White smokes+gasoline+black spark plugs

[Tiree]

I have a 1973 C&C27MkII, and I am a new member located in Montreal, Canada.
I am having very recent problems with my A4: it's suddenly smoking a lot of gray/white smokes, gasoline is ejected by the exhaust, and my new spark plugs are already very black and wet.

During this last weekend, I have checked the compression (which is the same into the four cylinders - 90PSI), changed the spark plugs, checked&adjusted the distribution and the carburetor. And following that, I have completely drain and changed the possibly contaminated gasoline, checked the gas filter, drain the carburetor, cleaned the air filter and completely drain and changed the oil.

At the bottom line, the engine starts very well, and runs properly. But...

It's always smoking a lot of gray/white smokes AND gasoline is ejected by the exhaust pipe AND the brand new spark plugs are already very black and wet.

That being said, the bosun of my yacht club has given to me a white paste used to check if there's any water on the electrode of each spark plug; this paste remains white - the test is negative. That means, if the test is efficient and relevant, there's no water in the combustion chambers, and so, probably no necessity to change the head gasket.

Does anybody have any suggestion? Thanks in advance for any help or info.

Didier
Tiree-C&C27 MkII
BYC - Montreal

[roadnsky]

Originally Posted by Tiree

...At the bottom line, the engine starts very well, and runs properly. But...

It's always smoking a lot of gray/white smokes AND gasoline is ejected by the exhaust pipe AND the brand new spark plugs are already very black and wet.

Didier-
Welcome to the MMI forum. Hopefully you can find some wisdom here.

Could you please explain a bit more what you mean by "gasoline is ejected by the exhaust pipe"?
Given that you say your A4 is starting and running well, my first impression of reading your symptoms is that your carb only needs a little bit of adjustment.
It appears to be running RICH.
Have you tried turning the idle adjusting screw OUT a half turn at a time yet?
(See the attached drawing)


Give us a little more info and you'll get plenty of opinions...

[Tiree]

Thx for welcoming.

As the engine is running at idle, I have some fuel coming from the exhaust mixed with water and fumes.
I can clearly see some fuel stains on the surface of the water.

Didier

[CalebD]

Ca va Didier,
My first thought was that the carburator mix was too rich with gasoline/petrol as this usually makes the spark plugs dirty quite quickly.
My second thoughts bring me to believe that we may have lost something in translation. Gas/petrol readily evaporates and you can smell it and would not likely see it in liquid form coming out of the exhaust which is hot. Lubricating oil on the other hand would come out and create a sheen or slick of oil that one could see on the waters surface near the exhaust. Can you smell unburned petrol/gas fumes in your exhaust? Or do you just see a shiny slick by your exhaust?
Blue/gray smoke coming out of the exhaust would indicate that the engine is burning some oil. White 'smoke' could be steam.
If the spark plugs quickly foul up with black gunk could indicate that the carburator is too rich but it could also be that the cylinder rings are allowing oil into the combustion chamber which would also give the spark plugs a 'wet' look as well as help foul them quickly.
Your engine is old enough to have piston ring issues. One of the routine maintenance tasks many of us do is to squirt a small amount of Marvel Mystery Oil into our cylinders while the spark plugs are out. This can help to lubricate the valves and piston rings. Marvel Mystery Oil is a very light weight oil (around 5W) that also contains rust inhibitors and smells like spearmint. It is an inexpensive thing to do and seems to help our old A4 engines running. If you can not find it in Montreal it is available from the MMI store.
Another more remote possibility is that your exhaust system has some restriction or blockage in it that allows a back pressure to develop.
I suspect that you are burning some engine oil rather then gasoline/petrol or fuel coming out of your exhaust.
To narrow the focus of discussion it would be helpful to know the answers to these questions:
How long have you owned this boat?
Has the engine always behaved this way? (or since you have owned it.)
Are you sure the ignition wires are all new?
When was the distributor and rotor last changed?
Does your ignition system use 'points' or is it an electronic (newer) system?

You could be spitting petrol/gasoline or fuel out the exhaust if one or more of your cylinders is not firing properly.
Can you smell unburned fuel in the exhaust?

Bon chance et bon soir.

[Tiree]

Many thx for your respective inputs. And I'm trying to do my best with English in dealing with mechanical terms

I do agree with you: the mixture is too rich! And I will try turning the idle adjusting screw out a half turn as suggested by Jerry.

Regarding the fuel stains on the surface of the water. I was wondering if these stains were oil or fuel. With throttle high, the engine is smoking a lot of white smokes and these fumes smell fuel. And as I have changed the fuel of my gas tank, I made a test in dropping a few fuel droplets on the water, and observe if it appears the same things. The test is positive. And these stains evaporate very quickly. I understand that you suspect that this A4 is burning its engine oil. And I think these white smokes could be steam. Therefore I'm a little bit disappointed and anxious.

I was wondering if this black gunk on the spark plugs could be oil. But the unburned fuel can do the same, doesn't it? And as the color of the fumes is not blue, and the liquid which is coming out the exhaust pipe seems to be... unburned fuel..., I assumed that the piston rings are in good condition.

That being said, I will try to squirt a small amount of Marvel Mystery Oil - thx for the advice.

Your comment on my exhaust system is interesting. This was one of my inside conclusion. How can I test and repair such a restriction or blockage?

Relevant info:
-I have bought this C&C27 in 2007
-I did never experienced any mechanical issues with this A4
-I used to prepare the engine for spring and winter service in following the instructions of the user's manual
-these fumes have appeared suddenly 10 days ago after refueling my gas tank (therefore I was immediately thinking about a contaminated fuel - but after having drained and completely changed my gasoline, the engine is always producing these fumes)
-I have an invoice of the previous owner attesting that in 2003, the engine has been removed form the sailboat at Treasure Island (D.C. Marine Ltd), bring to shop, strip down; the block heads have been sent to machine shop, the transmission has been stripped.the wires, the points and the rotor has been replaced in 2003 - I have checked the rotor last weekend, and it is very cleaned. I could changed the wires of course.

I thank you in advance for your time and advices. I hope I will find out a solution very shortly.

Didier
Tiree-C&C27 MkII
BYC-Montreal

[CalebD]

Didier,

I must admit that I am really not sure what could be causing this situation you are experiencing. Most of the people here have owned their A4's longer then I have and had previous hands on mechanical experience on other engines. My experience is limited by comparison.

What seems obvious is that if you are getting unburned fuel in your exhaust then at least one or more cylinder is not firing properly. The culprit might be in the ignition system then. It could be that your spark plug wires are not set up in the correct sequence of firing (1,2,4,3). If the wires are set up as 1,2,3,4 then cylinders 3 & 4 would likely not get a spark at the correct sequence leading to unburned fuel in the exhaust.

Our A4 came to us with an electronic ignition set up so we have no points to fuss with. As I understand it when your ignition uses points then it is important to get the timing sequence set up and aligned properly with the engine. If the timing is off then you may not get all cylinders firing leading to unburned fuel in the exhaust. Unfortunately since I do not have points I can't really advise you on how to set up the timing. I am fairly sure it involves the orientation of the distributor cap. Hopefully others with more knowledge will contribute their thoughts.

Good luck.