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Bikerchris
Samba Member
Joined: May 08, 2010
Posts: 290
Location: Texas
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 Posted: Fri Apr 20, 2012 4:36 pm Post subject: DIY cylinder head temp sensor plug |
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| If I have a VDO cylinder head temperature sensor gauge and all the wiring except the end piece with the plastic plug and ring for the spark plug can I make one? I already have a compatible plug. Does it require special wires for the heat? How do the 2 wires connect to the ring for the spark plug? Thanks. |
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donmurray
Samba Member
Joined: December 30, 2008
Posts: 841
Location: Frisco Texas
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Bikerchris
Samba Member
Joined: May 08, 2010
Posts: 290
Location: Texas
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| Posted: Fri Apr 20, 2012 7:07 pm Post subject: |
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| Ahh... they are different metal types. Thank you. I'll just order a sender for $20 and be done with it. |
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JustBuggy
Samba Member
Joined: August 01, 2010
Posts: 851
Location: SF Bay Area, Ca.
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| Posted: Sun Apr 22, 2012 2:52 am Post subject: |
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Has anyone modified the sending unit and mounted it on a bolt istead of under a spark plug?
It just seems like a hoaky way to do this as the act of moving the wires while changing plugs, it would seem that eventually the wire will crystalize and break. Anyone? |
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donmurray
Samba Member
Joined: December 30, 2008
Posts: 841
Location: Frisco Texas
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| Posted: Sun Apr 22, 2012 6:26 am Post subject: |
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I cut off just the loop part. Ground a shallow grove close to the spark plug. Secured the crimped part of the sensor in the grove with JB Weld. While the JB set, the crimp was forced tight in the grove by a weight. Seems to read about the same as under the plug. Compared to a head bolt, I thought that location would give a better/quicker sensing of the combustion chamber temp. The temp of the head metal close to the plug should be about the same, but an under-the-plug sensor is getting some high heat from the plug tip that is conducted to the head via the plug body. Thinking about it, the plug tip may be hotter than the head material. What do you really want to measure?
The loop on the plug is just a bad idea when you can't see what's going on as the plug is removed & replaced. I was careful, but still had trouble with the loop on the plug setup. Had to fish the loop around using a mirror and hook. |
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JustBuggy
Samba Member
Joined: August 01, 2010
Posts: 851
Location: SF Bay Area, Ca.
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| Posted: Sun Apr 22, 2012 7:07 am Post subject: |
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| donmurray wrote: |
| ......The loop on the plug is just a bad idea when you can't see what's going on as the plug is removed & replaced. I was careful, but still had trouble with the loop on the plug setup. Had to fish the loop around using a mirror and hook. |
That was what I was thinking. I just installed Cyl. head temp gauge and the new engine will be going in within the next couple of months. I'd like to get this small part finallized before engine installation.
If need be I can TIG weld a small raised boss very close to the plug and drill and tap for this purpose. |
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kadub
Samba Member
Joined: November 04, 2004
Posts: 444
Location: Auburn, Wa
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| Posted: Sun Apr 22, 2012 7:35 am Post subject: |
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The problem with mounting the TC sensor anywhere other than under the spark plug is that the temp reading will be different than 90% of the people out there who post temp readings for you to compare to. Under the plug is the "standard" when it comes to head temps. You want to know how hot the heads are getting near the valve seats. If the sensor is mounted anywhere else, it's likely to get a cooler reading that reacts slower to changes, etc. Unless you mount it closer to an exhaust port, but that reading will be more exhaust temp related than combustion chamber temp  .
The ring terminals are cheap and easy to replace if they get damaged. |
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