Quick&Short T-Stat question!

[only8v]

I am having this issue as well!     Its killing me

I have installed new rad, hoses, water pump, 3 thermostats, overflow tank, coolant sensors, overflow sensor, thermofan switch.......

car runs EXACTLY how OP said.   upper rad hose is hot, lower is cool, Fan never comes on. Uses no coolant, and no oil.


Any answers?

[8v-of-fury]

I am having this issue as well!     Its killing me

I have installed new rad, hoses, water pump, 3 thermostats, overflow tank, coolant sensors, overflow sensor, thermofan switch.......

car runs EXACTLY how OP said.   upper rad hose is hot, lower is cool, Fan never comes on. Uses no coolant, and no oil.


Any answers?

If the upper rad hose is hot, and the lower is not.. does this not make you think the coolant is not getting through the rad?? If you have checked everything but the rad itself, i would guess a blockage.

[Smokey Eddy]

yeah that sounds definitely like a blockage... everything should feel hot to our sensitive hands. even the "cold" side of the rad.

the gauge in the dash could just be faulty... or do you have over heating problems?

[only8v]

this is a new rad. no blockage. I thought that is what it was, but that has been eliminated.

what would you classify as overheating.    no coolant bubbling, but upper hose is slightly pressurized.

could it be the thermostat again?

[Smokey Eddy]

does the gauge simply just read higher than you want?...
if so then i'd stop wasting your money. the gauges are old... tired... don't work 100% accurate.
Get an external one if you're worried about it. or run a  70 degree T-stat.

[only8v]

the gauge will fluctuate from normal to really hot in a few min.  The strange thing is that the heat from the heater does the same thing. When the gauge reads hot, the heater output is scorching. The fan never comes on, but has been jumper tested and works. should the lines be slightly pressurized?

[8v-of-fury]

uh-oh... Head gasket?

these are all tell-tale signs aren't they Ed?

pressurized hoses, loss of heater heat, gauge going crazy, rad not getting hot. But you said it doesnt use coolant or oil.... Hmm Still could be a HG... if it were putting enough air in the system to cause the liquid to not move around

[Smokey Eddy]

Yes.

well if it's not over heating then i don't know what the issue is?

...

I have no problem with driving my car the way it is now. the oil isn't above normal temp.
If it really concerns you you can very easily (even just temporarily) rig up a water temp gauge and drive around with it.


EDIT: Oh YES Jer, well spotted. Does the temp light flash? does the reservoir seem to drain?

The hoses will always be hard under normal driving conditions.
but honestly, i'd get a gauge on there with numbers and see what is really going on.

[clbanman]

the gauge will fluctuate from normal to really hot in a few min.  The strange thing is that the heat from the heater does the same thing. When the gauge reads hot, the heater output is scorching. The fan never comes on, but has been jumper tested and works. should the lines be slightly pressurized?

You need to get an accurate definition of "really hot".  Mine runs between 5/8 and 3/4 on the factory temp gauge and never overheats (other than the one time the water pump belt was slipping in a thunderstorm).  My fan rarely ever comes on.  Hot coolant goes into the rad.  If the rad is very efficient, what comes out won't be very warm.  My rad outlet hose only feels hot on warm summer days when I've been beating on it.  On mine,  the fan only comes on in the summer and even then not often except for stop and go traffic.   At this time of year the thermostat only seems to open for brief periods, lets a little coolant through the rad to drop the temps, and then either closes partially or fully.  The fact that your heater temp is fluctuating indicates to me that something in your system is dropping the coolant temperature, which I can only see as being the rad or even the heater itself.  On cold days when I'm running my heater, the temp can drop below my "normal" range and the heater output will drop but the rad never sees flow.  If your rad is taking enough heat out of the coolant, your fan may not ever need to come on.   These type of problems are when I miss the rads that have a cap on the rad itself.  You can leave the cap off and visually see when you have flow through the rad.  Upper hose should be slightly pressurized as most cooling systems pressurize to about 16-18 pounds.

[burn_your_money]

Yeah I don't think I have ever heard my rad fan come on. My gauge usually runs at the last white mark on a late mk2.

When I get home today after work I'll try to remember to grab my rad hoses and see what they are doing

[Smokey Eddy]

Don't burn your self tyler!!!

[only8v]

ok, so I drained my coolant again (5th time) and decided to check my thermostat. I also purchased 2 other thermostats for good measure.  I bought two motorad stats a 160, 180 deg(71, 82 deg ) and compared them to my other new thermostat (which was in the car) a WAHLER 188 deg (87deg). For the record, the Wahler thermostat is 10X the quality of the motorad products. the opening is at least  1.5 X the diameter and the overall construction is far superior.  It makes me sad that it was not operating in the rated range. I wonder if the later opening is caused by the much larger preload springs on the Wahler?  

I put a pot of water on the stove and put all three thermostats in and watched when each of them opened. The 160deg opened at around 170 and was full open at about 185deg. The 180 started opening at around 185 and was fully open at 195. The 188 deg opened at around 205 and was fully opened well after boil.  

I think this could be my issue. I am going to swap out to the 160deg and see if my gauge reads back in the normal range.

Thanks for all the help.

[jtanguay]

ok, so I drained my coolant again (5th time) and decided to check my thermostat. I also purchased 2 other thermostats for good measure.  I bought two motorad stats a 160, 180 deg(71, 82 deg ) and compared them to my other new thermostat (which was in the car) a WAHLER 188 deg (87deg). For the record, the Wahler thermostat is 10X the quality of the motorad products. the opening is at least  1.5 X the diameter and the overall construction is far superior.  It makes me sad that it was not operating in the rated range. I wonder if the later opening is caused by the much larger preload springs on the Wahler?  

I put a pot of water on the stove and put all three thermostats in and watched when each of them opened. The 160deg opened at around 170 and was full open at about 185deg. The 180 started opening at around 185 and was fully open at 195. The 188 deg opened at around 205 and was fully opened well after boil.  

I think this could be my issue. I am going to swap out to the 160deg and see if my gauge reads back in the normal range.

Thanks for all the help.

i had the same problem as you.  $30 thermostat from the dealer.. i'll never do that again  :roll: my cars temp would climb wayyy too high!  in the winter its nice to have gobs of heat though... but maybe only for those less than -20C days/nights???

i went to c-tire and bought a 192F t-stat, confirmed that it was opening in the right range with boiling water, and i've never had a problem since.

[sdwarf36]

Since I run WVO-warm is good. I have the hottest thermostat I can get (195?) My temp gauge runs at the 3/4 mark all the time-except the 20 mile stretch of hiway where it might drop down on the coldest days. I have a cover blocking my radiator also. Funny thing-i pull the cover off the grill this time of year the water temp doesnt change-but my (veg) oil temp drops. And my fan also will only come on in stop+ go traffic on the hottest day.

[Smokey Eddy]

I'll be changing mine soon too with this warmer weather.
stupid little things can cause so much damage.