[Becky]

Would anyone here know the approximate weight of a Mariah Z280 that has the 454 engine?

Also, we are thinking of converting to a diesel engine for this boat since we plan to run it in salt water starting next summer (instead of lake water.) Any suggestions?

As for myself, my husband and I live in Arizona, very close to Lake Havasu and even closer to Lake Pleasant. We have been boaters for 39 years and have owned several power boats and sailboats. In fact, we once spent six years on a 34' sailboat traveling about 25,000 miles. Currently I still own a Cape Dory 25 sailboat. So, we have like "his" and "hers" boats.

[ColoradoDiablo]

Welcome to MOC Becky!
Your Z280 weighs in at 7350 lbs. That is dry with no goodies onboard.
As for your thoughts on the diesel conversion............My first thought is PRICEY !
That is going to be a complete refit of the entire system.
Sure would be a great setup.
Maybe some of the other members can chime in with better info for you.

Once again welcome.

[roger rowley]

Welcome aboard Becky,
I have a volvo penta 5.7 petrol engine a 238 on the east of the U K no probs insult water what so ever, The thing you MUST do however is change the anodes to zinc for salt water! and wash it all the time

[Becky]

Thank you both for your input.

I agree that the diesel change up would probably not be worth the price. we've already put a small fortune into this boat! I told my husband, ENOUGH! I'm wondering, though, about putting a heat exchanger on the boat.

Your advice about changing out the anode for zinc is a great idea. Glad you are using yours in salt water, Roger, with not problem. That's encouraging.

[ColoradoDiablo]

Here is some cool info on Closed cooling systems Becky.
Price doesn't seem to bad either.

Marine Closed Cooling Systems

[Hudson River Steve]

Converting to diesel would be nice...but probably about the same or maybe even more $ than the boat is worth.

Adding a heat exchanger solves the problem of scaling in the engine block and exhaust manifolds if you cool them with anti-freeze rather than raw water but it still doesn't solve the issue of the risers scaling as this is where the raw salt water is injected with the exhaust stream. You are looking at close to $1,000 for parts not including labor to retrofit to a close cooling system.

My raw water cooled 99 Z280 spent its first 10 years in salt water on the coast of Long Island NY. For the past 4 years it has resided in the brackish waters of the Hudson. You just need to keep an eye on the exhaust manifolds and risers. They tend to scale and clog up faster in salt water which can lead to over heating or worse. A good rule of thumb is to change them every 5 years to be safe.

My next project is to install a mechanical Faria 0-10 psi pressure gage to monitor the output of the raw water pump. I will use this gage to know when the manifolds/risers need to be replaced (high pressure) or when the impeller in the raw water pump needs to be replaced (low pressure).

[ColoradoDiablo]

Originally Posted by Hudson River Steve

My next project is to install a mechanical Faria 0-10 psi pressure gage to monitor the output of the raw water pump. I will use this gage to know when the manifolds/risers need to be replaced (high pressure) or when the impeller in the raw water pump needs to be replaced (low pressure).

Now that is a great idea Steve.
Make sure you take pics and do a write up for us.
Where in the system do you plan to install the pickup for the gauge?

[Hudson River Steve]

Larry,
I haven't decided exactly where to monitor the system but I have narrowed it down to two locations. Probably the best place is the outlet of the raw water pump but it is way down in the bilge and difficult to access. The easiest place to access is on the top front of the engine where the cooling water enters the engine. I plan to cut a section of the cooling hose out and replace it with a short PCV pipe section into which I will install a threaded bushing and a hose barb.
In the dashboard I plan to remove the round Faria hour meter and the rectangular trip odometer which doesn't work anyhow. Replace the round hour meter with the new pressure gage and replace the trip odometer with a new rectangular hour meter. Last step will be running the small diameter hose from the gage to the pick-up on the engine cooling hose.
Steve

[gchavezb]

Steve, please post pictures on how you installed the mechanical gauge for the water output pressure, that seems like a good idea to know when to replace impeller before it goes bust !!!