You probably should first make sure you don't have any air in the cooling system. If everything were working properly, the fact that it's getting hot that fast would lead me to believe your thermostat isn't opening.

Do you know whether your cooling fans are coming on? Without them, these cars will overheat. I'm not sure at what temp they should activate. I want to say 210, but that might not be correct. I'm sure a search would probably turn up the answer.

 

First fan (or low speed) at 226*F, second fan (or high speed) at 235*F. Early 94's operate as fan #1 nd fan #2. At some point in the model year, they switched to dual-speed fans.

 

Shouldn't the fact that despite my car sitting on the edge of overheating, there was no heat coming from the vents with the heater on full blast tell me something? Couple that with the fact that within a minute or two of turning on the heat, the engine temp dropped back to normal and heat started pumping out of the vents....

Is that a thermostat issue?

It's weird though that on some days, the engine temp increases VERY QUICKLY when started up after sitting all night, and on other days, it takes its usual long sweet time.

Equally unusual is that two days ago, when the engine temp was rising quicker than normal after initial start up, I saw that at around 185-190, the temp suddenly dropped to about 170, meaning the thermostat opened (I assume). It did NOT go on to overheat that day. And for the record, I had never seen this car's engine temp hit 185-190 and then drop suddenly to 170 or so...when functioning normally, it was always a smooth slow rise to around 185 and that is where it sat unless I was stalled in traffic or stopped at a long light.

Yesterday, the engine temp was rising normally when first started, but then continued to rise at a slow pace until it is almost overheated, necessitating the starting and stopping I outlined above, and then the turning on of the heater...no heat...then engine temp dropped suddenly back to normal...then the heat starting blowing out the vents...

The symptoms are never the same lately.

And I've never had any overheating issues with this car over its 15 year lifespan until now...after having the water pump, t-stat and radiator replaced a couple of months ago. (And they were replaced after I noticed the car was loosing coolant, but I couldn't figure out from where...eventually they figured it was the WP as coolant was coming out the weep hole).

But now they tell me after all of this work, I must have a blown head gasket, which is what is causing these current overheating issues...never mind that right before they replaced the WP and Radiator, they did pressure tests and exhaust gas tests on the coolant and told me I passed both tests, meaning probably not a head gasket.

I wish I knew someone out here on Long Island that I could trust to look this thing over and give me a definitive diagnosis....

 

And for the record, yes, the coolant level is low in the radiator, and has been since I first started noticing coolant loss issues before the WP and radiator were replaced.

Even after multiple trips to the dealer and having them do coolant flushes with a special vacuum they said ensured all the air was sucked out of the system, I would still get low coolant in the radiator within a few days later...freakin' nightmare lately...lol

 

Add the proper coolant to the radiator, all the way to the bottom of the filler neck. Keep checking it for several days, adding coolant as necessary, and if it keeps getting low, there is a leak somewhere.

Also check the oil and see if it looks contaminated.

 

don't forget that it will take a few heat cycles to get all of the air out of the system just from installing a new radiator. It should be 4-5 maybe 6 drives to full operating temp before you get all of the air out of the system.

 

It's possible to have multiple issues. You just have to address them as they're identified. Do your fans come on when the car gets hot?

 

They used to...but during the last day or two, I don't think I heard them come on...I listened for them but don't think I heard them come on (nor did I notice a dip in the battery charge gauge)...

Not that it would have mattered anyway...the issue isn't really the cooling fans at this point, but what is causing the engine temp to climb to the point where the cooling fans would be needed...

Let me post this question...I thought I read where there are two temp sensors in this car...one on the driver side of the engine and one in the water pump...if the thermostat isn't functioning properly, wouldn't the temp in the water pump register a lot cooler than the temp sensor on the engine?

Which temperature sensor triggers the fans to come on?

 

The temp sensor in the water pump is the one that communicates with the PCM, and triggers the fans. The one on the side of the block goes to the temp gauge in the instrument cluster.

Perhaps I'm wrong, but if the thermostat isn't opening, the water pump would only be circulating the coolant in the block, which would eventually get very hot.