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1994 Seville STS
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18 Posts
Discussion Starter · #1 ·
Lately I’ve been smelling antifreeze but I cannot see any visible leaks under the hood or on the ground. I had to add about a half gallon of antifreeze 2 weeks ago but the add coolent message hasn’t reappeared. Since I didn’t notice a leak in the engine compartment I was thinking of examining the heater core. I’ll probably try looking under the hood while someone revs the engine to about 4000 rpms and see if I can notice anything in the engine compartment again but if no luck there I’d like to examine the heater core. I’d appreciate If anyone has any instructions on getting to the heater core. I think I saw someone taking out the glove box in a Deville so i might start there. Any advice is appreciated. Thank you!
 

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Super Moderator
2010 DTS
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88,781 Posts
If it is the heater core, the smell should be very prevalent in the cabin and you should probably see the windows steaming up or at least leaving an oily film on them.

A common, hard to locate leak point is the front of one of the side tanks as it is blocked from view by the condenser and coolant will evaporate before dripping. You may need to do a pressure test when the engine is cold for the leak to show itself.
 

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Registered
1994 Seville STS
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18 Posts
Discussion Starter · #3 ·
If it is the heater core, the smell should be very prevalent in the cabin and you should probably see the windows steaming up or at least leaving an oily film on them.

A common, hard to locate leak point is the front of one of the side tanks as it is blocked from view by the condenser and coolant will evaporate before dripping. You may need to do a pressure test when the engine is cold for the leak to show itself.
Thanks. I’d rather not check the heater core. I smell antifreeze in the cabin with or without the air on but no steam as I’m running the air with this 90 degree weather. I think the smell is more with the air on but it could be pulling air from the engine compartment. When you mention side tanks are you referring to the side of the radiator?
 

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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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21,509 Posts
Lately I’ve been smelling antifreeze but I cannot see any visible leaks under the hood or on the ground. I had to add about a half gallon of antifreeze 2 weeks ago but the add coolent message hasn’t reappeared. Since I didn’t notice a leak in the engine compartment I was thinking of examining the heater core. I’ll probably try looking under the hood while someone revs the engine to about 4000 rpms and see if I can notice anything in the engine compartment again but if no luck there I’d like to examine the heater core. I’d appreciate If anyone has any instructions on getting to the heater core. I think I saw someone taking out the glove box in a Deville so i might start there. Any advice is appreciated. Thank you!
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I’ll probably try looking under the hood while someone revs the engine to about 4000 rpms
rather than revving the piss out of the engine - which will probably show NOTHING -
I would suggest using a cooling system pressure tester -
you can "rent" one for FREE from autozine - o'reilly's and other auto parts stores -
 

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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
·
21,509 Posts
Thanks. I’d rather not check the heater core. I smell antifreeze in the cabin with or without the air on but no steam as I’m running the air with this 90 degree weather. I think the smell is more with the air on but it could be pulling air from the engine compartment. When you mention side tanks are you referring to the side of the radiator?
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the heater core has a constant flow of hot coolant going through it -
regardless of whether you are using the AC or have the heat cranked up -

if the heater core is leaking -
I would expect to see/feel coolant on the passenger side carpeting -
 

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1994 Seville STS
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18 Posts
Discussion Starter · #6 ·
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I’ll probably try looking under the hood while someone revs the engine to about 4000 rpms
rather than revving the piss out of the engine - which will probably show NOTHING -
I would suggest using a cooling system pressure tester -
you can "rent" one for FREE from autozine - o'reilly's and other auto parts stores -
You sound like my dad some 50 years ago. :))
 

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1994 Seville STS
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18 Posts
Discussion Starter · #8 ·
Found a leak in the engine compartment poking around this morning. The bottom nipple where antifreeze comes out of the heater core broke inside the hose and was slowly leaking. I touched it and it fell off. My guess is if the nipple sticks out 2” there’s probably only 3/4” sticking out now and the nipple feels loose. I’m going to have my auto shop look at it as it is in a very difficult area to get at and worse case I’ll have them bypass the heater core. :-(
 
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