| Author |
Message |
WhirledTraveller
Samba Member
Joined: January 09, 2008
Posts: 1399
Location: Cambridge, MA
|
 Posted: Fri Aug 01, 2014 5:16 pm Post subject: |
 |
|
Thought I'd update this thread with a little CHT info that some may find useful.
I've been running for several years a 4-channel CHT (MGL Avionics Stratomaster), using 4 "J type" thermocouples I made myself out of the steel braided high temp ebay wire. Initially I installed all 4 into the head near the spark plugs by drilling a small hole, and potting the thermocouples with JB weld.
This worked very well. As expected, 3 and 1 where the hottest and 4 and 2 the coolest.
At some point #4 quit working... I guess my homemade thermocouple wasn't up quality. So I made another one, and rather than drop the engine to redrill the hole, I just JB welded it onto a cylinder head fin, kind of off to the side of the plug towards the back of the bus (exhaust side). All of a sudden #4 was consistently the hottest! So I guess location really does matter, and the spark plug location is NOT the hottest part of the head. It's hotter towards the exhaust valve (naturally).
Recently I tried another (temporary) experiment, I made a spark plug ring terminal thermocouple and installed that on #3 as well. (no longer reading #2, it's always cool anyway).
The 2 readings on #3 cylinder (one from the ring, and one from the potted thermocouple) are very close. Typically the potted thermocouple reads about 5 degrees hotter than the ring terminal thermocouple. Sometimes as much as 10 degrees, but not more.
What's my takeaway from all this? I think potting a thermocouple near the plug on #3 cylinder is the best possible solution for most people. It is the hottest cylinder, and the readings will be comparable to other folks readings, and avoids the problems associated with the sealing of the plug. Only real negative I see is that it needs to be installed with the tin off.
_________________
1977 Westy, Automatic. Big Valve heads, CS Cam. |
|
| Back to top |
|
 |
white74westy
Samba Member
Joined: May 02, 2011
Posts: 777
|
| Posted: Sun Aug 03, 2014 6:28 pm Post subject: |
|
|
| WhirledTraveller wrote: |
Thought I'd update this thread with a little CHT info that some may find useful.
I've been running for several years a 4-channel CHT (MGL Avionics Stratomaster), using 4 "J type" thermocouples I made myself out of the steel braided high temp ebay wire. Initially I installed all 4 into the head near the spark plugs by drilling a small hole, and potting the thermocouples with JB weld.
This worked very well. As expected, 3 and 1 where the hottest and 4 and 2 the coolest.
At some point #4 quit working... I guess my homemade thermocouple wasn't up quality. So I made another one, and rather than drop the engine to redrill the hole, I just JB welded it onto a cylinder head fin, kind of off to the side of the plug towards the back of the bus (exhaust side). All of a sudden #4 was consistently the hottest! So I guess location really does matter, and the spark plug location is NOT the hottest part of the head. It's hotter towards the exhaust valve (naturally).
Recently I tried another (temporary) experiment, I made a spark plug ring terminal thermocouple and installed that on #3 as well. (no longer reading #2, it's always cool anyway).
The 2 readings on #3 cylinder (one from the ring, and one from the potted thermocouple) are very close. Typically the potted thermocouple reads about 5 degrees hotter than the ring terminal thermocouple. Sometimes as much as 10 degrees, but not more.
What's my takeaway from all this? I think potting a thermocouple near the plug on #3 cylinder is the best possible solution for most people. It is the hottest cylinder, and the readings will be comparable to other folks readings, and avoids the problems associated with the sealing of the plug. Only real negative I see is that it needs to be installed with the tin off. |
When you run your wires, do you run them under the tin?
I asked this question in the "Stupid Question Thread" earlier...still no response:
| white74westy wrote: |
Would it be bad to run the wires for the CHT gauge under the engine tins? Question
I will be running the MGL all in one gauge. All four cylinders will be monitored. Aside from the possible difficulty in accessing the terminal rings, is there a problem running the unsheathed thermocouple wires directly over the engine? Will this skew the readings in any way? At this point, it is simply a matter of esthetics. I would prefer there to be less clutter, but not at the expense of function. Any advice would be greatly appreciated! |
Would love to get some input. Thanks! |
|
| Back to top |
|
|
1975 Kombi
Samba Member
Joined: August 12, 2007
Posts: 2452
Location: Acton, Ontario, Canada
|
| Posted: Sun Aug 03, 2014 7:48 pm Post subject: |
|
|
| white74westy wrote: |
| WhirledTraveller wrote: |
Thought I'd update this thread with a little CHT info that some may find useful.
I've been running for several years a 4-channel CHT (MGL Avionics Stratomaster), using 4 "J type" thermocouples I made myself out of the steel braided high temp ebay wire. Initially I installed all 4 into the head near the spark plugs by drilling a small hole, and potting the thermocouples with JB weld.
This worked very well. As expected, 3 and 1 where the hottest and 4 and 2 the coolest.
At some point #4 quit working... I guess my homemade thermocouple wasn't up quality. So I made another one, and rather than drop the engine to redrill the hole, I just JB welded it onto a cylinder head fin, kind of off to the side of the plug towards the back of the bus (exhaust side). All of a sudden #4 was consistently the hottest! So I guess location really does matter, and the spark plug location is NOT the hottest part of the head. It's hotter towards the exhaust valve (naturally).
Recently I tried another (temporary) experiment, I made a spark plug ring terminal thermocouple and installed that on #3 as well. (no longer reading #2, it's always cool anyway).
The 2 readings on #3 cylinder (one from the ring, and one from the potted thermocouple) are very close. Typically the potted thermocouple reads about 5 degrees hotter than the ring terminal thermocouple. Sometimes as much as 10 degrees, but not more.
What's my takeaway from all this? I think potting a thermocouple near the plug on #3 cylinder is the best possible solution for most people. It is the hottest cylinder, and the readings will be comparable to other folks readings, and avoids the problems associated with the sealing of the plug. Only real negative I see is that it needs to be installed with the tin off. |
When you run your wires, do you run them under the tin?
I asked this question in the "Stupid Question Thread" earlier...still no response:
| white74westy wrote: |
Would it be bad to run the wires for the CHT gauge under the engine tins? Question
I will be running the MGL all in one gauge. All four cylinders will be monitored. Aside from the possible difficulty in accessing the terminal rings, is there a problem running the unsheathed thermocouple wires directly over the engine? Will this skew the readings in any way? At this point, it is simply a matter of esthetics. I would prefer there to be less clutter, but not at the expense of function. Any advice would be greatly appreciated! |
Would love to get some input. Thanks! |
And also should the wires leading up to the head be rapped in a heat protector sheath like the BBQ have for their igniter wire??
_________________
Brett
“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.
75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v |
|
| Back to top |
|
|
WhirledTraveller
Samba Member
Joined: January 09, 2008
Posts: 1399
Location: Cambridge, MA
|
| Posted: Sun Aug 03, 2014 9:20 pm Post subject: |
|
|
I ran my wires under the tin, exiting near the intake runners, to avoid interfering with the spark plug access. I did use stainless over glass insulated high temp thermocouple wire. But I think that's probably unnecessary, a lot of the high performance polymer wire is good to 500F which is hotter than it'll ever get. Running the wires over the hot engine doesn't change the readings, the nature of thermocouples are such that only the junction temperatures matter.
I've come to the conclusion that monitoring all 4 cylinders, while impressive, doesn't really add that much. If I had to do it again I'd just monitor #3 and avoid the hassle of all that wiring.
_________________
1977 Westy, Automatic. Big Valve heads, CS Cam. |
|
| Back to top |
|
|
white74westy
Samba Member
Joined: May 02, 2011
Posts: 777
|
| Posted: Mon Aug 04, 2014 12:30 pm Post subject: |
|
|
| WhirledTraveller wrote: |
I ran my wires under the tin, exiting near the intake runners, to avoid interfering with the spark plug access. I did use stainless over glass insulated high temp thermocouple wire. But I think that's probably unnecessary, a lot of the high performance polymer wire is good to 500F which is hotter than it'll ever get. Running the wires over the hot engine doesn't change the readings, the nature of thermocouples are such that only the junction temperatures matter.
I've come to the conclusion that monitoring all 4 cylinders, while impressive, doesn't really add that much. If I had to do it again I'd just monitor #3 and avoid the hassle of all that wiring. |
Thanks. I'll let you know how it turns out! |
|
| Back to top |
|
|
kkjellquist
Samba Member
Joined: June 04, 2013
Posts: 752
Location: Asheville, NC
|
| Posted: Fri Aug 08, 2014 4:54 am Post subject: |
|
|
Installed my DD last night w/ engine in. Had no issues getting the ring terminal under the #3 plug. I did put the smallest amount of grease on top of the terminal between it and the plug. I think that allowed the terminal to stay stationary while I turned the plug. Really not nearly as difficult as some would have you believe.
So here's my dumb question....the rubber sleeves on the sender, are they supposed to cover the connections?
_________________
1977 Sage Green Deluxe Campmobile - "Turtel"
(1978 2L FI, Pertronix, Hydraulic Lifters)
Turtel - http://www.thesamba.com/vw/forum/viewtopic.php?t=561195
Pisgah Bus Rally - New Year's Day
http://pisgahbusrally.blogspot.com/ |
|
| Back to top |
|
|
korfmach
Samba Member
Joined: February 28, 2014
Posts: 247
Location: Fort Collins, CO
|
| Posted: Mon Sep 01, 2014 7:58 pm Post subject: |
|
|
So here's my dumb question....the rubber sleeves on the sender, are they supposed to cover the connections?[/quote]
Yes. It's actually heat-shrink; get a hair dryer and seal it up.
_________________
1989 Westy
2016 Golf TSI
Gone, but not forgotten:
1974 Dorper Baywindow, "The Bleeding Trout"
1998 Jetta TDI, "Trixie"
1987 GTI, "Heike"
1974 Thing, "The Luftwaffel"
1974 Ghia
1966 Ghia |
|
| Back to top |
|
|
korfmach
Samba Member
Joined: February 28, 2014
Posts: 247
Location: Fort Collins, CO
|
| Posted: Mon Sep 01, 2014 8:32 pm Post subject: |
|
|
As previously threatened in this thread
http://www.thesamba.com/vw/forum/viewtopic.php?t=589535
I'm now posting some CHT data. The gauge is a DD, installed per DD instructions with a ring terminal and machining of the head to accommodate it.
Engine: 1800 T4 with 009 distributor, dual PDSITs with stock jetting, static timing 4 deg BTDC, 28 deg BTDC at full advance. Bus is Dorper conversion with poptop.
Test conditions: No load, 75 deg F (22 deg C) ambient, negligible wind. Flat road. Elevation 5000 feet (~1700m)
55 mph: 380F
60 mph: 385F
65 mph: 390F
Test conditions: As above, uphill approx. 2% grade.
60 mph: steady increase from 380F to 425F maintaining 4th gear. The same hill, taken at 45 mph in 3rd gear, gave 415F.
Test conditions: 100 lb (45 kg) load plus driver, 100F (38 deg C) ambient, crosswind, flat road. Elevation 6500 ft (1990m).
55 mph: 385F
60 mph: 395F
Test conditions: No load, 85 deg F (29 deg C) ambient, 25 mph (40 km/hr) headwind, 3-4% grade. Elevation 8000 ft (2440m) (West approach to Monarch Pass, CO)
55 mph: steady increase from 390F to 455F, test terminated as I felt it wise to slow down and downshift! Continuing in 3rd gear at 45 mph, temp dropped to a more reasonable 425F.
Test conditions: 250 lb (115 kg) load plus driver, 45 deg F (7 deg C) ambient, long 3-7% grade (west approach to Eisenhower Tunnel, I-70, CO), elevation 9000-11000 feet (2740-3350 m), negligible wind.
55 mph (4th gear, WOT): 415F
45 mph (3rd gear): 410F
General impressions:
*Headwinds strongly affect CHT.
*Long, gradual highway grades that can be taken in 4th gear with about 3/4 throttle caused the highest temperatures. Although the Bus can climb these kinds of grades in 4th gear, downshifting to 3rd seems a more prudent course and results in a steadier, lower CHT.
*I've observed some dramatic CHT swings on long downhills after cresting a pass, i.e., 420F down to <200F in only a few miles. Rapid temperature swings are deleterious to most machines; my practice is to keep the transmission in gear and let the engine spin on downhills until it cools off to about 300F, and then coast in neutral to prevent further rapid cooling.
*Ambient temps had more effect than I expected. Have to dig out my old heat transfer textbook one of these days and review what I once knew about delta-T.
_________________
1989 Westy
2016 Golf TSI
Gone, but not forgotten:
1974 Dorper Baywindow, "The Bleeding Trout"
1998 Jetta TDI, "Trixie"
1987 GTI, "Heike"
1974 Thing, "The Luftwaffel"
1974 Ghia
1966 Ghia |
|
| Back to top |
|
|
Randy in Maine
Samba Member
Joined: August 03, 2003
Posts: 34890
Location: The Beach
|
| Posted: Tue Sep 02, 2014 8:32 am Post subject: |
|
|
Suggestion....
Invest in a better distributor (ideally you would get the carbs correctly tapped for ported vacuum to run a SVDA). A 009 is not doing you any favors.
Have you turned the carbs using a gas sniffer?
I would not use the "georgia overdrive" (ie coasting out of gear).
In reality those temps are not too bad at all. |
|
| Back to top |
|
|
korfmach
Samba Member
Joined: February 28, 2014
Posts: 247
Location: Fort Collins, CO
|
| Posted: Tue Sep 02, 2014 8:59 am Post subject: |
|
|
| Randy in Maine wrote: |
Suggestion....
Invest in a better distributor (ideally you would get the carbs correctly tapped for ported vacuum to run a SVDA). A 009 is not doing you any favors.
Have you turned the carbs using a gas sniffer?
I would not use the "georgia overdrive" (ie coasting out of gear).
In reality those temps are not too bad at all. |
I'm going to dump the 009 this winter when I've got the bread for an OEM distributor...carbs are still tapped, but I've plugged the vacuum ports. The 009 and 1800 are not friends. I think I've got the carb tuning about as good as it can be with a junky distributor.
I don't have access to an exhaust monitor--have been using Colin's procedure to tune the carbs although I can't follow all the steps using a 009.
I'm fairly pleased with the CHT results...as near as I can tell, they're pretty typical for a mid-70s Bus.
_________________
1989 Westy
2016 Golf TSI
Gone, but not forgotten:
1974 Dorper Baywindow, "The Bleeding Trout"
1998 Jetta TDI, "Trixie"
1987 GTI, "Heike"
1974 Thing, "The Luftwaffel"
1974 Ghia
1966 Ghia |
|
| Back to top |
|
|
Thrasher22
Samba Member
Joined: October 05, 2010
Posts: 858
Location: Calgary, Canada
|
| Posted: Tue Sep 02, 2014 9:23 am Post subject: |
|
|
On a semi related note, has anyone else had difficulty getting a good seal when installing a CHT on a spark plug? I've tried putting one on #3 a couple times following the German Supply instructions, and get crap compression when its on.
_________________
1975 Westfalia - http://www.thesamba.com/vw/forum/viewtopic.php?t=516701 |
|
| Back to top |
|
|
mnskmobi
Samba Member
Joined: February 28, 2005
Posts: 536
Location: Melbourne, Australia
|
| Posted: Tue Sep 02, 2014 7:59 pm Post subject: |
|
|
| Thrasher22 wrote: |
| On a semi related note, has anyone else had difficulty getting a good seal when installing a CHT on a spark plug? I've tried putting one on #3 a couple times following the German Supply instructions, and get crap compression when its on. |
Yes, indeed! It gets worse when the sender ovals out. 
I have had success with taking off the spark plug compression washer, putting on the CHT sender and reinstalling the compression washer. |
|
| Back to top |
|
|
airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
|
| Posted: Tue Sep 02, 2014 8:57 pm Post subject: |
|
|
| mnskmobi wrote: |
| Thrasher22 wrote: |
| On a semi related note, has anyone else had difficulty getting a good seal when installing a CHT on a spark plug? I've tried putting one on #3 a couple times following the German Supply instructions, and get crap compression when its on. |
Yes, indeed! It gets worse when the sender ovals out.
I have had success with taking off the spark plug compression washer, putting on the CHT sender and reinstalling the compression washer. |
Two comments, which seem to get neglected:
1- some heads have incredibly deep and narrow plug wells. This will never allow the sender crimp to coexist with a spark plug socket. See here:
2 - if you bent the sender the wrong way, the issue gets compounded. This picture shows up in this thread every few pages, but someone usually has an epiphany…
http://www.itinerant-air-cooled.com/viewtopic.php?f=46&t=9835
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
|
| Back to top |
|
|
airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
|
| Posted: Tue Sep 02, 2014 9:15 pm Post subject: |
|
|
For a more scientific test approach, it's prudent to do the same route but then in the opposite direction to rule out headwind and/or grade variables. The bus doesn't care if the road is steep or the headwind is fast or the handbrake is accidentally engaged- a load is a load is a load. Treat them the same for testing and eliminate them for a go-round.
| korfmach wrote: |
*Long, gradual highway grades that can be taken in 4th gear with about 3/4 throttle caused the highest temperatures. Although the Bus can climb these kinds of grades in 4th gear, downshifting to 3rd seems a more prudent course and results in a steadier, lower CHT. |
Do the long grades push your temps into your personal danger zone? I can NOT get my bus above 420 floored on a 100* day, so I set that as my "something is wrong" limit. A slightly lower RPM in 4th gear has less combustion events per foot/second/whatever, so it might be worth keeping that gear if the speed and temps hold steady. Did you floor your accelerator to see if your carbs have a "power circuit" for dumping extra fuel in when needed? On any distributor with a vacuum element to it, that effectively cuts the vacuum advance off too, preventing overheating. Half to 3/4 throttle for most is what engages the vacuum advance, and that can actually cause higher temps, (and usually more power,) than full throttle.
| Quote: |
*I've observed some dramatic CHT swings on long downhills after cresting a pass, i.e., 420F down to <200F in only a few miles. Rapid temperature swings are deleterious to most machines; my practice is to keep the transmission in gear and let the engine spin on downhills until it cools off to about 300F, and then coast in neutral to prevent further rapid cooling. |
If your thermostat is adjusted for the best health of your engine, it will often hold a higher temperature on the long downhills. I used to have those swings, but after a careful round of adjustments, my hot idle and downhills never dip below 315. Do you even have one hooked up?
| Quote: |
*Ambient temps had more effect than I expected. Have to dig out my old heat transfer textbook one of these days and review what I once knew about delta-T. |
The ambient trends are still vague to most. I personally think this is where we see the most difference in opinions caused by build of engine/lack of tin/state of tune. I know some engines that HOLD 380 on the flats, snow or shine. Mine tends to show 3XX at 60mph, with the last two digits being a tad lower than ambient temperature. I know some that cruise at 340 and spike to 440 at the slightest hill/headwind.
Thanks for taking the time to share with us.
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
|
| Back to top |
|
|
korfmach
Samba Member
Joined: February 28, 2014
Posts: 247
Location: Fort Collins, CO
|
| Posted: Tue Sep 02, 2014 11:40 pm Post subject: |
|
|
| asiab3 wrote: |
| For a more scientific test approach, it's prudent to do the same route but then in the opposite direction to rule out headwind and/or grade variables. The bus doesn't care if the road is steep or the headwind is fast or the handbrake is accidentally engaged- a load is a load is a load. Treat them the same for testing and eliminate them for a go-round. |
Wasn't really trying to fully assess the effects of grade and wind...although I'm tempted to install a datalogger and a few thermocouples and really get after it.
| korfmach wrote: |
*Long, gradual highway grades that can be taken in 4th gear with about 3/4 throttle caused the highest temperatures. Although the Bus can climb these kinds of grades in 4th gear, downshifting to 3rd seems a more prudent course and results in a steadier, lower CHT. |
| asiab3 wrote: |
| Do the long grades push your temps into your personal danger zone? I can NOT get my bus above 420 floored on a 100* day, so I set that as my "something is wrong" limit. A slightly lower RPM in 4th gear has less combustion events per foot/second/whatever, so it might be worth keeping that gear if the speed and temps hold steady. Did you floor your accelerator to see if your carbs have a "power circuit" for dumping extra fuel in when needed? On any distributor with a vacuum element to it, that effectively cuts the vacuum advance off too, preventing overheating. Half to 3/4 throttle for most is what engages the vacuum advance, and that can actually cause higher temps, (and usually more power,) than full throttle. |
Long grades generally won't produce CHTs above 430 in my Bus. The high temps observed on Monarch Pass were anomalous--I'm guessing the headwind, combined with the less-efficient cooling of thin, 8000-foot air might be responsible. I don't know whether PDSITs have a power circuit--WOT does seem to stabilize CHT a bit.
| korfmach wrote: |
*I've observed some dramatic CHT swings on long downhills after cresting a pass, i.e., 420F down to <200F in only a few miles. Rapid temperature swings are deleterious to most machines; my practice is to keep the transmission in gear and let the engine spin on downhills until it cools off to about 300F, and then coast in neutral to prevent further rapid cooling. |
| asiab3 wrote: |
If your thermostat is adjusted for the best health of your engine, it will often hold a higher temperature on the long downhills. I used to have those swings, but after a careful round of adjustments, my hot idle and downhills never dip below 315. Do you even have one hooked up?
|
Thermostat functioning, checked it with a heat gun a while ago and it opened about as I expected. Flaps functioning also. Didn't know any of that was really adjustable...what do you suggest?
_________________
1989 Westy
2016 Golf TSI
Gone, but not forgotten:
1974 Dorper Baywindow, "The Bleeding Trout"
1998 Jetta TDI, "Trixie"
1987 GTI, "Heike"
1974 Thing, "The Luftwaffel"
1974 Ghia
1966 Ghia |
|
| Back to top |
|
|
Thrasher22
Samba Member
Joined: October 05, 2010
Posts: 858
Location: Calgary, Canada
|
| Posted: Wed Sep 03, 2014 8:45 am Post subject: |
|
|
| mnskmobi wrote: |
Yes, indeed! It gets worse when the sender ovals out.
I have had success with taking off the spark plug compression washer, putting on the CHT sender and reinstalling the compression washer. |
| asiab3 wrote: |
Two comments, which seem to get neglected:
1- some heads have incredibly deep and narrow plug wells. This will never allow the sender crimp to coexist with a spark plug socket. See here:
2 - if you bent the sender the wrong way, the issue gets compounded. This picture shows up in this thread every few pages, but someone usually has an epiphany…
|
Thanks guys! I hadn't seen/read that before. I was installing it without the crush washer as I thought it would cause the plug to be too far out, and will make sure I've bent it the correct way 
_________________
1975 Westfalia - http://www.thesamba.com/vw/forum/viewtopic.php?t=516701 |
|
| Back to top |
|
|
brainwash
Samba Member
Joined: June 22, 2014
Posts: 64
|
| Posted: Fri Jan 02, 2015 5:44 pm Post subject: |
|
|
| mnskmobi wrote: |
| I have had success with taking off the spark plug compression washer, putting on the CHT sender and reinstalling the compression washer. |
On my NGK BP6ET spark plug, the compression washer doesn't seem to want to come off  I was going to heed your advice and put the sender between the plug and the washer. How did you manage to get the washer off (and then back on again)?
The sender ring thickness is a bit thinner than the compression washer of my NGK BP6ET spark plug, so I guess I'd rather have a bit too much with the washer and sender than clip the washer out to substitute the ring as the washer. Will the extra couple of millimeters less depth for the plug's spark negatively affect the proximity to the AFM?
When connecting the sender to the Dakota Digital SEN-11-8 wire, from what I've read, I believe it goes long to long, right? I mean the long wire off the sender goes to the connector of the longer red wire? I'm trying to get it right the first time 
Also, I'm guessing that the heat shrink wrap section gets shrunk around the connectors from the sender to the wire, correct? Was thinking about snipping some electrical tape to go around the crimp after the bend. |
|
| Back to top |
|
|
airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
|
| Posted: Fri Jan 02, 2015 6:54 pm Post subject: |
|
|
| brainwash wrote: |
When connecting the sender to the Dakota Digital SEN-11-8 wire, from what I've read, I believe it goes long to long, right? I mean the long wire off the sender goes to the connector of the longer red wire? I'm trying to get it right the first time |
The red and yellow wires (different offsets) are dissimilar metals and must be matched. So I'll try to draw out the wiring, from gauge to sender:
----o---------------------o----------
--------o---------------------o------
See how the offsets match up? If you lay the brand new wires out, you'll see how they're constructed to hook up without any bends or slack.
The tricky part comes it at the DD quality control; recent productions of the ring senders are offset incorrectly, so you'll need to switch the wires in the engine compartment so one is short and one has too much slack. This makes the shrink wrap obsolete…
| Quote: |
Also, I'm guessing that the heat shrink wrap section gets shrunk around the connectors from the sender to the wire, correct? Was thinking about snipping some electrical tape to go around the crimp after the bend. |
As long as the connectors don't touch, you're ok. If you want to use tape, go for it. Shrink wrap, go for it. I keep mine uncovered because I had to do the polarity swap (mentioned above) and it makes removing the engine easier.
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
|
| Back to top |
|
|
brainwash
Samba Member
Joined: June 22, 2014
Posts: 64
|
| Posted: Sun Jan 04, 2015 6:36 pm Post subject: |
|
|
Thanks, Robbie. I went ahead and cut off the crush washer and have the sender installed with the plug. I would have expected to wire it up with the offsets in place so that it maintained the length on both wires, but read that it was backwards for some. Trying the originally factory intended connection of the wires first in the hopes that DD hasn't botched QC recently and the polarity is as intended.
Just need to figure out the wiring for the rest of it now as I'm not sure yet where/how to connect the blue wire for night display to the headlight circuit. What amp fuse should I use to protect the gauge? |
|
| Back to top |
|
|
airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12728
Location: on a bike ride somewhere
|
| Posted: Sun Jan 04, 2015 11:49 pm Post subject: |
|
|
| brainwash wrote: |
| Thanks, Robbie. I went ahead and cut off the crush washer and have the sender installed with the plug. I would have expected to wire it up with the offsets in place so that it maintained the length on both wires, but read that it was backwards for some. Trying the originally factory intended connection of the wires first in the hopes that DD hasn't botched QC recently and the polarity is as intended. |
Ay, I have had three senders hooked with my gauge, and two of them were backwards.
| Quote: |
| Just need to figure out the wiring for the rest of it now as I'm not sure yet where/how to connect the blue wire for night display to the headlight circuit. What amp fuse should I use to protect the gauge? |
You have an entire row of spade terminals on the fused end of your fuse panel that are protected sources; take a look at your owners manual to find the one that services your instrument panel lights. Crimp on of these connectors onto the add-on gauge wire, slide your OG wire off the fuse block, slide this on, and slide the OG wires onto this one's tab. That way your original wiring isn't messed with, and you can take it out when you get sick of the gauge. 
I use the instrument panel lights, because the low-beams and high-beams have separate fuses. I originally installed mine on the low-beam circuit, but then when I switched my high-beams on in the mountains, the CHT gauge lit up really bright! Now it's on the instrument panel wire which means it's on the first click of my headlamp switch so it doesn't depend on a certain headlamp function.
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com
Last edited by airschooled on Mon Jan 05, 2015 7:56 pm; edited 1 time in total |
|
| Back to top |
|
|
|
