added coolant, now temp gauge reads colder

[tbomb]

i had a service station change my oil & filter 2-3 weeks ago and they also checked all of my other fluids. they noticed that my power steering was a little bit low, so they topped that off, and they noticed that my overflow bottle was empty - that's how they checked my coolant level. even though i only drove 4-5 blocks to get to the station and the engine wasnt "warm", i dont blame them for not popping the cap off the radiator. anyway, they added a quart of coolant. ever since that day, my temp gauge in the dash is now reading a little bit on the low side. i dont recall if the needle used to point at "50%" (right in the middle), but now it reads around 35-40%, which looks to be a little on the cold side.

is this normal? bad? what happens if there's too much coolant in the system? etc? i'd appreciate any comments/advice/whatever that you guys have to say.

TIA.

oh, btw, it's a 98 explorer 4.0 SOHC, 5R55E, 4wd, ~68,000 miles, blah blah blah, if that matters.

 

[MalcolmV8]

You cannot put to much coolant into the cooling system. It will only draw as much as it needs from the over flow bottle. When warm the coolant expands and excess is pushed into the overflow bottle. If you had driven 5 blocks and nothing had expanded in to the bottle there's a chance you were missing some coolant in addition to the bottle been empty. So probably you were running a little hot with air pockets in the cooling system?
Unfortunately the factory gauges are more like glorified idiot lights and not very accurate. Neither are the sending units.
Of course your thermostat could be stuck open too but luke warm heat from the vents usually gives this away.

 

[Eki]

There is nothing wrong with your temperature. According to Ford manual all readings between low and high is acceptable. Mine is same as your 40%, it sometimes get over 50%. I would be more worried with too empy system. Check coolant level when your engine is cold. Open radiator cap it should be full of coolant, coolant level in the overflow bottle should 40-50% no more than that.

 

[tbomb]

You cannot put to much coolant into the cooling system. It will only draw as much as it needs from the over flow bottle. When warm the coolant expands and excess is pushed into the overflow bottle. If you had driven 5 blocks and nothing had expanded in to the bottle there's a chance you were missing some coolant in addition to the bottle been empty. So probably you were running a little hot with air pockets in the cooling system?
Unfortunately the factory gauges are more like glorified idiot lights and not very accurate. Neither are the sending units.
Of course your thermostat could be stuck open too but luke warm heat from the vents usually gives this away.

thanks for the reply. i wasnt sure if the temp gauge was actually a "real" gauge, or just an idiot light. so i guess everything is normal then.

the shop didnt diagnose any problems, they just made sure my fluids were at the correct levels, so they just added the quart of coolant and called it a day.

i havent been getting luke warm heat from my vents; it's been HOT air out of the vents, just as it always has.

i suppose it's possible that i simply was just a little low on coolant...and if it was running a little on the hot side with air pockets in the system, i guess that may account for the gauge reading a touch on the cold side now (though, it's really just an idiot light.)

i'm glad to hear that you really can't have too much coolant in the system (obviously, i'm not stupid and wont go filling the overflow bottle to the top on a cold engine, heh.) i'll just keep an eye on it.

and if anyone else has anything to say, please keep replying here.

thanks.

 

[MalcolmV8]

No problem. Although by definition the gauge is real. It does vary with temperature. It's just not very accurate and that's why I call it a glorified idiot light. Notice how instead of degree F markings it just has the word NORMAL on it? Well that allows for a lot of tolerance and "slop" in how it works. I've swapped out brand new sending units for replacement brand new sending units and there is a variance in how they read. So if yours is reading on the "O" of "normal" and a buddies is on the "R" I wouldn't be to worried. As long as it's not on the L or beyond or sitting below N you should be fine.