Engine Swap

[sh1bby69]

In my Mercruiser we have a Chevy 350 in it. The engine per mechanic has a blown water pump on the engine and on the actually outboard. It over heated. My friend has rebuilt Chevy 350 engine that was originally going to go into a hot rod but we were looking into putting this one instead since we are not sure how the our current one was maintained by the previous owner and may seem better. Here are the options:

Option 1: The mechanic want to charge us 515 both water pumps, repair/add temp gauge, change hydraulic oil, change engine oil
Option 2: New rebuilt 350 Chevy $1500
Option 3: Rebuild current engine $2000

If we do decide on the engine swap what major parts of the engine will be need to be good for marine use?

Thanks guys! We just want to get the boat out back on the water with a reliable engine with our money spent smart.

 

[jtybt]

Re: Engine Swap

Generally not a good idea to put a hotrod engine in a boat. Not enuff torque when and where you need it.

 

[cpubud]

Re: Engine Swap

minamum you would need marine freeze plugs,head gaskets,and a cam for the rpm range that would work at the rpm range you run at and makes max tork at that range.

 

[Bronc Rider]

Re: Engine Swap

Its a little hard for me to understand what you are trying to do. Is it just the water pump thats bad? What do you have, alpha or bravo? As mentioned already, automotive hot rod engines don't generally do good on boats. Aside the torque thing you also have to worry about water reversion with a boat. A different cam might be all it takes to make it suitable for marine use but, I really have no idea what the specs are to said engine.
What is the reason for the engine swap?

 

[littlebookworm]

Re: Engine Swap

To add to what's already been said: You need to know whether both engines have the same rear main seal configuration, one piece or two piece main. OK, your engine overheated. Was there damage to head gaskets, heads, etc.? Did anything crack, or was it a simple overheat that you shut down before any real damage was done? If all that's gone are the water pumps, then you should probably just replace them. The pump on the engine itself is similar to an auto pump (but don't replace with an auto pump; use a correct marine pump). If your friend can rebuild an engine he can certainly replace that pump for you. The outdrive pump (assuming Alpha 1 outdrive) isn't complicated. Just follow the info found in a repair manual and elsewhere here on this site. Granted, you may need to replace the engine if the present one is really bad, but why do that if the problem is relatively minor. You need to get more info. Good luck and let us know how it all turns out. Hy

 

[havasuboatman]

Re: Engine Swap

Check out your current engine.
How's the oil pressure?
How's the compression?
Does it burn oil? Leak oil?
How did the oil look when you bought the boat?
How'd the drive oil look? People who neglect a boat motor tend to ignore the outdrive.
How's the carb look? Signs of leaking? Spark arrester clear or clogged?
What exactly does your mechanic mean by a "blown" circulating (engine pump)? Cracked? Seals leaking?
Is he a MARINE mechanic?
Just because you don't know the history of a motor, doesn't mean you can't tell if it was abused.
If the things above check out ok, replace the pumps. That is a fair price for parts and labor.
And don't put a hotrod car motor in your boat. Your don't have a jet drive, so the power bands are wrong.
The SMC motor is a hog, it'll take a lot of abuse.

 

[cr2k]

Re: Engine Swap

Not sure (either) what you are talking about. Maybe have someone edit your post.

The pump on the engine is called a Circulation pump.
OutDRIVE (not outboard) is called outdrive, drive or leg.

It is rare for a circulation pump to go bad.

Water pumps (outdrive) need to be repalced at least every other year as regular maintenance.

What Hydraulic oil is he wanting to replace? The only hydraulics on that boat should be the tilt/trim and the power steering. Neither of which would be effected that much by an overheat.

Do you mean the drive oil?

At the very least I would take it to another mechanic, a Marine mechanic.
Just because it is in an automotive block, doesn't mean it is an automotive engine. There are many internal differences.

If fuel and electrical components are not Marine Grade you risk fire and explosion.

We are all here to help you and answer questions, but you need to be clear on your questions and tell us what you are working on, i.e. Make, Model and Year.

Some of the things to change for marine use include; Starter, Carb., Circulation pump, Distributor, Fuel pump, Headgaskets (need to be stainless steel for corrosion) "Freeze" plugs to stainless or brass, camshaft.

 

[Bondo]

Re: Engine Swap

We just want to get the boat out back on the water with a reliable engine with our money spent smart.

Ayuh,.... Option #2,... A GM Goodwrench pickup truck motor for about $1500....

Btw,.... Forget about the Hot Rod 350,...
It'll co$t more to make it Marine friendly than a brand new mexican 350 noted above...

 

[sh1bby69]

Re: Engine Swap

Thanks everyone. I'll get some more info on our engine. Boating is truely new to me and my friend. The mechanic is experianced on marine engine and has rebulit many marine engines before. He said that if we do decide on the rebuilt hot rod engine he would have a cast iron intake manifold along with that replace the gaskets to a marine grade. He understands that the cams are different but the one he has installed will work as he says.

Also how would I determine of my outboard or out leg is an alpha or bravo?

Thanks for all you help. I'll do the best I can to get more info on what we have. Again everything is new to me. Our real goal is to have this boat be able to make it to Catalina. It is a 1979 20' Mercruiser. I can post picks up later but for now this is where we are at. Thanks again!!

 

[jtybt]

Re: Engine Swap

I hope you take some time to learn about your boat and how it handles along with learning about your local water conditions before trying to make the crossing to Catalina. That's not a short distance for a 20 footer. Learn how the weather and water conditions change from hour to hour and season to season. Some days will be like a lake. Some days will start out like that and turn bad.

The ocean is very UNFORGIVING.

 

[Alpheus]

Re: Engine Swap

You can go this route and have one shipped to your front door and know that it will work for $1550.00...

http://www.rapidomarine.com/default.aspx?p=/engines/default.aspx

 

[sh1bby69]

Re: Engine Swap

You can go this route and have one shipped to your front door and know that it will work for $1550.00...

http://www.rapidomarine.com/default.aspx?p=/engines/default.aspx

Thanks! I think we are going to get it looked over by another mechanic. We are going to see what this ones says about my our engine. Thanks for your help guys. I'll keep posting to keep you guys updated on the process of the boat.