OK so she just rolled over on 150k on a trip from FL to TN. At about 151k a lifter collapsed, replaced in the parking lot of an O'Reillys. Head gasket set and all lifters replaced, oil change and coolant changed. All is good until just after I ran vinegar and water through it to flush everything. Now shes overheating, second blue line just before 260, estimated 240?...I have replaced the thermostat twice, water pump, fan clutch, and now the radiator still same problem, holds a consistent 225ish if i keep the fan on by running ac or defrost. If i turn the ACC. fan off she runs at a solid 230-240(just under second blue line). Pressure tested the coolant system with a rental tool and pumped it up to 16psi, barely lost 1lb over 5 minutes. Also the temp sensor was replaced right after the lifter failed because i broke the old one. Burped very well, even checked by removing back sensor and water comes out instantly. Fan shroud is on, bottom is broken but has been that way for over 30k miles, she used to run at a perfect 210 with almost no fluctuations at all. Were about to move from FL to AZ and the jeep has to make the trip, I dont want to run it that long of a distance with such hairy temps. Any and all suggestions welcome.
Im at a loss, could the head gasket be leaking with no other signs? No coolant/white smoke from tail pipe, no coolant loss, no air bubbles in radiator with cap off.
forgot to post infrared temp tests:
Upper Hose 176f
Lower Hose 156f
Temp sensor at rear of head 230(aimed at brass)
Cylinder head where temp sensor screws in 180
Head measured between plugs 180
Gauge reads a center line of 210 and a max of 260, my needle is pointing between the two. There is a blue line just before the red which maxes out at 260 im assuming the blue line is 240. From there I believe the gauge is reading 225-230(aux fan on) 240(aux fan off)
Ill swap the sensor today, probably going to buy mopar if its not too bad on price...The metal housing was reading that temp but would the coolant inside be hotter than the housing temp anyway?....I thought it could be the sensor but thought it was such a simple sensor they couldnt mess it up. Also the brass on the sensor was reading 220-230.
So Im on the phone with Chrysler and they cant find the sensor. The only sensor Im being offered is the one that goes in the thermostat housing. Part number 3300-4281, comes up as the dual pin sensor. Im looking for the sensor in the back of the block, just went through a parts manual and cant find the number in there either...Anyone have another way to look up this sensor?
Ok finally figured it out, for anyone that may need this in the future.
Temperature sensor in the rear of the block for the gauge Mopar part#5602-7012
Temperature sensor in the thermostat housing for FI and electric fan Mopar part#3300-4281
The sensor in the rear of the block can only be looked up under switches with the switch for cars equipped with a light instead of gauge. Stupid.
My GF just picked up the Mopar sensor, will install tonight. Also I noted that the electric fan never comes on(unless ac or defrost is on), im thinking maybe this is because the temp really isnt that hot?
Another question to throw out there...my valve cover is completely in the way of that sensor (or well at least the Oreilly one) I have to loosed the valve cover and move it slightly, install the sensor then tighten the valve cover again. Anyone else notice this issue?
Ok well the problem was the sensor. The aftermarket part has a smaller probe but threads in further, this allows the probe to hit the wall of the exhaust port, hence reading much higher temps. So the BWD replacement will does. Nit work with these motors.