2nd Gen Overheating issue

First place I would start in diagnosing the problem is to be sure the temp gauge is showing the right temp.

The Prostar engine normally runs between 194-215 degrees. That being said checking your overflow bottle from time to time is good maintenance. Check you radiator: is there debris in it (bugs, etc)? Are a lot of the fins bent over? Are you running an aftermarket front grill and/or a lower grill block off? Both of these things can impede airflow to the radiator.

It sounds like it is low on coolant since when you start driving and the coolant starts circulating more it goes back down to the normal temp. On my 2020 R I never saw a temp over 212 (even when it was 105 degrees and I was waiting to go into the Grand Canyon). As you stated normal is around 196 or 198 with of course an slight increase in traffic and at signals.

Quick question: can you hear the fan coming on when the temp increases?

Have you made sure that the fan is coming on? If the Slingshot is staying cool while driving and this only happens while sitting still, sounds like the cooling fan is not operating properly.

Check the thermostat. Mine wasn’t opening all the way, causing the fans to come on while sitting in traffic or at traffic lights. Not an issue when cruising down the highway. Replaced thermostat and issue went away.

Quote from Jared Felder

Too answer all, Dave and Billy- Yes both fans are coming on at temp 210 every time during visual inspect and I have been able to hear them come on as well while operating as they only come on when I'm stopped at a red light. As far as the amount of antifreeze, I have had the DDM coolant tank for a while now and it works amazingly. The fluid is right above the bubble.

Respond to xd675x-Also no bugs or bent fins. I do also have the LED lower front grill from DDM but again I've also had that for quite awhile especially during hot summer days without issue.

Weird question but could the temp sensor be sending the wrong temp to the display? And it actually isnt getting hot? I do know the sensor is operating fine while probing I do receive an open circuit I just can't remember what the temp was when it opened. Thanks Everyone!

Have you looked up at the fans and that area in general? Can you feel the air coming out from the fans when you hear them come on?

Quote from Jared Felder

Update- But first to answer Dave - Yes I have in my garage a number of times including today while working on it.

Update - I ordered the thermostat direct from Polaris and installed it today. Went and test drove in downtown Columbia, SC so I would have plenty of stop and go, also parked and allowed it to cycle its temp a few times. Temp is the same while driving 198ish, while stopped fans would kick in at 210. Temp would increase to 216 (Max) then cool down to 201 and then repeat. Again thank you to all for helping on this journey, lol.