Heating up going downhill
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Heating up going downhill
Howdy everyone,
I've got a 2008 cayenne turbo 957 and when im driving at low speeds downhill on dirt roads it starts heating up. As far as I've known, coasting or going downhill with zero throttle activates the fuel shutoff so there should be no heat being generated by the engine or at least not enough for the water temp to climb. additionally, going up that hill at almost the same speed ( maybe faster) does not result in almost any temperature climb.
is this normal? what are the chances that I have a cooling fan issue? I did notice once that just idling in very hot california weather had the engine temp climbing slightly. All of this seems strange to me considering ive never had another car where the temp climbs at an idle. I also drive a subaru outback up and down that same hill and it's water temp gauge does not move at all.
Any insights are appreciated
I've got a 2008 cayenne turbo 957 and when im driving at low speeds downhill on dirt roads it starts heating up. As far as I've known, coasting or going downhill with zero throttle activates the fuel shutoff so there should be no heat being generated by the engine or at least not enough for the water temp to climb. additionally, going up that hill at almost the same speed ( maybe faster) does not result in almost any temperature climb.
is this normal? what are the chances that I have a cooling fan issue? I did notice once that just idling in very hot california weather had the engine temp climbing slightly. All of this seems strange to me considering ive never had another car where the temp climbs at an idle. I also drive a subaru outback up and down that same hill and it's water temp gauge does not move at all.
Any insights are appreciated
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The temp gauge in a 957 won't move from about 180 - 220 F. If you're seeing movement beyond staright up on the gauge, you're getting hot. I wonder if in sport mode it does the fuel cutoff thing. Maybe try sport mode or use manual mode and downshift with the buttons to keep the RPMs near 2k and see what happens.
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The temp gauge in a 957 won't move from about 180 - 220 F. If you're seeing movement beyond staright up on the gauge, you're getting hot. I wonder if in sport mode it does the fuel cutoff thing. Maybe try sport mode or use manual mode and downshift with the buttons to keep the RPMs near 2k and see what happens.
as far as I know, all modern engines do the fuel shutoff when there’s no throttle applied and you’re still moving forward, although regardless of if it’s even just idling down the hill, I don’t see why it would be heating up.
i changed the thermostat a few months ago as well, so it shouldn’t be that either
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Can't say, I'm basically off-road illiterate. all I know is you can get up and down the road in even a 2WD car if you maintain momentum. theres a steep part or two but for the most part its not bad. its no regular road either, but not bad.
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I guess either my thermostat, water pump or maybe a cooling fan could be defective although again its strange that it heats up going downhill and almost not at all going uphill. I changed both around this time last year. There is no leak that I know of, and i dont think theres one i dont know of considering I have not had to put any more coolant since I changed those two parts.
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just wondering if there is air in the system and the angle is causing the reduction in performance
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Originally Posted by Libast;[url=tel:18193475
18193475[/url]]just wondering if there is air in the system and the angle is causing the reduction in performance
just checked the DTC codes, only have p0455 which is something related to the evap.
Does a malfunction in the cooling fan cause a DTC code? What about if it’s only the low or high speed portion that’s failing?
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That's going to make everything generate a little more heat than normal. I bet if you don't do that the temp stays lower. It's probably fine.
When I use my low range and plow through mud or snow my temp goes up a bit.
When I use my low range and plow through mud or snow my temp goes up a bit.
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Originally Posted by oregondave;[url=tel:18197771
18197771]That's going to make everything generate a little more heat than normal. I bet if you don't do that the temp stays lower. It's probably fine.
When I use my low range and plow through mud or snow my temp goes up a bit.
When I use my low range and plow through mud or snow my temp goes up a bit.
very interesting to see what a difference the gearing does. I didn’t expect the engine revs to generate that much heat even without throttle.
has anyone noticed temps rising at idle (in a parking lot, for example) when it’s 90f out? I notice my temps rise slightly every once and a while
Last edited by omarcrysis; Jun 27, 2022 at 02:11 PM.
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I tried going downhill *not* in low range and you seem to be correct, it didn’t heat up at all.
very interesting to see what a difference the gearing does. I didn’t expect the engine revs to generate that much heat even without throttle.
has anyone noticed temps rising at idle (in a parking lot, for example) when it’s 90f out? I notice my temps rise slightly every once and a while
very interesting to see what a difference the gearing does. I didn’t expect the engine revs to generate that much heat even without throttle.
has anyone noticed temps rising at idle (in a parking lot, for example) when it’s 90f out? I notice my temps rise slightly every once and a while