Need help with this one... 1996 SW1 1.9L Car overheated two weeks ago the shop replaced the radiator with a brand new one. One week later it overheats again. Shop tells me the fan is not engaging thats the reason. Well i bring it home and throw in a new thermostat solve the fan issue and replace the cooling temp sensor to fix the guage that stopped working. Car still rides around 3/4 on guage and the heat and a/c does not work fan kicks on when temp is getting close to the redline and does cool it down. I need some pointers i am thinking one or all of these symptoms, Blown head gasket, water pump, heater core or heater sensor let me know what you think thanks.

 

You need to verify that the engine is actually reaching those temps first off. Never trust factory gauges. On my sl my gauge reads in between half and 3/4 before the fan comes on. With a manual gauge on it only reads 195-210 degrees. Nothing close to what my dash says. With a infrared heat gun same thing. (1)If the coolant system was not maintained, the aluminum heads corrode leaving trash and white sludge behind and block coolant passages on the head, head gasket, block if severe. (2) Saturn heads are known for obtaining cracks, leaking valve stem seals on LLO engine in paticular, prone to blow head gaskets. (3) Get or rent a block tester to check and see if you have a blown head and or a cracked one. Check for water in oil, oil in water, pressure in coolant resevior ( if this was the case you would know).Take you water pump off and check the impeller. Most likely from experience i would suspect head/head gasket problems. As far as the cooling fan issue. SW1's and SL1, Some cars have 2 coolant sensors and some have one. One by the thermostat area and one on the end of the head. SW/SL Problems : Power distribution blocks have been known to have bad connections to the relays and melt the plastic, Bad wire or connection from the ecu to the coolant sensors, or worst case the ecu.

 

In the SW1 1.9L engine is there one or two coolant temp sensors?

 

GM told us that there are some models that have 2. One was for the cooling fan and one was for the gauge. I have only seen a hand full of these come through the shop that have the second sensor in my 5 years at saturn. Chances are you only have one. And your problem is most likely head related.

 

what test should i do to determine the head? i am willing to invest in the tools just dont know which one to go with. thank you.

 

First thing i would do is go buy a good block tester and the adapters for the coolant reservoir. The instructions will tell you what to do. Snap On and Matco Sell a good one if you want to spend the money. Or just go to O-Reilly Auto Parts and order one.This test will tell you if you have compression/fuel or other contaminates in the system. Which would indicate a bad head or head gasket. As far as the cooling fan issue. Check all wiring and relays. Power Distribution Blocks on these cars have a habbit of melting around the underneath side of the relays. From bad connections.

 

sounds good thanks and the fan i had already fixed by replacing the cooling temp sensor.

 

95 was the last year for 2 coolant temp sensors, 96 and up share one for the PCM and the gauge.

If the fan is not engaging and that WAS the problem, why'd they replace your radiator (was it leaking. blocked?) Sounds like a lame diag on round 1. Ask for your money back -- they did not fix your problem (unless it was leaking, etc.)

Indeed, the SOHC heads are prone to cracking, esp the mid 90's ones from all the posts on the forums.......

Compression check may also yield some insight.
If head gasket, you should see oil in coolant or vice versa (per earlier poster).

How much volume of coolant mix did you lose when it overheated? What did you replace it with?

 

Not much coolant at all was lost when it overheated a week after the radiator was replaced. I then put in a new thermostat and cooling temp sensor i did add another 1/4 of a jug more than what i drained. I am not driving the car anymore since i did these repairs but it has been driven for a 30 minute trip and 30 back three times since i did the repairs and it did not overheat but the needle dances round 3/4 then fan kicks on and goes back down but when i turn the heat on (not much heat at all coming out) it does seem like the temp raises but i turn it off in fear of overheating.

 

sounds like a partial blockage in the cooling system or possibly a water pump issue. If you're not getting heat, then I suspect the coolant is not circulating properly through the cooling system...could be a blockage or could be that water pump is not doing its job.