Re: Mercruiser 3.7 L (model 470)
This is another of those questions that a lot of people have strong feelings about one way or the other. Most that say "Don't buy one" also have never owned one, so keep that in mind.
I have worked on them for years, they came out in 1976 and under many different names were used up till 1989.
It's a Mercruiser engine, designed and built by Mercruiser. Aluminum block with a cast iron Ford 460 head.
Here are a few of the common problems with them.
1. The aluminum block is an open deck design, meaning the cylinder walls are not attached to the block at the top of the cylinder, only at the base of it. The problem with this, is that ANY time there is an overheat, things move around and you can expect the head gasket to start leaking, and you will have to replace it.
2. Many of the major parts, like intake manifolds, exhaust tubes, etc. are no longer available. If they go bad, you are stuck looking for good used parts like many other 470 owners.
3. The engine circulation pump is run off the end of the cam shaft. Problem with that, is the cam seal wears a groove in the cam. Recommended fix is to replace the cam, many have successfully used a speedy sleeve to fix the problem. Just something to keep in mind.
4. The charging system is designed like an outboard. Has a stator under the front pulley that is lined with magnets. The magnets come loose and destroy the stators. Problem is, the pulleys are also NLA (No longer available). The stators and regulators are available, but big time expensive.
Work around for this is to install a regular marine alternator. There are a number of kits available for this UP GRADE, and is the best thing you could do.
On the plus side, they do have a lot of torque, and horse power for a 4 cylinder engine, and run nice when everything is in good shape.
It also has a closed cooling system.
Like any engine and drive in a used boat, you have no idea what the maintenance has been like. Normally in boats, it's usually a fix if it breaks type maintenance program, which is not a good thing for this engine
