Spray On Hi Temp Electrical Insulation?

Joined
Mar 17, 2011
Messages
810
Location
Florida
I have a wiring harness that is in an awkward spot against the firewall near the exhaust manifold on my 98 Expedition. At one point, when I had my transmission dipstick tube replaced, the mechanic routed the wiring harness on top of the exhaust manifold and melted the plastic looming and the insulation on a couple wires. I liquid taped the 2 wires with melted insulation, positioned them in between the good wires, so they could not short in the event of failure of the liquid tape, then used a replacement looming and routed and strapped the harness to the dipstick tube away from the manifold. Apparently the looming I used is not heat resistant enough to withstand the heat from the exhaust, since it has melted in some places.
Is there any sort of high temp spray on insulation that I can use to re-insulate the harness from heat? I can't get to it to replace the looming, it is in a tight and awkward place and no room to work where it is without a lot of tear out to get to it.
Melted Looming Wiring Harness.jpg
 
Last edited:

AutoMechanic

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I’m not sure of any heat safe stuff. One idea that comes to mind right off is get some of that plastic tubing that has the slot in it and put that on then wrap it in heat resistant duck tape maybe. I do know they sell like a paste kinda like RTV that is heat resistant made for exhaust repairs maybe you could put that on there with it somehow.
 
Joined
Feb 20, 2007
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^^^ creatively unorthodox and I like his thinking.... rtv should be able to handle the heat If you just want to slather something in to it with bamboo skewers or something similar. Any spray I can think of will leave a mess and probably not handle heat well. You might follow the rtv bath with a piece of metal somehow arranged between as a heat shield.
 
Joined
Sep 27, 2015
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USA
Are you sure the harness belongs there, like anywhere near there? It's very close to the exhaust and usually car designers don't do that.

If that nut on the A/C lines will come off, you could fashion a tin heat shield and use the nut to hold it on. Alternatively or in addition wrap the harness with aluminum foil to block heat.
 
Joined
Mar 2, 2004
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Kentucky
I agree with the above. A high temp RTV slathered on there should be a permanent fix. I've also used aluminum foil as described above to protect hoses from close proximity to exhaust components, don't see why it wouldn't work on a wire harness.
 
Joined
Jan 22, 2011
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I don't think any spray on product is going to help with being in a high temperature environment. I would fabricate a metal shield.
 
Joined
Dec 11, 2009
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Battle Creek, MI
I think you would get better results blocking the heat from the insulation instead of increasing the temperature resistance of the insulation. As Lubener said a metal shield or header wrap?
 
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