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93 Northstar water temp.


thompsb

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Hi, new to your site, looks like a wealth of information. I belong to a diesel site and it has helped me more than you can believe!

Here is my issue: 1993 Eldo w/Northstar, 93000 miles, digital dash, runs great, shifts great. but........

My water temp. runs between 199 and 226 degrees.... up and down never over 226 yet.

The water pump, belt, 180 degree thermostat, are all fine. Radiator is clean as can be so is inside engine.

The fans work. hoses upper and lower are new. ALL air out of cooling systen and rad cap checks good.

When driving the temp goes up and down between above stated. Is this normal? Never runs bad or over heats..

I would think the temp would stabilize?? What do you all think??

Live in northern Illinois. Cold temps while this is going on...

Regards/Bruce <_<

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Your temps are relatively normal. I am not sure how sensitive the '93 gauges are. I know that they where dumbed down to keep people from freaking out. Keep an eye on it. If it gets much higher, then it may be time for concern.

Sounds like you did your homework and pretty much checked all the likely problem points. Nice work.

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You said the belt is fine, but what about the tensioner pulley, it can get stuck an lose tension causing the belt to slip. My bet would be that the ratio between the coolant and water is off. Anything above or below a 50/50 concentration may cause problems. How old is the thermostat? This is just a few things I could think of.

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My 93 ETC was running 208 to 223 before I replaced the radiator and thermostat. With those changes, I run 196 to 215.

If your thermostat isn't new, a fresh one may help lower your numbers some. But yours are not out of the range of what I've seen others report.

My temp does tend to fluctuate depending on how I'm driving.

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Not to highjack the forum or anything, but how come they stopped displaying the temperature in the DIC? Is it because more and more people are not car literate? My 03 Lesabre shows the exact oil pressure and exact temp, but Cadillac stopped that. I miss that from my 97.

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Not to highjack the forum or anything, but how come they stopped displaying the temperature in the DIC?

I seem to remember Guru saying something about a flurry of "the engine is running over 2XX and thats too hot" complaints, (or something like that) and GM just decided it was too big of headache. I believe the digital display was stopped in '95 (I have it...and I love it! :D ) however im relatively certain there is a way to activate it through the DIC in the 96&97 model years.

In regards to the original topic: I have found that the coolant/water ratio has a direct influence on Engine temps. My N* will typically run substantially cooler after a complete drain&fill with 50/50. I've overheated it a couple times and added straight coolant in order to top it off. While I haven't researched the matter I've found 2/3's of a gallon or so of straight coolant will cause the engine to run substantially hotter, maybe 7-10 degrees.

My avg temps typically run in the upper 190's to 21X during the fall winter, and it's not uncommon to get into the 230's during summer w/the ac on.

A.J.

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196-226 is pretty normal temp. In the colder weather I would expect around 200-205 for steady freeway driving. Sometimes it can briefly go a bit higher for no reason I can figure. In summer I would expect 205-226 for similar driving conditions. These engines do run hotter than many other's, it is part of the design.

If the car is new to you, I highly recommend changing the coolant at earliest opportunity. Worn out coolant is the number one problem with the Northstar; and many other aluminum engines. As it wears out you lose the corrosion protection, and thats when you start getting head gasket seepage, along with a big $$$$ repair bill. Use only the green coolant (silicone type) for replacement, mixed at 50/50! Add two tubes of Bars Leak Gold powder to the radiator hose that connects to the thermostat housing, NOT the surge tank. This is the normal OEM additive, for the Northstar engine, when changing the coolant.

Check the small hose that goes from the bottom of the surge tank to the hollow bolt near the water pump. It must flow freely to allow air to escape the water pump, or you will have cavitation problems, which can cause the engine to run hot. On a cold engine, loosen the surge tank cap, and then slip off the small hose at the hollow bolt location (see attached image). Coolant should flow out the hose and from the hollow bolt. If not clear them both, then reconnect them.

As mentioned by another, be sure the water pump belt tensioner is working freely, and can apply full pressure to the water pump belt. If the belt appears worn, look at the inside of the belt, replace it. Inexpensive belt and easy to replace.

Change your oil and filter as indicated by the Oil Life Monitor, usually about 6,000,to 7,000 miles. Regular oil is best, synthetic is a waste and can exacerbate seepage.

-George

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Drive'em like you own 'em. - ....................04 DTS............................

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196-226 is pretty normal temp. In the colder weather I would expect around 200-205 for steady freeway driving. Sometimes it can briefly go a bit higher for no reason I can figure. In summer I would expect 205-226 for similar driving conditions. These engines do run hotter than many other's, it is part of the design.

That is exactly my experience with the last three Northstar Eldorados I've owned. I wouldn't expect you have anything to be concerned about.

Coolant temperatures vary widely from moment to moment. It's the nature of this aluminum beast. Don't let it concern you.

If you have a 50/50 coolant mixture (VERY important) and you hit 250 degrees, then be VERY concerned. Otherwise, drive on!

You know about WOTs, don't you?

Regards,

Warren

P.S. I'm a big fan of "Tier-2" gasoline. Others would argue with me. Your call. You could search.

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There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises

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There is an override bit to set in the IPM to display coolant temperature in the DIC, according to the 1997 FSM. You can do it through the HVAC controls. I've dome a little customization from time to time, but not that one. I did disable the "Press brake to shift" message though; if someone doesn't know that, I don't want them driving my car.

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Yes, you can add the coolant temperature to the DIC, on '97 models for sure. I posted a how-to in the how-to forum (here is the link: http://caddyinfo.ipbhost.com/index.php?showtopic=179). I'd always run with that on, on my '97 SLS. The '98+ Sevilles don't have that option...not sure on the '98+ Eldorados.

Thermostats can have a big difference on the stabilization temperature as well -- some are just calibrated "higher" or "lower" within the manufacturing tolerance. My '97 ran directly on 190*F all the time, unless I was in traffic without A/C, and it'd go up to around 222*F before the fans kicked-in. But steady-state cruising, it'd never go above 200*F. Before I put the new thermostat and water pump in (due to the original pump seal leaking), it'd run about 194-201*F normally.

If your temperature cycles between 200*F and 225*F while you're driving straight down the highway, at a steady speed, that doesn't sound right. But under any other conditions (city/country driving with varying speeds), it can be a normal condition. Remember, these cars don't have mechanical fans, so there's no cooling air through the radiator unless the car is moving fast enough or the cooling fans are on (which doesn't occur until a high enough coolant temperature). That's why you see the cycling at slower speeds, and that's why the coolant temps (should) never go much over 226*F or so -- the coolant fans are on and should cool the engine back down.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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The only problem that I have is that you stated you had a 180 degree thermostat, stock is 195, if I am not mistaken. At 180 you might get poor heat.

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Not to beat up on the thermostat issue - but in the case of the two Northstar OEM thermostats I have had in my hands, neither one of them had a temperature value stamped on them.

My '98 Service Manual says nothing (that I can find) about thermostat temperature specification.

My '04 Deville Service Manual, page 6-14, says the thermostat full open temperature is 185 degrees.

Jim

Drive your car.

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Yes, I know that there is some question/variability in the stat spec, but I do recall the guru stating the putting a 180 in was not advisable and to stay with 195, the NS in question here is a 93, I believe the spec for my car is 195. I do know that they sell less than 195's, I just recall the guru being adament about 195 in most cases. My NS runs at 192 in the winter with a 195 stat, and my heat is adequate. I just saw the 180 stat discussed by this member and thought he used it because he felt his temps were high, and a side effect of that MAY be, poor heat...

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

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See, I don't think the stock 'stats ARE 195*F. My '97 service manual also specifies a full-open temperature of 185*F. It's impossible for the thermostat to be a 195*F if your car runs at 192*F -- a 195*F thermostat doesn't begin to open until 195*F...so it, by definition, can't regulate the temperature below that figure.

The reason our cars use a cooler thermostat, but still run in the 190-220*F range, is because the thermostat is on the inlet side of the cooling system, where temperatures are cooler. Conventionally, you have an outlet side thermostat, and the thermostat begins to open when the coolant IN THE ENGINE reaches its spec temperature (typically 195*F). That means the thermostat is regulating the HOT coolant at about that temperature (or typically in the low-200*F range). Because our thermostats are located on the inlet side of the system, they begin to open much sooner. The engine still runs at a "normal" range (low 200s typically), but the thermostat is spec'd differently simply because of where it's located in the system.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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All the stock Northstar thermostats are 180 degrees f . The normal output temperature is 195 F (rolling down the road at 30 mph to 90 mph). The difference of 15 degrees is due to the fact that the thermostat is at the point of intake from the radiator which is the coolest point in the engine, and the ECT sensor is on the outside of the rear of the right cylinder head, which is arguably the hottest point on the engine.

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-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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See, I don't think the stock 'stats ARE 195*F. My '97 service manual also specifies a full-open temperature of 185*F. It's impossible for the thermostat to be a 195*F if your car runs at 192*F -- a 195*F thermostat doesn't begin to open until 195*F...so it, by definition, can't regulate the temperature below that figure.

The reason our cars use a cooler thermostat, but still run in the 190-220*F range, is because the thermostat is on the inlet side of the cooling system, where temperatures are cooler. Conventionally, you have an outlet side thermostat, and the thermostat begins to open when the coolant IN THE ENGINE reaches its spec temperature (typically 195*F). That means the thermostat is regulating the HOT coolant at about that temperature (or typically in the low-200*F range). Because our thermostats are located on the inlet side of the system, they begin to open much sooner. The engine still runs at a "normal" range (low 200s typically), but the thermostat is spec'd differently simply because of where it's located in the system.

I see your point, but when I did my water pump, it said 195 on the box and it was stamped 195 on the brass pindle. IF it opens at 195, I in fact should NOT see less than 195, you are right. I see these 192's at highway speed, and get 192's only since I replaced the crossover gaskets, I never saw less than 195 at highway speed before that. I wish the guru's posts were still here, I remember him being adament about keeping the 195 stat in place due to the computer and heater.

This muddy spec is NOT unlike the spark plug gap that we have discussed in the past that has ranged from .050 to .060, the guru didn't think that the gap spec was too important if I recall that you found out

Pre-1995 - DTC codes OBD1  >>

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How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

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A 180 F thermostat will begin to open a little under 180 F and be fully open at 185 F. That's what the 1997 FSM test requires when testing the thermostat. I didn't think that 180 F was right, either, until I looked at the offerings from Rock Auto and the listings from the manufacturers, then drilled down in the FSM and looked at the testing process. The FSM gives a part number, not a temperature, for the thermostat, but the Rock Auto and other listings for thermostats for the Northstar are rated at 180 F. And, the requirement that it be fully open at 185 means that it needs to be a 180 F thermostat.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
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When I installed my new thermostat, it was a new ACDelco thermostat, and didn't have anything stamped on it that I recall. My normal running temperatures dropped from the high 190s to just about right at 190. Discussing this with the guru, I suggested that it was probably simply due to the fact that this particular thermostat was on the "low" end of the manufacturing tolerance, in terms of opening temperature; he agreed. I just think he didn't want to see folks putting in colder-than-stock thermostats, designed to run the engine at 180*F (which would actually open at 170*F or less probably).

Maybe they're stamped "195" because that's the temperature at which the engine should run with that thermostat -- because that's what most people associate that figure with (as opposed to an opening temperature design spec). Does that make any sense?

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Good information guys! OK, here is the latest. I drove to work this morning it was ZERO degrees outside. My water temp. ran between 199 and 206 (by my dash readout) I consider this great. IF I just idle, the temp. will slowly rise till the fan relay kicks in (about 226) and bring back down to 199~202. So I would say this is normal for this Eldo. Here is some more info on what I have done since aquiring this vehicle. (I have known this car since new, I am the second owner) Since 1993 all required service work has been completed, I have every record on file. After I got it, I have done the following.

Repalaced accessory and water pump belts.

Replaced both tensioners.

Replaced both radiator hoses.

Inspected radiator and old hoses for sludge etc, All were spotlessly clean.

Replaced stat with 180 degree as specified (A-C Delco 12559807)

Tightened/inspected all small heating etc, hoses.

Coolant (green) checked good. 50/50 (might change in summer)

Added Barrs Leak in process of new hoses (wet mixed b/4 pouring in hose)

Cleaned throttle body, inspect air cleaner.

Installed 4 new Michelins.

Needs!

Front rotors and pads, work good look bad (cheap rotors) will use better aftermarket.

Exhaust from cat back is OK but should replace this summer. (performance muffler?)

Get rid of the "apply brake to shift" say a post above that says you can do that.

Disable door locks when you put in gear, hate that...

Like!

This car is FAST when you WOT it for a mile! Top speed????

Rides great and I have averaged 18.5 MPG.

Appreciate all the feed-back !!!!

Freezing in Northern Illinois.

Thx/Bruce :D

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Looks good to me. Keep your coolant fresh and the oil changed.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Repalaced accessory and water pump belts.

Replaced both tensioners.

Replaced both radiator hoses.

Inspected radiator and old hoses for sludge etc, All were spotlessly clean.

Replaced stat with 180 degree as specified (A-C Delco 12559807)

Tightened/inspected all small heating etc, hoses.

Coolant (green) checked good. 50/50 (might change in summer)

Added Barrs Leak in process of new hoses (wet mixed b/4 pouring in hose)

Cleaned throttle body, inspect air cleaner.

Installed 4 new Michelins.

Good job. Looks like you have most of the bases covered. Very good preventive maintainence.

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The difference of 15 degrees is due to the fact that the thermostat is at the point of intake from the radiator which is the coolest point in the engine

If I remember correctly, it is just the opposite. The stat is on the outflow side to keep the engine temperatures more stabilized. If it where on the inflow side, the engine would get a slug of cool coolant when the stat opens (not good for head gaskets). When it got too hot it would close and then reopen again and the hot/cool (relatively speaking) would continue.

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The Northstar and the latest generation of bow-tie engines (the LS series) use reverse-flow cooling systems. Because of that, it's more than possible to put the wrong type of thermostat in one of these engines, or to put it in backwards. This also leads to use of a lower temperature thermostat; if the Northstar had the thermostat on the output it would have to be a 195 degree.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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It's an inlet design, Larry.

This contains more information than required for this thread (the design intent is important) but here is part of an exhaustive post on the subject from you-know-who (the writing style is distinctive).

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

"The main consideration of an all aluminum engine is NOT the absolute

coolant temps observed but maintaining thermal stability throughout

the engine. Keeping the hot spots cool and the cool spots hot

eliminates thermal fatigue of gaskets and seals and allows the

engine to "grow" and "shrink" with coolant temp changes as a single

entity...not dissimilar parts that stress the fasteners and gaskets.

This is accomplished by having VERY HIGH coolant flow rates thru the

block and heads constantly so as to maintain an even temperature

gradient across the engine regardless of the observed coolant temp.

Keeping in mind that the water pump can pump about 105 GPM at

6500.....only about 45 GPM is directed to the radiator. That is

sufficient for the heat rejection required and is the maximum that

is allowable for the long term life of the radiator....erosion of

the tubes, tanks, and end-tank oil coolers would result with more

flow. So....where does the other 60 GPM go....???....it is

recirculate back thru the block and heads in a re-circulation

loop....part of which is the heater core circuit which accounts for

about 7 GPM of flow at maximum engine RPM. The main part of the

recirculation circuit is the cast passages inside the water

crossover casting that the water pump resides in. When you remove

the stat you can see one of the coolant bypass passages at the end

of the thermostat mounting port...the large hole that the spring

loaded paddle covers.

The inlet thermostat design is used to minimize the efficiency of

the water pump and to limit thermostat induced temperature cycling

in colder weather. The stat has many functions. The spring loaded

paddle at the end closes off the bypass port (the bypass that

bypasses that 60 GPM back thru the heads and block) until sufficient

coolant pressure blows it off and establishes flow. Under normal

conditions the temperature sensing element is bathed in the bypass

flow consisting of the direct bypass port, the heater core circute

and "cold" water that is being admitted by the thermostat. This lets

the stat see a true operating temp of the engine as opposed to a

more conventional exit side stat that only sees coolant temp when it

opens and coolant is flowing past."

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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