Stange Happenings after Thermostat Change?

[MotoDog]

Ok, on 96 4.0L had heating problems for over a year. Loss of water. Finally after limping home on bottled water from the 24 packs of drinking water I took it apart. Turns out, the metal pipe (thermostat housing) had rusted out.

A little hole on the bottom. Figures because we have been putting water in it for a year with no coolant.

Ouch, lots of rust coming out!

So, the local Parts Store ordered a replacement pipe-Housing. This was the 40 mm one. Not at bad price!
Less than $18 by Dorman.
Next all day, 2 times off and on. Dropped those 6mm bolts into the dirt 10X!

New thermostat finally throw in boiling water for check. I can not get the dash
Gage to come up to normal temperatures! It used to set Half way, and when it overheated went upwards.
Now, it sets at cold, and some times a quarter a way up? I just drove 10-15 min drive. I never saw it go much past cold? I finally drilled a small (3/32") bypass hole in the new thermostat. I wonder what is happening.
Maybe needs air burping?
I don't want to fry the engine because the water temp is funky. I would change the T Sensor, but it worked OK a few days ago. So, I am left driving around with the Gage on C or a little past it. I wonder if the water is getting to the sensor?

Wondering what the REAL engine temperature is?

Mike

 

[lobo411]

Probably needs burping. After servicing, I'll fill mine until the radiator neck is full. Then I'll start the car with the radiator cap off, and let it gurgle out air, adding coolant every time it settles down. Usually after a minute of running, enough air will be let out that I can't add more coolant, so I replace the cap and drive it around. Let it sit overnight, and then check the radiator coolant level again the next morning. Usually, I'll need to add more coolant. Repeat until the filler neck is full first thing in the morning.

I did have a lazy temp gauge once too, though. I replaced the gauge temperature sender (the one with a single wire), and my dash gauge went from hanging out in the lower 1/3 to smack-middle.

 

[Bootless]

i have the same issue i replaced the sender but it still hangs out at the first line before normal

 

[96eb96]

some OHV engines have an issue with cooling and keeping the gauge correct. There was a bypass correction kit that isn't available anymore. These engines don't have a bypass hose and they said there is an issue with steam formation. My gauge never stays in the center, but wanders in 25-50% range. This is going on for years, have new sender, temp sensor, motorcraft stat, wp, clean coolant. I think I run a bit cool too, I scanned the truck and it never goes over 188. Heat is hot otherwise, runs fine.

Maybe I never burped the coolant right, the owners manual has a weird paragraph saying these engines need 7500 miles to full burp air. Bizzare.

 

[koda2000]

Are you sure that the thermostat is not defective and stuck open? I'v encountered more than a couple of defective new thermostats over the years. If you don't have one of those laser temp reading guns, you can use a meat thermometer, remove the radiator cap and stick it in there and run the engine for 15 mins or so to see what temp the coolant reaches. It shouldn't boil over as the coolant shouldn't be reaching anywhere near boiling point, but you might spill a little.