| Vehicle Speed Sensor Failure [message #219614] |
Fri, 23 August 2013 12:29  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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The Fuel Injection Forum suggested I tell this here as well.
I have a Vehicle Speed Sensor (VSS) for my fuel injection (EFI) and Delphi cruise control. When I installed it I wrapped it with reflective heat tape. After numerous trans/final drive/speedo work the tape was sort of flaking off. It was one of those things "I need to do something about".
I have headers and suddenly had the engine stop while on a freeway. Luckily I was going down hill and there was an off-ramp at the bottom. Looking at fuses I had one burned. Took me a while to find the short. It was part of the VSS/Cruise control but the melting heat did damage to several wires. The VSS had melted and burned wires down into the unit. Clipping the power to the VSS revived the system and allowed me to continue home.
When I called JimK for another VSS he said he had seen this before. So, if you have a VSS for speedometer or EFI or cruise and it is down by the transmission I suggest protecting it. If you have a particularly clever way of protecting things down by the headers, I will be happy to hear about it.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Vehicle Speed Sensor Failure [message #219622 is a reply to message #219614] |
Fri, 23 August 2013 13:26  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| George Beckman wrote on Fri, 23 August 2013 13:29 |
The Fuel Injection Forum suggested I tell this here as well.
I have a Vehicle Speed Sensor (VSS) for my fuel injection (EFI) and Delphi cruise control. When I installed it I wrapped it with reflective heat tape. After numerous trans/final drive/speedo work the tape was sort of flaking off. It was one of those things "I need to do something about".
I have headers and suddenly had the engine stop while on a freeway. Luckily I was going down hill and there was an off-ramp at the bottom. Looking at fuses I had one burned. Took me a while to find the short. It was part of the VSS/Cruise control but the melting heat did damage to several wires. The VSS had melted and burned wires down into the unit. Clipping the power to the VSS revived the system and allowed me to continue home.
When I called JimK for another VSS he said he had seen this before. So, if you have a VSS for speedometer or EFI or cruise and it is down by the transmission I suggest protecting it. If you have a particularly clever way of protecting things down by the headers, I will be happy to hear about it.
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George,
I digested the entire write up on the EFI forum, and thought to add some experienced based advise. As you may have guessed, in an engine lab, heat is a big issue. It will become obvious that the problems in an engine bay are more like baking than broiling. But the heat from a header is definitely more of the radiation type. This is to say that trying to reflect the heat or insulate the item you choose to protect, may be more difficult than you imagine. If you cover the turkey with aluminum foil, it will bake just fine. If put up a shade of some sort, the heat of the sun can be mitigated.
So, if you have something you need to protect from heat, you need to have some take the heat that gets through you insulation or reflector away. This is why your reflective tape was likely to fail given time. If you put something, even like a tube rolled out of aluminum foil, around the new vehicle speed sensor that is arranged so the heat air can circulate up and out, it might survive a very long time.
Example, we tried everything on spark plug wires and boots. This was after burning up the silicon rubber boots and wires. We wrapped them with refractury cloth tape - good to 2000°F - tape. The tape didn't burn, but the wires inside got cooked and failed. The thing that worked best was plain aluminum foil. What woke us up was that it worked best when it was barely wrapped around the wires. But what worked best was very thin wall aluminum tubing. It was sized to jam on the hex and had holes drilled in the engine end and came out three or four inches past the manifold so air could circulate inside it. Any parts like this worked, but polished worked even better.
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: [GMCnet] Vehicle Speed Sensor Failure [message #219694 is a reply to message #219614] |
Sat, 24 August 2013 08:26 |
Jp Benson
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
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George,
Are your headers ceramic coated or uncoated?
Thanks,
JP
>________________________________
> From: George Beckman <gbeckman@pggp.com>
>To: gmclist@temp.gmcnet.org
>Sent: Friday, August 23, 2013 1:29 PM
>Subject: [GMCnet] Vehicle Speed Sensor Failure
>
>
>
>
>The Fuel Injection Forum suggested I tell this here as well.
>
>I have a Vehicle Speed Sensor (VSS) for my fuel injection (EFI) and Delphi cruise control. When I installed it I wrapped it with reflective heat tape. After numerous trans/final drive/speedo work the tape was sort of flaking off. It was one of those things "I need to do something about".
>
>I have headers and suddenly had the engine stop while on a freeway. Luckily I was going down hill and there was an off-ramp at the bottom. Looking at fuses I had one burned. Took me a while to find the short. It was part of the VSS/Cruise control but the melting heat did damage to several wires. The VSS had melted and burned wires down into the unit. Clipping the power to the VSS revived the system and allowed me to continue home.
>
>When I called JimK for another VSS he said he had seen this before. So, if you have a VSS for speedometer or EFI or cruise and it is down by the transmission I suggest protecting it. If you have a particularly clever way of protecting things down by the headers, I will be happy to hear about it.
>--
>'74 Eleganza, SE, Howell + EBL
>Best Wishes,
>George
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