MerCruiser 3.7L 190 HP 4 cyl

[BigManDan72]

I recently purchased a very old Wellcraft with a 3.7L 190 HP 4 cyl engine with a 4 barrel carb. I was of the understanding that this what folks call a 488. My boat is in the shop for some maintenance and the mechanice tells me that the 190 and the 488 are different engines. I guess I thought it was pretty straight forward that there was the 470 and 488 but he tells me there is the 165, 170, 470, 188, 488 and 190 (and maybe others that I've forgotten). What's the history on these MerCruiser 4 cyl engines? How interchangeable are the components of these engines?

 

[BigManDan72]

... and how crazy am I for buying one of them??

 

[Bondo]

How interchangeable are the components of these engines?

Ayuh,.... They're generally known as the Merc 470,....

All of 'em are basically the same, with various dressin's on 'em,....

... and how crazy am I for buying one of them??

Crazier than I,....

 

[harleyman1975]

When they run they are great. Problem is that parts are getting scarce as they haven't made them for around 20 years or maybe more. They have some known issues for which there were aftermarket fixes but now even some of these are getting scarce. perhaps your engine already has an external alternator and has had the "speedy sleeve" put on the camshaft and the water pump replaced as well as new head gasket and rebuilt head...if it does you might be able to use it and enjoy it for a while.

 

[stonyloam]

No crazier than anyone buying a thirty year old boat. They are all about the same basic long block. There is (as you know) a 4 bbl and 2 bbl version. About 1983 they changed the exhaust manifold and reservoir, and went to a 4" diameter heat exchanger. About sn 6218037 I THINK, so don't quote me on that. Here is a link to the parts diagram of the new exhaust : http://www.mercruiserparts.com/Show...r=70&bdesc=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW . Now for the other stuff the voltage REGULATOR is the problem, and the problem is not that it is unreliable (there are lots of 30 year old regulators that still work fine), it is that they are expensive, and it is cheaper to go with an alternator than replace the regulator. The camshaft seals will eventually leak and need to be replaced (about $100 DIY job). The biggest problem is that if you overheat chances are that the head gasket will fail. Not a huge job, but a PITA. One thing you should do is a compression check to make sure the HG is OK. The advantages are that it is a strong light engine, and being antifreeze cooled runs at a higher more stable temperature and is probably a little more efficient. Winterization is a snap, check your antifreeze (50/50 is about right) and pull the aft drain plug on the underside of the exchanger and let it drain, 5 min. (if you are slow) and you are done. Never a cracked block, so in the spring when you see all the folks here with the "good" engines whining about "milkshake" oil and my "freeze plug" popped out you can go boating. Lots of guys with 470's here so you an get help with any problems. Welcome to the "470 Club":facepalm:

 

[8celebrity9]

I have had my 89 celebrity with the 3.7 mercruiser for 2 years now. From all the research and talking to many shops, yes almost all the parts are interchangeable. Got to love these old boats!