Carver Risers and manifolds

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Cheers,

Alfred

On behalf of user "ADAMBOMB"

Sure, some rust where the mani meets the elbow, but I've certainly seen much worse. I'm not an expert but I love to research and read, and from what I've read the most determining factor is your engine temperature due to constricting water flow. I know on my 350's I stay at 170 deg's F or below WOT. I'd guess that you probably have 454's and temp shouldn't exceed somewhere around there either, maybe a bit higher since you're FWC with a heat exchanger. What does she show WOT? Tom.

Operating Temperatures

Another bit of information, if your engines seem to run ok at cruise but heat up once you pull back on the throttle, that can also indicate blocked exhaust manifolds.

Mine were Raw Water Cooled, which is uncommon on newer boats.
The engine ran great if I started them and ran at cruise.
Once I slowed down to "no wake " my temps would shoot up.

We were in Oxford MD and I got a guy to drive to Hatfield from SE PA then turn around and drive to Oxford with 4 new manifolds. Vacation saved and it kept three guys busy rather than walk around Oxford shopping w/ the little ladies.

Turned out to be a pretty good day........

the weaping in that pic does not seem excessive.

To me, that pic alone withouth anyother heating related issues would not be a concern.

hit it with a wire brush, re Tq the bolts, and hit it with some paint...
and keep an eye on it on your maint schedule.

you should be able to get 2-5 years out of the risers.....

When I was running a gas boat, i changed or boiled the risers every 2-3 years, it was part of my maint schedule

A suggestion, use a IR temp gun to check the mainfolds and risers in different locations, both engines should be pretty close (but not exact) to each other.
If you get used to checking the risers (while running and at idle) you will notice the temp differences and know when you have a problem creeping up on you so you dont get surprised on a trip or at someother wrong time.

If part of your head gasket blew and let water into any cylinder you'd know it by loss of power I think; hydro-lock. Most common result is overheating.

the joint between the manifold and riser gets alot of expansion and contraction because that is where the heat is transferred from the coolant to the raw water. The manifolds and risers are cast and there is a SS block off plate and some gaskets at that joint. There is alot going on there.....


I think a small amount of weeping and minor surface rust without anyother heating related issues in not a cause for immediate concern

keep an eye on it though....

Got a 4207 with 454's. Starboard engine temp runs up pretty quick toward redline at WOT. Settles back down to normal range when I pull back to idle or slightly higher rpm. Strainers are clean. No oil pressure indications. Maybe a slipping belt? What should I be looking for?

Raw water impellor would be my first check, it should be changed every 2 years or 200 hours.

I've seen dozens of gas inboards that have met their fate from leaking exhaust manifolds and/or risers. A few got off lucky with a bent valve or two. It is the single most killer or gas inboards. Do an internet search on 8.1L mercruiser manifold issues.....Mercruiser thought it was a good idea to use Aluminum manifolds and s/s risers for the first couple of years......not good.......they've since switched to cast iron manifolds and s/s risers.....I'd replace manifolds and risers every 5 years in saltwater. Checking the riser temps with an infrared gun at cruise a couple of times a year is a great thing to do......you can also check other parts of the manifold......