Hey guys and gals, I am a technician at a california shop and we got a 2001 Saturn L200 2.2L in the other day. Vehicle came in overheating. The upper radiator hose was hot to touch up at the engine but not hot towards the radiator. the lower hose where the Thermostat was not hot at all. so I recommended a T-Stat.

Replaced that T-stat and no cure. So I took the T-stat out and Made sure it was opening (It does at 200 degrees) So I left it out and was checking for pump flow. I couldn't really see any volume of coolant being pushed through the system so I suspected a bad water pump.

Replaced the water pump after ordering the special J-tool and still couldnt really see any good flow. So I decided to take the radiator out and make sure it wasn't plugged, ran water through it seemed fine to me but to make double sure I took it and had it flow tested. came back good.

Put the car back together and I still have the same lower radiator hose is cold at 220 degrees and the Upper hose is Hot. So I have a New water pump, New T-stat that I have reconfirmed opes at 200 It is an OE 180 thermostat. I cannot figure out for the life of me what else could be wrong at this point....

ANY IDEAS!?!?!?

 

Also the heater core hoses are not getting up to temp either.

 

No offense to you, but you didn't mount the t-stat backwards did you?

 

Nah I thought of that too, but it's correct. I even confirmed with alldata pictures. Plus it would'nt fit upside down into the housing.

 

Here is my problem with your description of the problem.
Over heating means things are hot. Every car I ever had that over heated, water hoses were hot. Nothing is cold.
You described hoses as upper and lower.
Radiators in these things are probably cross flow which means water goes from side to to side. I'm old school, old school cars water went from top to bottom.
Heat rises, cold falls.
If you get old enough, cars did not have water pumps.
When the water got hot, it rose out of the engine into the radiator where it got cold as if fell through the radiator and went out the lower hose back into the engine.
It wasn't horribly good as a system because engines were not all that powerful etc. etc.
but it worked.
Also every car I ever worked on had the thermostat in a water housing that went to the upper connection to the radiator, not the lower.
Even in Cross flow radiators.
Recently I bought a tool from Harbor frieght I could use in situations like this, a thermal gun you could point at the radiator and measure the termperature of it.
I figured with problems I have had where heat was a symptom of the problem I could measure it instead of guess.
SO
Something sounds wrong here, Heat >should< be in the upper hose with the thermostat not the lower one. Upper hose should be hot, lower hose should be cold so why do you think it is over heating? The gauge says so?
I think I would be trrying to find out why the gauge says so.
But I could be wrong too.

 

Yes, it's GM's reverse flow system. Thermostat is at the lower hose. I have my snap on scan tool reading the sensor temps. I cut it off at about 220 for there is no reason to go any further the T-Stat opens at 200. Today when I get some time I plan to bypass the heater core and make sure something funky isn't going on there.

 

By any chance, are you using the original hoses, or have you changed them out as well ??

 

So! I look up GM Reverse flow like a newby dummy and what do I find?
http://www.procarcare.com/icarumba/r...a_cooling1.asp
An INLET side thermostat on the lower hose!
And the water pump is gear drive!
Wanna bet the water pump gears are stripped or something like that and ain't working?
Now to emphasise, the lower hose on the radiator is always the inlet side hose, the upper hose is still the out let side, it should be hotter than the lower hose. Water still goes through the radiator more or less from top to bottom.
Although, sensors, and all are not perfect and temperatures can spike, if the temperature of the sensor indicates there is 220 degrees using a scan tool before it stabilizes, personally I still would like to know the temperature of the radiator, i'd also like to know what the heat gauge is saying, but I'm **** that way.

 

Yea i don't know man, The pump was replaced by a brand new pump and even the old one I took off wasn't stripped or damaged in any way, I even submerged it in water and made sure it was pumping. I blew shop air through every little hose I could find that went to the coolant system and even poured water from Various points to make sure it could make it back to the radiator. Even with the T-Stat out it just wouldn't flow through the radiator.

But when taking the radiator out and sending it out to be check the radiator shop said it was good. so I am still lost... Spent the better part of 2 and a half days on this car alone. Even re block checked it again yesterday.

Finally I just admitted defeat, offered to give the customer his money back and showed him everything that was done. I guess we'll really never know what the problem was here.

As far as the guages and radiator temp though the guages didn't work due to a faulty BCM so I had to use my snap-on scanner to read the temp sensor and I don't have a gun to detect temps but it wasn't 200 degrees. It would get Pretty warm but no where near too hot to touch. Coolant from the system would not flow into/out of the radiator or bypass hoses.

2 known good pumps. All I can think of is some restriction in the head or block somewhere. But I would still think if I poured water in from several locations and it made it through the whole system it would do the same with the pump, apparently not lol!!!

 

I hate deefeet. I built a fuel injected engine in 2000 and it ran poopy under 2000 rpm. I spent a lot of time and frustration on this thing over the next 5 years checking with tech support on the fuel injection and reading this and that. I finally got mad enough to park it for 6 months.
Finally figured it out, almost by accident.
The fuel injection was calibrated to run with a loose torque converter. For specific reasons I built the transmission to run with a tight torque converter. When it finally dawned on me what was happening and called a local transmission shop and had them build me a 2200rpm stall lock up torque converter, problems solved.
I and no one else either, had a clue.
Too bad, it would have been nice to know what was wrong.