67 429 Eng. Question need advice -- phase II

[cadillacproject]

Hi again all!  New issue.  My motor was running just great.  In fact I am ready to get the car into paint.  But before I did that I wanted to make sure that there were no major mechancial issues.  Well today on a short test drive the car started to blow white smoke.  I think that this is steam its not blue or black and leaves no residue.  Engine runs OK.  This was not happening two days ago.  Think I have a head gasket problem?  The engine was rebulit some years ago. 

When the car is first started there is no white smoke.  After it warms up there is a stead stream of smoke.  Not super dense but noticable and sometimes gets thicker when accelleration takes place.  Again I am sure this is steam and not oil or gas burning.  I had the engine so nicely detailed { do I need new head gaskets?

[Ted in Olympia WA]

Not sure if the 429 had water going through the intake but if it did I would say the problem may be there; since you just had it off.

Give it a compression test and see if any are low; this will tell you about a blown headgasket.

Good luck

TED

[cadillacproject]

No water through the intake on the 429 motor.  Which is nice.  The exhaust does not smell like antifreeze.  Could it be transmission fluid getting sucked throiugh a bad modulator valve?  Ill have to check that too.  How does one verify a bad head gasket anyway?

[The Tassie Devil(le)]

Usually, White Smoke is burning Transmission Fluid.

Check your Vacuum Modulator by removing the Vacuum line from the Transmission to the Manifold and block it up.

Take it for a drive and if no smoke emits, then the Modulator is bung.  Or leaking actually.

Bruce.

[cadillacproject]

OK.  I did the test with the modulator line disconnected and plugged at the manifold.  Still white smoke.  When I first go the car I saw no smoke at all. Now I have driven it mabey 30 miles total.  It has idled a lot while I did the tuning etc.  I did change to synthetic oil ( mobile 1) is it possible its burning oil now past the rings?  I don't see any oil in the radiator or any sign of water on the dipstick.  The exhaust does not smell like antifreeze.  Should I change back to dino oil?

The smoke increases with engine load and revs.  Its quite noticable. 

[Dave Shepherd]

Condensation in the muffler can this but it would be gone in 10-20 miles of warmed up driving. If it were a head gasket you wpould loose coolant and have a coolant smell in the exh. as you mentioned.  Cpld temps can cause this also.  If you pressure test the cooling system an and it holds pressure the head gaskets are ok.

[bill henry]

how long has this car been sitting maybe the exhaust system is full of condensation it will not start to boil out till the exhaust is hot . happens to my 70 every spring

[Otto Skorzeny]

To rule out your question about Mobil One oil , change back to normal oil and see what happens.

Personally, I wouldn't recommend synthetic oil for your car but that's a whole different discussion and yes, that might be the culprit but I doubt it. From your description, it sounds more like steam than smoke.

Get to the bottom of this nonsense. Perform a wet and dry compression test if driving 30 miles doesn't cure the problem.

[The Tassie Devil(le)]

I was going to add that when changing over to a Synthetic Oil, I think that the internals of the engine HAVE to be totally clean as the Synthetic Oils don't mix with Petroleum-based Oils.

I may be wrong, and a lot of times am, but I have heard of problems with simply swapping Oils.

Bruce.

[cadillacproject]

Well I changed back to Castor Oil GTX 10-30 and the smoke iis alll but gone.  I have used synethitic in my other classic cars but none are the big GM engines.  Anyway the smoke went away with just the oil change.  I think that under hard accelleration I can still see some smoke.  My theory is that the rings are worn and the synthetic oil does not seal them as well and got past and into the combustion chamber.

[The Tassie Devil(le)]

Great news, but I can remember somewhere that it is very hard to bed rings in with Synthetic Oils.

Bruce.

[Otto Skorzeny]

Try 20w -50 in your engine and I bet the remaining wisps of smoke will disappear.

[Brian Daum]

If you ever take an old engine apart, you will be amazed by the amount of sludge and guck that has built up over the years. This sludge is deposited around in the engine, and using synthetic oil will dissolve some of these deposits, and it will eventually end up in your bearings. That is why I never use synthetic oil in my old classics. In my newer cars, yes.

I have in the old 56 gone over to 30W Pennzoil, I change the oil once a year, no matter how far I drive. I average appr. 1500 miles a year on it.

[TJ Hopland]

Im thinking this may just need to get driven a bit since none of the usual signs are showing.

FWIW I have gone back and fourth between full synth and regular several times in crusty old engines.  Last few years it was in my 78 Deville's 425.  That motor I suspect was a low mileage due to short trips over its life. It had a thick layer of sludge over everything. On that I did extra frequent changes (with regular oil) over the first 1000 or so miles and tried to take it on longer trips.  It really seemed to help because it began to run nice and smooth and the oil started staying clean.  Currently in my 75 Eldo.  Im using it because of cold to extreme cold starts since they have to sit outside.   Both motors have a leak or two and dont seem to consume or leak any more or less based on the oil Im using. I also have not noticed any signs that the synth cleans any more than regular (unless you run it longer and it just gets dirtier).

[cadillacproject]

I think that the driving will certainly help.  I drove it for perhaps 15 mins the other day and I could already notice the smoke going away virtually completely.  The car has not been driven at hiway speeds in months. Since I believe that the engine is sound now I have the car getting painted.  Once that is done I can put the trim and bumpers back on.  I plan on doing the interior last (its all stripped out now) but before that I can give it some good long drives once I get the bumpers, lights, and license plates on.  I just stick the front seat in and its drivable. 

I will try some oil experiments with synthetic vs. regular oil etc. after some driving and see what happens with smoke etc.   I thought a heavier synthetic says 10-40 or more might work as well once I give it some good driving.   Thanks eveyone for the help. I hope to post pictures in about a month when the paint is done.

[TJ Hopland]

Getting it good and warmed and a few miles on it will likely help.  Just keep an eye on the fluid levels to make sure its not using something.  Extra fequent changes for a while will also likely help because it introduces a fresh batch of detergents. 

[Ted in Olympia WA]

In 1985 the wife and I spent 5 weeks in Queensland Au.  We purchased a Kawasaki ST1000 to get around on (no insurance required for a bike).  The problem is that it burnt oil like crazy.  As the oil level went down I would purchased a new litre and put it in (this was about every 300 miles).  We had very little money for the 5 weeks and were camping along the way and this expense was not in our budget.

I notice that you could buy a 4 litre container for the same price as 3 litre of oil so I thought this would be a good investment.  So I purchased the large container, put a litre in the bike and it never burnt another drop.  I had to carry this container of oil with me for the rest of the trip and I gave it to the new owner.  By the way we purchased the bike for $1,000 and sold it for $800; what a deal.

Anyway it does help sometimes just to give it a nice long drive.

That being said; the other day I tore down what looked like a very nice 1968 472 engine and all the top rings were broken.  I just think that the today's gas it too good for the old high compression engines.

TED