I have a '94 Bonneville, non-supercharged, that runs great with 183K miles on it. However, I just noticed the other day that, after running for 5 or so minutes, white smoke starts coming out the exhaust. My first thought was a cracked head or gasket and, upon warming up, it started sucking antifreeze. However, in the last 2800 miles the coolant level has not changed. Also, it doesn't smell like burned antifreeze; it'* more an oily smell, but it'* white smoke, not blue.

I guess it could be bad rings but A) it runs great with plenty of power and B) Wouldn't it smoke from start up and be more blue?

My question: is there something else that could be being sucked through a vacuum line into the engine? (like tranny fluid from turbo 350'* with a bad vacuum modulator or ps fluid from Toyota pickups)

I haven't had this car for long and I hate to think it'* dying on me; anybody have any ideas? Thanks.

might be sucking fuel into the vacumme line on the Fuel Pressure Regulator could smoke a little white after idling awhile. pull the vacumme line off if you see or smell gas replace it

LIM gaskets leaking and/or UIM burn through at EGR tube. Change them now or be looking for a new ride.

Thanks. When it warms up a bit this morning I'll follow up on those. Pardon my ignorance, but what do the abbreviations LIM and UIM mean?

lower and upper intake manifold. both gaskets love to go on these motors. gm thought it would be a good idea to use plastic ones. if/when you replace them make sure to get the updated metal ones.

Sorry if this is a repeat. I replied to this but it didn't show up. I pulled the vacuum line on the fuel regulator -- no fuel and very little smell. I started the car and ran it a bit and tried it again -- still the same. Since I have a parts car I'll pull its regulator and try it, but I don't think that'* the problem.

I then drove the car at highway speeds for 30 minutes. I couldn't see anything coming out the back the whole time. I parked it at home and let it idle -- still no smoke. At 2 minutes, it started puffing whitish smoke and I shut it down.
I'm convinced the rings are fine and that this vacuum thing will pan out. Is there some way to test the intake manifolds -- spray starter fluid or something. Or, is it a safe bet that at 183K they need to be replaced? Thanks.

If no gas or gas smell from the FPR then it is fine and I would not change it.

Good bet you need to change the manifold gaskets. Intake leak is coolant getting into the oil problem causing white smoke. If you haven’t noticed a coolant drop then maybe you are lucky and catching it early. What does the oil look like?

Also not sure about a 94 but you may need to get a reduced diameter EGR Stove Pipe that goes into the Lower Intake Manifold it replaces a plastic sleeve that also fails.

I haven’t done this on my 98 166k - but plan on it when weather warms. I gather from searching posts that it is not IF the gaskets will fail but WHEN.

https://www.gmforum.com/mechanical-134/uim-lim-gaskets-l36-297702/

Since I have the parts car and don't have immediate access to new manifold gaskets, I quickly swapped out the fuel regulators (wishful thinking!). I started it up, and, sure enough, just short of 2 minutes it started smoking. Since I first noticed the smoking -- 5 days ago -- I've meticulously watched the coolant tank level and checked the oil several times. The coolant level doesn't seem to be dropping and I can't see any sign of coolant mixing into the oil. No water in the oil makes sense if it'* just sucking coolant in and throwing it out the exhaust. Also, I've not let the car sit around idling and I've only put 50 highway miles on it since I noticed it, so I haven't given it a lot of chance to suck away coolant. Maybe I'll get the gaskets ordered then take the car to town to run errands and let it idle between stops. Maybe that will make a dent in the coolant level and confirm the gasket theory.
Will I be able to get the manifold off without messing with the injectors and rails, or will they have to come off too? It looks like, if it can slide up between the rails, it shouldn't be that difficult of task. I guess it'* time to track down directions and start getting psyched up to do it....

The fuel rail and injectors have to come off. I would suggest the Dorman intake as it will have all the necessary gaskets and injector o-rings with it. The LIM gaskets you want to get are GM 89017816.

samething happed to my LSS right after engine rebuild. white smoke with no coolent loss, smells more like oil. Its your vacoum modulator on your trans. very easy to replace and costs $13. also its the same modulater used on turbo 350'*.