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2002 DHS
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16 Posts
Discussion Starter #1
I recently inherited a 2002 DHS from my 94 yr, old grandfather, due to the state of California canceling his driving privileges.
He had a few to many fender benders in his mini van & lucky for me, his DHS was only driven on special occasions.
The car is immaculate, inside & out with not even one scratch, & with a 82000 original miles, this garaged kept Cadillac
looks as good as the day he first bought it. So I let my wife drive it & she calls me up & said it overheated & it did..The radiator split...So I replaced it with a new one& while I was at it I got new hoses,upper & lower & a new t-stat also.,,,After that
the car continue to overheat,,,So I install a new water pump,& overheats again...Then I notice some gooey deposits in the heater hose that comes from the heater core so I replace all the heater hoses from the expansion tank all the way back to & from the heater core back to the water pump,,,still overheats,,,so thinking the heater core might somehow be clogging the system, I bypass it & sure enough it still overheats... The expansion tank is clog free & has no cracks in it& holds down plenty of pressure, the purge line works great pushing out liquid & air while the car starts heating up.I got a new radiator cap for it also but
no matter what without leaking a drop of coolant the car heats up & is headed for the red every time,,,,,So now iam thinking head gasket but no water in the oil, or the exhaust at all. No misfire or any signs of cracked block,head or gasket ....So I rent a block tester from Orileys for $30. & conduct several tests for possible exhaust gasses in my cooling system & they all came back negative, so Iam pretty convinced its not a blown head gasket...Iam starting to get a little frustrated here.. Has any body had this problem??? Is there some trick Ive missed.? Ive read plenty of similar stories in this forum, most pointing back to a burnt gasket or leaky cracked expansion tank, but a lot of them were left unanswered because when someone found a fix& they didn't bother to update or finish the post... Anyways if anybody .has some answers or suggestions......thanks for reading
 

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98 DeVille, 97 DeVille d'Elegance
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7,345 Posts
Sounds like you've covered all the bases... Half the parts are new and you checked the purge line.
Are the fans operating? Both should run on low with AC on.
If it heats up after 20 min driving sounds like hg to me. N* very very rarely dump water into the oil so that is not a good way to check for HG.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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87,177 Posts
Re: Got the DHS blues

Not sure why you would replace a WP if it is still spinning and not leaking, but you seem to have replaced about every component in the cooling system. I'm with Rod, sure sounds like a HG.
Did you do the block test right after an overheat episode?
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,840 Posts
Re: Got the DHS blues

I rent a block tester from Orileys for $30.
& conduct several tests for possible exhaust gasses in my cooling system
& they all came back negative,

I just want to confirm that when you say the results were negative -
that there was absolutely no color change at all -

the slightest color change would be a positive result -
the fluid does not have to turn yellow -
 

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1995 Deville
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164 Posts
Re: Got the DHS blues

I am no mechanic but did you ever think that your temperature sending unit might be faulty?
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
You say the purge line was pushing out liquid and AIR? That's not a good sign.
 

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2002 DHS
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16 Posts
Discussion Starter #7
Re: Got the DHS blues

To answer the questions about the block test ,, iam pretty confident that the results were right considering Ive used one before a few years back on a different vehicle with the opposite results,..The only difference is that instead of the radiator, you have to stick the tube in the expansion tank...I did the test three
times ...
once when the car was cold...once when the car was slowly warming up & once when it was so hot I had
to use a towel to twist & run when removing the cap. All three times no color change what so ever..after squeezing the ball for a good 2-3 minutes, the solution remained bright blue . I also used some dye kit
made to use with dex so yo can pick up traces on an ultraviolet light but its not leaking any fluid.
It sure seems like a HG to me also but iam not ready to pull this motor out if I dont need to...I went ahead & ordered a new expansion tank from ebay , even though I dont think its the problem but a brand new one
shipped for under $50. I couldn't resist.. that wont get here until the 19th.

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You say the purge line was pushing out liquid and AIR? That's not a good sign.
I thought thats what the purge line is supposed to do, is purge the air out of the system

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Also I meant to say in my first reply was thank you for the quick replies, everyone.... they are much
appreciated ,.

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Yep both fans are working great...Iam definitely open to any suggestions on somehow detecting an HG leak
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,840 Posts
Re: Got the DHS blues

All three times no color change what so ever..
after squeezing the ball for a good 2-3 minutes,
the solution remained bright blue

EXCELLENT -
I feel safe to say you do not have a head gasket problem - at this time -

did you use a STANT - or ACDelco T-stat?

what about the pressure cap?
did you test it to hold 18psi?

with all you have already done -
I wonder if it's actually overheating -
or a faulty temp sensor -

it's a cheap part - but somewhat of a PITA to replace -
 

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2002 DHS
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16 Posts
Discussion Starter #9
Re: Got the DHS blues

Iam not sure of the brand of stat I got but I know there was a cheap one & an expensive one at Orileys & I
bought the more expensive one. Same thing with the cap, it said on the cap that its made to hold 18lbs of
pressure. Now I recently forgot to plug my MAP sensor back in after working on it & the check engine light came on.so I put the scanner on it ,
found my mistake & reset the light so i know the obd2 system is working. SO if I had a bad sensor,...wouldn't it have popped up on my scanner?Also when it overheats you can for sure tell that everything is a lot hotter than it should be under the hood . Although a bad sensor would be a dream come true, Iam pretty sure its not.. Is there an easy way to check that particular sensor?
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,802 Posts
Re: Got the DHS blues

You do know that the car has its own built-in code scanner/reader/memory ?

You use the 3 buttons/rocker right of the DIC and the proper year/model instructions in the sticky post on the Deville main threads page titled "How to pull codes".

Have you read all the stickys in any forum of interest as well as studied the entire Cadillac Technical Archive way up ^^^ in the top black bar ??? It was written by one of the GM/Northstar powertrain engineers and by the engineer that does the research work on the OLM systems.
 

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1973 Cadillac Hearse, 2002 Cadillac DHS
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288 Posts
Did you check the water pump belt tensioner? If its weak it will not keep the correct tension on the water pump belt and the pump will not spin. Push the water pump belt with your finger (engine off!) The belt should deflect very little. If it feels sloppy or you notice the tensioner moving replace the tensioner. I would replace the belt as well.

As far as HG's a sure sign is pressure left in the system after it has cooled to ambient temperature. After the car sits overnight give the radiator hose a squeeze. It should not be stiff and if you pop the coolant cap it should NOT sound like a bottle of soda opening. Remove the cap and take a whiff of the inside of the coolant tank. It should not smell like gas/exhaust or solvent. It should smell like coolant only. Pressure in the system after cooldown and exhaust smell in the coolant tank point to leaky head gasket(s). If you have a HG leak, think Lay's potato chips, don't do just one
 

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2002 DHS
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16 Posts
Discussion Starter #12
..I went to start the car last night & it misfired & shook for about 30 seconds...right about then as the motor smoothed out, my eyes started burning from the two huge clouds of toxic steam pouring out of my exhaust..
I guess Ill be heading over to that new harbor freight store to buy a cherry picker... Thanks for all the help guys
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,802 Posts
If he's going to lift the body off the powertrain he will .............. a head gasket change calls for either inserts or studs, and the drilling and machine work is a LOT easier with the engine on the floor or a stand.
 

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2002 DHS
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16 Posts
Discussion Starter #15
Well after looking at the job I figured the front would be no problem but the rear....I dont know... I figured
either out the top or out the bottom ....although it kind of seems like a guy might be able to break it loose
from the mounts, remove all the radiator support, etc., then maybe pivot everything forward enough to get
some long stud work done.....but then again .... Has anyone heard any success stories ?
 

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98 eldo/KD54 w/N37,T96,QA1,D55,DS3,U1Z. U3R next
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2,125 Posts
Take off the radiator UPPER TIE BAR, remove the front bumper and bar, hang the condenser to the right, remove radiator, unfasten engine from transmission and mounts, drag engine forward like a G 10, 20, 30 removal....

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BEFORE you even do any of that,

!. Make sure surge tank is NOT overfilled above cold line

2. Make sure engine oil level is correct, that's right engine oil level

3. Make sure you're getting coolant NOT HOT VAPOR OR STEAM going into the surge tank line with the vehicle running.

4. Run vehicle with heater on to operating temp or just to start to over heat with surge tank cap OFF, shut vehicle down for 10-15 minutes and note coolant level in tank. If it drops lower you have air in the system, and I do mean plenty of it. These things are horrible to get the air out after you do a thermostat or crossover gaskets. The main thing is to make sure the surge tank is not overfilled .

5. You many have to repeat step 4. a few times before is stabilizes.. preferably an overnight cool down. First thing in the morning, check the level and fill to cold mark. Start car, replace cap (IGNORE LOW COOLANT LEVEL MESSAGE) until vehicle has reached operating temperature after driving a bit. You may have to purge it one more time before all the air is out.....

Good luck
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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87,177 Posts
Well after looking at the job I figured the front would be no problem but the rear....I dont know... I figured
either out the top or out the bottom ....although it kind of seems like a guy might be able to break it loose
from the mounts, remove all the radiator support, etc., then maybe pivot everything forward enough to get
some long stud work done.....but then again .... Has anyone heard any success stories ?
You can (with difficulty) get away with that method if you use inserts, but not with studs.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,840 Posts
..I went to start the car last night & it misfired & shook for about 30 seconds...right about then as the motor smoothed out, my eyes started burning from the two huge clouds of toxic steam pouring out of my exhaust..
I guess Ill be heading over to that new harbor freight store to buy a cherry picker... Thanks for all the help guys
===========================
..I went to start the car last night & it misfired & shook for about 30 seconds...
right about then as the motor smoothed out,
my eyes started burning from the two huge clouds of toxic steam pouring out of my exhaust..

well that sure doesn't make sense -after passing the BLOCK TEST - 3 times -
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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87,177 Posts
my eyes started burning from the two huge clouds of toxic steam pouring out of my exhaust..
Are you sure that was "steam" and not unburnt fuel vapor?
 

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2002 DHS
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Discussion Starter #20
No iam pretty sure it was steam because it bellowed out for about 5 min straight & was very thick clouds
then thinned out to a constant small stream that kind stayed in rhythm with the motor idling. Iam pretty
sure that the BLOCK TEST I did a few nights ago was accurate & that the original problem that Ive been
talking about has just bit me again. Now instead of a splitting a crack in the radiator, this time it finally just blew the HG. Now I got this feeling that after I DO change the HG, Iam STILL going to have this car
heating up for some reason...but of coarse I could be wrong...I should be getting my brand new expansion tank in the mail any day now, so we'll see what happens. BTW My POS $30. chiltons repair manual seems to be lacking when it comes to HG work ....Does anybody have access to a good shop manual perhaps I
could look at a few pages....This car is starting to drain me ...thanks again for reading..

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Take off the radiator UPPER TIE BAR, remove the front bumper and bar, hang the condenser to the right, remove radiator, unfasten engine from transmission and mounts, drag engine forward like a G 10, 20, 30 removal....

----------

BEFORE you even do any of that,

!. Make sure surge tank is NOT overfilled above cold line

2. Make sure engine oil level is correct, that's right engine oil level

3. Make sure you're getting coolant NOT HOT VAPOR OR STEAM going into the surge tank line with the vehicle running.

4. Run vehicle with heater on to operating temp or just to start to over heat with surge tank cap OFF, shut vehicle down for 10-15 minutes and note coolant level in tank. If it drops lower you have air in the system, and I do mean plenty of it. These things are horrible to get the air out after you do a thermostat or crossover gaskets. The main thing is to make sure the surge tank is not overfilled .

5. You many have to repeat step 4. a few times before is stabilizes.. preferably an overnight cool down. First thing in the morning, check the level and fill to cold mark. Start car, replace cap (IGNORE LOW COOLANT LEVEL MESSAGE) until vehicle has reached operating temperature after driving a bit. You may have to purge it one more time before all the air is out.....

Good luck
Hey than x a lot for the reply. Now your saying to do this because the possibility that the HG might not be
bad & that I could have a problem with air in the system? because I have most definitely overfilled the
tank MORE THAN A FEW TIMES..I should be getting a new expansion tank in the mail any day now so Ill be sure to double check what you said to do befor I start tearing into the motor.. thanks again for the advice
 
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