I took the Vette to the road course yesterday. I have been to this course before with no problems, but yesterday I was getting a lot of white smoke coming from the tailpipe. There was a little smoke under heavy acceleration, but a huge cloud under deceleration and turning. Before yesterday, this engine has never smoked. Now, here is some more history and what has changed:

Changed (as in yesterday was the first time the car was run with these changes):

Fuel injection and distributorless ignition
New intake manifold for FI
Distributor plug replaced distributor
New Fel-Pro intake manifold gaskets


History:
Block and heads surfaced when I rebuilt engine
No issues with carb (Lars built)
Stock intake (I looked through receipts from engine build and didn't see a charge for machining the intake; I can't remember)

After seeing the smoke for the first time, I pulled in to check things out. What I noticed was oil leaking around the distributor plug. The hold down was tight, but there was clearly oil leaking from the plug. There was no oil coming from my breather on the pass side valve cover (used to have small amount of oil seeping from the breather). I checked the PVC valve by sucking on it from the intake side (nice taste in the mouth) and if flowed freely. The oil level was between ADD and FULL on the dipstick.

My thought is that the intake manifold is leaking and pulling oil from the valley. However, the engine will idle at 600-650 RPM. I would think it would idle faster than that if the manifold were leaking. I'm also a little afraid that I have been running the engine rich while doing the fuel injection install and setup, washing down a cylinder. I have not done a compression test yet. I also started with a known fuel map from a small block and then adjusted for my displacement and injector size. I don't believe the engine was running that rich.

So, any suggestions or ideas? Sorry for the long post, but this has been bothering me since yesterday. The engine didn't smoke before, and I would like to get back to that.

Thanks
Ken

 

Need more info about this smoke, bluish white(oil), white with moisture and a sweet smell(water and antifreez)? Running rich gives off blackish smoke.

 

If it's truly white ... it's water-coolant.
New intake can be sucking water-coolant across gasket into as few as 1 or as many as 4 ports.
If it's bluish, it's oil ... intake could be sucking that across too.
Many paved tracks have a ban on any anti-freeze ... slicks up the track.

Is there any bubbling of combustion gases inside radiator? (cracked head/leaking head gasket).

Were any guides in head(s) replaced during your rebuild? (BB will leak coolant around guides & into cc).

 

Auto transmission? If so, check modulator valve to intake.

Agree with Jackson, white smoke normally indicates coolant leak.

 

As for the color of the smoke, it was white. Whether or not it's bluish white, I couldn't really tell looking in my mirror. My impression was that the smoke was from oil. I lost about a 0.5-0.75 quart during the run. Other people around or behind the car on the track thought it was oil smoke as well.

I have not had the overflow tank cap off with the engine running yet, but I will take a look at that. However, why would it smoke under braking/acceleration? The vacuum is almost as high at idle as it is under deceleration. Would I see just as much smoke when the engine was idling if this were coolant?

Nothing was changed in the heads during the FI install. The car is a manual. I put my nose right in the exhaust while it was idling and didn't smell any anti-freeze. How long would the anti-freeze smell stick around? Do you think I would be able to smell it on the plugs?

Thanks
Ken

 

My money is on the leaking intake.

 

A little update:

I haven't had a lot of time to work on the issue until this week. I checked the compression and got a solid 150 PSI on all cylinders. However, when I pulled the plugs, the threads were all wet with oil. One plug was fouled up pretty bad with oily deposits. Also, with the car idling, I noticed oil seeping from the passenger exhaust manifold gasket.

The good compression and oil on the spark plug threads, to me seems to confirm the intake is leaking. What do you guys think? I just want to be sure before I take the intake off.

Thanks
Ken

 

Did you pull the oil dipstick and see milky looking oil? If so, then you have coolant leaking in which is causing the white smoke. I originally thought head gasket, but if the compression looks good on all cylinders, then I would consider pulling the intake and replacing the gaskets

 

Monitor your coolant level, my hope is the intake but it could also be a head gasket. If its a head gasket you can also get a pressure build-up in the cooling system from the offending cylinder. Has the car been belching coolant?

 

I just checked the oil and there are no signs of coolant in the oil. The oil smells fine (like oil) and it is not milky.

Is there anything else I am missing? If not, I guess I will go ahead and get some more intake manifold gaskets and get started.

Thanks for the replies.
Ken