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Engine Specific Info and Questions => IDI Engine => Topic started by: paolomarks on November 23, 2011, 08:23:56 am
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I've got a westach egt gauge and probe installed in my Vanagon diesel AAZ. How should I connect the 2? Specifically what gauge wire and should it be soldered or crimped. How will more/less electrical resistance in the wire affect gauge readings? Thanks, Paolo
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You need to use an actual thermocouple extension lead. You can't just use any old wire or your gauge will read wrong.
A thermocouple is actually just a junction (connection) between two different types of metal. A tiny electrical charge is created by the two metals touching. If you use say copper wire to connect your EGT probe to the gauge, the junction between the thermocouple's wire and the copper wire will create yet another thermocouple. If you were to say just try and use something like speaker wire, you'd be adding 4 new junctions total (two at the gauge, two at the thermocouple wiring)
Here's a couple sources for extension leads:
http://aircraftspruce.tv/catalog/inpages/micro1pyroprobes.php
http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=179
I believe crimping is the way to go, however I'm sure Aircraft Spruce or Auber Instruments would be more than happy to tell you what they think is best. I don't think solder is a good idea as it adds tin/lead to the mix.
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What should I use to crimp with.? Thanks, Paolo
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I'm not sure it matters as long as the wires are actually crimped together - the important thing is ensuring that the EGT wires and the extension lead wires are in physical contact with one another.
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Thanks for the response. I went ahead and bought some thermocouple wire as suggested. I have one more question. Are the two different color wires that make up the lead made from different materials , ie. "dedicated" wires , or are they identical save for insulation color. Thanks, Paolo
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EGT wire is EGT wire.. just make sure its hooked up right..
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The individual wires are different dedicated materials.
What he said... your probe should have color coded wires, the extension wire SHOULD have the same color code provided it is intended for the same market. I believe Europe and the US use different colors.
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Thanks, I'm should be good to go. PAOLO
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You shouldn't have 2 threads. I almost commented on this in again as I had thought I already did...I did in the TDI section.
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sorry about the two threads , it was a mistake. Paolo
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separate, but identical threads really clutter up our nice, neat forum..
usually, if the forum users dont answer your question in one section, then what makes you think that just putting it in another section will change ANYTHING??
most of us post in all sections, not just the TDI, or just the IDI sections..
anyways, i (and quite a few other users) would appreciate it if NOBODY made duplicate posts in different sections on purpose.. unless it was absolutely necessary..
i mean, if VW was having a blowout sale on all the rest of their older TDI long blocks, for like oh, 99% off retail, then that would be a worthy of posting identical threads in different sections :)
(thank you!!)
8)
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To connect the wires to the back of my gauge:
I wrapped the wire around something small to make a coil, this coil slid tightly over the post on the back of the gauge.
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Here's 50 feet of type-K wire and a set of connectors for $24 shipped... He has extra connectors for a buck. Best price I've found so far except bulk rolls.
http://www.ebay.com/itm/110783554486?ssPageName=STRK:MEWAX:VRI&_trksid=p3984.m1438.l2661 (http://www.ebay.com/itm/110783554486?ssPageName=STRK:MEWAX:VRI&_trksid=p3984.m1438.l2661)
Which Westach EGT gauge did you get? Link or pics? ;D
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I found some k type thermocouple wire on the internet. It has one red and one white insulated 7strand wire covered by a braided steel sheath. Talked to the guy who sold sold it and he said the white is negative and the red positive. My thermocouple has a red (negative) and yellow(positive) wire. Does this sound right?
My gauge is a westach 10-01273 from Aircraft Spruce. Paolo
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IIRC that is exactly how mine is hooked up. Red to yellow and white to red.
I checked mine by sticking a lighter up to the probe and watching the gauge.
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I tried hooking the wires up in all possible ways and my readings were always way low. Like half what they're supposed to be. I talked to the tech guy at Westach and this is what he said:
"You don't want to use thermocouple wire to extend our leads. The gauge is calibrated for the 4 foot sender type K . If you use thermocouple wire you will add added resistance into the system, that is why you are getting low readings. You want to use standard 18 gauge copper wire to extend. You can use up to 20 feet before it affects the readings enough to be noticed."
He also said soldering is not a problem. Paolo
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:P That is exactly the opposite of conventional wisdom regarding thermocouple extensions. WTF? I guess Westach instruments are designed specifically to use regular wire as extensions. ???
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I'll have to dig mine out, but I bought the thermocouple probe and an extension from aircraft spruce, designed to work together.
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that is what I told you in the TDI thread. Whenever I talked to the guy though he didn't say I could solider. I only used about 4 foot of the K type so I was good. The other thing is when you ask them to buy the 18gauge wire to extend, they didn't have it, at least for me they didn't.
On another note, the aircraft spruce micro 1000 probe says that it is calibrated to adjust for ambient temp. When used correctly with K type thermocouple and acceptable gauge...that is why I used the K type as well.
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IIRC that is exactly how mine is hooked up. Red to yellow and white to red.
I checked mine by sticking a lighter up to the probe and watching the gauge.
The best way to check for accuracy (at sea level) is with iced water and boiling water. 32 F and 212 F is what you should see.
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Do you really think an EGT gauge is going to have a reading for 32*F ;<)
212* is also going to be right at the bottom of the scale, so it won't tell you much either. I don't think I would worry too much about checking the calibration of a new gauge. If I were concerned, I would call the manufacturer and as him how to check it. I would suspect that using a flame of a know temperature and heating the probe to equilibrium and seeing what the gauge reads is how they do it.
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I was just meaning to see if the gauge was moving the correct way, not really calibrating it. I had mine hooked up wrong and the needle started to move below zero with the lighter. Quick switch of the wires and it is all good now.
To see if it was reading somewhat accurately I used an infared gun and a torch. It wasn't a real accurate way as there would be heat loss in the open air and what not, but I got it to read within 25F of eachother. I figured it close enough.
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"Do you really think an EGT gauge is going to have a reading for 32*F ;<)"
YES, it should be within +/- 3 to 4 degrees.
"212* is also going to be right at the bottom of the scale, so it won't tell you much either. "
It will tell you if it's going to be off at the higher temperatures
"I don't think I would worry too much about checking the calibration of a new gauge. If I were concerned, I would call the manufacturer and as him how to check it."
I called a manufacturer (Auber instruments) and they told me to use iceed water and boiling water.
"I would suspect that using a flame of a know temperature and heating the probe to equilibrium and seeing what the gauge reads is how they do it. "
Calibrating at the higher temperatures can only make the calibration better but the equipment needed will be a lot more expensive than iced water and boiling water.
;)
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I was just meaning to see if the gauge was moving the correct way, not really calibrating it. I had mine hooked up wrong and the needle started to move below zero with the lighter. Quick switch of the wires and it is all good now.
To see if it was reading somewhat accurately I used an infared gun and a torch. It wasn't a real accurate way as there would be heat loss in the open air and what not, but I got it to read within 25F of eachother. I figured it close enough.
To see if the gauge is moving in the right direction, just put your fingers on the probe. it should rise if the ambient is below 90 F
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This is an EGT gauge we are talking about. On my VDO the scale starts at 100*. You are going to have to heat it to at least 300* to get it to move.
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This is an EGT gauge we are talking about. On my VDO the scale starts at 100*. You are going to have to heat it to at least 300* to get it to move.
What p/n is that EGT gauge? I'll make sure to never buy one. Thermocouples can read accurately down to 0 degree and lower. Whoever makes your EGT gauge had to do more work to not display temps below 100*. Don't know why they'd do that.
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Like I said its a VDO. Its in the dash. Came with a Banks kit in my F-350. EG temps below 100* just mean that the engine is not running. They are meaningless.