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'94 Eldorado
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26 Posts
Discussion Starter #1
Curious...what is the normal high-end (hot) coolant temp for this car? I live in a very hot town, where it's common to have 100-teens throughout the summer. I noticed my coolant temp registered in the 220's, up to 230. That just can't be normal? I have never flushed or changed the coolant since I've owned the car ('94 ETC bought in '98), just topped it off from time to time. Is it possible that the original coolant has lost it's ability to cool the engine? If so, will flushing and re-filling with new coolant help keep the running temps down?
 

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'93 STS (sold), now looking for a CTS Wagon soon!!
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503 Posts
Wouldn't hurt to refresh the coolant.

Use the correct coolant with the tablets. Search in this site for 'coolant'.

My ride gets to 218 up a hill, then at the top ( going slow) it goes to 223, then cools back down to 196. The temp changes are very consistent in my car.

My coolant is a year & a half old.

Make sure both fans turn on.
 

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White Diamond '03 DHS (with DTS floor shift)
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86,969 Posts
I have never flushed or changed the coolant since I've owned the car ('94 ETC bought in '98), just topped it off from time to time.
:eek:OMG! Change it now!

Is it possible that the original coolant has lost it's ability to cool the engine?
No, but it HAS lost its ability to protect the engine from corrosion and the head gaskets from deterioration. A '94 needs to be changed it every 2 years.

220-230 is a tad on the high side. Cooling fans come on low at 224 and I think high at 229. Follow Mouties advice an be sure they are working. BTW, they also run on high anytime the A/C is on.
 

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1992 STS / 2005 MB G500 / 2003 STS / 2006 XLR-V
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11,694 Posts
You had ample opportunity to change the coolant on that vehicle, at this point I'd say it is sounding like the beginning of a headgasket problem to me, the car is now FOURTEEN years old and has never had the coolant done.

I hope it is not, but thats along time for any car to go without something as rudimentary as a coolant change.

Replace the coolant and see if the condition persists... If it does, the quickest way to rule out any HG issues a cylinder leakdown test. This is a fairly inexpensive procedure.
 

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94 ETC 78 Eldo 69 Eldo
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170 Posts
for years my 94 eldo runs at 230f around town in slow stop and go traffic

moderate stop and go traffic runs around 220

highway runs around 207-212f

change colant every year (pull lower hose and refill and use 2 or 3 tabs)

fans come on as programmed and cool it down to about 212-217f

if i run around town with A/C on 212-220f

the engine is smart enought to protect itself

remember some cars are different than others (there are alot of variables)

i let my surge tank oeprate where it wants, usually about 3-inches or so below the top tab

every 2 or 3 thousand miles might have to add a pint sometimes, no big deal

everything seems to operate fine,

just my experience in the north east part of the country
 

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93 ETC
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77 Posts
You may benefit from a fresh thermostat. On my 93, I lowered my temps about 10 degrees across the board with a new stat.
 

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Cadillac 1992 Seville, Past 1993 Seville & a 2006 STS V-6
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121 Posts
my 1993 seville and my 1992 seville both go to 234F then the fan would come on, but this is on a hot day then the temp goes down to 199F I have never had a head go, but these are both 4.9 L
 

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1993 ETC, in Windsor, Ont.
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301 Posts
You definitely shoudl change the coolant, that's scary. But as far as operating temps go, I have read a report done on Northstar testing in the desert heat of Arizona, and they actually LIKE running hotter. The engines, upon teardown, are cleaner and in better condition, so don't worry about the temp.

But pleeeease change that coolant! You are scaling and rusting and corroding your cooling pasages.
 

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'94 Seville STS N*
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247 Posts
highest i've seen my northstar go is 223f (aside from when the radiator was leaking & my cap wasn't holding pressure correctly).

usually sits at about 217f when idle.

normal operating temps 196f(highway) to 210f (city traffic)
 

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1990 Sedan de Ville 1995 eldorado 2000 buick century
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89 Posts
well i got a ? then because my 95 eldorado was running in the 220's and my tank was leaking on the radiator so i replaced it went to the dealership and got the cooling system tablets and now it runs in the 230's and i live in atlanta so its hot here occasionaly in the 240 range but the fans come on and go off so it isnt as if they are constantly running, car has 104 k and i didnt change the thermostat or the cap because it wasnt running hot its just that the tank on the radiator was leaking any suggestions?
 

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'94 Eldorado
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26 Posts
Discussion Starter #13
Re: '94 Eldo Normal HOT Coolant Temp? UPDATE

I recently had my radiator replaced, based on a local allegedly trusted radiator specialty shop, telling me there was a 30 degree difference in temp range from the top to the bottom of the radiator. He said that was above the normally acceptable range of a properly functioning radiator, so I allowed them to replace it. They showed me the old radiator and I was able to see visible clogging in the bottom part of the radiator. Since then, the coolant temp, during 105-110 degree days, with a/c going, still peaked at 228! The guy at the shop also said he belives he saw evidence of the pump leaking and said it wouldn't hurt to replace the thermostat either. I don't want to be bent over a barrell, but I do have a 13 year old Eldo! Not sure what I'm going to do...
 
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