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02 DTS overheating

4K views 44 replies 5 participants last post by  02-Deville 
#1 ·
Hi. New to Cadillacs and I have an 02 Deville that is overheating. I put a new water pump and a new thermostat in it today. There is no flow through the top radiator hose. Not sure what to do now.
 
#2 ·
Re: 02 Deville dts overheating


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check the PURGE LINE -

the PURGE LINE is the only way of expelling air from the Northstar cooling system -

it is a 3/8 diameter hose that goes from a hollow bolt in the thermostat/waterpump housing area of the engine - and plugs onto a nipple on the side of the SERGE TANK -

with the engine running - there should be a gentle - constant flow of coolant - from the engine - to the serge tank -

if there is no flow - the most likely cause is a blockage in the hollow bolt -

follow the hose towards the engine - with the engine OFF - remove the hose - use a straightened metal coat hanger - or something similar - and poke it into the hollow bolt -

the coat hanger should go in about 2 1/2 inches -

once the hollow bolt is cleared - you can briefly start the engine to verify coolant flow - be sure to use some sort of container to catch the coolant so you don't make a mess -

check the hose and serge tank for blockage -
 
#5 ·
Re: 02 Deville dts overheating

I changed it cuz there was no flow. And yes I used the right thermostat. Its a 180 degrees. And I let the car idle for 10 minutes then drove it around the block. Then I checked it. The overflow tank was full. I looked at it this morning and there is no fluid in the tank and the purge line and bolt is clear.
 
#8 ·
Re: 02 Deville dts overheating

I looked at it this morning and there is no fluid in the tank and the purge line and bolt is clear.
Obviously there was air in the system. Top it off to the correct level (1/2 full) and take it for another ride. Then check it again after it cools. Top off again if necessary and repeat until it stabilizes. Might take 2 or 3 times.
 
#7 ·
Read the cooling system operation article up ^^^ in the Cadillac Technical Archive - in the top- black bar.

Read the sticky posts on cooling system operation and temp gauge operation in the stickys in Northstar Performance.

Check coolant level cold only, and maintain the surge tank at the FULL COLD mark noted on the tank top and side.

When you changed the water pump, did you check the belt tensioner pulley for smooth, quiet, viscous operation?

Your thermostat is supposed to begin opening at 188 and be fully open at 206. With no A/C function set, fans go to SLOW at 224 and FAST at 236. With any HVAC function set that calls for A/C compressor operation, fans run in SLOW all the time.

Annotated temperature gauge in my albums.
 
#18 ·
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That purge line is a hole new thing to me
the PURGE LINE is unique to the Northstar motor -
it is the ONLY way to purge air from the cooling system -
hence the name - PURGE LINE -

if there IS air in the system - you will NOT have circulation -
the water pump can not pump air -

go back and read #2 - THEN follow the directions -

there is nowhere in the cooling system
that you can actually see coolant flow -

EXCEPT THROUGH THE PURGE LINE -
providing the PURGE LINE isn't plugged up -

like Ranger said in #14 -
If the belt is attached, the tensioner is not frozen
and the pump pulley is turning, you have coolant flow

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EXCEPT IF THERE IS AN AIR LOCK -
due to a plugged PURGE LINE -
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something you said does bring up a question -

When the car is running and worm
I grabbed the hoses and there was no fluid flowing through them.
They were squishy when they should be hard


if you are saying that the engine was at full operating temperature -
and the system was NOT pressurized -
either the pressure cap needs to be replaced -
or you have a leak in the system - bleeding off pressure -

coolant NOT under pressure WILL boil around 215* -
and that could explain a lot -
 
#21 ·
Most cars/trucks with divorced pressure surge tanks have purge lines. Ford calls it a degas line - in the F-150 series - check out the drawing ..................

The chances of having a cracked head are slim and none.

Surge tank caps are a dime a dozen at any parts store or NAPA. probably even at WallyWorld. Your DTS uses an 18# cap.
 
#24 ·
Ok put a new cap on and let it run for like 20 minutes was fine never went over the halfway mark. So I turned the heat on hi and it came out super hot for a while then got cold so I messed with the control and it went back to super hot. Should I be worried about it getting cold
 
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