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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #1 ·
Hey guys. Yesterday while driving on the highway my Lacs temperature got into the red ,the ac fan shut off, n I drove it for about another 10 min off the highway before I could stop. I parked it and it sat for about 3hrs. After, I drove again about a 10 mins drive w no problems(temp gauge stayed dead center) except, the "change engine oil" indicator came up on the dash. When I got to my destination I checked the fluids--engine oil good. Low on coolant. Drove again - home - about a 20 min drive (temp dead center) n topped off my coolant. Question is, did I burn the viscosity of the engine oil ? Should I change it before driving ? Car didn't smoke or wires short or nothing like that??
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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When you get an overheat warning the OLM goes to 0 immediately. If you were able to get off the road quickly I doubt if the oil is harmed, but if it looks cloudy or smells burned then change it and the filter tomorrow morning.

Now diagnose the low coolant and cause of the overheat. Check the coolant purge line for correct flow. Check the water pump drive belt system - the tensioner pulley.

Butt plug & air box 2 notes.JPG


Water crossover assembled.gif
water pump drive pulleys.gif
 

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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #3 ·
Hey Sub. Thanx for the response. N info on coolant. Gonna check the purge line now. But also why would the change engine oil indicator come on? And...what is olm

Thanks again.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Owner's manual. OLM = Oil Life Monitor, that complicated system that watches driving conditions and posts a Change Oil Soon when it determines it's time.

Oil is the only thing that cools the engine machinery guts. It passes its heat off the the block surfaces and oil pan surface for coolant and air cooling. Coolant loss and subsequent engine overheat overheats the oil.
 

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Super Moderator
2010 DTS
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88,013 Posts
But also why would the change engine oil indicator come on?
Oil deteriorates when subjected to very high temperatures. When the engine overheats (gauge goes into the red), the PCM then trips the CHANGE OIL warning.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Here's your temp gauge, tick mark meaning, and fan settings.

Temp gauge - my numbers.jpg
 

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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #8 ·
So had just got the Seville just before the San Antonio winter storm. To prevent a radiator freeze I poured in some of the general (all vehicle) green prestone 50/50 that my grandma had at home. After the storm, while driving her, i noticed a low coolant leak. Looked into it and found out I was supposed to put in dexcool. As well as sealant when doing a coolant change. I did a radiator flush with distilled water then added the half dexcool and half distilled water. Since I've been having overheating problems. I think due to the bars leak pellets..or rather bricks they looked more like. Question is should I try to flush it out? And how do I ?
 

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89 Deville, 06 DTS
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98 Posts
FLUSH IT OUT!!!!
There’s a lot of misinformation on these forums about using bars leak in the cooling system. It was initially recommended in 1980s GM products due to leaks in the porous aluminum engine castings, but GM has since rescinded the recommendation due to other issues caused by using anti-leak products in the coolant.

Get every trace of that stuff out of the system. If you put in in upstream of the thermostat, it’s most likely caused a stuck thermo, causing your overheat issue.

I’m sure by now you’ve read up on how DexCool reacts when exposed to the green stuff. Get every trace of old coolant out of the engine. A simple radiator flush isn’t gonna do it (at least it wouldn’t if it were my car).
 

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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #10 ·
FLUSH IT OUT!!!!
There’s a lot of misinformation on these forums about using bars leak in the cooling system. It was initially recommended in 1980s GM products due to leaks in the porous aluminum engine castings, but GM has since rescinded the recommendation due to other issues caused by using anti-leak products in the coolant.

Get every trace of that stuff out of the system. If you put in in upstream of the thermostat, it’s most likely caused a stuck thermo, causing your overheat issue.

I’m sure by now you’ve read up on how DexCool reacts when exposed to the green stuff. Get every trace of old coolant out of the engine. A simple radiator flush isn’t gonna do it (at least it wouldn’t if it were my car).
K. So what's the proper/best cost efficient way to flush it out?

How do I properly flush out bars-leak? Can I, should I use Prestone radiator flush and cleaner?
 

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There are coolant filters used for trucks. If there is room to install one that would allow filtration of anything you added as the car runs. The most effective would be an adapter for one of the hoses which has a spin-on filter similar in appearance to an oil filter. I'm not sure if you have room for something like that.

Scott
 

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89 Deville, 06 DTS
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98 Posts

I know I’m gonna get flack for posting a Scotty Kilmer video here, but this is the way I choose to do a block flush. If you’ve shoved BarsLeak down the block, you’re gonna wanna remove the thermostat anyways, at least for inspection and cleaning.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The Northstar cooling system is very, very, very different from that Toyota. Use the correct GM service manuals.

Lots more info on coolant, overheating, purge line, and other such stuff in the stickies in the Engines, Northstar forum.

Use any coolant you like, no sealant tablets (discontinued in 2006 or 2007), and change it every 4 years. The GM/Cadillac/Helm service manuals used to state that the sealant tablets were crushed and installed in the lower radiator hose.

For the correct online GM/Cadillac service manuals subscribe the car to www.alldatadiy.com

Clean out that purge line and hollow bolt/nipple. If it's clogged the engine WILL overheat.

The heater core is full flow at all times and so is probably clogged, too.

Water crossover assembled.gif


Butt plug & air box 2 notes.JPG


Temp gauge - my numbers.jpg


There are coolant filters used for trucks. If there is room to install one . . . .
No way. No room. Won't work. Gotta be a proper, dedicated, frustrating, long, tedious flush job and correct fill and purge done with 50/50 or 60/40 coolant to clean water.
 

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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #14 ·
The Northstar cooling system is very, very, very different from that Toyota. Use the correct GM service manuals.

Lots more info on coolant, overheating, purge line, and other such stuff in the stickies in the Engines, Northstar forum.

Use any coolant you like, no sealant tablets (discontinued in 2006 or 2007), and change it every 4 years. The GM/Cadillac/Helm service manuals used to state that the sealant tablets were crushed and installed in the lower radiator hose.

For the correct online GM/Cadillac service manuals subscribe the car to www.alldatadiy.com

Clean out that purge line and hollow bolt/nipple. If it's clogged the engine WILL overheat.

The heater core is full flow at all times and so is probably clogged, too.

View attachment 598008

View attachment 598010

View attachment 598009



No way. No room. Won't work. Gotta be a proper, dedicated, frustrating, long, tedious flush job and correct fill and purge done with 50/50 or 60/40 coolant to clean water.
Ok kool Thanx. How do I find "engine" in the forum and stickys?
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,051 Posts
You scroll back to the top of this page, upper left, the Forums tab, scroll down to General Discussion, Engines, Northstar. Stickies are always at the top of the first threads page in any forum, marked with a push pin. Stickies are timeless info for all users of that forum.
 

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1999 STS
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26 Posts
I did an experiment before putting green coolant into dex cool and it creates a jelly like film throughout the entire system, I have been told dex cool should only be used in these motors due to the additives in the coolant itself protecting the motor, you can switch to green coolant after a complete proper flush however the green coolant needs to be changed every 2 years
 

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2000 Deville DHS
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1,142 Posts
I did an experiment before putting green coolant into dex cool and it creates a jelly like film throughout the entire system, I have been told dex cool should only be used in these motors due to the additives in the coolant itself protecting the motor, you can switch to green coolant after a complete proper flush however the green coolant needs to be changed every 2 years
How long did it take to form the sludge? And what kind of vehicle did you decide to sacrifice?
 

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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #18 ·
So my seville has been having high heating issues plus I keep smelling antifreeze. I have flushed it twice, replaced the thermostat, radiator cap, checked and ensured the purge line is clear all with no avail. There is no leaks. My guess is it is a clogged heater core. It's a 2000 so I'm sure it needs to be replaced along with the ac evaporator and will be when I have the time alil in the future. The question is (it is hot down here in Texas), can I BYPASthe heater core for the time being and see if it solves the smell and the overheating issue for the time being?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,051 Posts
You can bypass the heater core but it's quite a job due to the routing and location of the hoses/piping.

But - do you get heat - lots of it - when you set the HVAC to manual, blower on, heat, 90 degrees? The heater core is full flow at all times so if you get heat then it's OK.

Did you ever get a real GM/Cadillac/Helm service manual set from eBay or subscribe the car to www.alldatadiy.com? You NEED the procedures and diagnostic trees to correctly track down and repair your problem(s).

That heater coolant supply pipe quick-connect can be a leak problem if you crack the nylon retainer clip.

Water crossover assembled.gif


Heater hose connections - outlet.gif
Heater hoses at firewall.gif


1, 2 - quick connect and special pipe -
Heater hose quick connect - inlet.gif
 

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2000 Cadillac Seville sls
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40 Posts
Discussion Starter · #20 ·
Hey Thanx Sub.
No I haven't gotten one of them helms service manuals. Yet. I been using haynes.
I'm gonna double check the heater temp again when heading out. If i did bypass the heater core couldn't I just run a hose from the the metal pipes running per image..
598887


Bypassing one of the rubber lines and the metal piping running into the firewall?
 
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