Cold exhaust components??

Nixon1 · 01-18-2003, 07:57 PM

Ok....the fan is wired to kick on with the fuel pump since there isnt a switch in..so it runs 24/7. Meaning the car always runs very cool...guesstimate, around 170 lightly driving..not much more than that. Now, I started it and let it warm up, and let it idle for probably a good 15 mins and shut it off. 10 mins later my friend tells me my exhaust is cool to the touch, even cold, and I pop the hood and my headers are so cool that I can lay my hand on them no problem...like they never even warmed up. Seems if they DO heat up, they don't hold it.. That can't be normal...? Could this be affecting anything during running, in terms of backpressure, exhaust operation, etc.? Thanks

HotRoddin · 01-18-2003, 08:28 PM

Ten minutes seems a little quick for them to cool down that much, but remember headers are relatively thin metal and there is a lot of surface area exposed to outside air, so they are going to cool off rather quickly if its cool outside. Also you don't generate much exhaust heat at idle.
You need to put a higher thermostat in there too. You're engine is much more efficient above 180 or 190, also your oil tends to sludge up more at that low a running temp.

Nixon1 · 01-19-2003, 08:29 AM

What's the best temperature range for power? The prev. owner replaced the t-stat but I don't know the temperature of the one he threw in...he told me a lot but didn't get specific on anything....could be something like 180 but since the radiator is brand new and so is the electric fan, and the fan stays on 24/7, it's overcooling the engine...

01-18-2003, 07:57 PM	#1
Nixon1 Registered Member Join Date: Jan 2003 Location: Palm Bay, FL Posts: 432	Cold exhaust components?? Ok....the fan is wired to kick on with the fuel pump since there isnt a switch in..so it runs 24/7. Meaning the car always runs very cool...guesstimate, around 170 lightly driving..not much more than that. Now, I started it and let it warm up, and let it idle for probably a good 15 mins and shut it off. 10 mins later my friend tells me my exhaust is cool to the touch, even cold, and I pop the hood and my headers are so cool that I can lay my hand on them no problem...like they never even warmed up. Seems if they DO heat up, they don't hold it.. That can't be normal...? Could this be affecting anything during running, in terms of backpressure, exhaust operation, etc.? Thanks __________________ '91 Mustang GT 5.0 AOD Daily Driver Current stats: NEW 302 short block, E-303 cam (@.050, 220/220, .498/.498, 110 degrees), 1.6 roller rockers, Performer RPM heads (aluminum, 1.9/1.6, 60cc chambers), Cobra intake, Granatelli 75mm MAF, Billet AFPR, Equal-Length Shorty Headers, Off-Road X Pipe, Flowmasters, 4.10 POSI 13.73 at 103.8, ~2.2 60'

01-19-2003, 08:29 AM	#3
Nixon1 Registered Member Join Date: Jan 2003 Location: Palm Bay, FL Posts: 432	What's the best temperature range for power? The prev. owner replaced the t-stat but I don't know the temperature of the one he threw in...he told me a lot but didn't get specific on anything....could be something like 180 but since the radiator is brand new and so is the electric fan, and the fan stays on 24/7, it's overcooling the engine... __________________ '91 Mustang GT 5.0 AOD Daily Driver Current stats: NEW 302 short block, E-303 cam (@.050, 220/220, .498/.498, 110 degrees), 1.6 roller rockers, Performer RPM heads (aluminum, 1.9/1.6, 60cc chambers), Cobra intake, Granatelli 75mm MAF, Billet AFPR, Equal-Length Shorty Headers, Off-Road X Pipe, Flowmasters, 4.10 POSI 13.73 at 103.8, ~2.2 60'

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01-18-2003, 08:28 PM	#2
HotRoddin cranky old man Join Date: Sep 2001 Location: Longview Texas Posts: 683	Ten minutes seems a little quick for them to cool down that much, but remember headers are relatively thin metal and there is a lot of surface area exposed to outside air, so they are going to cool off rather quickly if its cool outside. Also you don't generate much exhaust heat at idle. You need to put a higher thermostat in there too. You're engine is much more efficient above 180 or 190, also your oil tends to sludge up more at that low a running temp.