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1998 Seville STS Exhaust smoke


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Hello,

I'm in need of some guidance. My car is starting to smoke on startup and run rough. Then as i drive it warms up the smoke goes away and the car runs fine. I notice that the Coolant level warning comes on even though it's full. The car does leak coolant from time to time for no apparent reason ( like it doesn't leak for a couple days than I will come out and find a puddle ) . that being said it doesn't run hot and I figured since I had a puddle that the coolant loss wasn't due to a blown head gasket. I really like the car and I'm hearing all these horror stories about time inserts and replacing engines. I saw from a previous thread that the guy replaced his throttle body and a sensor? I thought that the throttle body just controlled the air flow. I hope I don't sound crazy and someone can help make sense of this. Any help is appreciated

Tankman

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"Smoke" or more likely steam (more than normal) and running rough at start up point towards a HG failure. Not using coolant (with no external leak) or running hot does not. Where exactly are you finding this puddle of coolant?

No need to replace the TB, just give it a good cleaning. That could solve your rough idle.

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Tis the time of the year (where condensation vapor) will/can be much more visible until the car's exhaust gets fully heated. You may have a problem but it may also be normal; any codes.

Chuck

'25 CT5, '04 Bravada........but still lusting for that '69 Z-28

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"Smoke" or more likely steam (more than normal) and running rough at start up point towards a HG failure. Not using coolant (with no external leak) or running hot does not. Where exactly are you finding this puddle of coolant?

No need to replace the TB, just give it a good cleaning. That could solve your rough idle.

Thanks Ranger for responding. The puddle appears on the driver side and it seems to flow toward the middle front of the egine block (At least that is where the fluid hits the ground) I thought it may be a leaking Water pump and the fluid would flow along the block but I didn't see or feel any wet fluid around it. I will get the cleaner tonight and go for it. I will let you know what happens.

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Tis the time of the year (where condensation vapor) will/can be much more visible until the car's exhaust gets fully heated. You may have a problem but it may also be normal; any codes.

Thanks for responding C&C

I agree. The check engine light is on, but that came on when a pulley bolt backed out and snapped in the block. The shop repaired it but the check engine light wouldn't go off after. I figured it was a setup because the wanted to charge me to find out. Now I fear this allowed something bad to go unnoticed. I will copy the codes and let you know.

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Ok the check engine light is on, you need to extract the codes. Go to the bottom of this post by me, click the link and follow the directions for your year and post the codes here.

If you have a check engine light, you have a code a DTC code that is set, lets see what it is

It may be, from the low coolant message, but lets see, it could be related to your ROUGH IDLE.

You say it states LOW COOLANT even thought it is NOT LOW, is that correct? That could be a bad coolant level sensor in the coolant tank. Try flushing the tank good and check the sensor's connections first, if that does not solve it you will need a new tank. You may be able to get a new level sensor however. You will need to remove the tank to flush it good.

DONT jump to conclusions about head gasket until you do diagnosis and find the leak. There are a few hoses on the driver side that can be bad and the crossover has seals that can go bad. Have the cooling system pressurized to find the leaks

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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"Smoke" or more likely steam (more than normal) and running rough at start up point towards a HG failure. Not using coolant (with no external leak) or running hot does not. Where exactly are you finding this puddle of coolant?

No need to replace the TB, just give it a good cleaning. That could solve your rough idle.

Thanks Ranger for responding. The puddle appears on the driver side and it seems to flow toward the middle front of the egine block (At least that is where the fluid hits the ground) I thought it may be a leaking Water pump and the fluid would flow along the block but I didn't see or feel any wet fluid around it. I will get the cleaner tonight and go for it. I will let you know what happens.

Keep in mind that there is a splash shield down there and if coolant is leaking onto it, it may pool and drip somewhere other than under the actual leak.

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"Smoke" or more likely steam (more than normal) and running rough at start up point towards a HG failure. Not using coolant (with no external leak) or running hot does not. Where exactly are you finding this puddle of coolant?

No need to replace the TB, just give it a good cleaning. That could solve your rough idle.

Thanks Ranger for responding. The puddle appears on the driver side and it seems to flow toward the middle front of the egine block (At least that is where the fluid hits the ground) I thought it may be a leaking Water pump and the fluid would flow along the block but I didn't see or feel any wet fluid around it. I will get the cleaner tonight and go for it. I will let you know what happens.

Keep in mind that there is a splash shield down there and if coolant is leaking onto it, it may pool and drip somewhere other than under the actual leak.

Ranger,

I cleaned the TB and the car ran better for about a day. Now it is smoking longer now after start up and after sitting after a short run to a store. I called a couple of mechanics and one quoted my 3800 for machining the block, time inserts, pressure testing, loaner cars and such. Another quoted 1250 if I didn't need the powertrain separated to repair any oil leaks ( I have none of those ). The more expensive shop said the the coolant leat is coming from the gap created when the block cooled. I am really nervous with the price difference. I will visit the cheaper shop later today.

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Ok the check engine light is on, you need to extract the codes. Go to the bottom of this post by me, click the link and follow the directions for your year and post the codes here.

If you have a check engine light, you have a code a DTC code that is set, lets see what it is

It may be, from the low coolant message, but lets see, it could be related to your ROUGH IDLE.

You say it states LOW COOLANT even thought it is NOT LOW, is that correct? That could be a bad coolant level sensor in the coolant tank. Try flushing the tank good and check the sensor's connections first, if that does not solve it you will need a new tank. You may be able to get a new level sensor however. You will need to remove the tank to flush it good.

DONT jump to conclusions about head gasket until you do diagnosis and find the leak. There are a few hoses on the driver side that can be bad and the crossover has seals that can go bad. Have the cooling system pressurized to find the leaks

Thanks for responding Fisher,

I click the links and will try them tonight. The coolant does leak, but after I replace the missing fluid the low coolant message never goes out. The white smoke is getting thicker now. I called a couple of mechanics ( See my response to Ranger below ). I will see what codes come up, but feel the repair shop is looming in the windshield.

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The white smoke is getting thicker now.

Go back there and take a good whiff of that "smoke". Does it smell sweet like coolant or like burnt oil?

P.S.

There is a slim possibility it could smell like gas.

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The white smoke is getting thicker now.

Go back there and take a good whiff of that "smoke". Does it smell sweet like coolant or like burnt oil?

P.S.

There is a slim possibility it could smell like gas.

Definitely not smelling like oil, it smells sweet like coolant, but faintly.

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Do what BBF says. Get the loaner kits from autozone DO the system pressure ck along with the surge tank cap and check for exhaust in the coolant with autuzones BLOCK/HEAD GASKET tester. Check for leaks with a strong light and mirror. These test are a MUST before you turn the car over to mechanics. Checks are easy,fast and cheap. Also make sure your surge line is flowing.Mike

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Definitely not smelling like oil, it smells sweet like coolant, but faintly.

That does not sound good. Do the block test.

Smoke on start up could be from a rich fuel mixture while in open loop and everything goes normal when the loop closes and the PCM compensates.

I have NEVER seen any car smoke from running overly rich while in open loop. The PCM is still in control even while in open loop.

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Do what BBF says. Get the loaner kits from autozone DO the system pressure ck along with the surge tank cap and check for exhaust in the coolant with autuzones BLOCK/HEAD GASKET tester. Check for leaks with a strong light and mirror. These test are a MUST before you turn the car over to mechanics. Checks are easy,fast and cheap. Also make sure your surge line is flowing.Mike

I agree. I will do the checks this weekend. I agree I talk to 3 mechanics. I want them to check the wheel bearings and 2 said it would cost 400+ to change it, the 1 said the labor is already done if he was replacing the HG and would only charge for parts. If the tests show a failure he sounds like the one I should go with. Just trying to keep a back plan ready.

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Hello everyone,

The pressure test didn't go well. In fact after I did it I saw the rear area of the engine was leaking coolant ( I used one of those Leak Detection Dye kits ). So I bought 2003 STS (62000 miles vs 183000) and I will send my 1998 into the repair shop and give it to my dad. The car is clean so he will be happy. I want to thank everyone for their comments. I learned a lot from this and I hope to learn more about these cars so I can help someone in the future too. Please have a great Christmas and New years!!!

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