Hello, all! I have a 1998 Chevy Blazer with about 123,000 miles on it (I’m the original owner). Currently, it gets driven about once a week. When I started it last weekend, the engine started off running kind of rough, and I thought it might stall out. After what seemed to be 10-15 seconds, it smoothed out, and so I went on my way. As I turned out of my driveway and started up the road, my car was enveloped in smoke that was either white or light gray. I looped around the block to return home. The was still smoke coming out the tailpipe, but I don’t think it was as bad as it had been at first. I was surprised that the “check engine” light didn’t go on through all of this.
I’m kind of assuming that this is an indication that there is oil or coolant is leaking into the engine while the vehicle is parked, and that it’s not likely worth trying to fix given its age. But, I thought I’d reach out to see if there were any other causes that might be worth investigating.
What did it smell like? Burnt oil or sweeter? Sweeter is coolant.
Is the check engine light on? How long has it been on?
Does it have any leaks to the ground? Oil or coolant…
Is coolant disappearing with no puddles under the truck?
Is the oil level going down?
Why? Is a rust bucket? Or are you just figuring no one will want it?
The check engine lights on a 98 will be limited. Start it up again and smell the exhaust to see if it is oil. Check a few plugs for fouling and you can even do a coolant test for exhaust in the coolant. Also a compression test might help, then might try motor medic or something to free the rings up, if oil. Now tappers leaking down will cause a rough running until they pump up again, but sounds more like ya either got a head gasket, stuck or worn rings, for it to do it after running a while. Even my car that went through a quart of oil every 500 miles didn’t smoke though. But what do I know?
White smoke out the exhaust pipe could be coolant from a head gasket problem, but you’d usually notice a significant coolant loss, having to add coolant all the time to keep it topped off. Grey to black smoke could be an overly rich fuel/air mixture. Unless you’ve had a significant engine overheating incident in the past, that’s my guess. The best test for this is an OBD II scan tool fuel trim test. Beyond that, take a look at the O2 sensors, do any seem coated with gunk? If so, clean them off, see if that helps. While looking in that area, do you see any signs of an exhaust leak, especially between the exhaust manifold and the cat? Look for blackish marks on the exhaust system, esp near connections. An exhaust leak will confuse the computer’s air/fuel calculations to no end .
Problems with the ignition system should also be considered, esp the high voltage portion. Do you see any weird lights jumping around in the engine compartment when idling the engine in the dark with hood open?
Good info above. If exhaust smoke appears immediately after starting a cold engine, problem is unlikely O2 sensor related.
hmmm … any other ideas? … maybe an engine valve stem seal leak has developed. The symptom is a big puff of black/blue smoke out the tailpipe when first starting the engine, then the exhaust appearance usually returns to normal. An injector stuck in the “on” position could cause back smoke out the tailpipe. A problematic evap system might do that as well. The fact that the car is only driven once a week still makes my first suspicion some sort of problem w/ the exhaust system .
Let me re-phrase. Whether obd 1 or 2, there is no code for exhaust in the coolant, or coolant in the oil. If you see white smoke, blue smoke, or steam it the tail pipe, you need to rely on a mechanical investigation by a mechanic, not expect a trouble code to pop up telling you what is wrong, although there may be codes that indicate a particular problem. The computer does not test the condition of the oil or coolant. But then I may be wrong since I am not a professional mechanic or code reader.
Thanks, everyone, for the quick replies! When the problem happened last week, I didn’t notice any particular odor, either that of burning oil or of something sweet.
I finally had the chance to run it again last night. This time, it started fine without any roughness. Immediately after starting the engine, I ran around to check the exhaust. There was no smoke this time. There was a faint odor of gasoline, but that dissipated quickly. I drove around the neighborhood for about 15 minutes to get the engine hot. There was still no smoke or unusual odors, and the check engine light stayed off. I haven’t had a chance to look at the exhaust system yet (maybe this weekend)
I checked the coolant level. It’s a little on the low side. I don’t think it’s much lower than the last time I checked it hot. Now that I think about it, it’s also been 11 years since the system was last flushed and refilled. I don’t know if that’s related, but I should probably get that done again.
The oil level was fine. There’s a small oil stain under the vehicle, but nothing worse than it’s been doing for the last 7+ years.
So, the problem seems intermittent. The only other obvious variable is that it was in the morning and about 80 degrees outside when I had problems with it, but a little over 90 last night. The humidity was probably higher in the morning, too. That doesn’t seem like a big difference to me, but maybe it mattered.
Regarding Mustangman’s original question, my Blazer has the following (presumably unrelated):
The air conditioning doesn’t work. It’s always passed the pressure test and no one could find a leak, but I was refilling the system every two summers (since around 2012). A couple years ago, the refill lasted less than a year, and I gave up refilling it since I drive it so little (even though I’m in Georgia and it’s hot). The compressor is relatively new (less than 8 years), though, so the problem is probably somewhere else.
The mechanism controlling where the air comes out of the vents is broken/stuck. Air comes out at the feet, the dashboard and the defrost vents all at once regardless of the setting. From what I can see of the vacuum lines behind the glove box, everything seems to be intact. The temperature control still works, but the “door” (I don’t know what it’s really called) makes a creaking sound when it moves. I’ve been expecting for that to fail for the last few years.
I seem to get water inside the hood when it rains. My parking lot is sloped. If I park with the driver’s side at the low end and there’s a good rain, I hear water slosh around when I back out of my parking space and it pours out towards the right front corner of the vehicle when I drive downhill to exit the parking lot. Parking so that the driver’s side is uphill fixes the problem.
There is a bit of rust, mostly cosmetic. But there is a clean track in the dirt on the inside of the windshield that suggests that a small amount of water enters when it rains. I’ve never actually seen it, and it stays dry when I’m driving in the rain.
There’s a small leak in the gasket/strip of the driver’s door that lets in rain water. It’s negligible, though, when the driver’s side is uphill.
The mechanism to stow the spare tire under the vehicle rusted shut, so now the spare lives in the trunk.
The windshield wiper fluid tank has a leak. I think it’s at the junction where the pump draws fluid for the rear window, which should be an easy fix. However, it looks like I’d have to take apart several other things to get to it, so I’ve just kept the fluid level low and filled it more often.
The controller for the side mirrors doesn’t work. When I last replaced them, I used a 9-volt battery and a couple paperclips to adjust them. Since I’m the only driver, it’s not an issue for me, though.
Number 3, waterunder the hood, suggest to not defer that fix. Could damage engine components or cause a rusted firewall, both are very expensive repairs. You probably just need to replace some gaskets, and/or the drain-pathways that direct rain water that hits the hood/windshield to flow to the ground are clogged.
Renewing the coolant is next ton the priority list imo, another that should be done asap.
As far as the engine problem, I think if I had that problem on my earlier-era Ford truck my first test would be to measure the engine compression. You may have a sticking valve.
Funny story, I was a teenager when I bought my truck. I used to measure the compression every 6 months… lol … don’t know why, it never changed. But I was determined it needed to be measured. Now, it hasn’t been measured in 30 years. No reason to measure it. I do measure the intake manifold vacuum every two years, so that gives me some insight about the engine compression.
Could it be the intake gasket leaking? Some GMs from this era were known for that. I think they mostly leaked externally though and not internally but I might be wrong.