525 and Black Transom Plague

[Havasu Dreamin]

WOW! Was I ever surprised at the amount of exhaust left on the transom from the frist trip out. I know with a new motor it is running rich so I kind of expected it but the amount of it was just amazing to me! Will this stop after the break in period and the motor gets it's first service? I was running 87, from Unocal, just as Mercury says to run. I know the 496's had this problem intially as well.

[Rivercrazy]

I would assume the 525 is similar to the 496HO on the black transom cause its from Merc!

The first time I took mine out it was really bad. I think its a combination of the rich ECM programming and burning a little oil.

It gets better after 10 hours, 20 hours. Then it basically doesn't get much better after that. I still get a little black transom on mine. I wash it down at the end of every boating day or it will really build up on multiple boating days if you don't. A soft sponge with some 409 takes it right off.

The one thing I have noticed is that when you start the boat you will see some carbon floating on top of the water and I think that is where most of the black transom comes from. As soon as you start it and the idle is low pop in in forward for a few seconds. I've noticed it helps quite a bit.

[TooMuchFun]

Echo Rivercrazy. You have now experienced one of the down sides to a big hp big block engine. My Innovation Marine 650 is similar. Put together under the Volvo parent company with the GM 540ci block.

First 10 hrs. of breakin were horrible, with soot everywhere. Next 10 were a little better. I can still after about 60 hours write my name in the soot on the transom after idling out of the marina and running up Mead to Calville or LVHB beach.

Your engine will burn some oil and run extra rich for the first 50 hours + or -. It takes this long for the piston rings and some other parts to completely seat themselves in your type of engine setup. Until then, check the oil regularly and clean the transom at the end of each use. I use Marine Clean-All from West Marine and it works well. I bought a 5 gallon bucket of the stuff to save on cost as I go through it each season http://www.lasvegashotboats.com/iB_html/non-cgi/emoticons/sad.gif. If you leave the soot for an outing or two and let it dry on the gel it may never come off unless you use a really abrasive agent and rubber gloves to protect the skin.

I run 91 octane in mine which makes for better performance in the power curve and engine longevity, but the soot is a little heavier. As Rivercrazy says, most is also produced during idle when it runs really rich. But remember, a fat engine is a happy engine ... lean runs mean and you may get a mile or two more at WOT, but then you risk damage.

I used to run Volvo's version (the 420) of Merc's 496 and had the same challenge to a lesser extent. The smaller engines are putting this stuff out as well, just not enough to really notice unless you leave it on for multiple outings. Nothing like a big loud grumbling big block cranking up on the lake though to make the extra amount of soot cleaning worth it in my mind http://www.lasvegashotboats.com/iB_html/non-cgi/emoticons/smile.gif.

TooMuchFun

[KC_Nelson]

The good news is that it will get better after 20 hours or so, the bad news is that the mess will always be there. Both motors run rich, especially at idle.

SimpleGreen works great!

Mercury replaced the ECM on mine with a more current one, did help - yours is probably as current as it could be.

[titties and beer]

my 1-500 is not to bad,if i run 91oc it gets black ,my friend has 2-500 in his flame and his get real black

[Rude]

i've noticed my transom doesn't get quite as black if i run 87 octane instead of 91 octane.

[CrazyHippy]

Hmmm... my outboard doesn't have this problem http://www.lasvegashotboats.com/iB_html/non-cgi/emoticons/tounge.gif

BJH

[Rude]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (CrazyHippy @ Mar. 05 2004, 9:47 pm)</td></tr><tr><td id="QUOTE">Hmmm... my outboard doesn't have this problem http://www.lasvegashotboats.com/iB_html/non-cgi/emoticons/tounge.gif

BJH[/QUOTE]<span id='postcolor'>
my outboard never made my transom black, but it sure did work on keeping ALL of the mesquitos away http://www.lasvegashotboats.com/iB_html/non-cgi/emoticons/biggrin.gif http://www.lasvegashotboats.com/iB_html/non-cgi/emoticons/biggrin.gif i have to admit though, i do like the smell of a two-stroke motor running.