Rough idle

[postalpsycho]

Hey, guys, i'm new here, but i've been looking around, and you all seem quite knowledgeable. I'm hoping you can help me on this one:

 

I've got a 1991 Oldsmobile CS with the 3.1L V6. Just yesterday, after about a 60 mile trip, I got into town and was sitting at a stop light when the car began to idle extremely roughly. I drove it home (a couple blocks) and had it running while I was looking over the engine. It wasn't making any unusual noises, but after a few minutes of running, it began pouring LOTS of white smoke out the tailpipe. I shut the car off, let it cool, and came back out and started it again. It still idles rough, and hestitates and stutters at low rpm acceleration, but once the rpms get up, it seems to accelerate and run fine until I start coasting or come to a stop. And whenever i'm sitting at a stop light, it starts billowing the white smoke again, but upon acceleration from the stoplight, the smoke disappears. I can't figure it out.

 

If I need to explain anything in further detail, i'm sure you'll let me know. Any help is greatly appreciated, thanks!

[DaveFromColorado]

sounds like one of two things, either the first one, you need a new intake manifold gasket, or second, you blew a head gasket - I'd be willing to put money on needing the intake manifold gasket.

 

--Dave.

[postalpsycho]

If I blew the head gasket, I should expect the whole "milkshake oil" scenario, though, right? My fear was that it was the head gasket as well, because i've had some overheating problems recently, but was always careful to stop driving once I saw the overheat light. However, since this idle problem started happening, I've noticed that with the heater on, no heat comes out, even though the coolant level is proper. I just had the radiator repaired, flushed, and replaced the thermostat. (I hope it's not the head gasket, i've been checking the oil after every drive, and it all looks proper...)

[DaveFromColorado]

if the coolant is just burnin' into the cylinder and not to the oilpan then you could still have a broken head gasket, however, it's MORE likely that it's the intake manifold gasket - that's just from past expirence, without actually seein' the car, it's really hard to tell.

 

--Dave.

[1990lumina]

If I blew the head gasket, I should expect the whole "milkshake oil" scenario, though, right? My fear was that it was the head gasket as well, because i've had some overheating problems recently, but was always careful to stop driving once I saw the overheat light. However, since this idle problem started happening, I've noticed that with the heater on, no heat comes out, even though the coolant level is proper. I just had the radiator repaired, flushed, and replaced the thermostat. (I hope it's not the head gasket, i've been checking the oil after every drive, and it all looks proper...)

 

As for the heater not blowing out any air...sounds like your heater core is plugged up and not allowing coolant to pass through it.

I had this problem with my RX-7 when I replaced the oil cooler...there was a nasty air lock in the heater core...but turning on the heat fixed it quite quicky, so I'd say something is jammed in the passage way or is clogged up...Just my 2 cents though.

[postalpsycho]

I was pulling spark plugs earlier today, and when I pulled the number 3 plug, there were a few beads of water on it. And i've lost maybe a half gallon of coolant in the last couple of days. Soooo...i'm guessing the rear head gasket? *Sigh*

[Brian P]

your loss of the heat could be air getting into the system as a result of the possible failed head gasket. However in that case, your temperature gage (do you have one?) would fluctuate. Why did you get the radiator, T stat replaced, and flushed? Any past problems? leaks? overheating?

[postalpsycho]

Unfortunately, no, I don't have a temp gage. I had the radiator repaired because there was a four inch crack in the plastic end reservoir part of it that dumped coolant like crazy once the car warmed up. It was leaking pretty bad for a period of a couple weeks, and it only overheated a couple of times (temp light came on) during that period. I was always careful to stop driving pretty much immediately after the light came on so as to prevent damage, buuuuut... I replaced the thermostat shortly before that just to be sure that my problem wasn't being compounded by a stuck thermostat. And while my mechanic was working on the radiator, he flushed it to ensure it was good and clean. Other than that, i've been driving the car with no problems for the last couple of years.

 

More on replacing the spark plugs: like I said, when I pulled the number 3 plug earlier tonight, there were a couple beads of water on the tip of it. And my coolant was low. After swapping those back three plugs (I replaced the front three yesterday), the car doesn't want to start, and won't stay running unless it's pretty well floored. I refilled the radiator with coolant as well, and now I get a strong smell of antifreeze when the car is running. If I can't get it to at least run without dying at every light, stop sign, or even while rolling along at 25 mph, looks like i'm gonna have to start biking to work. (Ah, well, it'll be good for me, right?)