470 blowing white smoke

[Eagleridge5]

I've had this boat for 15 years. Mostly it runs well but recently I've been noticing the coolant reservoir getting empty but no noticable leaks and oil is good. Yesterday I noticed a lot of white smoke coming from exhaust, it started heating up so I shut it down. The reservoir was half full after a few minutes. Does it sound like coolant getting into the exhaust?? How is it doing that??

 

[airdvr1227]

Re: 470 blowing white smoke

Cracked block or bad head gasket would be my guess. Pretty common in the marine world.

 

[EddiePetty]

Re: 470 blowing white smoke

Have your cooling system pressure tested. More than likely you'll find a defective head gasket, a leak in the heat exchanger or a defective gasket between the exhaust manifold and elbow. As you have a closed cooling system, and live in sunny California, a cracked block seems very remote.

The cooling system pressure test will isolate your problem.

 

[6meter]

Re: 470 blowing white smoke

White smoke = your burning coolant, as well as fuel.

 

[Eric 3.7LX Alpha 1]

Re: 470 blowing white smoke

Has the engine ever overheated?

As Eddie mentioned, a cracked block or heat exchanger damage from freezing is last on the list of causes for you.

A cooling system pressure test on the engine before you start ripping things apart would be my plan of attack.

http://www.harborfreight.com/radiator-pressure-tester-kit-65053.html?p=2

Good Luck

 

[rodbolt]

Re: 470 blowing white smoke

yes pressure testing not only the cooling system but individual area of the cooling system is mandatory BEFORE wrench twisting.
the original cast iron manifold had a tendncy to crack back near #4 cyl and dump colant into the exhaust as well.
thats what the AL manifold kit came out to correct.
the manifold assy can be tested seperatly from the block assy.
a leakdown test can quicly and efficiently find head gasket leaks.

 

[stonyloam]

Re: 470 blowing white smoke

All of the above advice is good. You can get the tools for the cooling system pressure test and compression test at Autozone. They will lend them to you for free. Pull the plugs, if the ceramic tip is white (rather than tan or brown) it is a sure sign of coolant leaking into the cylinder. If you have to replace the head gasket use an OEM Mercruiser gasket. Good luck.

 

[zbnutcase]

Re: 470 blowing white smoke

Look at the manifold to riser/tank gasket joint. Any signs of weeping or leaks? If so, that would be the first place to look if pressure test shows leakage, especially problematic on the aluminum manifold engines.

 

[Don S]

Re: 470 blowing white smoke

If your 470 ever overheated, a blown head gasket is a very common problem due to the open deck design of the aluminum block against the cast iron head.

 

[stonyloam]

Re: 470 blowing white smoke

If your 470 ever overheated, a blown head gasket is a very common problem due to the open deck design of the aluminum block against the cast iron head.

Even if it has never overheated. Mine never did. The head gasket was not "blown" but sure was leaking coolant into the cylinder.

 

[Bifflefan]

Re: 470 blowing white smoke

Cracked block

I will never understand why that is the first thing out of most people's mouth.

 

[stonyloam]

Re: 470 blowing white smoke

I will never understand why that is the first thing out of most people's mouth.

Because most folks are not lucky enough to have 470s.

 

[Eagleridge5]

Re: 470 blowing white smoke

I will try the cooling system pressure test and check the plugs this weekend and let you know what I find out. Thanks for all the replies.

 

[guyaverage]

Re: 470 blowing white smoke

Even if it has never overheated. Mine never did. The head gasket was not "blown" but sure was leaking coolant into the cylinder.

x2

Mine never overheated either, just a few wisps of steam every so often and a very slight loss of coolant. The head and deck checked flat as can be. These engines have an appetite for head gaskets like no other. I've seen small block Chevy's practically catch on fire they were so overheated, with no problems. You stand near a 470 with a slightly warm beer and that gasket goes bye-bye.