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98 Cadillac Seville STS, also have a 96 Voyager (work car)
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102 Posts
Discussion Starter #1
So I've recently changed the water pump and thermostat on my 98 STS. It used to overheat like crazy before this but not so much now. The the temp gauge goes up towards hot once in a while but it goes back to the middle when I give it a little gas in either drive or idle, doesn't matter. I also hear a weird "gurgling" sound when I give it a little gas. ??? I constantly need to keep adding coolant, I would say every 2-3 days so the leak is still there and some slight overheating is still there. I seriously doubt it's the head gasket because there's no smoke coming out from anywhere and plus I think I would be able to tell if it was the head gasket, you can't miss it I would imagine. Surge tank looks fine to me as well. I'm thinking maybe the radiator? Any suggestions and/or advice would be fantastic. This overheating/coolant leaking problem is really starting to get to me. Thanks in advance.
 

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White Diamond '03 DHS (with DTS floor shift)
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I really hate to say this, but you have classic early head gasket symptoms. Have the coolant tested or get the kit and test it yourself before you start throwing any parts at it.
 

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1999 Cadillac DeVille
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279 Posts
They call it a BLOCK TESTER at napa when I bought mine I said head gasket tester and they looked at me like I was nuts.
 
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Seems like most (myself included) waste the money to fix the water pump before we find out it's really the head gaskets. Sucks.
 

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98 Cadillac Seville STS, also have a 96 Voyager (work car)
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102 Posts
Discussion Starter #8
Oh I don't mind, I'm actually glad I changed the pump and thermostat. It helped stop the overheating a bit plus those parts were getting old and tired considering the high mileage and it only cost me about $90 for the parts and as for labor I did it myself.
 

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1997 Eldorado
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637 Posts
Oh I don't mind, I'm actually glad I changed the pump and thermostat. It helped stop the overheating a bit plus those parts were getting old and tired considering the high mileage and it only cost me about $90 for the parts and as for labor I did it myself.
is it hard to replace? i have a 97 eldo
 

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NORTHSTAR98

Did you get anything figured out? I have the same problem where if I am stopped or in traffic my temp raises then it will lower after i get moving again. It overheated a couple days after I bought the car (January in wisconsin now in kansas city) so I called the dealership and they wanted me to bring it somewhere to get checked. The repair place I brought it to said it was the head gasket. I brought it to another place they said it was not and then a third place said it was. I drove it all the way back to Wisconsin and they did a pressure test to test for leaks and left it over night. They found no head gasked leak. The gurgling was air in the system so they blead that and got about a gallon more coolant in the system. I got my car back and the temp still raises. The dealer told me it is going to do that because the cadillace temp gauges move in increments so it shows the raise then the fans turn on. I just dont get why it would cool back to the middle then back up again if I stay at a idle or slow moving. Sorry about the long story but just wondering if you got anything taken care of.

I have another post on here from a couple months ago also, Thanks ranger for the feeback.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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What heating/cooling mode are you in, and exactly what do you mean by "the temperature raises" ? Where, on the gauge below, does the temperature go to in traffic, and where does it run on the open highway or country road ??

IF your car is not in some AUTO or A/C ventilation mode, the fan(s) do not run constantly. It will be perfectly normal if the gauge goes from 12 o'clock to 1 o'clock and back in traffic as the fan(s) start and stop (low speed comes in at 224 degrees, high at 236.).

(Going back through all of your earlier posts on this subject, your temperature rises were normal........)

Maybe, just maybe, you should invest in a new 18 psi surge tank cap. If that leaks, the cooling system cannot pressurize and will then boil at 216 degrees. At 18 psi with 50/50 coolant it will not boil until 276 degrees.
 

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98 Cadillac Seville STS, also have a 96 Voyager (work car)
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102 Posts
Discussion Starter #13
I would say the overheating on my car is a bit more extreme than what you were describing Submariner. One time (this was after the water pump and thermostat replacement) the gauge went almost all the way up to HOT then it dropped back to the middle. Now I totally agree that its perfectly normal for the guage to move from 12 to 1 o clock but mine goes up to bout 2 and 3 o clock regularly AND it never used to do this before. It was even worse before I changed the pump and although it didn't solve the problem completly, it was still a big help in minimizing the overheating. The surge tank cap sounds like not a bad (and inexpensive) idea, I'm gonna get one of those along with the block tester kit. I would feel much better if I got a new radiator as well, considering the fact that I probably need one anyways.

As for the water pump repair, it was pretty easy but like Ranger said you're gonna need that socket. You need it to remove the old pump and to install the new one. Got it a NAPA for about $50 I believe.
 

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98 Cadillac Seville STS, also have a 96 Voyager (work car)
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102 Posts
Discussion Starter #14
NORTHSTAR98

Did you get anything figured out? I have the same problem where if I am stopped or in traffic my temp raises then it will lower after i get moving again. It overheated a couple days after I bought the car (January in wisconsin now in kansas city) so I called the dealership and they wanted me to bring it somewhere to get checked. The repair place I brought it to said it was the head gasket. I brought it to another place they said it was not and then a third place said it was. I drove it all the way back to Wisconsin and they did a pressure test to test for leaks and left it over night. They found no head gasked leak. The gurgling was air in the system so they blead that and got about a gallon more coolant in the system. I got my car back and the temp still raises. The dealer told me it is going to do that because the cadillace temp gauges move in increments so it shows the raise then the fans turn on. I just dont get why it would cool back to the middle then back up again if I stay at a idle or slow moving. Sorry about the long story but just wondering if you got anything taken care of.

I have another post on here from a couple months ago also, Thanks ranger for the feeback.

Hmm... I was suspecting that gurgling sound was air. Does anybody know how to bleed the air out of the cooling system?
 

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White Diamond '03 DHS (with DTS floor shift)
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The Northstar is self purging. No need to bleed anything. It does it itself if the purge line is clear. Do the block test BEFORE spending any more money.
 

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1997 ETC (GAVE TO STEPSON 2011), 2000 DTS (RIP)
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1,702 Posts
Right - if the purge line is not clear, all the way through, it WILL overheat. Too much sealer will clog it.
 

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1997 Seville STS, 2000 Seville STS
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Its not the line that plugs, its the fitting on the waterpump housing. Pull the line off at the waterpump end with the car idling and cold. If you don't see a good stream of water coming out then rout out the fitting with a long nail, or a piece of weedwacker line till it flows clear.
 
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