1990 350 EC - Merc 454 Inboards- Steam in exhaust / raw water flow low

[rmarkko]

Hey guys, I relatively green as far as maintenance on my boat goes, but not totally ignorant to basic mechanics. Here's what I'm seeing... Coming in this weekend I was pushing a lot of steam of both exhausts. I immediately checked the strainers and no blockage/excess debris (tho port did have some rust coloring in the water).

It seems as though I am not getting enough water through to properly cool. Too little water is exiting at the exhaust, which could explain the steam, as what water did make it in could be evaporating from excess heat.

What should be my next step in troubleshoot, and/or what else might I be looking at here? Thanks for the help!

Richard

1990 350 Express Cruiser
Twin 454 Merc Inboards
Raw Water Cooled

 

[Quint4]

I would change the impellers.

 

[ks65609]

I would change the impellers.

I second that

 

[Jimmy Buoy]

How long have you had the boat? The reason I ask is that may of the mid-ship engine express cruisers (including my own boat) have substantially long exhaust tubes that seem to produce more steam than the same Sundancer models. I thought I had a problem too when I first had the boat, but the engine temps were bang on and the water flow seemed ok at idle - still lots of steam coming out of the thru-hulls once on plane. Still, I changed the impellers just to be sure and backwashed the hoses to ensure that no old impeller pieces were stuck in there. No difference.

I happened to be on Sea Ray's Archive site and saw the brochure photo for my boat. There were two distinct steam trails coming from the exhaust ports on that new boat. For some models, this is more common.

How are your engine temp readings?

 

[rmarkko]

Quint and KC, thanks for the advice. That was my plan this weekend. I'll let you know how it goes......and maybe ask for more advice

 

[rmarkko]

Jimmy, my temp readings were about normal. Tho i have noticed and inquired about the steam you've mentioned, and uncovered the similar info regarding MINIMAL steam output. My concerns here were three fold, I guess. Water flow was significantly down. Steam in exhaust was significantly up. Strainers (always my first check before start up, along with oil) were clear. Thanks for the insight, though, and please keep it coming. I have a lot to learn and am eager to do so!

 

[ks65609]

How long have you had the boat? The reason I ask is that may of the mid-ship engine express cruisers (including my own boat) have substantially long exhaust tubes that seem to produce more steam than the same Sundancer models. I thought I had a problem too when I first had the boat, but the engine temps were bang on and the water flow seemed ok at idle - still lots of steam coming out of the thru-hulls once on plane. Still, I changed the impellers just to be sure and backwashed the hoses to ensure that no old impeller pieces were stuck in there. No difference.

I happened to be on Sea Ray's Archive site and saw the brochure photo for my boat. There were two distinct steam trails coming from the exhaust ports on that new boat. For some models, this is more common.

How are your engine temp readings?

It is important to know when the raw water impellers/pumps were last serviced. I think a general rule of thumb is every 100 hrs. The last thing you want is a failure when you are under way. By the time you may notice a high temp reading it could be too late and it gets expensive in a big hurry.

 

[Jimmy Buoy]

Richard,

It appears that you have made two identical posts. You will find that one post will actually make it easier to get everyone in on the same discussion. Most members including myself click on the "new post" button (beneath the "home" button) after logging in to see what's been posted vs checking out individual forums. We will easily see any new posts regardless of what forum title under which you enter your new topic.

I hope this tip helps. Lots of people willing to help here at CSR!!