Overheat

[Griff]

I ran and drove my car for the first time on Thursday afternoon after installing a radiator that is in great shape and the car did really well; the temp gauge stayed in the middle. When I turned the car off and switched the ignition to accessory a few times, the temp gauge would immediately shoot to the top (maybe there is still some air in the system?). Most of the time when switching to accessory the gauge would just go back to the middle position again. Note that it was like 25 degrees out and snowing heavily. Then, yesterday afternoon, I was running the car again while still watching the temp gauge. The temp gauge began to climb (reached right bellow red) but when I checked the engine the upper rad hose and radiator where still cold (I think this means the thermostat wasn't open). I also put my finger on the side of the cylinder head and I could comfortably keep my finger on it and not get burnt. It was comparable to the temp of a hot tub. I removed the radiator cap and bleeder screw and coolant didn't shot out (so the coolant didn't have a high temp/pressure). The fans didn't turn on (I have never actually had the fans turn on, though I have only had the engine run a few time). When I switch the AC on the fans still do not come on either (I do not have an AC belt on so this may cause this). The idle wouldn't drop bellow 2k either (still choked?). Note, when the cars temp gauge said the engine was overheating it was still very cold out and snowing but I didn't drive the car around that time.

I have replaced the water pump (Gates), thermostat and gasket (OEM), upper and lower radiator hose (Gates), water pump/alternator belt (Gates), head gasket (OEM with resurfaced head and clean block deck as well as proper torque and sequence on head bolts), and picked up a used radiator that is in really good shape. I used good brands so it is unlikely something failed. I bled the cooling system (filled coolant until it came out of the bleeder screw and ran the car with the rad cap off a bit). The car doesn't lose any fluids.

I am writing this right before I go and try to figure it out myself. I am going to try to run it as is to see if it heats up again. If it does I will remove the thermostat and install the old AC belt in an attempt to be able to run the fans. I will also try to bleed the system again making sure I cycle coolant into the heater core. Hopefully this works!

What else do you guys recommend I do?

[Dr_Snooz]

Sounds like your gauge is wrong. Could be the sender, the wire or the gauge itself.

[conozo]

A few basic things to check. Make sure the bleeder hole in the thermostat is on the top and your thermostat is in the correct direction. Also make sure that you didnt mix up your upper and lower radiator hoses. I know it sounds impossible, but they do run right next to each other.

I think you still have air in your system otherwise the bleeder valve would have leaked something when you open it anytime the engine is on.

[Griff]

I replaced the temp sensor for the gauge today with a junk yard part. When driving the temp on the gauge showed just bellow the middle but when the car was just sitting the gauge would sometimes spike to the red and then come back down (all with the thermostat still closed).

Thermostat was put in correctly. The way I have it the upper coolant hose connects the thermostat housing to the top of the radiator (I believe this is right?). When the bleeder screw was open with the engine on it would spray coolant out.

After driving the car around for like five minutes today (letting it warm up to open the thermostat before driving)the upper and lower radiator hoses felt very hot. The lower hose was only slightly less hot. The fans did not come on at all; I am going to try to jump the sensor on the bottom of the radiator to see if they work. I'm thinking about just buying an aftermarket temp sensor; the previous owner had one on the thermostat housing that I unfortunately broke. Any recommendations on a specific set up to get?

I'm also looking into picking up an IR thermometer to check the engine temp.

[conozo]

Well, now it sounds like its working correctly although the spike in the temperature reading is still concerning. You did mention that it was 25 degrees, it is harder to get the air out when the outside temperature is a low as that. Any days where its at least 45-50 degrees.

[Griff]

I think the temp gauge is giving me inaccurate readings (or at least I hope this is the case). When it was showing proper operating temp and spiking to red while sitting the engine still felt just warm to the touch and the thermostat was closed. I bled to cooling system again right after installing the thermo sensor, and it was around 60 today. I wasn't aware that bleeding the system in cooler temps isn't as effective, however. I'll pick up an IR thermometer in the morning and check the engine, coolant hoses, and radiator with that to see how well the engine is cooling.

The last thing I need to be doing is blowing another head gasket!

[conozo]

You can still bleed the system in cold weather it just takes longer for the car to fully warm up and sometimes it gets rushed because you don't normally sit there watching the engine warm up and dont realize how long it takes sometimes when its cold out. so i was just mentioning that.

[Griff]

Looks like the car is running great now.

The sensor in the bottom of the radiator wasn't screwed in all the way and was dripping coolant (stupid mistake not to check everything was tight before installing the radiator). I screwed it in all the way and now the fans turn on. The cheap Craftsman infrared thermometer showed the engine wasn't over heating. It gave some whacky numbers at times but I didn't expect it to be super accurate.

The temp gauge on the dash now seems to be working well too. I'm guessing the lose sensor allowed air into the system and messed with the temp gauge.

The car does burn some oil when really cold, however. I read that this resembles bad valve stem seals, but I hope it's just a bad PCV valve.