Excessive Smoke at Startup Only????

FastcatchIII

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Jun 1, 2003
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Hello Gentlemen, hoping someone can shed some light on this? I have a 1988 28' Wellcraft Coastal w/ twin 260HP Mercruiser 5.7L carbuerated inboards. I performed a complete tuneup/oil-change last week. After changing plugs, coils, distributor cap/rotor and ingnition module in both engines, I warmed them up before oil change. After the oil change, my starboard engine "smoked" excessively for 15 minutes??? I did spray-paint the motors as well. Ever since, it has done the same thing..."burning-smell" type of white smoke until it is warmed up...then none at all? I checked the oil level 15 times...it is fine...no water in oil...all cylinders firing...but have not checked the compression yet. Engine acheives full RPM's and except for this smoking problem at startup...runs great? Could it be a stuck valve?...worn rings? Both engines have 850 hours on them.<br /><br />Thanks for your help!<br /><br />Bob
 

FastcatchIII

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Re: Excessive Smoke at Startup Only????

...also...the engines are FWC. I'm almost thinking that the white smoke could be antifreeze burning off?...it is definitely NOT condensation from the heat exchanger!...it has a "burning" smell to it and does not dissipate rapidly.<br /><br />Could it be a head-gasket? cracked block? But why would it clear itself after running a few minutes???
 

crazy charlie

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May 22, 2003
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Re: Excessive Smoke at Startup Only????

You may have a small enough leak that once the engine heats up.it exoands a little and stops leaking.If you suspect the head gasket,try putting some radiator sealer in the antifreeze and see if it stops or slows the smoking.I would suspect that it may be a manifold or riser.How old are they???????Charlie
 

FastcatchIII

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Re: Excessive Smoke at Startup Only????

Charlie,<br /><br />I have owned the boat for 3 years...not really sure how old the manifolds and risers are???...but could be 5-10 years? Can you give me anymore tell-tale signs of a bad manifold or riser...other than them getting too hot...which they are not?<br /><br />Thanks!<br /><br />Bob
 

crazy charlie

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Re: Excessive Smoke at Startup Only????

Usually it is too late when the risers go.They let water or antifreeze go back into the cylinders.Clogged ones will be hot,worn ones usually kill your motor without much warning if any.You may have the very beginning of the end of them and got lucky to catch them early enough to save your motors.If you dont know how old the mani and risers are you should replace them before you need to replace the motors.Did you say that both motors started smoking only after you did your tune up etc. to them??
 

Cobotr

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Mar 26, 2003
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Re: Excessive Smoke at Startup Only????

Is this smoke coming out of the exhaust, external of the boat? Or is it coming from inside the engine compartment?
 

FastcatchIII

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Re: Excessive Smoke at Startup Only????

Some answers to your questions:<br /><br />1) Just the one engine started smoking after complete tuneup/oil-change...the other is fine.<br />2) Smoke coming out of exhaust excessively during warmup only...stops completely after 3-4 minutes.<br /><br />Just went down to the boat again today...it was nice and in the mid 70's here in NJ. Started the motor in question...NO SMOKE!?!@*&%@(&(Y!<br /><br />We have had a ton of rain over the last 2 weeks...and was much colder at nite...with extreme temperature variences...<br /><br />Is it possible that I am over-reacting...and the engine exhibited much more condensation than the port engine???<br /><br />Rechecked oil...perfectly clean as a whistle...rechecked that all cylinders are firing...and both risers are only warm to the touch...no hotspots...the manifolds are FWC...so I would doubt there are any problems with them?
 

Derk138

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May 18, 2003
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Re: Excessive Smoke at Startup Only????

It is normal to blow some smoke, but if last for more than five minutes there can be a problem. I don't think you have anything to worry about since it only last a few minutes. I had the same problem and it only smoked for a few minutes, but i had cleaned the carburator (anouther problem I had)and it has stopped smoking. Since the smoke was blue it sounds like it there was to much fuel in the carbs.
 

magster65

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Sep 1, 2002
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2,573
Re: Excessive Smoke at Startup Only????

I'll bet ya' one of your risers is going. I had a similar problem that was the riser, it did leak anti-freeze into the manifold but I caught it soon enough that the engine survived. You can pull them and have a look for the price of 2 gaskets / sealer and it only takes a few minutes.
 

crazy charlie

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May 22, 2003
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Re: Excessive Smoke at Startup Only????

Why dont you pull the plugs out and have a look.Oil fouled will let you know the smoke is oil leaking into the cylinders and thats your smoke.If the plugs show some rust that will point to the risers.As I said earlier,my money is on the risers.I hope for your sake thats all it is.Risers are a cheap repair that you can do yourself. Charlie
 

akriverrat

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Oct 31, 2002
Messages
588
Re: Excessive Smoke at Startup Only????

water white "smoke", oil blue smoke, gas black smoke and soot on water.
 

FastcatchIII

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Jun 1, 2003
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Re: Excessive Smoke at Startup Only????

Thanks Gentlemen for all your replys!!!<br /><br />I am replacing the risers on both engines to play it safe...and to give me a good 5-8 years of "peace-of-mind"!<br /><br />Thanks again!<br /><br />Bob
 

FastcatchIII

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Jun 1, 2003
Messages
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Re: Excessive Smoke at Startup Only????

Well....replaced the risers today on both Port and Starboard engines....$671.00 in parts...5 hours of my labor...boy do I hurt tonite!...LOL<br /><br />The manifolds are in great shape...being FWC...just some carbon deposits...no sign of water or antifreeze. The risers were pretty rusty...had a load of carbon...but did not appear to be leaking. I still think it was a good investment...I doubt they had much more time left on them. No smoke at all today, other than some fuel during warmup when the choke-plate is closed...and she purrs like a kitten.<br /><br />Thanks again for your help here...great bunch of guys!
 
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