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I'm not sure what to make of this.


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A couple days ago I started noticing a very slight misfire when first starting the car. It doesn't matter if it has been sitting 10 minutes or overnight, it always does it and it goes away within a minute or so. The exhaust also sounds somewhat muffled when it's first started. Then yesterday my boyfriend left to go somewhere, and when he started the car there was a white-ish cloud from the exhaust. A few hours after he got home I went to the store. It was a 5 minute drive and when I got out and walked around the back of the car I happened to notice that the tailpipes looked wet. I stuck my finger in it and smelled it, and it smelled like coolant. It was a faint but very distinct smell. I started thinking it was probably a head gasket. Then today I went out of town and noticed it's running hotter than normal. Not overheating, but still higher than usual, spiking to 235, then dropping to 220-ish and staying there (it normally doesn't ever exceed 215, even when it's hot out). This reinforced my thought about it being a head gasket. I got to my parents' house, parked it, and let it cool off. I made sure the coolant cap was on correctly. Then I checked the coolant, and the level was fine. Still in the same place it was when I checked it a couple weeks ago. I also sniffed it for exhaust gases and it smelled perfectly fine. I even got a test kit to confirm there were no combustion gases in the coolant, and it showed that there weren't. My radiator hoses are all holding good pressure, and there are no apparent leaks aside from the pinhole nuisance leak in the water pump cover (which has mysteriously stopped leaking over the last few dayshuh.gif).

I am at a total loss as to what could be causing this. Higher-than-normal temps, misfire on startup, white-ish steam/smoke from the exhaust, and what appears to be coolant in the tailpipes after a short drive. All of this with no actual overheating, no obvious loss of coolant, no loss of power, and no combustion gases in the coolant tank.... I'm starting to doubt that it's a head gasket. The only thing I can think of is that maybe there is a very small amount of coolant leaking from the crossover into the intake, but I'm not even sure if that's a possibility on this engine. Any ideas?

P.S. I checked the codes and there aren't any.

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Those are the symptoms of head gaskets just starting to fail... BUT, on the other hand, the absence of combustion gases in coolant does not support the first claim. Let's see what the Northstar experts will say.

The saddest thing in life is wasted talent

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Those are the symptoms of head gaskets just starting to fail... BUT, on the other hand, the absence of combustion gases in coolant does not support the first claim. Let's see what the Northstar experts will say.

That was my thought as well. I'm just wondering if it is possible to have a head gasket breach without having combustion gases in the coolant. If so, then I think that's my problem. If it's a hg, then I will get another beater to drive for now and garage the Caddy until I can get it fixed. I'm not going to part with my car even if it means tons of blood, sweat, time and money to get her running right again.biggrin.gif

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Not good signs, that sounds exactly like the way mine started to go.. higher temps and a mis on startup that goes away, I eventually smelled coolant at the tank

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It isn't having any drive-ability problems at all. Rather than assume off the bat that it IS a head gasket, would it be safe to keep driving it for a while, keep a close eye on the temp so that it doesn't overheat, and see if other symptoms develop that can verify that as being the problem? It's kind of funny that less than a week ago I noticed the case-half seal is leaking pretty badly, and I said to my brother "oh well. At least it isn't a head gasket. I'll just wait until the head gasket goes someday and change the case-half when I have the engine apart anyway.".... and now it would seem I'm in that boat.dry.gif

But hey, it could be worse. smile.gif It's far from the end of the world.

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You have all the classic symptoms except for coolant usage (so far) Carla. IF it is a head gasket, it will let you know in due time. The symptoms will get worse. There are several tests you could do if you really want to know know.

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Let's hope that the worst case scenario is that the head gasket leaked a bit and the coolant sealer was able to take care of it and that otherwise you won't have anymore problems for the foreseeable future. If I remember correctly, didn't the Guru mention that sealer is could seal slight head gasket seepage?

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You have all the classic symptoms except for coolant usage (so far) Carla. IF it is a head gasket, it will let you know in due time. The symptoms will get worse. There are several tests you could do if you really want to know know.

I thought about doing a coolant pressure test, but it would lose pressure regardless of whether or not it's a hg because I have that stupid nuisance leak on the water pump cover.... Is there any other (fairly simple) test I can try that wouldn't involve pressurizing the cooling system?

For the moment I am going to keep driving it and see if it tells me anything new.... I'll check the coolant level a couple times a week and monitor the temps closely to see if they get any higher. I'll keep everyone posted if anything changes.

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If you've made sure the purge line is flowing, then the gaskets can be checked with the method below.

With the engine cool, pressurize each cylinder with 120 psi shop air while the respective cylinder is at top dead center on the compression stroke. You'll need to lock the flywheel in place to keep the crankshaft from turning. Watch the surge tank for bubbles - if there are bubbles, the head gasket is bad. Check the remaining 7 cylinders the same way.

You can make a spark plug air adapter from an old spark plug, an air line fitting and some pipe.

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Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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If I remember correctly, didn't the Guru mention that sealer is could seal slight head gasket seepage?

Nah, not a chance. Cooling system sealer will not even come close to sealing a head gasket leak.

I thought about doing a coolant pressure test, but it would lose pressure regardless of whether or not it's a hg because I have that stupid nuisance leak on the water pump cover.

A cooling system pressure test will not diagnose a bad head gasket unless it is so bad that there is no longer a question.

Is there any other (fairly simple) test I can try that wouldn't involve pressurizing the cooling system?

Yes, a block test kit from Napa or you may be able to rent one from a parts store. It simply samples the air in the surge tank above the coolant. The fluid in the kit is blue and if there are any exhaust gases present, it turns yellow. DO NOT test after topping off the coolant. That can give a false negative.

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I agree with Kevin, check the coolant flow first. Then check the coolant concentration, how close it is to 50/50 and when was it changed last. Then check the cooling fans. It could also be a weak pump or binding pump belt pulley. I would try to stay focused on it NOT being the head gasket, because you can miss something simple.

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Checked the purge line- no issues there.

I got the NAPA test kit and did it the day I started this topic. It came out fine. The coolant hadn't been topped off for at least a month before that, and I did the test after driving for a while just as soon as it was cool enough to take the cap off.

I've checked the coolant cap- that seems fine.

Water pump belt and tensioner pulley are less than 2 months old, so I doubt there is a problem there.

Coolant was changed in January, and a 50/50 mix was used.

Cooling fans appear to be working fine.

Since Sunday, I have not noticed any more coolant at the exhaust. There is still a miss and white smoke/steam when I start the car, but the moisture buildup in the exhaust tips appears to be water... The car is still running hotter than normal.

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Checked the purge line- no issues there.

I got the NAPA test kit and did it the day I started this topic. It came out fine. The coolant hadn't been topped off for at least a month before that, and I did the test after driving for a while just as soon as it was cool enough to take the cap off.

I've checked the coolant cap- that seems fine.

Water pump belt and tensioner pulley are less than 2 months old, so I doubt there is a problem there.

Coolant was changed in January, and a 50/50 mix was used.

Cooling fans appear to be working fine.

Since Sunday, I have not noticed any more coolant at the exhaust. There is still a miss and white smoke/steam when I start the car, but the moisture buildup in the exhaust tips appears to be water... The car is still running hotter than normal.

Carla, the NAPA tester probably does not "feel" low concentrations of gases.

The saddest thing in life is wasted talent

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The radiator is very clean. It actually looks like it's fairly new.

I'm not sure about the heater core... I don't know how to check it. My heat is working fine, I don't know if that's any indication or not.

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The radiator is very clean. It actually looks like it's fairly new.

I'm not sure about the heater core... I don't know how to check it. My heat is working fine, I don't know if that's any indication or not.

It means the heater core was either flushed or replaced.

The saddest thing in life is wasted talent

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I have discovered the cause of the misfire.. Turns out that the spark plug boot on plug 5 was pulled up a bit. I pushed it back down, and viola, no more misfire. I don't understand why the misfire went away within a minute or so after starting the car though if it was caused by the boot being pulled up. It seems to me it would have been a constant misfire. Either way, problem solved.

My temps are still running kinda high, but there has been no more coolant at the exhaust... I'm beginning to wonder if I made a mistake and thought it smelled like coolant, but it was really water?? There is still a lot of moisture in the exhaust it seems. I'm wondering, after reading through another recent thread, if perhaps my catalytic converter is clogged and causing the higher temps? As mentioned in my first post in this thread, my exhaust sounds extremely muffled when I first start the car. Everything in my cooling system seems to be functioning perfectly fine.

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I have discovered the cause of the misfire.. Turns out that the spark plug boot on plug 5 was pulled up a bit. I pushed it back down, and viola, no more misfire. I don't understand why the misfire went away within a minute or so after starting the car though if it was caused by the boot being pulled up. It seems to me it would have been a constant misfire. Either way, problem solved.

My temps are still running kinda high, but there has been no more coolant at the exhaust... I'm beginning to wonder if I made a mistake and thought it smelled like coolant, but it was really water?? There is still a lot of moisture in the exhaust it seems. I'm wondering, after reading through another recent thread, if perhaps my catalytic converter is clogged and causing the higher temps? As mentioned in my first post in this thread, my exhaust sounds extremely muffled when I first start the car. Everything in my cooling system seems to be functioning perfectly fine.

That's sounds good (the plug boot). The mufflers have small drain holes. Make sure it is not plugged.

The saddest thing in life is wasted talent

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I'm beginning to wonder if I made a mistake and thought it smelled like coolant, but it was really water?? There is still a lot of moisture in the exhaust it seems. I'm wondering, after reading through another recent thread, if perhaps my catalytic converter is clogged and causing the higher temps? As mentioned in my first post in this thread, my exhaust sounds extremely muffled when I first start the car. Everything in my cooling system seems to be functioning perfectly fine.

You likely mistook the normal condensation in the exhaust as coolant residue. All exhaust will look like steam when it is cold outside.

Clogged cat-cons were extremely rare in your car's era. I believe the huge issue with clogged cat-cons spanned the 2001-2003 model years.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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If I remember correctly, didn't the Guru mention that sealer is could seal slight head gasket seepage?

Well, your memory is almost correct. The Guru mentioned that the sealer could seal slight intake manifold seepage but this applied to previous generation 4.X (4.1/4.5/4.9) engines. These engines had an aluminum block, cast iron heads and an interesting aluminum intake manifold that kind of integrated with the heads. As you all know, cast iron and aluminum have different expansion rates which made sealing on these engines a challenge. So to prevent coolant from getting the oil, adding sealant tabs was recommended on these engines.

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I'm beginning to wonder if I made a mistake and thought it smelled like coolant, but it was really water?? There is still a lot of moisture in the exhaust it seems. I'm wondering, after reading through another recent thread, if perhaps my catalytic converter is clogged and causing the higher temps? As mentioned in my first post in this thread, my exhaust sounds extremely muffled when I first start the car. Everything in my cooling system seems to be functioning perfectly fine.

You likely mistook the normal condensation in the exhaust as coolant residue. All exhaust will look like steam when it is cold outside.

Clogged cat-cons were extremely rare in your car's era. I believe the huge issue with clogged cat-cons spanned the 2001-2003 model years.

The thing is, it hasn't been cold outside. This has been happening even if it's 80 degrees out.

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I'm beginning to wonder if I made a mistake and thought it smelled like coolant, but it was really water?? There is still a lot of moisture in the exhaust it seems. I'm wondering, after reading through another recent thread, if perhaps my catalytic converter is clogged and causing the higher temps? As mentioned in my first post in this thread, my exhaust sounds extremely muffled when I first start the car. Everything in my cooling system seems to be functioning perfectly fine.

You likely mistook the normal condensation in the exhaust as coolant residue. All exhaust will look like steam when it is cold outside.

Clogged cat-cons were extremely rare in your car's era. I believe the huge issue with clogged cat-cons spanned the 2001-2003 model years.

The thing is, it hasn't been cold outside. This has been happening even if it's 80 degrees out.

Until the engine/exhaust warms up, there will be steam/condensation from the exhaust.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I went to a doctor's appointment out of town yesterday. On the highway on the way there, my temp was sticking around 228. Once I got off the highway and was sitting at a red light for a few minutes it shot up to 239, then dropped back to 228 once I started driving again. After my appointment when I went to leave, I noticed that the car felt sluggish. I hadn't done a WOT in a little while, so I figured why not? I did it 4 times. The first time I floored the gas, a huge cloud of black smoke came out of my exhaust. It smelled awful. A mix of sulfur and some other smell I couldn't quite put my finger on. The 2nd and 3rd time I did it, still a bit of black smoke but not as bad as the first time. The 4th time the exhaust looked normal. Obviously something was clogged up. After that though, my temp hasn't gone over 215. Still no codes present either. Was this likely from the EGR system?

Also, it seems people love to mess with my car... Over the winter someone took a sharpie marker to my cloth top (which I finally got most of it out). A little over a week ago someone keyed my trunk. Then yesterday when I left the doctor's office, I noticed that someone had rear-ended my car. mad.gif The driver's side rear bumper is shoved forward about 3 inches, and there are several scrapes and chunks of paint missing. Looks like I am going to have some cosmetic work to do after I get everything else taken care of.

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I never heard of Northstar running hot because of carbon deposits. As for rear-ended Eldo, the doctor office may have security cameras.

The saddest thing in life is wasted talent

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It's beginning to sound more like a clogged cat. If so, you will likely eventually have a cat code. This may be an opportunity to get an OBD-compliant high-flow cat for about $125, but I wouldn't spring for it until I was sure that you were fixing a problem.

Both mufflers being clogged can also be a source of both overheating and accumulation of carbon. As adillac said, make sure that the muffler drain holes aren't plugged.

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