Only over heats with the head lights on

[whichonetodrive]

this is a new one for me. A couple of days ago I checked my water level and saw that I was a little low, so I added 50/50 mix. Last night I decided to run around a little and after warm up noticed the car was running around 205-210 which it has never done before. I pulled into a local drive in to let it cool off for a while. When I started it back up the temp was at 180, turned on my head lights and the temp went to 205, turned the lights back off and back to 180. weird thing is the temp gauge is the only thing effected by the lights. anyone ran across this one before? and the gauges are VDO's if that helps.

[Jerry Clayton]

head lights are taking the current needed to run the electric fan

[m5extc]

I have run into this on another car. Do you have a ground strap to your engine? Try running a jumper wire from the temp sensor (or near it) directly to ground. Also check your headlight ground wires.

Andrei

[Ronbo]

What's your volt/amp gauge showing when this happens?

If it's instantanious it's electrical loading (grounding or weak alt. output), if it's gradual I'd suspect what Jerry stated about the fans.

Even if you have a ground strap, check for corrosion or loose connection.

[Rwillia4]

Independent of what sounds like a grounding problem or a supply power lien that is too small to run both lights and fan.
With a 50/50 mixture you are perfect for cold winters up north about 1000 miles but in Dallas you could probably use 80 water to 20% anti freeze. This will allow for better cooling. I would alos add a bottle of Water Wetter from Red Line, it will help your engine stay cool even before fans are needed.

[Blas]

If both your fans are running, can you turn your headlights on?
If yes, at idle engine rpm's or only at highter rpm's?
What is the alternator output (with seperate gauge)?

[Steve Gallegos]

Check your light switch or water gauge ground for a short. Mine does the same thing. When I turn my lights on the temp goes up 10 to 15 degrees. If it's not grounded right to the ground bar behind the dash, this could be the problem.

[whichonetodrive]

thanks for all the help, I will check it out this week and see if I can find it. I bet steve hit it on the head, the volt meter shows 14, when I turn on the fan and lights the gauge goes down to about 12.5. Rwillis4 even though I live in dallas it can get cold here and I have to say all my cars have 50/50 mix. I also use water wetter. hope the problem is a ez fix since I still have a carb gremlin thats pops up every once in a while.

[392cobra]

Another LSC here with the same problem for over 7 years now.

I first noticed it when I would pushed the cigarette lighter in,up the tempt guage would move.
I cleaned all grounds...Everywhere.Added two big braided grounds off the engine to the frame.Installed a 100 amp 1-wire alternater.

This work helped the car as a whole in manys ways.....but pull the headlights on or push in the cigarette light,the tempt guage still moves up about 15 degrees.

[whichonetodrive]

392, I now wonder if this is something to do with LSC's. I see you are # 240 mine is
# 238, I hope some other LSC might chime in and say if this is a problem with their cars. have to say also I dont have a cigarette lighter in my car, but would be nice to power up a few things.

[Rick Parker]

Although this is focused on Headlights (no pun intended) it also can be directed to any current consuming device.

http://madelectrical.com/electricalt...adlights.shtml

[undy]

The Painless Wiring harness provided with our cars (or at least in mine) was woefully inadequate in a lot of it's wire sizing. I was getting terrible voltage drops every where. I ran new 0 gauge main wiring with #10 for my headlight circuit, #8 for my engine fan and a #10 for the ignition circuit. I went with a one wire 160 amp alternator, also rated at 70 amps output at idle. The idle rating is probably the most critical output requirement that we usually suffer from. The difference from 12.5 volts and 14.x volts will also cause your meters to read differently.

With my LSC, with the original wiring harness and alternator I was getting 10.4 volts to my fan with everything running at idle. I was drawing heavily off the battery. The wiring and the alternator just couldn't keep up. After all the modifications I now maintain 14.2 volts running at idle or cruise no matter what's on..

[Joe Wicked]

Fred and whichonetodrive,
I would be happy to try to help either of you guys find the solution. It definitely sounds like an improper wire size or grounding issue.

whichone, if you want a power outlet, we can do that easily. I have helped out a couple other members of the Dallas Cobra Club with issues. I have worked on electrical mechanical issues for years. Installing a power port is quick and easy.

[whichonetodrive]

Joe, thanks for the offer. I will take a look at it this weekend and if its not something ez I will email.

[Xavier]

Ditto on the Painless setup - the wire gauge size is poor and the wiring itself, I believe is poor. Once I redid the wiring many of the problems I had went away....