My 99' SE is running cold

[TJ4Jim]

I've been performing some overdue maintenance and TLC on her and as odd as it seems she is running cold.

When I made my way across country 13 months ago I noticed the gauge reading unusually cold so I chalked it up to the thermostat going bad. The conditions at that time were temps below freezing and heavy snow. I pulled out the thermostat the other day (fairly new 195 deg Super Stat) and replaced it with a new 195 deg Stant Super Stat and she is still on the cold side. I confirmed the temps with an infrared scanner and via the OBD reader that displays the stats and both show about 169 deg at idle indoors with +/- 50 deg ambient temps. When I raised the idle to about 2K for 5 minutes the temps dropped to 162 deg. The heat works fine btw.

The only thing I can figure at this point is the fan clutch has internally locked up and is not doing it's job.

Any thoughts ??

 

[StG58]

Even if the fan clutch was locked up, the thermostat should keep the engine temp in the 200 degree range. Bad thermostat from the factory? It's not unheard of. See if it opens and closes in a pot of boiling water, or throw another one in there.

 

[TJ4Jim]

Even if the fan clutch was locked up, the thermostat should keep the engine temp in the 200 degree range. Bad thermostat from the factory? It's not unheard of. See if it opens and closes in a pot of boiling water, or throw another one in there.

Unfortunately in my eyes only 2 thing will cause a temperature drop when the throttle is raised, a bad stat or fan clutch. I was just at a mental point of eliminating the stat when you posted your response, thanks.

I don't disagreed but 2 bad Stant's ?

Testing the stat may have to be the next move.

Update: Just had a brain fart and I am going to test the original stat rather then ripping the new one out.

 

[TJ4Jim]

Update: Just tested the old thermostat and it worked well within spec so it's not a thermostat issue. I do not see how I can blame the new stat when the same problem persists after a stat replacement, Could the 1/8" bleeder vent in the stat bypass the stat enough, I would not think so.

 

[Jerry Bransford]

Ever see big trucks on the highway in super-cold conditions with a big piece of cardboard in front of the radiator. That's done to help get the engine up to temperature when the air passing through the radiator is too cold to let the engine warm up enough. So it's possible your air temp is just too cold right now. The fan clutch shouldn't be able to cause any problems since the less it runs in cold conditions the better.

 

[TJ4Jim]

Ever see big trucks on the highway in super-cold conditions with a big piece of cardboard in front of the radiator. That's done to help get the engine up to temperature when the air passing through the radiator is too cold to let the engine warm up enough. So it's possible your air temp is just too cold right now. The fan clutch shouldn't be able to cause any problems since the less it runs in cold conditions the better.

I have seen that done and used to to that on my diesel pickup but ambient is 50 deg here right now. Can the fan clutch be locked up causing over cooling ?

 

[Jerry Bransford]

I have seen that done and used to to that on my diesel pickup but ambient is 50 deg here right now. Can the fan clutch be locked up causing over cooling ?

Based on that I'd figure out the problem with the thermostat to figure out why it's not closing enough to allow your engine to warm up. I can't recommend anything more than the Stant SuperStat you said you installed. It's facing the right direction and it's not getting clogged up with gunk keeping it open?

And your HVAC heater is not putting out hot enough air either to verify the engine truly isn't warming up? I ask to just verify the temperature gauge sender hasn't gone bad.

 

[TJ4Jim]

Based on that I'd figure out the problem with the thermostat to figure out why it's not closing enough to allow your engine to warm up. I can't recommend anything more than the Stant SuperStat you said you installed. It's facing the right direction and it's not getting clogged up with gunk keeping it open?

And your HVAC heater is not putting out hot enough air either to verify the engine truly isn't warming up? I ask to just verify the temperature gauge sender hasn't gone bad.

The heater is putting out decent heat and I did verify the operating temps with the hand held IR reader. The coolant is reasonably fresh GL5 and is running clean. I do not think it can be installed backwards as the t-stat housing will not accept the bulb end so that's pointed towards the block.

 

[Gigantor]

The heater is putting out decent heat and I did verify the operating temps with the hand held IR reader. The coolant is reasonably fresh GL5 and is running clean. I do not think it can be installed backwards as the t-stat housing will not accept the bulb end so that's pointed towards the block.

Hi- did you ever find the solution to this? I have all the same symptoms

 

[TJ4Jim]

Hi- did you ever find the solution to this? I have all the same symptoms

Actually it resolved itself without any issues since, was going to try another stat since is was the likely cause.