CHT Nirvana (cylinder head temperature) gauge/sender FAQ

[ratwell]

There is a good photo of the procedure here:

http://huelsmann.us/bugman/FilterTech.html

Know that early Type 4 cases already have a threaded plug in that location:

http://homepage.mac.com/ratwell/.Pictures/Parts72Bus1/36-OilGalleryPlug.jpg

The other day I had this great idea...why not produce a billet oil pump cover with a boss that is threaded for a standard VDO oil temperature sender. I think there is enough space for one and it would give good readings (recirculating oil temp). Good idea?
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'78 Westfalia CDN
'76 Doublecab
Read the Baywindow FAQ

[spiffy]

I decided against getting a oil temp gauge because of the lack of options for placement and accuracy..... so I would love to see something new and functional!
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78 Riviera
67 Riviera

www.rivieraregistry.com

[russ1302]

Here is a source for Thermocouples with 14mm loops for a decent price. Also CHT gauges and combo gauges.

http://store.wagaero.com/product_info.php?products_id=172

[billbeemer]

I want to do this on my dualport 1600 (see photo link) - but I was wondering how to create a break in the line as to make engine removal easy... e.g. attach temp sender to valve head with wire running up about 12 inches - then have the wire from the gauge on the dash hanging inside the engine compartment - 'click' - the two wires are attached and there is no lose in temp sensitivity - any ideas??

http://www.germansupply.com/xcart/skin1/images/tech/cht/TIVSenderInstalled.jpg
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1971 Westy "Chester"

[SlowLane]

[vwkombi1966]

[Basilbomb]

AN old thread, but here's an inexpsensive solution: Wag-Aero suppllies CHT gauges for aircraft engines, starting at $55.00.

http://store.wagaero.com/index.php?cPath=15_24

Given the application I would assume they are pretty rugged. They are NOT temp compensated, but precise if not accurate, and the literature for the gauge spells out the correction and calibration nicely:

For COLD JUNCTION temperatures HIGHER than 75 DEGREES P. : The Indicator will read ONE DEGREE LOW for each DEGREE of COLD JUNCTION temperature ABOVE 75 DEGREES F.
For COLD JUNCTION temperatures LOWER than 75 DEGREES F. : The indicator will read one DEGREE HIGH for each DEGREE of COLD JUNCTION temperature BELOW 75 DEGREES P.

As long as you have a general idea of the temp, you can have a pretty good idea of head temperature. They list 4 foot thermocouples that will work under a standard 14mm plug for 10 bucks, and you can use a patch cable to the gauge.

I think that having aircraft guages in your VW would be way cool. I think I would throw in an oil temp or pressure guage to match. You could also install an aircraft outside air temp guage and really be precise!

[Fibersport]

When you mention cold junction, is that the ambient temp at the source or is it the difference between the ends of the sensor wire?

In any case, if the CJT is 100, then the gauge would be reading 25 degrees low; conversely if the CJT is 50 then it would be reading 25 degress too high??
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1973 Standard Beetle

[Basilbomb]

As I understand it, the thermocouple works by generating a voltage proportional to the temperature difference between the two ends of the thermocouple. The one end is attached under the spark plug - the other end (the cold junction) will be the temperature of the air surrounding it, whether it is inside your vehicle or outside. It's important that this end is not near the exhaust or the engine for obvious reasons. And you are right, for every degree differnce the cold end of the thermocouple is from the preset of 75 degrees, alters the Gauge reading one degree.

[Fibersport]

Thanks for the explanation, so that means that in the Midwest winter the gauge would usually be reading about 40 degrees high !
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1973 Standard Beetle

[Basilbomb]

It sounds like a good deal to me - $55.00 for the gauge, $10.95 for the thermocouple, and a 15 ft. patch cable (part #A-112-115) for $11.50 ea. Less than a hundred bucks and all the parts are there and you know the temp of your cylinder head. I'm going to install oil temp, outside air temp and CHT.

[ratwell]

FYI. My source for inexpensive 14mm ring terminals passed away and my supply has run out.
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'78 Westfalia CDN
'76 Doublecab
Read the Baywindow FAQ

[xfrench]

As a new bus owner (since Dec) and a huge fan of ratwell.com ;) I went ahead and got the Dakota Digital CHT gauge. My friend's mechanic (who'd never heard of DD) put it in for me last week (as one of several fixes and upgrades) and we went for a drive over the Cascades. I am very happy and relieved to confirm that my engine's doing just fine, but I have a few questions...

The gauge starts blinking at me at 380 degrees. I know in theory one can set the warning temperatures, but where should I set it? The hottest it got was somewhere around 420, and I realized I didn't know if I was supposed to be worried or not. The dipstick was never hot when I stopped and checked.

Since we're driving to Reno next week (from Seattle) I'm hoping you can give me a bench mark. At what temp do you pull over and sweat? ie How hot can your engine get before you are really worried and starting to damage stuff? I also have OT and OP gauges as well, which seem pretty steady and tell me not to worry, but all that blinking got a little distracting.

x
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'76 Transporter 2L F.I.
"Simon (TZV)"

[IFBwax]

I'm not convinced anyone knows the answer to that question.

To me, a lot depends on how hot for how long. The rule of thumb I've heard is anything over 400 is worrisome. Anything over 425 should get your attention.. I'd begin to sweat bullets and pull over at 450.

The other side of the coin is that ideally you want to run around 350 if you can. Which I don't think a stock engine with a stock exhaust is capable of... without running way too rich.

I think the real question is what is your consistent running temperature? I wouldn't want to run at much over 400 for longer than 15 minutes or so, just to be safe.

If I could run at 65 MPH at around 375, I'd be really happy. If you're on a seven hour trip and running plus 400 the whole way, I personally would be a bit worried.

That said, I'm sure these engines have run much hotter than that for years and years before anyone got CHT gauges.
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Owner of: "The Party Pickle" (a 1979 2 Liter FI "Raby Camper Special" Sage Green Westy Campmobile) & "Charlie Brown" (a 1979 2 Liter FI "Rob Grant Rebuild" Agate Brown/Dakota Beige Station Wagon)


www.partypickle.blogspot.com

[TheTominator]

I too am a big fan of ratwell.com. This thread convinced me I need this DD CHT guage. The price is up to $119.95, but the good news is they now offer an 18 foot thermocouple length for only $15.00.
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"A foolish faith in authority is the worst enemy of truth" Albert Einstein - 1901

If I can't curse, I can't fix it.
71 Bus
78 HD FXS Lowrider 1200cc
An Oldsmobile for crying out loud.

[m4mke]

Not to brag or boast but... I took my '83 vanagon to go-westy over my lunch break a few weeks ago to dial in the afm. The lead mechanic worked on it for 45 min or so and told me it was to rich (LM1 test) and something was up w/ the O2 sensor. He told me to take it for a test drive and i didn't notice any major difference. Until I took it for a drive on the higway, now it cruzes a 350 @ 65 and occasionally hits 370 pushin' it on grades. I should ad it has mucho more pulling power on uphills. Case & point adj the AFM.
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Don't tell my wife I'm in here.

[thewalrus]

OK, I've decided to get a Dakota Digital Gauge too. I just want to make sure before I buy the gauge that this is what everyone’s talking about:

http://www.dakotadigital.com/index.cfm/page/ptype=...prd347.htm

If it is…..I'm a little confused........is the last option the 14mm ring everyone’s been talking about?? Or do I still have to go hunt one down / make one?? And I need the 18ft of wire option right??

If it matters I have a ’75 with a 2.0 engine.
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'73 Transporter 1.7L Dual Carb

[JMazier]

[Vwman55]

Yes, That's it 18ft sen-11 option. The sensor is part of the sen-11. A note here on my experience. I ordered the sen-11 asked for the 14mm ring and it was too small, called they sent me another, package said sen-11/18ft/14mm, it was also too small. Used a small rat tail file to fit it. Be careful its just soft copper under that zinc coating. I also did Scott Lyons method to mount it under number 3 plug(thanks Scott). Works great.

[1977_L63H_P27]

Just curious; Has anyone tried putting the terminal ring under a case/head stud? I know the reading would be a little cooler, but you wouldn't have to move it every time you did a tune up. Peace!
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