Hey, I have just purchased a 93 Saturn SC2 DOHC. I only paid 700 so I expected some glitches, but the previous owner didn't mention anything about it overheating. I took it to a MIDAS and they tested it and put about 350 dollars in it to stop it from overheating and it is still doing it. Here is what I know:


Midas replaced the thermostat and bypassed the sensor that kicks the fan on, because it didn't seem to be working, they installed a switch that leaves the fan on constantly while the car is on. They pressure tested the entire system and there are no leaks. Fluid is pumping through it fine, so the water pump appears to be fine.


If I start it up and let it sit, it goes to about the half way mark on the heat gauge and stays there and does not overheat. But once I start to drive it, it creeps above half way mark untill I stop at a stop sign or traffic light and then the heat gauge creeps up to the 3/4 mark and higher, that is when the overfill tank starts to overflow and sprays the engine with coolant and I start to get steam/smoke from the coolant on the engine.


So far it hasn't hit the actual red indicator on the gauge but it gets close enough and the overfill tank starts releasing coolant. The coolant indicator light just started comming on last night, but I think it is because I am low on coolant from it comming out of the overfill tank.


Midas thinks it is an electrical problem, but since they bypassed the fan, what other electrical components are involved with the coolant system. I have had vehicles in the past overheat and have had head gaskets blown because of it. So I don't want to take any chances, but I am also not convinced it is an electrical problem, although to be honest I do not know what all electrical components are involved.


PLEASE HELP and provide any suggestions or tips you can think of. This is the only transportation I have to get to work and need it to last at least a few months till tax return.


I thank you in advance for any suggestions or advice you can give,


Tim

 

FYI a constant running fan is bad news. An engine that is too cold is very bad.

 

The sensor that kicks the fan on is the Engine Coolant Temperature sensor (ECTS), which is one of the most critical sensors on an S car engine, affecting everything from when the aux cooling fan comes on to air/fuel mix to ...... The PCM uses this temp to tweak many parameters.

1) Replace the ECTS and connector with Saturn OEM brass tipped replacement. REPLACE THE CONNECTOR. Trust me. Corrosion here is a killer.

2) If the fan does not kick in on its own as the dash guage nears the 3/4 tick, check the fan relay. Sounds like the fan motor itself is okay since they were able to wire it to run constantly.

3) Idling at about the 1/2 tick is normal (usually a bit below, but ok). Not overheating at idle is also a good sign. Also means that thermostat is probably </span>opening properly, and water pump is somewhat functional.
However, flow rate through cooling system is low (based on low rpms) when idling. Heat and the rate </span>at which it is generated by the engine is also lower at idle.

If it begins to overheat only when you drive it, this literally is telling you that the car's cooling system cannot dissipate the heat quickly/efficiently enough. You said they pressure tested the cooling system and it has no leaks.

Did they check your radiator cap? I would replace it with Saturn OEM to be safe. It may be defective and releasing cooling system pressure before it is supposed to, which fills the expansion tank with coolant and makes it impossible for the cooling system to keep the engine cool (not enough coolant!)

If the radiator cap does not solve the issue ,then my guess is that you have a partial blockage somewhere in the cooling system (cooling channels in the block, radiator, etc) which is preventing the coolant from circulating freely enough to adequately dissipate the heat generated by the engine.

Derf

The previous owner cannot
possibly claim to have never "noticed" this -- I do believe there are
laws against concealing such things.....


Edited by: derf

 

My Saturn exhibits the same condition. The cooling system tank and cap are new, the fluid is at the proper level and there appears to be no leaks since the tank was replaced.


Does anyone have an electrical diagram of the cooling system (ECTS and aux fan)?


thanks in advance

 

Talldredge & Mjeltema,
That time of year to replace your coolant anyway so do a few extra`s.I have taken out my t-stat temporarily
to flush before and has worked well.I will send a drawn diagram of how your system works friday.for now you need to see if you can burp your engine the tstat removed will help and start with a cold engine and let her drink
while warming up.Now as derf would probably say why dont you just pour sand in it. Just kidding. The fan issue is from a 30amp fuse that feeds your relay of which both are located in the fuse compartment next to your air cleaner.You can swap out your ac relay or get a new one after you check the 30 amp fuse if its good. If these fail I believe there is an inline fuse on the black/pink wire going to the fan.I don`t know the extent of the hardwire they did for you.there are a couple other tricks but you might not need to go that far. Loss of ground could also be the culprit.
Good Luck,
Darryl T

 

I replaced the sensor and the connector assembly (very good advice regarding replacing the sensor connector also, spend the extra $23). The sensor had a split in tip and coolant had leaked into the connector area. With the new sensor and connector the engine temperature has never been so well controlled. It fluctuates slightly around the half-way mark now. This was money and time well spent to fix a nagging issue. Thanks for your help!