Cylinder head temp wire Baywindow

[cchris]

I just purchased a VDO cylinder head gauge for my 76 Bay and was wondering if the sender kit with the 15' length is going to be long enough to get it under the dash, and if not is it possible to lengthen the wires without affecting the readings Or is there a longer one on the market that i haven't seen yet?
Thanks!

[SGKent]

no. You can extend it as long as it is on the regular wire side and not on the shielded side. Make sure you use a good wire, preferably the same color, solder it, and protect it from chafing and corrosion. I take the crush ring off the plug and let the ring act a seal. You can also use a copper crush ring. The normal ones will wedge out the ring terminal and eventually cause it to elongate.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[cchris]

Thanks SGKent that's exactly what i wanted to hear and i didn't even think about the crush washer on the plug Thanks again!

[Wildthings]

With the ring terminal and standard pigtail that came with my gauge plus a 15' extension reaching the dash was easy.

[raygreenwood]

Yes....you can extend the thermocouple (TC) wire as long as you use the same type of TC wire.

Virtually all of the head temp gauges are a K type thermocouple. You can simply buy K type TC wire and make a very clean crimped butt connection on each wire. Mind the colors. The wires are color coded not for positive/negative but for wire metal type. Virtually all TC wires use a universal color coding for the specific type.

Check here:
https://www.omega.com/techref/colorcodes.html

You can buy TC extension wire...probably from the source I listed above...or from Mcmaster carr....or from a wide range of other places.

You can extend the wire using TC wire...as long as you do not get the wires mixed up...or disturb the T junction where it mounts at the cylinder head sensor/ring terminal. This T-junction is usually a welded bead in a crimped application.

I just finished extending a 15' K type thermocouple to 31 feet yesterday for a client where we will be using it on Monday. Its accurate to within 1*.

Ray

[SGKent]

The question is regarding the VDO set. This answer is ONLY for the VDO set.

you can use any quality wire you want as long as you don't change the wire from the plug in connector to the plug ring. That wire is the sender wire, and contains the junction. The long wire (signal wire) under the bus is only a carrier of the signal voltage so as long as the length and quality of that voltage signal is not degraded the gauge will work fine. VDO says the same thing in their publications. You can change the signal wire but not touch the sender wire.

Do NOT cut or extend

Ok to cut or extend

_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[raygreenwood]

[Wildthings]

If you don't use thermocouple wire to make the extension then where in the rig the splice is made become important. If you make the connection in the hot engine compartment that will give different results than if you make the connection in the cab or underneath somewhere. If the gauge itself isn't compensated then it become less important where you make the connection as the gauge isn't going to be super accurate anyway. Ideally you would want the splice to be at the same temperature as the gauge.

As Ray says using Type K thermocouple wire is best. Not sure that the wires being the same length is important at all though.

[ToolBox]

[Wildthings]

[SGKent]

I have spoken with VDO on this is the past. The junction is in the shielded wire. They call that the SENDER WIRE. They call the colored wires the SIGNAL WIRE. You can extend or shorten the SIGNAL WIRE. Those of you who say otherwise must know more than VDO engineers know.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

[SGKent]

[Wildthings]

[SGKent]

[Wildthings]

If you put the cold junction in the engine bay then as Ratwell says you have to compensate for the difference in the temperature of the engine bay, as you have added two more thermocouples in the engine bay, you may also still need to compensate for the two additional thermocouples at the gauge. Essentially your reference temperature is a variable, which varies from ambient to many degrees above ambient throwing your reading way way off. With a compensated gauge the effects will be even more unpredictable, as the dissimilar types of wires at the gauge will create additional voltages there that throw the accuracy of the gauge off.

It is not desirable to use copper wire for either a compensated or non compensated gauge, but I guess if you always carry an ice chest with you you could just use thermocouple wire as far as the ice chest and then copper wire from there forward, but only with a non compensated gauge, with a compensated gauge ALWAYS use thermocouple wire the entire distance between the sender and the gauge.

Since you like to quote Ratwell consider what else he said:

[Westfalia73]

Where's Ray? im just settling down to watch another SGK - Wildthing - Ray show, this shits better than the discovery channel
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1973 tintop westfalia weekender.
1973 beetle.
1981 Brazilian baywindow kombi.

[Clatter]

[SGKent]

did I miss a bru ha ha? That is so unlike me. must be getting old. Should have realized that when Clatter beat me into the ground and mopped his garage with me last month. Every blow on that suspension he rebuilt he was heard to mumble - I'll get SOB SGKent …
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[airschooled]