OK... I just got done w/heads/cam/intake and a bunch of other goodies, car runs good, seems ok, however sometimes on decel from high speeds it starts pumping out what looks to be (in my rear view mirror) white smoke... However, it does it on accel sometimes too

Now here's the strange thing, before I did all this work, the car did this also sometimes, I don't think it's head gasket...

What should I be looking for? what should I check? What tests should I run? Anything maybe just connected wrong?

Any help appreciated.
Mike

 

TTT

 

Well, I since I have a six speed I haven't studied much about the 4L60E, but I know that I was getting white smoke in my 71 chevelle before and that somebody told me that it could be the vacuum modulater on the tranny going out, so I was sucking tranny fluid up into the intake and it was burning through the exhaust. The only other thing of course would be coolant getting into the cylinders, and of course you are burning it out. But if you say you were having the problem before heads and cam, I would hate to say maybe a cylinder wall cracked or something along those lines. Do you recall if any of the cylinder walls nice and shiny? Hope this helps!!!

 

White smoke is burning Oil isnt it? Maybe need new rings? How many miles are on the car?

 

I had the same problem...after a leakdown test..compression test I found the #7 piston was burnt. Oil was leaking and I had white/grey smoke out the exhaust. The strange thing was there was no loss of power. I would check to see if there is any oil residue in the exhaust when cold. ...also pull ALL the plugs to see if any of them show a oily residue. It's always the last plug that's the culprit.Hope things work out for you.

BTW ...I went with a new 382 stroker rebuild.

 

Thanks all, I'll take a look. I don't think it's a cracked cylinder as wouldn't that do it at all times even high revving idle?

I'll pull the plugs this week and see if any of them look strange (should be easy to tell, brand new plugs put in 40 miles ago).

I'll also watch the oil consumption... guess it's time to start shopping around for a 382 short block...

 

White is coolant usually, I would top off the coolant drive it around for a while, let it sit and check the coolant again to see if you are eating any.....

Could possibly be that a head gasket didn't seal right....

 

white is coolent. Like the bigbos said, head gasket might not have sealed.

 

Let's not jump to conclusions.

Keep in mind that you probably are burning off some gunk too.

Top off the radiator cold for a couple of days, and then start to monitor it. Make sure none of your hoses are leaking, I know two MFBA guys who thought they were using coolant and just had loose hoses.

 

ok, few more things I've thought of

1. Seems like it's only occurring under heavy vacuum (Deceleration after WOT, or acceleration at high speeds)
2. I had this problem before (blowing white smoke out on deceleration from WOT at high speed), and never saw any coolant in the oil, which would lead me to believe it's not a cracked block
3. It occurs much more now than before, which could be oil blow by caused by raised compression? (it looks white in the rear view mirror, but I've never seen oil burning so dunno how noticable the blue tint is)
4. One of the things I changed was I had my Stock Throttle Body Ported... does anyone know if it's possible for a crack to develop in the TB allowing coolant in from the coolant lines that run through the throttle body? If there was a minor imperfection before, ported would make it worse, and under heavy vacuum it would try to suck it through the intake... I'm going to try the TB bypass mod this week
5. I never noticed low coolant before when I had this problem, and never had excessive oil consumption (changed every 3000 miles not much lower than when I filled it)
6. One of the things I changed is I went from the LS1 style PCV to the LS6 style PCV, could this have changed anything?

Now, if it were a cracked block I would definetly find coolant in the oil right? Also wouldn't I also wouldn't it almost always be puffing out white smoke? Not just under heavy vacuum scenarios?

I know I'm running rich now , is it possible that excessive water is building up in the exhaust after the cats and this is steaming causing the smoke, so not actually in the combustion chamber but in the exhaust instead?

Also, when we changed the heads, the plugs that were in the heads looked ok, and the pistons all had carbon buildup but nothing major... heads weren't discolored at all , looked normal.

Finally ... is there any kinda dye that can be added to the coolant so that it will stain anything it touches? This may help in trying to find a crack somewhere or a busted coolant line...

Thanks!

 

If you had a cracked block you'd have big problems right now.

Chances are that's smoke from burning oil. But top up the coolant and keep an eye on it. When I had coolant usage a long time ago it was obvious, I would use a pint or more a day. I'd be down a quart every other day. After two weeks it would become noticeable when I was driving.

I think your TB is fine.

I'd autotap to see how rich you are running, if your 02's are close to 1000 you migth be seeing smoke from running rich.

 

Good luck in your journey Mike. Here's a TTT for ya.....Maybe let Speed check it out.