Cooling problems

This weekend I burped the system and replaced the radiator cap. With the A/C off, it doesn't heat up too bad. The temp gage might get to the "M". But when I turned the A/C on in the afternoon on Saturday with outside air temp about 85 degrees, it started getting hot again. This morning, the air temp was only about 65 and the engine temp didn't get above the "N". It also seems to take awhile for the car to heat up, especially when it's cool out. Yesterday I had driven about 5 or 6 miles before the temp needle got above the white line. To me, this indicates a possible sticking thermostat. This is the same symptom I had with the old thermostat though. Is it possible I put in a bum thermostat? Do Mr. Gasket t-stats have this problem? I realize the gage is crap but it is acting funny relative to how it acted in the past.

When I burped the system, I didn't notice any air bubbling out so I can only assume all the air is out of the system.

I also checked the grounds. It looks like I have 3 small grounds on the front panel so I cleaned those up. I thought it was weird that they're attached to painted metal though. Shouldn't the metal be bare to get the best conductivity? I figured what the heck though, it came from the factory like this so it's probably fine. What did bother me though is that the battery to engine ground was either cut or tore off so I need to rig up my own fix for that. I also couldn't find an engine to body ground. Could anyone give me some pointers on rigging up my own grounds? I think that might solve some of my electrical problems and could even fix this cooling issue as noted above by Bullitt95.

I'm thinking the next step after I repair the grounds, if it's still running hot, is to tear out the thermostat and just let the coolant flow unrestricted. That way, if it's still getting hot, it's either the radiator or water pump. What do you all think?

Thanks for the tips so far fellas!

Bullitt95 said:

I had a similar problem in the past where the dash gauge needle would be on A while driving on the highway, and later discovered that the actual temp. was only 194*F when I checked it with my infrared thermometer. I'd also noticed that all the gauges would flicker if I added an electrical load (e.g. headlights on or AC on). I added a ground cable from the upper intake to the firewall and that cured it. The gauge reading fell from A down to O at a coolant temp. of 194*F and the other gauges no longer flickered when an electrical load was added. Now I can trust my stock temp. gauge knowing that the difference from one letter to the next is 7*F (A is actually 215*F).

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Man, I bet that felt good to get fixed! I'm definitely thinking this is mainly an electrical problem. I hesitate to rip apart my cooling system when (this is my theory anyway) it could just be the car heating up to normal operating temp, plus a warm day outside increasing underhood temps, which then cause the grounds to get worse due to the heat. I have some free time tomorrow so I'll be heading to the parts store to pick up a couple (4 AWG?) cables to act as ground straps. I'm crossing my fingers!

If the grounds are fixed but it's still overheating as indicated by my gage, checking the thermostat in boiling water will be my next step.

HISSIN50 said:

Does it run cooler at speed or while idling (stationary)?

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The temperature is indicating it is running hotter at higher speeds. What has been happening is the car heats up slowly after start-up and gradually heats up to the "A" or "L" on the temp gage if I am cruising on the highway. This usually happens slowly, like over the course of hours. If I am doing the stop-and-go dance in traffic, it doesn't usually heat up past the "R" or "M". However, if I turn on the A/C, all bets are off and it will get HOT due to the extra load, I guess. Also, if I keep the A/C on, underhood temps will get high enough to cause that low pressure switch to malfunction and the A/C will just stop working. I think that's what is going on anyway.

If the temperature gage is at all functioning correctly and the car really is getting hotter at highway speeds, that would be indicative of a bad water pump, correct? The theory being the impeller would most likely be worn and/or corroded bad enough to not pump very efficiently at the higher RPM's. Some have alluded to this in earlier posts. I'm thinking it would most likely not be the radiator since the radiator should be more efficient at higher speeds, not less, since you have more airflow. Is my reasoning correct?