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Bad Thermister?
Posted by: BobV66Vair ()
Date: July 02, 2016 11:07AM

Tested my Thermisor. Bad. Now to find one and, worse, figure out how to remove it.

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



Edited 1 time(s). Last edit at 07/02/2016 11:14AM by MattNall.

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Re: Bad Thermister?
Posted by: MattNall ()
Date: July 02, 2016 11:11AM

Carefully!! lots of penetrant...

Aluminum expands faster than the T-mister.... Warm the surrounding area..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo




Edited 1 time(s). Last edit at 07/02/2016 11:15AM by MattNall.

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Re: Bad Thermister?
Posted by: davemotohead ()
Date: July 02, 2016 12:07PM

Did you check the Gage on the dash first to make sure its working properly?



Email me at: Dave Motohead

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Re: Bad Thermister?
Posted by: BobV66Vair ()
Date: July 02, 2016 02:36PM

I tested the gage, wiring, ground and narrowed it down to the thermistor. It has no resistance, or continuity, across it. That is supposed to say its bad. Now I'm just worried about heating a head that is still in the car. Fire? Damage?

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Re: Bad Thermister?
Posted by: MattNall ()
Date: July 02, 2016 03:28PM

Very unlikely unless covered with oil..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Bad Thermister?
Posted by: jjohnsonjo ()
Date: July 02, 2016 04:51PM

attempt to turn in both directions to remove.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Bad Thermister?
Posted by: steve c goodman ()
Date: July 02, 2016 06:50PM

Bob I don't know what all you have tried BUT my first test is with key on ground the wire at the thermister. If gauge pegs to 600 the wire is good from thermister to gauge plus the gauge is getting voltage. Then you can suspect the thermister.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: Bad Thermister?
Posted by: g2schmidt ()
Date: May 15, 2017 09:57AM

Steve

I did ground the wire and the gauge did go to 600 but now the gauge is still at 600 with key and the ground wire off does that mean the gauge is bad?

Greg Schmidt
Moorhead, MN
1966 blue corsa convertible

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Re: Bad Thermister?
Posted by: Seth Emerson ()
Date: May 15, 2017 10:28AM

Bob - The best thing about removing that thermistor is that it is already bad. You don't have to worry about the unit, just the head. So, when the shell breaks off, be ready to gently drill out the center and (we hope) re-energize the threads for the replacement piece. (Or maybe, with luck, the whole thing will come out. I wonder if you could buy - or make - a piloted face cutter (like a counter-bore tool) with a lead diameter which would tightly slide into the shell of the thermistor, then slice out the shell leaving the remaining threads in the head. Anybody know the ID of the thermistor shell? There should be some around to measure!

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: Bad Thermister?
Posted by: antkoto ()
Date: May 15, 2017 10:45AM

PM sent.

Duane

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Re: Bad Thermister?
Posted by: g2schmidt ()
Date: May 15, 2017 01:28PM

Seth

In another post you stated you are running or will run a single temp gauge from both sides of the heads. I cannot find that post. but you gave a pic of the gauge with twin inputs and stated the company name. Can you share that info again? Also there was talk of cool down lengths for the wires. Are you running that setup and do you find it give good temp reading ?
Thanks

Greg Schmidt
Moorhead, MN
1966 blue corsa convertible

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Re: Bad Thermister?
Posted by: BobV66Vair ()
Date: May 15, 2017 02:20PM

Seth. I gave up on the stock gage altogether. I got it out cleanly and tested it, and the gage, but both tested good. I installed an under the spark plug gage. It is not great due to the long wire length and cooling. It does give a consistent reading so I can monitor the temp.

On my other car, which I intend to race, I am installing a dual CHT gage. One face but two needles. Each head gets a sensor. I have heard that the gage works well. The company is Westach and their part number is 2DC8. It requires two of their sensors, part number 712-7DK. I also got the light kit for it, part number 186 and two of their long, insulated wires, Part number 214-SS-SS.

Westach

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: Bad Thermister?
Posted by: g2schmidt ()
Date: May 15, 2017 02:58PM

Hello Bob

Thanks for that info.just what I was looking for

Let me know how installation goes. also will you have to extend the wires to reach the dash from the probes

Greg Schmidt
Moorhead, MN
1966 blue corsa convertible

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Re: Bad Thermister?
Posted by: 63Spyderd ()
Date: May 15, 2017 05:22PM

g2schmidt Wrote:
-------------------------------------------------------
> Steve
>
> I did ground the wire and the gauge did go to 600
> but now the gauge is still at 600 with key and the
> ground wire off does that mean the gauge is bad?


No it does not. With the key off, the CORSA gauge needle position is arbitrary. It is free to rest at any of 360 degrees.

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Re: Bad Thermister?
Posted by: MattNall ()
Date: May 15, 2017 05:26PM

Why not try one of Vairtrix new replacements?





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Bad Thermister?
Posted by: g2schmidt ()
Date: May 17, 2017 08:58AM

Hello Matt


From advice I got here, I was able to check the temp gauge and it did work by grounding the wire and turning on the key the gauge jump to 600. But it stuck there after I unhooked the wire. But it did return to 200.
I did check on Vairtrix web site but it says coming in June 2017 so nothing available yet from them.

Now I have to get the tack to work. how do I test that?

Does anyone know if the alt. light should come one when you turn the key to on? My temp light does but the alt only comes on when I engage the started, and when I unplug the wires from the back of the alternator with car running.
The temp sending unit is missing and the hole is striped out. And no wire to be found under the engine. Adding that to the list.

Greg Schmidt
Moorhead, MN
1966 blue corsa convertible

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Re: Bad Thermister?
Posted by: BobV66Vair ()
Date: May 17, 2017 09:10AM

I had similar problems with my 65 last year. Long post string. If you search it, you can find the post with the resistance chart for the thermistor.

If the thermistor hole is stripped, your in trouble. You might be able to re-thread it with a tap but it's hard to do. Worth a try since the alternative is to pull the head and take it to a machine shop.

The thermistor is supposed to work by sensing the temp in the head and converting that to an electrical signal. It actually registers resistance so it's measured in ohms. If you have a multi meter, put it on ohms and check the resistance at the thermistor, cold and then hot. If working, the readings will change from around zero to 5,000 ohms. (I may have that backward but you get the idea, changes dramatically). If you can get the wire connected, check the same resistance at the dashboard to be sure the connection is solid.

The wire connects to the main engine harness on the DS, top of the engine bay. It is a single wire connector. The wire then runs through the hole in the shroud and into the lower shroud through another small hole with a rubber grommet. The wire is available from Clarks.

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

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