Almost ready to pull trigger

[dboyd351]

The cooling passages in the risers can become clogged with rust as they get some age on them. Pulling them and cleaning the rust out may well solve the discrepancy as long as 1) the bolts aren't so rusted to the manifold that you can't get them off and 2) There isn't so much corrosion the risers need replacing.

That might not be what it is, but it sounds like a possible reason for what you are describing.

Having a mechanic check it out, as previously suggested, is certainly a wise decision, too.

[spareparts]

if this is the boat in the for sale section, it has one piece manifolds, the risers are made into it. They are not available any more, it will have to be changed to a two piece manifold/riser set up, not a big deal, just different. As far as the temps of the manifolds, I've had brand new engines run one manifold hotter than the other at lower engine speeds, usually with alpha set ups. The water pump doesn't create enough volume to completly fill each manifold before exiting, the water allways takes the path of less resistance, so one maniofld gets more water than the other. On bravo ste ups, the belt driven pump can flow more water at idle speed to fill to restriction both manifolds and risers. If the manifolds are getting unevenly hotter at high rpms, then there is a restriction. Also consider the age, around here in salt water, if the engine hasn't been flushed, figure manifolds every three to four years, if its been flushed regulary, then figure 6 to 8. The one piece manifolds haven't been around for some while, if you could determine how old the engine iks, it would help. Unless the engine was a new old stock, or the boat has been pickled for a number of years, I'd go ahead and figure on new manifolds and risers. About $800-$900 in parts, plus labor

[Bruce]

pay a mechanic to do a total assessment on the boat. If its a 2 piece riser/manifold setup, pay him to remove the riser to check it out to see if the gaskets indicate any water getting into the engine. This could be money pit waiting to happen, be smart on this.. You seriously do need a compression and leakdown test on this motor as well.. I've seen 4.3s run flawlessly but have the back two cylinders 50psi lower then the rest, thus needing some major work. Also the mechanic will check out the outdrive, bellows, etc, and see if the gearlube has any oil in it. If the bellows fail on this setup the boat sinks, be an informed buyer, Don't skimp now.

[Blue_Runner]

Sounds like you need to find a V20/V21 w/ an outboard....or bare hull & and hang an outboard on the back of it. No offense to the I/O guys!!!

[Skools Out]

sounds like clogged risers as stated earlier you can clean them sometimes with a rust eater then reinstall.

[THEFERMANATOR]

Or it could be a sticking check ball if it has the spring loaded valves in the T-stat housing. As for teh drop in RPM's, was it only under load or did it still do it in neutral? And that boat has been for sale for quite awhile now MANY times. It's been listed here 3 or 4 times that I know of over the last few years. She's a nice looking boat, but I always thought it looked too clean as well.

[t mac]

Thanks for all of the valuable information. I will get a mechanic to look at it. The boat was in gear when it peaked at 3200. In neutral it would rev all the way to 4800.

I have actually been looking for an I/O for no other reason then I know how to work on them. The OB is a bit intimidation to me. That said I would love to be talked into one. I am sure I could handle the basics on an OB.

I will just get a book. "Outboards for Dummies". I am sure it exists. I have not made a final decision yet but I would really like to be on the water this summer.