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98 SLS OVERHEATING


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ON LONG TRIPS 1HR OR LONGER MY 98 SLS WILL GET UP TO THE RED ZONE THE DASH READS:ENGINE COOLANT HOT-A/C OFF SO I PUT MY HEAT ON 90 HI WITH THE A/C OFF THE DASH THEN READS:IDLE ENGINE , SO I LET THE ENGINE RUN AT IDLE WITH HEAT ON A/C OFF AND THE TEMP GRADUALLY STARTS TO GO BACK DOWN TO NORMAL 12:00.I CHANGED THE TERMOSTAT THEN REFILLED THE SYSTEM WITH A 50/50 MIX. IM STILL HAVING THE PROBLEM. ALSO I THINK THERE MIGHT BE AIR IN THE SYSTEM DO THEY NEED TO BE BLED MANUALLY?ANY IDEAS THAT MIGHT HELP WOULD BE APPRECTIATED THANKS TO THE CADILLAC COMMUNITY.

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The system is self purging, assuming that the purge line is clear. the purge line is the 3/8" line that runs into the side of the surge tank near the top. Pull it while idling (cold, so as not to burn yourself). It should spit coolant. If it does, quickly plug it back in and reclamp it. If not, shut down, locate and clear the blockage. If it is clear, have your coolant tested for exhaust gases.

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The system is self purging, assuming that the purge line is clear. the purge line is the 3/8" line that runs into the side of the surge tank near the top. Pull it while idling (cold, so as not to burn yourself). It should spit coolant. If it does, quickly plug it back in and reclamp it. If not, shut down, locate and clear the blockage. If it is clear, have your coolant tested for exhaust gases.

OK I WILL TRY THAT THANKS. ILL LET YOU KNOW HOW I MAKE OUT TOMORROW.

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Check your water pump belt and tensioner for wear. The water pump belt is on the driver side front of the engine NOT on the passenger side where the serp belt is, Mike

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/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The tensioner can bind up and not apply the proper amount of pressure on the belt. The belt will slip at high speeds and not turn the pump fast enough. Look for cracks in your belt, glazing, check the pulley wheel and see if the tensioner is binding. You may need to remove the shroud (two nuts and a 10 mm bolt). Keep hands and loose clothing clear of moving accessories, if you take the shroud off.

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/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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With the engine cold, pop the hood and start the car with the A/C off. The radiator fans should be OFF. Then turn on the A/C on. The fans should be on, at low speed. If not, look at the fan fuses, relays, connectors, and fan motors.

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ALSO IF IM ON THE HIGHWAY AND I SEE IT GETTING TOO HOT IF I SPEED UP TO 80 MPH IT WILL GO BACK TO NORMAL TEMP 12:00

Might also check to be sure that the radiator is not half clogged.

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Bypass clogged? Heater core clogged?

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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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WELL I WASNT GETTING MUCH OUT OF THE PURGE LINE SO PULLED IT OFF BLEW AIR THROUGH IT IT WAS CLEAR. SO LET ME TO THE FAMOUS HOLLOW BOLT THAT COMES OUT OF THE HOUSING, BET YOU CAN GUESS WHAT I FOUND. YUP THE PIECE OF S%*T WAS CLOGGED SO I CLEARED IT OUT PUT BACK TOGETHER AND WARMED IT UP. IT SEEMS FINE NOW ALL THE HOSES GOT WARM EVEN ALL THE SMALLER LINES. SO I THINK I SHOULD BE ALL SET NOW.MY WIFE IS GOING TO TAKE IT ON A 2 1/2hr TRIP HOPEFULLY WITH NO PROBLEMS ILL POST THE RESULTS LATER.. BUT I WANTTO SAY THANKS TO ALL YOU GUY FOR YOUR HELP?

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ALSO IF IM ON THE HIGHWAY AND I SEE IT GETTING TOO HOT IF I SPEED UP TO 80 MPH IT WILL GO BACK TO NORMAL TEMP 12:00

The Northstar engine has a feature where at high RPMs coolant will bypass the normal flow so extra water can circulate providing extra cooling capacity. I see this happen often when my temp will decrease under high RPMs even though you might think higher RPMs produce more heat therefore hotter temps.

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WELL I WASNT GETTING MUCH OUT OF THE PURGE LINE SO PULLED IT OFF BLEW AIR THROUGH IT IT WAS CLEAR. SO LET ME TO THE FAMOUS HOLLOW BOLT THAT COMES OUT OF THE HOUSING, BET YOU CAN GUESS WHAT I FOUND. YUP THE PIECE OF S%*T WAS CLOGGED SO I CLEARED IT OUT PUT BACK TOGETHER AND WARMED IT UP. IT SEEMS FINE NOW ALL THE HOSES GOT WARM EVEN ALL THE SMALLER LINES. SO I THINK I SHOULD BE ALL SET NOW.MY WIFE IS GOING TO TAKE IT ON A 2 1/2hr TRIP HOPEFULLY WITH NO PROBLEMS ILL POST THE RESULTS LATER.. BUT I WANTTO SAY THANKS TO ALL YOU GUY FOR YOUR HELP?

VERY COOL.... That could definately have been your problem... Do a search of Rollingthunder, he had a blocked purge line and it caused overheating...

For future reference DO NOT blow into the purge line, IF you had a block you could clear it and NOT know you had one... The coolant not coming out of the purge hose strong was your clue... Take another look at your purge bolt in about a week to make sure its not clogging up.

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/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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WELL I WASNT GETTING MUCH OUT OF THE PURGE LINE SO PULLED IT OFF BLEW AIR THROUGH IT IT WAS CLEAR. SO LET ME TO THE FAMOUS HOLLOW BOLT THAT COMES OUT OF THE HOUSING, BET YOU CAN GUESS WHAT I FOUND. YUP THE PIECE OF S%*T WAS CLOGGED SO I CLEARED IT OUT PUT BACK TOGETHER AND WARMED IT UP. IT SEEMS FINE NOW ALL THE HOSES GOT WARM EVEN ALL THE SMALLER LINES. SO I THINK I SHOULD BE ALL SET NOW.MY WIFE IS GOING TO TAKE IT ON A 2 1/2hr TRIP HOPEFULLY WITH NO PROBLEMS ILL POST THE RESULTS LATER.. BUT I WANTTO SAY THANKS TO ALL YOU GUY FOR YOUR HELP?

VERY COOL.... That could definately have been your problem... Do a search of Rollingthunder, he had a blocked purge line and it caused overheating...

For future reference DO NOT blow into the purge line, IF you had a block you could clear it and NOT know you had one... The coolant not coming out of the purge hose strong was your clue... Take another look at your purge bolt in about a week to make sure its not clogging up.

IM DEFINETLY GOING TO RECHECK THE BOLT THIS WEEK END JUST INCASE MORE GUNK GETS IN THERE.YEA MIKE I DID MAKE SURE I TOOK THE LINE OFF COMPLETLY BOFRE I BLEW INTO IT, I DINT WANT THAT STUFF TO GO INTO THE HOUSING.BY THE WAY THE WIFE GOT JUST BACK FROM HER RIDE NICE AND SMOOTH NO PROBLEMS THE GUAGE WENT A LITTLE PAST 12 BUT SHE SAID IT WENT RIGHT BACK TO 12 AFTER A MIN. OR SO. I HOPE THAT WAS IT AND THANKS AGAIN GUYS FOR ALL YOUR HELP :hatsoff:

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  • 3 years later...

Hi FNG here, i am helping my neighbor figure out the heating issue of his 98 Deville, upon searching i found this thread , curious can someone give a better description of the "hollow bolt" and where exactly is it located ? thx for any help..

On Edit sorry about reviving a old thread...

<!--quoteo(post=122445:date=Mar 12 2008, 01:03 PM:name=BodybyFisher)--><div class='quotetop'>QUOTE (BodybyFisher @ Mar 12 2008, 01:03 PM) <a href="index.php?act=findpost&pid=122445"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec--><!--quoteo(post=122417:date=Mar 12 2008, 10:16 AM:name=CT-CADILLAC)--><div class='quotetop'>QUOTE (CT-CADILLAC @ Mar 12 2008, 10:16 AM) <a href="index.php?act=findpost&pid=122417"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->WELL I WASNT GETTING MUCH OUT OF THE PURGE LINE SO PULLED IT OFF BLEW AIR THROUGH IT IT WAS CLEAR. SO LET ME TO THE FAMOUS HOLLOW BOLT THAT COMES OUT OF THE HOUSING, BET YOU CAN GUESS WHAT I FOUND. YUP THE PIECE OF S%*T WAS CLOGGED SO I CLEARED IT OUT PUT BACK TOGETHER AND WARMED IT UP. IT SEEMS FINE NOW ALL THE HOSES GOT WARM EVEN ALL THE SMALLER LINES. SO I THINK I SHOULD BE ALL SET NOW.MY WIFE IS GOING TO TAKE IT ON A 2 1/2hr TRIP HOPEFULLY WITH NO PROBLEMS ILL POST THE RESULTS LATER.. BUT I WANTTO SAY THANKS TO ALL YOU GUY FOR YOUR HELP?<!--QuoteEnd--></div><!--QuoteEEnd-->

VERY COOL.... That could definately have been your problem... Do a search of Rollingthunder, he had a blocked purge line and it caused overheating...

For future reference DO NOT blow into the purge line, IF you had a block you could clear it and NOT know you had one... The coolant not coming out of the purge hose strong was your clue... Take another look at your purge bolt in about a week to make sure its not clogging up.

<!--QuoteEnd--></div><!--QuoteEEnd-->

IM DEFINETLY GOING TO RECHECK THE BOLT THIS WEEK END JUST INCASE MORE GUNK GETS IN THERE.YEA MIKE I DID MAKE SURE I TOOK THE LINE OFF COMPLETLY BOFRE I BLEW INTO IT, I DINT WANT THAT STUFF TO GO INTO THE HOUSING.BY THE WAY THE WIFE GOT JUST BACK FROM HER RIDE NICE AND SMOOTH NO PROBLEMS THE GUAGE WENT A LITTLE PAST 12 BUT SHE SAID IT WENT RIGHT BACK TO 12 AFTER A MIN. OR SO. I HOPE THAT WAS IT AND THANKS AGAIN GUYS FOR ALL YOUR HELP <img src="http://caddyinfo.ipbhost.com/public/style_emoticons/<#EMO_DIR#>/Laie_22mini.gif" style="vertical-align:middle" emoid=":hatsoff:" border="0" alt="Laie_22mini.gif" />

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Hi FNG here, i am helping my neighbor figure out the heating issue of his 98 Deville, upon searching i found this thread , curious can someone give a better description of the "hollow bolt" and where exactly is it located ? thx for any help..

On Edit sorry about reviving a old thread...

Pretty easy. Just follow the small hose back from the coolant tank to the engine. It will attach at the throttle body. Mike posted some pictures in a recent post on overheating but your model may differ slightly. The line on the '98 should be pretty straightforward to locate though.

Never underestimate the amount of a persons greed.

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F2504X4, Look for this recent post "Crazy Overheating Issues", Mike picture is on page 2 of the thread.

Never underestimate the amount of a persons greed.

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here is a pic. The hollow bolt is located on the side of the driver side torque strut(upper engine mount) You cant miss the black hose that goes into it.

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It's on the water pump crossover, on the rear of the engine, near the thermostat housing. Follow the 3/8" rubber hose from the front of the engine. It's the fitting that it pushes onto.

CTS-V_LateralGs_6-2018_tiny.jpg
-- 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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Thank you everyone for the quick responses, I will see if this is the cause of the over heating issues...the car is in very nice shape, it only has about 70 plus thousand miles on it...i would love to get it back on the road for him...

BTW i am a long time member on FTE hence my user name..

It's on the water pump crossover, on the rear of the engine, near the thermostat housing. Follow the 3/8" rubber hose from the front of the engine. It's the fitting that it pushes onto.

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