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Discussion Starter #1
Hi everyone - I have a 99 SLS and a few months ago, the coolant level light started coming on. I thought maybe there was a leak and took it to my mechanic who did a visual check but didn't see one. He topped it off and sent me on my way. However, lately, I started having to add coolant more often to get the light to go off. I would look under the car myself and couldn't see a leak. Now though, it is clealy leaking from underneath. You can see a puddle of the stuff whenever I drive it and I'm having to put it in several times a week. I know you're all going to tell me to take it in right away and I will of course, but have zero cash at the moment. The quick fix has been to just keep adding coolant but that is getting expensive too. I've read some threads here and some say to add a stop leak liquid to the radiator. Others say it could be the head gaskets which I know will be costly. It could just be some leaky hose too. Would your opinions be to maybe get the stop leak stuff first to see if that works? Then if not, then take it to the mechanic? The leak is like right under where you fill the radiator near the front driver side tire sort of. Any suggestions, advice, etc. would be appreciated. I just don't want to get the stop leak stuff and try that without asking you all if that is advisable. I don't want to make it worse than it is! Thanks very much for listening.

Nancy
 

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99STS,2004 Jeep Liberty Renegade,98 Deville RIP
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Nancy when you lift the hood, in the area that you mentioned is the surge tank, this is where you have been adding fluid, this tank may have a crack in it. Two other areas are the waterpump may be leaking, its also in that area or the waterpump crossover, you may also have a leaking purge line which is going into the surge tank. The best way to tell is to do a pressure test on the system and see where the fluid is coming out.
 

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Discussion Starter #3
Thank you so much Caddyshack! I appreciate the advice. I will take your post to my mechanic (he's cuban and there's a little bit of a language barrier when we speak!) I'll have him check those things. It kind of sounds like getting that stop leak stuff would be a waste of $$. Is it OK to keep filling it up until I can get into see on Saturday???
 

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2016 Honda Accord LX. Previous: 2004 Deville, 2000 STS
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The stop leak is a waste of money and can actually clog up your radiator costing even more $$$ as it would have to be cleaned. You should be fine adding coolant until you get some extra cash, but keep an eye on your temperature gauge and if it starts creeping up or the car gets too hot, you might have yourself a bigger and more expensive problem.
 

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Discussion Starter #5
Thanks Ryan! I'm going to take it in on Saturday. I'm glad I asked first. Last thing I want to do is damage my car further. I have a hard enough time maintaining my Caddy! Its been a great car though! Will definintely get another one!
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Also, while you're driving the car until the mechanic's checkup, DO NOT fill the coolant tank to the top - it should be half full, cold. If you remove the cap and look down in the tank, COLD, you should see a cross brace in there. It should be just barely covered ("underwater") with the engine off, cold. Make sure the cap is tight.

The engine coolant expands a lot during warmup and that airspace in the surge tank allows the coolant to expand and pressurize the system, thereby raising the boiling point of the coolant. If the coolant has no air cushion, it expands and blows off the cap relief, spilling coolant down the outside of the surge tank.
 

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Discussion Starter #7
Submariner - Thank you so much! I love this place... I learn so much... I know that little cross bar you're talking about and am guilty of filling it up past that bar! I can see on the tank a little fill level line that you're not supposed to fill it up past but its hard to tell exactly where the coolant is according to that line. I haven't been over-tightening the cap either for fear of not being able to get it off... I hope I've been tightening it enough. All this info has been so valuable. I get paid Friday and will take it in on Saturday for sure... Thanks again for all the info!

Hey, while we're at it... I hear a "fan" blowing rather loudly (sort of buzzing or rattling acutally) inside my dash near the windshield on the drivers side. Sometimes if I hit the dash, it stops, but then I hear it again. What is that??
 

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hey nancy, fwiw...i had a massive leak in the same spot and what i found is that i had a small pinhole leak at the bottom of my surge tank! knew a guy at the shop that hooked me up with a new one for 40 bucks! took 20 min to put in and now its dry as a bone!

now, it still sounds like my water pump is struggling and im afraid that will go soon. but i thought it might be worth a shot to check it out. oh, btw...it only leaked when the car was on and coolant under pressure and nothing, i mean NOTHING, fixed the leak.

hope that helps!
 

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Discussion Starter #9
That's interesting Gust.... Because now that you mention that, the reason I never thought it was leaking is because every time I check for a leak under the car, its usually after I've pulled into the garage or a parking space and gotten out of the car, when the car is off! I can see it is wet in the area I described and have seen puddles of what looks like coolant. But I'll have to leave the car on and then check for a leak.
 

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2010 DTS
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It is good that you are seeing the leak. That means it is external and not internal (head gasket). Could also be a radiator side tank, but it sounds like the leak is farther back from your description.

Hey, while we're at it... I hear a "fan" blowing rather loudly (sort of buzzing or rattling acutally) inside my dash near the windshield on the drivers side. Sometimes if I hit the dash, it stops, but then I hear it again. What is that??
That sounds like the aspirator fan. You should see a small 1" square grill in the dash near the steering column. That fan draws in cabin air and passes it over the in car temperature sensor for the climate control.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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If you have the grille as Ranger described, a little 1" square thing with about 6 slits, pull it out with a paperclip bent into a small hook. You'll see a tunnel into the dash - that's where the cabin air temp sensor is. Be careful not to bend the little black bead hanging into the tunnel - that's the first part of the sensor assembly.

Look in there with a flashlight - dusty ??? Start the car, set some air conditioning mode and blow down the tunnel with a can of computer compressed air (keyboard cleaner). That may help, otherwise you'll have to do some end-of-the-dashboard pulling and pushing with magic words to replace the sensor. Dealer item, BTW......
 

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Discussion Starter #12
Magic words!! I've been using a few of those lately! :) I do have that one inch little grill and that is where the noise is coming from. I'll try what you have suggested (with the magic words of course!) and see if that works.
 

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OK - down in there is a small electronic board with a tiny muffin fan (like on a computer board) which moves the air. They chronically either get dirty or lose lubrication, which means you have to pull the module out the side of the dashboard: The panel at the end, with the air pipe for the door window vent, pulls out and you get to the module from there.

If the blow job ( :lildevil: ) doesn't do the trick, somebody posted the entire replacement procedure in here or down in Cadillac Technical, Electrical, a year or so back. Iametarq, I think. Pictures, too. Not difficult. Dealer part.
 

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Yeah having small hands helps too lol!! Mines was buzzing this past winter and I attempted to do the job. Having large hands I couldnt get the job done and after an hour I gave up!! Damn fan!!
 

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Discussion Starter #16
Hi Guys! Took me a while to get back here to post the diagnosis of my coolant leak... the radiator expansion tank has a hole in it. The part is a little costly at the dealer. I just need the plastic expansion tank, not the whole assembly. Do you guys have any idea where I can get one cheap???? I have a 1999 Seville SLS. I live in Tampa, Florida but if I have to get one from a salvage yard elsewhere, I can certainly send the $$. Any ideas? My mechanic "patched" or glued it and it held for a few weeks, but now tonight it is leaking pretty bad again... HELP! :)
 

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Nancy, first of all it is not an expansion tank on the Northstar. It is a surge tank. Leaky tanks are somewhat common after several years of heat cool cycles. Getting another one that is 10 years old if a big gamble unless you are doing it to sell the car. Otherwise I'd advise getting a new one. If Rockauto http://www.rockauto.com doesn't have it, try http://www.gmotors.com.
 
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