so, you need drill some bypass holes in the stat itself to allow circulation, otherwise the engine gets hotter'n hell as the stat is too far away to get any circulation.....
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
sounds like you have the wrong sending unit for the gauge in the car. Put it back together like it is supposed to be and order the correct sender for your year. That should fix the gauge problem. Also you can put that fan sensor over in the passenger side head, there is a hole there that matches the one in the drivers side head. Annother thought is that the fan sensor did exactly what it ws supposed to do and worked fine as it was installed so you could run it that way. The fan only needs to come on to cool the radiator when its actually getting hot. While your running down the road the wind will do most of the cooling and the fans don't even need to run.
Personally I like a fan sensor on the radiator itself, down by the outlet. That way the fans never run unless they are actually needed, ie in traffic or idling when there is not enough wind to cool the radiator without the aid of a fan
Personally I like a fan sensor on the radiator itself, down by the outlet. That way the fans never run unless they are actually needed, ie in traffic or idling when there is not enough wind to cool the radiator without the aid of a fan
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Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
sounds like you have the wrong sending unit for the gauge in the car. Put it back together like it is supposed to be and order the correct sender for your year. That should fix the gauge problem. Also you can put that fan sensor over in the passenger side head, there is a hole there that matches the one in the drivers side head. Annother thought is that the fan sensor did exactly what it ws supposed to do and worked fine as it was installed so you could run it that way. The fan only needs to come on to cool the radiator when its actually getting hot. While your running down the road the wind will do most of the cooling and the fans don't even need to run.
Personally I like a fan sensor on the radiator itself, down by the outlet. That way the fans never run unless they are actually needed, ie in traffic or idling when there is not enough wind to cool the radiator without the aid of a fan
Personally I like a fan sensor on the radiator itself, down by the outlet. That way the fans never run unless they are actually needed, ie in traffic or idling when there is not enough wind to cool the radiator without the aid of a fan
the actual gauge sensor is the one that napa lists as being the correct one however i bought an autometer water temp gauge and installed it just to verify my readings.
the autometer guage says the fan comes on at 205 and cut off at 190.
pretty much dead on to what the fan is supposed to so it has to be a bad coolant sending unit from napa.
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
The way you talk about 'thermostat housing' makes me wonder...is that a divorced thermostat housing like I have from Offenhauser, with two hoses from the heads leading into it, then the stat and hose to the rad??? that includes the sensor and rad hose?? IF so, you need drill some bypass holes in the stat itself to allow circulation, otherwise the engine gets hotter'n hell as the stat is too far away to get any circulation.....
the thermostat itself is a failsafe with a hole already in it.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
there is no hole in the passenger side head. they are not the original 454 heads. they are the heads off of a 67 427. i have looked everywhere. no hole. unless you mean the giant hole right in the front of the head right above the VIN stamp.
the actual gauge sensor is the one that napa lists as being the correct one however i bought an autometer water temp gauge and installed it just to verify my readings.
the autometer guage says the fan comes on at 205 and cut off at 190.
pretty much dead on to what the fan is supposed to so it has to be a bad coolant sending unit from napa.
the actual gauge sensor is the one that napa lists as being the correct one however i bought an autometer water temp gauge and installed it just to verify my readings.
the autometer guage says the fan comes on at 205 and cut off at 190.
pretty much dead on to what the fan is supposed to so it has to be a bad coolant sending unit from napa.
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
maybe i should clarify
there are no holes in the heads period.
the coolant sensor goes into the manifold not the head.
i have looked for drain plugs, pipe plugs, anything that i can get a sensor into but on these heads nothing
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Well, I run my Mark VIII off a DC Control unit....
some folks don't like them; but mine works like a dream. It maintains temperature ± 10°F in every condition that I've run it in.
I also installed a backup Temp Switch that will kick on and bypass the DC Controller if my temperature goes too high.
The DC Control unit senses temperature on the radiator, near the return connection.
I also installed a backup Temp Switch that will kick on and bypass the DC Controller if my temperature goes too high.
The DC Control unit senses temperature on the radiator, near the return connection.
Thread Starter
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
hmm
something to look into if the temp switch i am using now doesnt work out.
i ordered a sender from lectric limited since i saw on another thread in the general section that the napa sender that i have reads too high. that pretty much confirms the readings i was getting with the aftermarket gauge was correct. using the aftermarket one the fan kicked on and off when it was supposed to.
something to look into if the temp switch i am using now doesnt work out.
i ordered a sender from lectric limited since i saw on another thread in the general section that the napa sender that i have reads too high. that pretty much confirms the readings i was getting with the aftermarket gauge was correct. using the aftermarket one the fan kicked on and off when it was supposed to.