Hello all, I have a 496 HO through hull boat that soots like crazy on the transom of the boat after a weekend on the lake. I always wash my boat after the weekend and it takes a bottle of Simple Green and a lot of wiping to get all that carbon off as it sticks to the gel. Has anyone tried a ceramic coating, or other coating, on the back of their boat that allows you to just spray it right off? I have tried wax before, but it did not really seem to make a difference and the Simple Green eats that right off.


Thanks!

I always waxed at least the transom of my boat every time I took it out, soot will never rinse off but it wipes off easy when there's always a good coat of wax on the boat. Got the boat ceramic coated a couple months ago and while it doesn't look any better or clean off easier than right after I would wax it, I don't have to spend 3 hours waxing it before I take it out. I would imagine somebody would just ceramic coat the transom for you and you would just have to wipe the soot off after each outing rather than use simple green and a lot of scrubbing.

Send the PCM to Whipple for a retune in the off season, I've heard they can fix the issue......then no more wax on wax off.....

This was an issue with early 496's. Merc made changes to the tune around '03 or so to eliminate the problem. My engine which was built in 9/03 does not have the sooting issue. Also, make sure to only run 87 octane.

the deal was Merc had a campain for the first couple of years --- the PCM 555 was sent back in for a retune because of the running rich issues especially at idle rpms. When the PCM came back a IAC muffler was in with the latest tuned PCM. You can ask any Merc dealer if your PCM has been recaled by Merc back in the day whenever ? You will need your engine serial number.

Also there is many other reasons that the 496 can be running rich that are very fixable. The fuel injectors also can be in the mix for rich running conditions. fuel pressure is very import as well - steady and correct fuel pressure readings --- 42 psi for stock specs. The flame arrestor and the internal throttle body dirty and or restrictions can cause bad rich conditions as well. The 496 one would be surprised how dirty it can become and not even show it externally. ( the flame arrestor )

Anyways there is many other things to look at for possible rich conditions on the 496. Spark plugs and wires as well. -- coils in the mix as well. Scan tool testing in the mix can pin point rich running conditions --- map , TPS - coolant temp and so on all play a part for injector m/s pulse width inwhich can cause rich condition when out there parameter ranges, Voltage and grounds another possibility. As mentioned the list can be long as to why you are running rich.

Plexoer your pm box is full...

Start with verifying the Merc re-tune on your PCM's and 87 octane only. These are easy things to accomplish and will make a dramatic difference in transom soot. If that doesn't solve it, then start digging deeper like BUP suggests.

at start up and idle you can it down but the design of the PVC being not external hurts with oil consumption. In the truck end of things they use to say that a qt of motor oil being used every 1000 miles was normal. IMO that was alot and too much..

Also the gen 1 intake manifold gaskets were bad for using oil not sealing very well and sooting the transoms.. The gen 2 intake gaskets design ( GM) was better at oil control that offered better sealing by far. .