calling all Mechanics!! Need Advice

Ok. So I bought a commuter car to park the truck and save on Gas. I knew the heat was mild when I bought it and am now trying to diagnose. Heat is very weak and almost cold, just enough to keep the windows from frosting up.

It is a 2000 Saturn with the 1.9. Pulled the dash out to get at the heater core thinking that was the problem. Heater core gets warm, (I can keep my hand on it when running) but when I put the blower on the heater core turns ice cold and can’t keep up. Both inlets to the core are warm when no blower is on so I don’t believe the core is bad or blocked. When blower is on, it takes all the heat out of the core so only one is warm and the exit is cold. I also felt all the hoses in the system. All are warm (not hot enough that you can’t touch them) which seems they are circulating)

Coolant level is fine and the temp sensor was replaced 2 years ago (35K). When running the temp gauge in the car runs between ¼ and 1/2 and stays steady.

I am at a loss of what it could be. My thinking is I have a thermostat that is stuck open and not allowing the coolant to get warm enough or possible bad water pump?

I am open to ideas and advice to anyone that has them!!

Thanks in advance.

Sounds like a thermostat to me if it was the waterpump it would over heat even in the cold temps. Not for sure what size a saturn uses but thinking maybe a 165 degree thermostat and u should not be able to touch the heater core. Remember your average home hot water is roughly 120 -130 and anything over 125 can cause scalding and burns. So i would start with a thermostat being that its an under $20 fix.

1st..Knowing the temp of thermostat you have in your car is helpful,some are as low as 150 and some would as high as 195 if possible have a scanner hooked up to the car during warm up and see what the running temp is and drive down the road with the scanner on to watch the full warm up (hot)temp is.If you see a low running temp,suspect a bad thermostat, if you see a good high temp, suspect a partial plugged heater core

2nd… and the easiest to replace would be the thermostat.

Hope this helps out.

Jeff

I have a 2007 Chevy Cobalt and at normal operating temp it runs at 190 degrees. I think your thermostat is stuck open also.

well you have it that fare apart you should put in a new core but since you can put your hand on it when runing and its up to temp i supect that you have a faulty t stat.that is if you dont have any run problems,engine miss.if you do might have a bad head gasket causing air to get in to the cooling sys.most times this happens the temp gage will act funy-be at normial then jump to hot.also you can smell a sweet smell out the tail pipe ie coolant.hope this helps.

This doesn’t sound like your issue but what I’ve seen before on saturns is the heater core fins will plug up. When this happes you won’t get very good air flow out the defrost. you can hear the fan spin harder but not much more air flow when on high than when on low fan setting. I’ve pulled them out and cleaned them and everything worked as it should after but it’s not fun pulling them out. Another good reason for cabin air filters.

Spec for 2000 saturn 1.9L thermostat opening temp is 182-190 degrees F. According to the GM service manual. I would recommend replacing the Thermostat.

Dude not to pick on you, but I would tried a $ 8 and a half hour thermostat, before tearing apart the dash… I’m willing to bet that’s you issue. I could try blocking the rad and driving a bit to see if that gets you some temp, my 5.4L would not even budge the temp with it stuck open.

when running at operating temp, are both upper and lower radiator hoses pressurized? did you checked to see if the heater core was blocked when you had it out? what you descibe from the gauge on the dash sounds like it is cooling in the normal range! is the temp at half when sitting idling and at a quarter while driving?

How’s the anti-freeze levels? Check under the cap and in the overflow tank. If the temp gauge is operating at 1/4-1/2 and not moving to cold, I’m willing to bet it isn’t the thermostat. I’ve had my temp gauge tell me the engine is cold if the T-stat is stuck open.

I helped a co-worker with a no heat issue and it was a common issue in this Volkswagon that the heater core gunked up inside (and vapor lock issues too). Had to backflush heater core, and some guys blew compressed air through the core after draining the system.

I googled “Saturn 1.9 no heat” and found people that have the same issue and they flushed the cooling system, backflushed the heater core and filled with new coolant. It worked for them. May be time for a coolant flush anyways??

Good luck.

Thanks for all the replys. Since I pretty much have everything taken appart, I am going to put in a new t-stat and heater core (parts are only 50.00) and flush with new coolant. I hope that will do the trick. Was going to try tonight, but it is alreay -2 and too cold! Should be fun with a non heated garage to work in!

Yikes! Yup been there done that, not much fun good luck!

I’m scarred from an old girlfriend’s Pontiac Grand Prix…

Or did I mention the time my power steering hose came off at -10 Working in the winter and the cold is easily 10X worse than any other time.

find out what the temp is for the old thermostat and throw it in water at or slightly above that temp and you should beable to see it pop open!

Some heater hoses have valves in them that allow a certain amount of hot water go to the heater core. Check and see if the valves are working right from the temp levers on the dash. Not saying yours do have them but Ive seen the times when the connecting cables were broken or the dash lever assembly itself was, not letting hot water go to the heater core. Check and see if you have them in the heater hoses and if they are there make sure thier opening and closeing with someone in the car operating the heat level levers. IT never hurts to change the heater core and flush the system. If the system ever had a leak chances are they tried to stop the leak with the leak stopper that is a brown liquid that has small chunks in it, this plugs radiator cores big time, never use that stuff, use the powdered particle stuff that comes in a tube thats about an inch in Dia, by about 3″ long, thats the stuff to use to stop leaks, the other stuff just plugs your radiator and heater core and makes a mess of the cooling system.

back flush heater core i have to do it on mine every winter

Thanks again. Just got the job done. Changed the heater core and the thermostat. Thermostat was harder than the core as you need baby hands to get to the bolts. Anyway have very hot heat now!

One more question. Now I have coolant all over my tools and bucket that I was using. Any advice on how to get the tools clean from any residue? I tried spraying them with starting fluid and that did not do the trick.

Any thoughts?

Dish soap and warm water in a bucket then spray down with WD-40