Normal Coolant temp

[cadillac360]

Hi. I bought my 96 deville about a year ago and never had any problems with it. There had always been a very slow coolant leak and when I noticed it they were using green coolant. I just recently had the water pump+belt replaced and the system flushed and replaced with dexcool (no leak now). Now my question is this: When i was running the green coolant my normal temperature ranged from 190-200's. The highest it ever got was 212. Now that the dexcool is in it, it runs around 200-220's. I know that the boiling point in good conditions is like 260 or something but i was just wondering if this was normal because for the longest time i never saw it go above 200.

It is a 96 deville with the 4.6 northstar with about 163K miles, and i drive it in florida and the temp is always in the 90's.

[BodybyFisher]

I have a 96 Deville also. You are not being specific enough with your 200 to 220.. While I don't have a problem with that range you have not told me when those ranges occur.

My temps will run 195 to 203 at highway speeds, and in traffic I will run up to 222 in the winter and 226 in the summer. In July in 99 degree heat after a 400 mile trip in bumper to bumper traffic I ran up as high as 233.

Drive a couple of days and restate your temps for us unless you know them

By the way, once green was used you will no longer benefit from Dexcool's long life. You will still need to change your coolant based on the GREEN schedule at 2 years/24,000 miles as the green has coated your cooling system with silicates once it was used. You can keep the Dexcool in but be sure to change it at 2 years/24K miles

[Cadillac Jim]

Both red and green antifreeze are ethelene glycol based. The difference is that green antifreeze uses silicates for corrosion prevention and leak prevention, while red antifreeze uses organic acid technology (OAT) for corrosion prevention. As you know, OAT does not live well with silicates, so you needed to flush your system to change over. Some recent OAT antifreezes are formulated to be compatible with silicates, and they are green. These are the ones that are compatible with all antifreezes. Your system may have had this in it. Look at the Wikipedia anti-freeze page for more information.

Nothing cools as well as pure water, but the Northstar cooling system has plenty of reserve. A cooling system in good condition will provide a very stable temperature gauge.

You are observing about a 10 degree increase in temperature that is very stable -- you see about 10 degrees higher coolant temperature for any given operating condition. Did you change the thermostate when you changed the water pump? Most people do, and most newer cars use a 190 degree or 195 degree thermostat. The Northstar uses a 180 degree thermostat.

[BodybyFisher]

My Northstar uses a 195 degree thermostat I think that is spec.

[Cadillac Jim]

I thought that 1997 ETC did too, because it was a California car if nothing else, until I bought one. I checked the Stant application bot on their web site to be sure before I made the last post, and only one thermostat was listed: 180 degrees.

[BodybyFisher]

That's the first I ever heard that, as far as I knew it was 195

[Cadillac Jim]

I had a hard time with that, too. That's why I checked the Stant part locator today before I posted. If your temperature readings agree with those of cadillac360, then there is probably no problem. Unless I noticed a decrease in performance or some such, I would not hurry about changing to an 180 degree thermostat. But, I would get the right one, and a radiator cap, from the dealer and put them on when I had an hour or two.

[Ranger]

My '97 Deville ran a consistant 206 in the summer and 213 in the winter. Your temps are fine.

I too thought that the Northstar used a 195 degree thermostat. I still have a '99 FSM and looked into it. While it does not mention at flat value figure, it does say that the operating range is 188 - 206.

[KHE]

The Stant information is wrong. The Northstar uses a 195 degree thermostat.

[BodybyFisher]

The Stant information is wrong. The Northstar uses a 195 degree thermostat.

I recall speaking to the GURU about changing from a 195 to a 180 and he was against the idea basically saying that the computer expected to see 195.

Its interesting to note however that Rockauto sells a 180 degree Gates stat along with an AC Delco (no degree mentioned)

[cadillac360]

I get those same ranges as you do fisher. In stop n go traffic the highest it got was 224. While crusing at about 50 it drops down to around 210-215. I havent got a chance to drive it on the highway yet. (I changed the thermastat about 6 months ago, and it seems to be working fine) I was just a little concerned because this is the first car I have owned that had the digital reads. I was a little suprised to see it jump to the 220s when it had barely ever reached 212.

So basically the dexcool runs hotter?

Why?

Oh and while im at it, I had the system flushed at a shop, will that remove the sealants from the green stuff, or will that always be there?

Sorry im asking so many questions, I just love my caddy!

[Ranger]

I don't think that Dex runs any hotter than green coolant. Jsut the nature of the beast.

If it was flushed or drained, the sealant was removed and should be added again.