VDO CHT gauge HELP??

Va914 · 03-22-2003, 01:34 PM

I am just now getting around to installing a VDO CHT gauge. The wiring diagram doesn't match the actual gauge????

The back of the gauge has 4 connections:
2 at the light
2 at the back bottom. (+ and -)

The wiring diagram shows 4 at the bottom???? Is the gauge I have a production error????

I have two wires coming to the gauge from the sender (spark plug hole). Id doesn't make any sense to plug them into the gauge with out having a power source @ the gauge???

ANy help

WOODPIE · 03-22-2003, 02:42 PM

Va914

The sender unit under the spark plug sends all the voltage the gauge needs to read. You will find the gauge still tells the temp after you turn off the car and walk away. Sorry, can't help with which two terminals are for the light bulb.

Ed

Va914 · 03-22-2003, 05:25 PM

Thanks..I know which 2 are for the light..

It doesn't seem to make sense about the two to the sender. Where does the power (+) come from?
It seem like I am missing a terminal????

Thanks

WOODPIE · 03-22-2003, 06:22 PM

I know; it's hard for me to understand also! But I've got two CHT's, and they both register long after the car is stopped! Maybe one of the electrical whiz folks can (try) to explain it.

Ed

ejm914 · 03-22-2003, 06:32 PM

Quote:

Originally posted by Va914
Where does the power (+) come from?

As WOODPIE said the voltage comes from the sender. The sender is a thermocouple , two wires of dissimilar metal twisted together that produce voltage when the junction is heated. Because the gauge is calibrate to account for the voltage drop in the wiring the instructions say not to cut, shorten or modify the harness supplied with the kit.

Va914 · 03-23-2003, 05:45 AM

THANKS...

I'll hook the harness up to the gauge and see what happens.

Thanks for you help guys.

Cheers

Kerry

Bruce Allert · 03-23-2003, 06:18 AM

If I wanted to see the temp my engine was running which would be best to have CHT temp or oil temp?
bruce

Va914 · 03-23-2003, 07:13 AM

Not sure if it's needed but I have both. I figure it couldn't hurt to have both.

I have all OEM idiot lights working, CHT gauge, Oil pressure, and an A/F gauge.

I have heard (read) the CHT gauge will not tell you anything you need to know... quick enough to do anything about it. I figure between the two I may see a problem starting to develop in th engine..

Cheers

Kerry

John Rogers · 03-23-2003, 04:44 PM

I think Kerry is right saying having both gauges won't hurt. I finally installed a VDO temp meter in my race car as we were having troubles with exhaust valves, mainly on #2 cylinder. We found that the temps came up pretty fast when the engine was started and level at about 250. Once racing started we noted that temps averaged about 325 and we were expecting 400 to 500 but it was lower. Once we went to the dyno and advanced the timming to 36 degrees full the temp during a race went to 375 but the exhaust valves cooled off some and valve and seat problems have dropped off.