so i've recently had an overheating issue. for the first time a few weeks ago the temp needle went into red, engine hot light came on, so i popped the hood and coolant was spewing from the reservoir cap.
got a new reservoir cap, did a coolant flush, cleaned out the coolant reservoir, put a new 180* thermostat in, made sure the air was out of the system, and so far it's been good.
however, two times since i did all that, its happened again. both times i was haulin ass on 95 and the needle was climbing higher than usual... as i pull up to the house the needle slowly goes into red and the engine hot light comes on. i let the car run for a minute to see if the needle drops, but it doesn't. i shut the car off, wait a few seconds, then turn the car back on, THEN the needle drops back down to like the 2/3rds mark.
any idea why when the needle goes into red i have to shut the car off and turn it back on for it to go down? or should i let the car run for longer with the needle in the red and wait for it to drop?
1. Check your oil to ensure that you do NOT have coolant contamination; that would be the sign of a blown head gasket.....and an eventual engine rebuild (been there, done that ).
2. Check to ensure that your radiator fans are operational.
3. Pressure check the your cooling system for a leak. An initial tell-tell sign of a system leak would be to check your coolant level.....but a pressure check would locate the the breach.
4. If the fans work OK and your coolant level is 'right', run the car for a few minutes with the reservoir cap off......you may have air bubbles in the system.
Running with the needle in the red is a risk. If you don't have a blown head gasket, this might get you one.
Agree with Baraka, check oil for coolant invasion, chemical head gasket test (napa is the one I use and requires you to do #4 on Baraka's list), pressure test (15psi held overnight is my go-to) and functioning radiator fans. ALso, would be good to know if they are running when temps are pegging.
Finally, dash and ECU temp sensors are in different places, would be good to know what ECU thinks temps are in comparison to dash gauge if you have a scanner.
This. Except before anything else. You want to know what the actual temp is at both to eliminate a false positive reading at the gauge and, should there be a problem, to better isolate where it's occurring.
If there doesn't seem to be a problem with the cooling system it self or if you don't have a blown head gasket you might have a bad connection or a burnt wire going to your temp sensor on the passenger side head. Happened to be before.
when your on rt 95 doing 80MPH the temp should drop down not go up. reason is the water pump is pumping more coolant and more Air flow thru radiator..
since that did occur you have a flow problem. could be head gasket that would create air bubbles. could be the water pump has corroded fins//no fins. so the flow is weak.
the more antifreeze in the engine the lower the corrosion if you do find the pump is in that condition.
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