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I think my Vairtrix thermocouple is dying confused smiley
Posted by: jetcat ()
Date: November 03, 2018 06:57PM

Today I took my Corvair coupe to our local cars and coffee. After a prolonged BS session, took off on the backroad home and noticed my temp gauge was indicating about 275°. Normally it ranges from 325 to 400° depending on load and ambient temperature. My trip to the bakery the temp was 325°, normal. When I got home and cycled power, I noticed the self test stopped and 350°, not the usual 400°. I had a spare gauge that I directly hooked up to 12V, gnd and the thermocouple output. Same reading for the self test, 350°. I installed it 7/17 and have around 1500 miles on it. I will say the inline molded circuit is close to the exhaust bend, about 6" away. Maybe too hot and cooked something? Noticed the Vairtrix website is down. Crap, I really liked this unit and the self test feature eye rolling smiley.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Turbo Corsa convertible
1966 Corsa 140 coupe

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: 66vairman ()
Date: November 03, 2018 07:17PM

Could you clarify? Does the self test indicate correctly?

If the self test is off then it could be a connection or ground problem at the gauge. The gauges are reliable, but I've had a few with poor contacts that I dismantled and cleaned up. After that the gauges worked fine.

If selftest indicates properly, but the indicated engine temperature is off, then the gauge is probably O.K.

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: jetcat ()
Date: November 03, 2018 07:22PM

Self test is incorrect. Reads 50° less (350°). I literally took test leads and connected ground, +12v and the output of the sensor to a different known gauge. Same reading for self test, 350°. Now, I don't know if the sensor ground at the head is changing.... I'll take off the sheetmetal tomorrow and check continuity at the head.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Turbo Corsa convertible
1966 Corsa 140 coupe

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: 66vairman ()
Date: November 04, 2018 07:59AM

Good troubleshooting and sounds like the gauge is good.

Checking the sender ground at the block is a good idea. To read 350 vs. 400 would mean an addition resistance between the gauge and sender ground of about 40 ohms.

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: Nickshu ()
Date: November 04, 2018 08:38AM

I have had erratic behavior with mine too. I bought one of the first ones that came out. It has never died, but it acts erratically sometimes, similar to how you describe. I have talked with Pete about it and he has told me that several updates and improvements have been made to the firmware in the little black tube that holds the guts of the unit since it's inception.

The warranty on the unit is through Clarks (as are all sales of the unit) so he recommended I just contact Clarks with the issue and they would replace it for me at no charge. However I have not bothered to do so yet since the problem is only present maybe 1 out of 10 times I drive the car.

Pete is very responsive if you want to contact him. Vairtrix@gmail.com

Nick
_______________________________________________________________________
1964 Monza Spyder Convertible #435 - Rotisserie restored - Check out my restoration thread here: [corvaircenter.com]
Recreational Mechanic/CORSA Member/COG Supporting Member/US Navy Veteran
Other fun car: Porsche 911 GT3
Boring daily drivers
Northern Colorado, USA

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: jetcat ()
Date: November 04, 2018 09:30AM

The ground at the head was fine, 0.1 ohm between the head and shield on the cable. My guess is the thermocouple is sick. Had it for 1 1/2 years, probably out of warranty. I always worried about the proximity of the moulded electronic circuit to the exhaust. Next one I'll wrap in heat shield.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Turbo Corsa convertible
1966 Corsa 140 coupe

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: BobV66Vair ()
Date: November 04, 2018 10:05AM

Interesting. Mine did a nice self-test from day one but only reads 275 degrees when the engine is hot. It can get to 290 but only under hard driving, like on a racetrack. I assumed that the temp was pretty close and I should only worry if it spiked. Now I am worried. I will contact Clark's and see what they say. I have very few miles on it.

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: jetcat ()
Date: November 04, 2018 10:15AM

One other thing you should know Bob, I replaced my 140 heads with 110 heads a few months ago. I understand that the 110 heads have the thermocouple in a different location and may indicate lower than the 140 heads. As far as I can remember, my reading seamed to be the same (between 325 and 400°) but my 140 engine was in terrible shape so I never pushed it..

Bob
Paso Robles, CA

Central Coast Corsa
1966 Turbo Corsa convertible
1966 Corsa 140 coupe

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: BobV66Vair ()
Date: November 04, 2018 10:29AM

mine is a 140. Should I worry that the reading is low? I have no lower shrouds so I think it may run that cool. Still, 275 is barely running temp.

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: MattNall ()
Date: November 04, 2018 11:06AM

Bob... these types of AUTO meters are for "Reference only" System is not calibrated....and the enviorment changes dramatically.

If you want a higher reading with stockgauge... add an inline resistor!





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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: 66vairman ()
Date: November 04, 2018 11:50AM

MattNall Wrote:
-------------------------------------------------------
> Bob... these types of AUTO meters are for
> "Reference only" System is not calibrated....and
> the enviorment changes dramatically.
>
> If you want a higher reading with stockgauge...
> add an inline resistor!

Actually the LM gauges are are very consistent in response based on my examination of them, so far. The issue is usually the wiring or the sending units. I bet Clark's and VairTex will work a deal to fix the problems.

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: Kyle_in_Mich ()
Date: November 04, 2018 05:31PM

Just to add a bit to the conversation, my Vairtrix auto test is low. like 200 on the gauge low. Its consistent after that so I have just come to think of it as a "as long as it reads the same, it's fine" but I bought it because it was supposed to work better than stock.

I will check grounds (pretty sure they are good though) before talking to Clarks to get an update one.

CORSA Member
Traverse City,MI
Daily driver- Bicycle
Fun driver/project- 65 Corsa 140/4 speed

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: jetcat ()
Date: November 05, 2018 11:54AM

I talked to Vairtrix today and discussed the symptoms that I'm having. He was "fairly" convinced I diagnosed all the other ancillary things that could have changed my readings. He had me arrange an exchange through Clark's because he wanted to evaluate mine.

First, I want to say both vendors are awesome!!!! To help me out with a 1 1/2 year old electronic part is the exception, not the rule these days.

Just to be clear, it has always self tested at 400° and my operating temperatures were 325-400° until 2 days ago. Then it changed to 325° self test and operating changed to 275° and has stayed that way since. It has worked perfectly and consistently until now.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Turbo Corsa convertible
1966 Corsa 140 coupe

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: BobV66Vair ()
Date: November 07, 2018 06:08AM

Has anyone tried removing the part and checking it? I wonder if there are any visible signs of a problem. Has anyone then reinstalled it using the original directions to set it into the head as required? I was not real clear when I installed mine as to the proper depth. It worked initially so I figured I got it right, or it's very forgiving. Is it supposed to bottom out on the head?

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: I think my Vairtrix thermocouple is dying confused smiley
Posted by: jetcat ()
Date: November 07, 2018 06:49AM

I just removed mine yesterday and it looks like the day I installed it. Hardly any heat discoloration. I used it with the brass adapter because I had 110 heads put on my 140 but the probe was still putting pressure on the head via the spring.

When you install the probe it should bottom out against the head and the spring should be screwed in to keep a bit of pressure on it.

Bob
Paso Robles, CA

Central Coast Corsa
1966 Turbo Corsa convertible
1966 Corsa 140 coupe

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