Dewitt Fans not coming on
Thread Starter
Racer
Joined: Nov 2010
Posts: 364
Likes: 0
From: Flower Mound TX
Dewitt Fans not coming on
I am trying to test my engine and all related areas (finally). I notice my temp gauge is creeping up and up until I turn off the engine and let it cool down.
I really cannot tell if it is a temp sender issue, gauge issue or issue with the switch in the radiator (possibly grounding issue). Whats the best approach for isolating the issue?
My 1st guess is that the radiator is not grounded well, but I am not sure how to test that theory. Is there a way to get the fans to come on with the switch in just the on position instead of letting the temp switch turn them on. I think that would tell me if it is not grounded right. The switch wire I added to the fuse box works fine otherwise the car would not start since it is what I use to turn on the AL-6.
The radiator is getting hot, so the water is flowing through the block and back into the radiator. I dont really doubt this cause it sucked most of the water out of the radiator into the blcok and I had to refill it during initial firing. plus the water pump and thermostat is brand new.
I really cannot tell if it is a temp sender issue, gauge issue or issue with the switch in the radiator (possibly grounding issue). Whats the best approach for isolating the issue?
My 1st guess is that the radiator is not grounded well, but I am not sure how to test that theory. Is there a way to get the fans to come on with the switch in just the on position instead of letting the temp switch turn them on. I think that would tell me if it is not grounded right. The switch wire I added to the fuse box works fine otherwise the car would not start since it is what I use to turn on the AL-6.
The radiator is getting hot, so the water is flowing through the block and back into the radiator. I dont really doubt this cause it sucked most of the water out of the radiator into the blcok and I had to refill it during initial firing. plus the water pump and thermostat is brand new.
Racer
Joined: Aug 2005
Posts: 456
Likes: 0
From: Forty Fort PA
I had a problem when I first installed my Dewitts setup. I had not grounded the radiator. I put a ground strap from the bracket on the radiator to steel structure beside the radiator (not the rad support). Worked fine after that.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I have Dual Spals from DeWitt, and so each fan has a red and black wire, I put the two black wired to the frame/cross member on a dedicated screw/eyelet, the two red wires go to the power relay on top of the housing just in front of the alternator, power to the relay goes through a 3 amp blade fuse right to the alternator output stud, the relay is controlled by one end of the coil going to a switched hot, such as the yellow wiper wire on the plug at the motor.... the other end of the relay coil is computer controlled on my car, but anything that grounds it should close the relay and fire off the fans.....
Thread Starter
Racer
Joined: Nov 2010
Posts: 364
Likes: 0
From: Flower Mound TX
I tried to ground it to the radiator support. the yellows ran to a power stud that comes off the main battery terminal as a junction box. Obviously the gray to the switch, and finally the last one went to the ign wire that I added to turn on the AL-6.
Thread Starter
Racer
Joined: Nov 2010
Posts: 364
Likes: 0
From: Flower Mound TX
I unhooked the gray wire and grounded it as tom suggested and the fans came on just fine, without any moving of any grounds, so that does not look like the issues.
I will try the temperature sender next to see if that is the issue, since the gauge moves and I don't remember it being broke when I took it all apart.
If I need to replace the switch in the radiator is there a recommended one to use?
Is there a way to prove that water is truly pumping through the system and that the water is heating up enough to trip that switch in the radiator? like I said water pump, thermostat are all new so those really should not be the issue.
Is there a way to find the true temp of the water in the radiator or of the engine itself?
I will try the temperature sender next to see if that is the issue, since the gauge moves and I don't remember it being broke when I took it all apart.
If I need to replace the switch in the radiator is there a recommended one to use?
Is there a way to prove that water is truly pumping through the system and that the water is heating up enough to trip that switch in the radiator? like I said water pump, thermostat are all new so those really should not be the issue.
Is there a way to find the true temp of the water in the radiator or of the engine itself?
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
I unhooked the gray wire and grounded it as tom suggested and the fans came on just fine, without any moving of any grounds, so that does not look like the issues.
I will try the temperature sender next to see if that is the issue, since the gauge moves and I don't remember it being broke when I took it all apart.
If I need to replace the switch in the radiator is there a recommended one to use?
Is there a way to prove that water is truly pumping through the system and that the water is heating up enough to trip that switch in the radiator? like I said water pump, thermostat are all new so those really should not be the issue.
Is there a way to find the true temp of the water in the radiator or of the engine itself?
I will try the temperature sender next to see if that is the issue, since the gauge moves and I don't remember it being broke when I took it all apart.
If I need to replace the switch in the radiator is there a recommended one to use?
Is there a way to prove that water is truly pumping through the system and that the water is heating up enough to trip that switch in the radiator? like I said water pump, thermostat are all new so those really should not be the issue.
Is there a way to find the true temp of the water in the radiator or of the engine itself?
Thread Starter
Racer
Joined: Nov 2010
Posts: 364
Likes: 0
From: Flower Mound TX
The wire off the radiator at the bottom is grounded to the same location as the relays were grounded (lower part of the radiator support). Is that the grounding point you are referring to?
ill try to move that ground somewhere else and see if that helps. Did not occur to me that that grounding may be the cause. I was focused on the relays not being grounded because I assumed the ground point was going to be fine since the relays worked and they are in the same spot.
ill try to move that ground somewhere else and see if that helps. Did not occur to me that that grounding may be the cause. I was focused on the relays not being grounded because I assumed the ground point was going to be fine since the relays worked and they are in the same spot.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
The wire off the radiator at the bottom is grounded to the same location as the relays were grounded (lower part of the radiator support). Is that the grounding point you are referring to?
ill try to move that ground somewhere else and see if that helps. Did not occur to me that that grounding may be the cause. I was focused on the relays not being grounded because I assumed the ground point was going to be fine since the relays worked and they are in the same spot.
ill try to move that ground somewhere else and see if that helps. Did not occur to me that that grounding may be the cause. I was focused on the relays not being grounded because I assumed the ground point was going to be fine since the relays worked and they are in the same spot.
Thread Starter
Racer
Joined: Nov 2010
Posts: 364
Likes: 0
From: Flower Mound TX
I moved the radiator ground to be the same location that the inginition and engine is grounded. so I know it is grounded properly now, but the fan still does not come on.
I let the car run, the temp slowly climb, when the gauge hit 210 I expected the fans to come on, but nothing, it kept climbing until I turned it off just before red line.
The upper hose got real hot when it got above 220/225, the lower hose stayed warm not hot. The radiator got hot also.
I know the thermostat wont open until temp is enough, but I am sure 200 range it should pop open, and to me the fan should come on soon there after.
Other than the fans not coming on is there any other things that raise a red flag??
I let the car run, the temp slowly climb, when the gauge hit 210 I expected the fans to come on, but nothing, it kept climbing until I turned it off just before red line.
The upper hose got real hot when it got above 220/225, the lower hose stayed warm not hot. The radiator got hot also.
I know the thermostat wont open until temp is enough, but I am sure 200 range it should pop open, and to me the fan should come on soon there after.
Other than the fans not coming on is there any other things that raise a red flag??
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
I moved the radiator ground to be the same location that the inginition and engine is grounded. so I know it is grounded properly now, but the fan still does not come on.
I let the car run, the temp slowly climb, when the gauge hit 210 I expected the fans to come on, but nothing, it kept climbing until I turned it off just before red line.
The upper hose got real hot when it got above 220/225, the lower hose stayed warm not hot. The radiator got hot also.
I know the thermostat wont open until temp is enough, but I am sure 200 range it should pop open, and to me the fan should come on soon there after.
Other than the fans not coming on is there any other things that raise a red flag??
I let the car run, the temp slowly climb, when the gauge hit 210 I expected the fans to come on, but nothing, it kept climbing until I turned it off just before red line.
The upper hose got real hot when it got above 220/225, the lower hose stayed warm not hot. The radiator got hot also.
I know the thermostat wont open until temp is enough, but I am sure 200 range it should pop open, and to me the fan should come on soon there after.
Other than the fans not coming on is there any other things that raise a red flag??
I just added a manual switch to my fans for when I run my air conditioning to cool the condensor.
http://forums.corvetteforum.com/c3-t...spal-fans.html