Having an issue with my 98 SW1 and it overflowing at the reservoir. Car doesn't overheat (temp gauge never reads at more than half, fan turns out brings it just below and repeats). After driving the reservoir overflows and spills out everywhere.

I replaced the cap and there was no change. Only overflows after I stop. Any thoughts on what to check or if this is a common problem with these Saturns?

 

Are you overfilling in the first place. There is a line on the tank to indicate max fill cold.

If you are not overheating, and not overfilling, then I would look at the bleed line to see if it is clogged up. Its a small diameter line that runs behind the engine to the bottom of the coolant reservoir.

 

Not overfilling for sure. This bleeder line just dumps behind the engine into the atmosphere? There seems to be A LOT more fluid overflowing than a bleeder line could handle. Almost looks like when the engine is overheating, not as bad but definitely overflowing in mass amounts.

 

Hey there Suicidecharley, welcome to the Forum! If your sure overheating is not the issue, and the coolant fans are working. Make sure both radiator hoses are hot at the radiator and block. Also good heat at the heater core hoses, both hoses should be hot, to weed out a restriction within the system and to make sure the water pump and thermostat are working properly. Next, I would recommend hooking up a pressure tester gauge to the coolant expansion reservoir. Install the pressure gauge at the over flow/expansion tank where the fill cap screws on, but don't pump it up, let the system build pressure on it's own, and see how high it goes. The proper pressure should be listed on your reservoir expansion cap. Anything higher than that, then pressure is building inside the cooling system. Possibly a cracked head or leaking head gasket. Make sure your oil is clean and clear looking, it should not look foamy like a milk shake. Compression can leak into the cooling system, but that doesn't always mean water will get into the oil, if it does it could damage the engine internally. Please let us know what you find.

 

suicide,

please create a signature that looks like ours for your posts.
First Name/Location
Year model mileage for all Saturns
Other rides you own (opt)

Go to top rt of page
clk on name>>userCP>>edit signature on left side.

This way we always know the basics of the cars you're posting about.
For example, we don't know the mileage on this vehicle.

How many miles on it?

While I'm at it:

Is it the original
----radiator
----water pump
----thermostat ?

 

134K new to me 98 SW1. As far as I know, original everything. I didn't get a chance last night to go through the checks recommended. I'll get through them tonight and report back late this evening. I appreciate all the help!

 

The bleed line does not vent to the atmosphere. It goes from the high point in the engine to the reservoir so any air bubbles end up in the reservoir.

 

It is not uncommon for an engine to heat spike once it is shut down. A heat spike would indeed cause water once heated to expand or some portion of the engine where flow of the coolant is restricted by age and/or an accumulating of crud for some reason or another. I do not know what might be the problem as it is not common, but water would normally continue to flow through the system as the engine cools down. I believe the word I am looking for is a thermo syphon system. For example the infamous Model T Ford of yesteryear did not have a water pump. Hot water rises and cold water falls so water would flow through the radiator by virtue of the water cooling thus falling to the bottom while hot water entered from the engine at the top. The point? If the overflow tank is overflowing than there might be something like a collapsed radiator hose or the thermostat is defective and closing when it should not be and once the engine is shut off thus shutting off the water pump, water or coolant is restricted to flow and as it expands it ends up in the water reservoir with no place to go but out. -(Sorry thinking by typing)-


Second thought.
I had a problem with my Saturn in that the overflow tank had been rubbing on a bolt or something like that and wore a hole through the plastic. It was on a side adjacent to the inner fender well and I believe the symptom was pretty much the same. It was a long time ago and it only showed up as a loss of water once the car was stopped. I had to physically remove the over flow tank to see the problem.

 

Sorry I was not able to get to this last night. Ended up working on my other vehicle. Keith thanks for the explanation on the vent tube. Makes complete sense.

Uncljohn I think there is something to what you replied with. Since this issue only happens after shut off maybe the thermostat is closing prior to cooling, car came with an extra thermostat so that might be a clue lol.

Drove the car to work today, no issues and temp gauge read a steady 1/4 all the way here. Cool morning may have assisted with that. No fluid dump. I'll be taking it out on my lunch as well to get it smogged. I'll check the radiator hoses once it's all warmed up and at the smog shop.

 

Ok went on a lunch run to get it smogged, noticed that when idling the temp gauge moved to almost half. Checked the hoses top driver side and thermostat side I could feel pressure as I squeezed. Didn't check again after temp gauge rose. no overflow this time.

As for the smog, the test module under the console isn't working properly. Went to two different shops and both of their computers weren't getting signals from the module. I'll need to research this as well.