Mercruiser 3.7 4cylinders

I am looking at buying a boat with twin 3.7 motors. Have never had engines this size before how are they? Any know defects known off?

Thanks
Ken

Re: Mercruiser 3.7 4cylinders

Run sir -- run. That is unless you are very mechanically included. If you use the search feature using the key words 3.7 motor you will learn about the dissues with this motor. Any there are two of them to contend with. Shucks -- just scroll down the list of threads and before you reach the bottom of the first page you will find a couple of threads regarding this motor.

Re: Mercruiser 3.7 4cylinders

they are a Ford 460 cut in half--they had several design flaws--but some people work them over, update and run the crap out of them--do research on them here on iboats.
I myself would run away!

Re: Mercruiser 3.7 4cylinders

26aftcab454 said:

they are a Ford 460 cut in half

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no

it is an aluminum mercruiser 4 cylinder block with a Ford 460 head

and they are garbage, do yourself a favor and find another boat with twin 4.3's or 305's or 350's

Re: Mercruiser 3.7 4cylinders

Any know defects known off?

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Ayuh,.... Run, Forrest,.... Run....

You Don't want a boat with Merc. 470 motors.....

I have a merc 165 are they the same thing, what are the best swap options? I am about to attempt a rebuild of mine, I am rebuilding the entire transom, stringers, deck, mounts etc, do my options are open but want to use all the same out drives, cables etc.

Re: Mercruiser 3.7 4cylinders

dubs283 said:

no

it is an aluminum mercruiser 4 cylinder block with a Ford 460 head

and they are garbage, do yourself a favor and find another boat with twin 4.3's or 305's or 350's

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I run twin 3.0's, they are also a good dependable engine. They have the added advantage of getting really good fuel economy, so dont count them out .

Re: Mercruiser 3.7 4cylinders

Had to chime in here. Junk is in the eye of the beholder. There are lots of 370 owners who have no major issues. Not to mention that many of these engines are more than 20 years old and have hundreds of hours on them before having problems. Now that said I wouldn't buy one unless I was mechanically inclined or have someone who can help me if it developes problems. Because most of them are old and can be expensive to repair.(more expensive than most engines). But when they are running right they are pretty powerful and economical on fuel.

Re: Mercruiser 3.7 4cylinders

Thanks for the advice, with that said I got a lot of run or I wouldn't get that but no reasons of why. I can work on engines and have a mercruiser certified mechanic that works for steak and beer and can show me around when I need help. I believe if you take care of something that it will last. I am very anal about maintenance so I think I will be ok. I have had a oil annalis (sp) done and according to that everything looks good. The boat is in VERY good to excellent condition and the price is so good that even if I had to drop two new engines in I would still be ahead of the game. I think I am going to get it tomorrow. Pics to come

Re: Mercruiser 3.7 4cylinders

I can work on engines and have a mercruiser certified mechanic that works for steak and beer and can show me around when I need help.

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There's a friendship that might go away in a hurry with twin 470's.

You obviously had your mind made up before posting 4 said run, one said he has one and they are wonderful, the other two didn't understand the question or know what engine you were talking about.
No information as to year, or anything.

Was it statements like this that made you decide to go for it?

There are lots of 370 owners who have no major issues.

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First of all, they aren't 370's and I doubt there is a 470 owner that hasn't had some sort of issue.
1. They are an aluminum block engine with an open deck design, with a cast iron head. You get an overheat, expect you will have to replace the head gasket. Facts of open deck design.
2. The cam seal leaks. Very common problem with them, cars don't have a design like that.
3. The charging system was a copy of an outboard charging system, expect to replace with an expensive alternator conversion kit when they go bad, because the parts that are available to fix them, are VERY expensive.
4. Depending on the year you are buying, if they have 3" heat exchangers, expect to upgrade to 4" to prevent overheats.

Just because an engine looks good on the outside, doesn't mean it was taken care of internally.

Good luck with your purchase. Oh, and just putting in another type engine isn't that easy to do.

Re: Mercruiser 3.7 4cylinders

Well my mind wasn't all the way made up, I have talked to several people who own a boat with that engine and have had very few problems, one did have a lot but for the most part not many. I understand that there are a few upgrades if not already done I can look forward to right away or in the near future ie. heat exchanger, alternator, and getting rid of the point system. I have taking the cost of these and factored that into the cost of the purchase. And if it isn't up to my mechanics specs then it is a no go. I think between the survey and his advice I should be ok was just wanting some more information.

Re: Mercruiser 3.7 4cylinders

yes Don I made a typo. I am well aware that they are 470's. And the point I was making was that all old engines have problems. And most of the time the guys who crap on them on here have never owned one, and are going on what they have heard.

Don S said:

There's a friendship that might go away in a hurry with twin 470's.

You obviously had your mind made up before posting 4 said run, one said he has one and they are wonderful, the other two didn't understand the question or know what engine you were talking about.
No information as to year, or anything.

Was it statements like this that made you decide to go for it?



First of all, they aren't 370's and I doubt there is a 470 owner that hasn't had some sort of issue.
1. They are an aluminum block engine with an open deck design, with a cast iron head. You get an overheat, expect you will have to replace the head gasket. Facts of open deck design.
2. The cam seal leaks. Very common problem with them, cars don't have a design like that.
3. The charging system was a copy of an outboard charging system, expect to replace with an expensive alternator conversion kit when they go bad, because the parts that are available to fix them, are VERY expensive.
4. Depending on the year you are buying, if they have 3" heat exchangers, expect to upgrade to 4" to prevent overheats.

Just because an engine looks good on the outside, doesn't mean it was taken care of internally.

Good luck with your purchase. Oh, and just putting in another type engine isn't that easy to do.

Click to expand...

Re: Mercruiser 3.7 4cylinders

I have a 33 year old 470 that is original except for normal wear parts (a few gaskets on the riser, a thermostat, etc), and a replacement heat exchanger or two. This engine has hundreds of hours on it and is still strong and economical. The ONLY reason I would consider changing it to a 3.0 is the fact that heat exchangers are getting a little harder to find ar low prices. I may convert this engine to raw water cooling just for this year and then part it out and put in a 3.0.