Oops, I forgot to mention, the shaft of the petcock steps down to a smaller size for the o-ring to slide on to. So the o-ring does goes on the petcock.

So so what could be causing that steam? Its not like a tea kettle whistling out. My buddy recommended that I start my car and let it idle without the coolant reservoir cap on to see how long it takes for the coolant to overflow out of the reservoir. Maybe I’m just seeing the coolant getting hot like when you’re boiling water and you see the vapor rising from the pot.

By the way, I let my car idle for about 20-25 minutes without the reservoir cap on and it never boiled over even though the temp gauge reads just a smidge over the one quarter line. That’s where my temp gauge normally reads when the engine is warm. Does that sort of rule out the head gasket being an issue? Im pretty sure he was saying if it’s the head gasket the engine should start overheating after 5-10 minutes of the engine idling with the reservoir cap off.

As for the current reservoir, it’s brand new. I just bought and replaced the old plastic reservoir a few weeks ago. The old reservoir cracked from pressure, so maybe there’s just too much pressure in my cooling system? What could be the cause of that?

The old one was weak and brittle and failed... you replaced it and as long as you don’t overheat I’m guessing you’re fine...

Sorry I haven’t responded, I might have to look at how my email notifications are set up because I didn’t get emails for these responses.

Right now I’m doing the “heavy duty” system flush, following the instructions on the Prestone system flush bottle. Tomorrow I’m going to flush the detergent out, get some 70/30 coolant mixture in there, flush it out again, then finally fill it with the 50/50 coolant mixture.

I havent driven it the way the way I normally do, which is as a delivery driver, like a pizza guy except with sub sandwiches, so it’s all in town, in traffic, from 4:30pm to 3am. I usually put about 600 miles on my Saturn per week. this week I’ve only driven it from a to b to the store and back. Only a few miles at a time. No issues whatsoever.

The original issue was the old reservoir cracking and spraying coolant everywhere, I resplaced the old reservoir and used the Dorman reservoir cap with the new reservoir. It gave me no issues for about a week, then it would start spraying coolant out of the cap after taking a few deliveries, so maybe 4-5 miles of hard city stop and go traffic driving.

after that happened I bought a new higher quality reservoir cap to put on the new reservoir. This time I was able to deliver through half of my shift, from 4:30pmvto about 9-10pm. In that time I probably drove it 50-60 miles without it spraying coolant out of the cap.

Im wondering if something was clogging up the system, so doing this flush will clear it out and stop this issue?

I also heard that the SOHC engine in these Saturns develop cracks in the head allowing exhaust gases to escape and cause overheating, could this be the issue? The car has just under 200k miles on the engine.

Any advice would be greatly appreciated. I rely on my car to bring the majority of my money home, so not having a vehicle I can rely on makes me anxious.

I will I’ll try what you said Derf, about putting the paper towel over the reservoir to see if there’s something other than water or coolant putting off that steam. I can also try to pressure test the cooling system with a pressure tester from my job at autozone, but I’m not sure what I’m looking for, or what my next step is once I do test the system.

Thanks guys

So I’m starting to suspect the new coolant reservoir is my issue. My coolant temp gauge is staying either right above 1/4 where I’m used to it sitting in this car and my old 97 Saturn SL. It goes a little bit above that almost to the halfway mark when I’m sitting in traffic and it’s hot out (it was around 85° out today), but it goes back down once I start moving again. My radiator fan doesn’t normally kick on until around the 3/4 mark on this vehicle before I started having this issue, same with my old 97 Saturn.

So im thinking it’s either the cheap Dorman reservoir I bought that isn’t properly sealing at the cap, or it’s flexing after I’ve been driving it for a few hours and breaks the seal, OR it’s the coolant temperature sensor/pigtail. a mechanic buddy of mine told me he suspected the cheap tank because the same thing happened to him with his Audi S4 when he bought a cheap Dorman replacement reservoir when his got old and cracked.

Im a little ashamed to admit that I forgot this, but the wiring for the coolant temp sensor has been played around with. The wires coming off of the sensor are connected to the wiring that goes to the car with butt connectors. I’m assuming the old owner was having overheating issues, and was hoping that they could replace the temp sensor and connector without doing the wiring for the connector. I’ll attach a picture of the Frankenstein wiring for the temp sensor.



Speaking of the wiring ring for the coolant temp sensor, how big of a pain is it to run the wiring for the connector?

Alright...I’m gonna do the pressure check right now.

Rock Auto sells few different brands, if nothing goofy happens with the pressure test I’m gonna order the spectra premium reservoir. Here’s a picture of what they have, I can’t remember if it said in the rules that external links aren’t allowed.

Wow that pressure test was extremely quick and easy. So when I hooked up the adapter to the reservoir air started leaking out of the cap at 5PSI. Is it safe to say that my reservoir can’t even allow my cooling system to pressurize so that would explain my temp gauge reading normal and my fan not kicking on?