99 sunfire 2.4L runs 223 degrees on highway.

LeeMan10

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Hi my sunfire runs hot only on highway, 223 degrees. Then cools off when I slow down around town. Fan works, I can hear kick on with a/c. New thermostat, rad, hoses, ECT sensor, coolant bottle. Flushed many times. Held 15 psi for 30 minutes at the shop. Tested with Combistion tester, in coolant bottle, didn't detect any combustion. New water pump as well. Could my timing be off slightly? Or pump be faulty.
 
have you used an IR gun to confirm that your gauge is accurate?
while you had it in a shop did they try to determine the cause of the running hot?
you have a new radiator?
there is nothing in front of the radiator blocking airflow?
 
have you used an IR gun to confirm that your gauge is accurate?
while you had it in a shop did they try to determine the cause of the running hot?
you have a new radiator?
there is nothing in front of the radiator blocking airflow?
I used a Temperature gun and it reads over 220 degrees by thermostat housing, and opened up coolant bootle and coolant is well over 200 as well, while running. Nothing restricting air flow. And the shop just did pressure test and that was it. I'm looking into trying a new water pump and new timing chain. Properly installed this time, cause i got my back yard mechanic to do the water pump last. Not sure if he pressed in tensioner or set timing right. Yes new radiator as well.
 
you see no loss of coolant?
have you done a compression test?
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No noticeable coolant loss, I haven't had a Compression test done. Maybe I'll get that done next. That's to test head gasket for leak?
 
actually if they did a hydrocarbon test on the coolant that should have shown a bad head gasket. Have you tried testing the new thermostat in boiling water to see if it fully opens up? Does it run hot on the highway when the AC is on? You need a shop with a TECH II or similar tool to actually check what the ECM is telling the fans to do at various temperatures.
 
Ok, tech ll, I'll look for the shop that has it. I have boiled my stats, 3 of them in a row, they all open. Still runs 222 degrees on highway. I'm thinking of just pulling my stay out, to see if that will help. Does the stat go in a certain direction for flow wise? I've heard of drilling 3 holes 1/8"... I haven't tried a brand new fan yet either, is there a temp switch on the fan?
 
the thermostat main body should fit into the engine.
the holes are for venting air there is no reason why you should have that issue
the fan should come on around 215-220, does it come on with the AC off?
the temperature sensor determines when the fan comes on but you may have two, one for the gauge and other to tell the ecm the temperature. One appears to be screwed into the head and the other into the block. Easiest way to figure which is which is to disconnect the plug, if the gauge stops working the other sensor is for the fan.
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Im experiencing the same issue, only I have the 2.2 ohv, new h2o pump, just topped off the coolant, bled the system, but its been 105 degrees here in cali, and I run the A/C almost all the time. Trust me when I say you cannot turn the A/C off for a minute, you will cook inside the car. I'm looking in to it.

My question is if everything checks out (fans turning on, etc) is it safe to run the 2.2 ohv at 195-230 degrees for a 45 min commute in traffic without hurting it (or risking blowing the engine)? (the freeway moves 65-80 mph when not blocked up) (i keep it at 75mph usually)

-is it okay if I use this thread, I thought why start a new one when this one is similar to mine.
 
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has the cooling system been chemically flushed?
those high temperatures, 230, are in slow moving traffic?
are you loosing any coolant?
 
no the cooling system hasn't been flushed that I know of, we just replaced the lost coolant when the h2o pump was replaced,

the high tempratures, actually is closer to 210 ( I read the gauge wrong ) and yes it is in slow moving traffic, or when going at 75mph constantly (when traffic clears)

no I am not losing any coolant that I am aware of
 
if it's 210 you dont have a problem
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