New Merc 7.4 MPI blowing smoke/steam

[geoffandjackie]

Can anyone tell me if a new boat with 32 hrs on it is supposed to blow grey smoke/steam from both engines. It did not do this on sea trials when I bought the boat. It started after about 25 hrs. Engine is FWC and has V drives. Any help would be appreciated<br />Thanks

 

[hondon]

Re: New Merc 7.4 MPI blowing smoke/steam

Since this is a twin 7.4 ,I would gather that this is not a trailer boat.What are your temp gauge readings?Any dry starts?Hull growth?Thru the transom or sterndrive exhaust?Give us a little more.

 

[geoffandjackie]

Re: New Merc 7.4 MPI blowing smoke/steam

The gauges both read normal, 175 for temp and 40 for oil pressure. No dry starts to my knowledge, exhaust is thru hull. You can really notice the problem when you are above 3400 rpm. Thanks for any help

 

[Walter]

Re: New Merc 7.4 MPI blowing smoke/steam

32 hours? I'd say she's probably still under warranty, so if you have concerns I suggest you get your dealer involved pronto. <br /><br />Walt

 

[Fouled Plug]

Re: New Merc 7.4 MPI blowing smoke/steam

With all of the exhaust/water being spewed out of the through-hull pipes, I'd be surprised NOT to see a bit of steam. Perhaps it was warmer when you test drove the boat and it wasn't so obvious? The water is what cools the exhaust, and above 3400 RPM's it has more cooling to do, so it heats up. Check with the dealer to be sure, but your gauge readings sound normal to me.