| Temperature sensor question [message #237016] |
Wed, 22 January 2014 13:06  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Now whenever I run the coach the stock gauge goes to 3/4 scale, then drops quickly to mid scale and stays there. I replaced the thermostat, thinking perhaps it was sticking, but no change.
Has anyone else seen this behavior? Is it normal? Thanks - Dave
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Temperature sensor question [message #237068 is a reply to message #237048] |
Wed, 22 January 2014 19:04  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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Good thread. It is an Echlin, which I've had good luck with in the past. I'm installing an actual temperature gauge this weekend. It will be interesting to see what it reads compared to the stock gauge.
FYI I bought a Sunpro mechanical temperature gauge last week. I tested it against a digital thermometer in water. Not only was the response reeeeeeeeeeealy slow, at the boiling point, with the digital thermometer reading 211 degrees, it only read 204. Not the quality I was expecting from Sun.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: Temperature sensor question [message #237095 is a reply to message #237016] |
Wed, 22 January 2014 21:57 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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I've tested some OEM temp senders for calibration in the past and found that they don't always read the same in a pot of water versus in the application. Depending on the sender, they can average the fluid temp with the temp of the material they are threaded into. A thin aluminum housing will be pretty close. A thick cast manifold may have some deviation. It all depends on its design intention and how it was calibrated.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: [GMCnet] Temperature sensor question [message #237198 is a reply to message #237197] |
Thu, 23 January 2014 17:32 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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That reference is exactly why I changed the sensor. I'm just little surprised that it gets to 3/4 before it cools off. Maybe it's a fan issue. Maybe that's just how it's going to be. - Dave
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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| Re: [GMCnet] Temperature sensor question [message #237210 is a reply to message #237198] |
Thu, 23 January 2014 18:43 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Otterwan wrote on Thu, 23 January 2014 18:32 |
That reference is exactly why I changed the sensor. I'm just little surprised that it gets to 3/4 before it cools off. Maybe it's a fan issue. Maybe that's just how it's going to be. - Dave
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Dave,
What you may be seeing is a artifact of the difference in placement between the sensor and the thermostat, so, jacket water can circulate past the sensor more easily than the t'stat until the t'stat opens. When it opens, it gets hit with a blast of hot coolant so it really opens. But guess what?? The hot coolant gets pushed out gets to push a load of cold coolant waiting in the radiator in to the now hot engine. Fortunately, it has enough mix time in 455 so it doesn't get to slam that poor t'stat closed again.
In a lab and with good instrumentation, I have seen an engine cycle an half dozen times on a WOT heat up. (This something you don't want to do to engine you would like to keep.
Didn't Joe Mondelo insist the engines leave his shop with no thermostat, but flow restrictor in its place. Maybe he knew something.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Temperature sensor question [message #237215 is a reply to message #237016] |
Thu, 23 January 2014 18:59 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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My 97 Tahoe at road load would creep warmer and then drop 20 deg in a rapid fashion all trip long. I put in a Superstat 195 and it's very stable now. They advertise a V taper valve for smoother metering. I'll say they are right. You're results may vary.
John Lebetski
Woodstock, IL
77 Eleganza II
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