1994 Saturn



May, 17, 2006 AT 9:50 AM

I have a 94 saturn (manual tranny)with 110000 miles on it. It over heats when in 5th gear between 45 and 60 miles an hour. Above this it cools down to the middle peg on th e gauge. The car has a 97 engine (~70000 miles)put in it that I put in so I had to tap into the coolant temp sensor that goes to the computer for my gauge in my cluster since the 97 engine didnt have a spot for it. I flushed the radiator, put in a new water pump, still same problem. It doesnt over heat to the red, just a few millimeters past the middle notch while at any low rpms.
Whats confusing is it will actually cool down at idle or rpms greater than 2750 so it doesnt seem like its a thermostat. It also has a rough idle when itwarms up as well and doesnt want to crank up when its warm. Please help!

oh yeah its a dohc engine 1.9 litre sc1 I believe


7 Answers



May, 17, 2006 AT 12:06 PM

What temperature is the T-stat. YOU must have one installed. A T=stat controls the minimum operating temperature of an engine.

The other issue is you may have an air pocket in the cooling system and it should be bled so there is no trapped air. Good luck



May, 17, 2006 AT 1:52 PM

Lol I do have a thermostat installed.
Airpockets. Freakin airpockets.
I'll try that.



May, 17, 2006 AT 3:14 PM

There should be a bleeding screw that looks like a brake bleeding screw near the T-stat housing or close by. Get the engine hot and open the screw and leave it open until it has a steady stream



May, 17, 2006 AT 4:00 PM

Holy freakin crap.
Why hasnt anyone beenable to tell me this?
I asked the dealership and various stores.
Oh well
I really apreaciate it



May, 17, 2006 AT 4:25 PM

I hope this will solve your problem. Sometimes they leave out the bleeders and you have to open a hose like a heater hose to get rid of the trapped air. Hondas are horrible about it as they have 2 or three bleeding screws.

I have owned a garage for over 40 years +. My main jobs were to fix things everyone had given up on, even the dealers. My specialty was automotive electronics.

Since then I have been living the good life after I closed my shop in 98 and traveling the country in our Winnebago. Every now and then I answer questions on the forum. I have over 1000 under my belt.

Feel free to e mail me if you have any other problems at losone@cableone. Net

I may be an old dude but I keep up with the times!

Have a good day




May, 17, 2006 AT 7:03 PM

This is possibly more than you ever wanted to know in reference to the cooling system on your saturn.

First off the 95 and earlier 1.9 ltr engines did indeed have two temp sensors. One for the gauge and the other for the PCM. I have been told that you should not tap into the ECTS for the PCM wiring to feed your gauge. Hopefully Losone will explain it better than I. Something about impedance and screwing up the PCM. I am really just a pup when it comes to electricity!

That said you need to add another temp sensor. You can simply drill and tap the boss (flat spot) on the 97s cylinder head. This would be similar in location to the 95s gauge sensor. If you are not comfortable with that there are many other options. I have seen them JB welded to the head, tapped into the metal coolant line to the coolant tank, a metal tee in a heater hose and a few more that I won't mention.

My two favorite locations are the elbow that goes into the intake manifold or into the gooseneck for the top rad hose. Both make it simple to prevent metal shavings from entering the engine. I will e-mail photos as I can't for the life of me figure out how to include them in this post.

Do this first and see if your " overheating" continues. If So post back. There are several other things that can be checked.

[i: ea1eed4fa3]Some very Saturn specific info[/i: ea1eed4fa3]. The S-series cars are pretty much self burbing. There is a small line going back to the coolant tank above the upper rad hose connection at the motor. Its function is to purge air.

The excessive use of stop leak products is a bad idea. Especially on a Saturn as they have very small coolant passages and flow coolant through the heater core constantly. Plug up the heater core with excess stop leak and you'll get a car that won't purge air and that runs hot. At this point you will need to repeatedly flush the system.

I told you too much info.

Good luck and let us know. : )



May, 18, 2006 AT 11:09 PM

Seems about right, you guys rock I'll try that and post back

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