EricStanley
Well-Known Member
- Thread starter
- #1
2020 Rubicon gas auto.
80k ish miles.
Recently the coolant temp gauge randomly will shoot up from normal (210ish) to 260 - 270ish. Dash goes red, audible alarm, and the engine fan kicks on to high speed. It’ll do that for a couple minutes and then go right back to normal. Sometimes manually kicking on the heat will help drop the temp quickly, sometimes that doesn’t work. At normal freeway speeds it seems to be fine - usually, though there have been a couple instances of it happening at freeway speeds. I can almost guarantee that it will happen when slowing from freeway speeds to stop & go / slow traffic.
There are no driveability issues when this happens. No signs of overheating except what’s described above (red dash & alarm)
On a side note, maybe related maybe not: when the truck is left overnight or for several hours, upon startup it will run rough for about 30 seconds to a minute, and then it smooths right out. It’s like it’s missing or the timing is off for that first startup. When this happens I get a message on the dash that the auto start stop function is disabled. At first I attributed this to a potentially failing battery, but now I’m wondering if it’s something else. For what it’s worth I replaced both batteries earlier this year.
This all started a couple weeks ago, and it started around 800 or so miles after an oil change by the dealer.
My gut tells me this is a sensor or something going haywire. Before I take it into the dealer, any ideas or suggestions to try first?
Oil and coolant levels are good, or so they appear. No fluids leaking that I can find.
80k ish miles.
Recently the coolant temp gauge randomly will shoot up from normal (210ish) to 260 - 270ish. Dash goes red, audible alarm, and the engine fan kicks on to high speed. It’ll do that for a couple minutes and then go right back to normal. Sometimes manually kicking on the heat will help drop the temp quickly, sometimes that doesn’t work. At normal freeway speeds it seems to be fine - usually, though there have been a couple instances of it happening at freeway speeds. I can almost guarantee that it will happen when slowing from freeway speeds to stop & go / slow traffic.
There are no driveability issues when this happens. No signs of overheating except what’s described above (red dash & alarm)
On a side note, maybe related maybe not: when the truck is left overnight or for several hours, upon startup it will run rough for about 30 seconds to a minute, and then it smooths right out. It’s like it’s missing or the timing is off for that first startup. When this happens I get a message on the dash that the auto start stop function is disabled. At first I attributed this to a potentially failing battery, but now I’m wondering if it’s something else. For what it’s worth I replaced both batteries earlier this year.
This all started a couple weeks ago, and it started around 800 or so miles after an oil change by the dealer.
My gut tells me this is a sensor or something going haywire. Before I take it into the dealer, any ideas or suggestions to try first?
Oil and coolant levels are good, or so they appear. No fluids leaking that I can find.
Sponsored
Antifreeze boils from 225 degrees to about 300 degrees depending on manufacturer, so for a few minutes you’re right there. Some of the shops over the years I’ve caught them “topping off” my coolant with Water, which dilutes the whole system and will not let the antifreeze do its job at the temperatures required. (maybe a gift from your dealer visit by a tech new-be)?
