3.7L Mercruiser Replacement

[Capt.P]

Looking at a new used boat for my father,1985 Chris Craft 211 Scorpion with the dreaded 3.7l mercriuser model mcm 190 ser#6925608 bravo 1 drive(I think). I've researched this engine here in Iboats and it seems not too many people like them and I can see why.My question is did they improve these by the 1985 year?
The boat is the thing that appeals to him because of the wide open deck space it's exactly what he is looking for, so the plan is to repower it after the first season if this engine is not dependable.Is it true a 4.3l will bolt up to the same outdrive? What about a 3L mercruiser?Speed is not important but fuel economy is very.

 

[Don S]

Re: 3.7L Mercruiser Replacement

Actually, they stopped building the 470 style engine in 89. It just didn't work out.
The gear ratio is perfect for a 4.3, but exhaust Y replacement, and things like stringers for engine mounts on the side of the engine will be needed to upgrade to a V6. Not impossible, and not cheap, but doable.

 

[DHPMARINE]

Re: 3.7L Mercruiser Replacement

Buying a used (and I guess a new) boat is an incredible experience.Just wait until you look at it in the morning.

But I can't suggest you buy a boat that you know has a problem motor, intending to repower it next season.The price of the boat and the price of the repower just doesn't make sense.

There are too many boats on the market.You don't have to purchase an inferior one and make it work for you.

Keep looking.

DHP

 

[Capt.P]

Re: 3.7L Mercruiser Replacement

I am going to take a closer look at this boat tomorrow to make sure the stringers,floor,transome ect are not rotted out so I will see if the stringer are suitable for a v6.I read somewhere thatthe hp for these 3.7l 190hp were rated at the crank and not at the prop, if so would a 3L not be close in rated hp and would it bolt up to the outdrive?
This is the boat he wants and after looking for 3 years we dont care if we have to repower it .There just isn't any boats of this style around for his needs(Fishing Guide) it took me 2 years to talk him into a I/O (he has ran a 21 ft inboard wooden boat with a chris craft model K for 40 years) and is kinda stuck in his ways if you no what I meen!

 

[Don S]

Re: 3.7L Mercruiser Replacement

Stick with the V6 if you are going to repower. The 3.0 will still require exhaust change, but it would also requiere a gear ratio change. HP and Torque are the reasons for different gear ratio's, not number of cylinders.
The V6 would also make the boat a lot easier to sell if/when you decide to change to a bigger or different type boat.
With a planning hull, running just off plane is going to be the worst possible fuel economy. The 3.0 will suck more gas because it won't plane, the V6 will plane and you can back off the throttle and be just on step and actually have better fuel milage with the V6 than with the 3.0L.

 

[Capt.P]

Re: 3.7L Mercruiser Replacement

That's a good point Don and I guess a 21 ft boat is probably too big for a 4cyl .Just wondering what year did they start making 4.3l or any v6 mercruiser fuel injected?Fuel injected would be better fuel efficient correct?

 

[dbric36]

Re: 3.7L Mercruiser Replacement

I would say give the 3.7 a chance. I have one and it runs great. If it was taken care of it might be one that is ok. Mine is in a Wellcraft 192 cuddy. Plenty of power at 165hp for that boat and easy on fuel.

 

[kcole683]

Re: 3.7L Mercruiser Replacement

I had a 3.7 in my last boat. I had good luck with it for over 4 seasons. It had a few quirks but I never experienced the dreaded circulating pump seal leaks nor did I have to change the charging system or voltage regulator. I would not buy a 3.7 unless the cooling system and charging system are checked out by someone familliar with the 3.7 series of engines.
If you are not a mechanic willing to work on the thing it could be very costly to keep it running. It seems alot of people don't want to work on anything more than a few years old.
The 3.7 requires the cooling system to be in top condition at all times overheating problems if you don't stay on it. The engine has an aluminum block with a cast iron head so when it overheats you have different expansion rates of the metals,possible head gasket problems. If the seals go on the circ pump that is a big problem that is fixable but not your every day deal. The charging system is goofy even when it works right. The voltage on the system will vary from 12 to 17 volts when running,parts are expensive to replace so an alternator conversion is usually the best route.

If you buy it Good Luck

 

[andy1canada]

Re: 3.7L Mercruiser Replacement

Howdy!

I agree with kcole...

If the 470' still has 'good' compression and there's no coolant leaking from the weep-hole at the bottom of the water pump cover - run with it till she blows up. Even if the camshaft/water pump seals do go, with a two-four of cold ones and some wrenches (incl. a puller), the job is doable. Here's a link to some good info on how to do the job.

http://www.sterndrives.com/470information/470coolantleakrepair.html

Make sure you have the 4-inch heat-exchanger; do the alternator coversion; join the '470/Merc' forum @ Breezeworks.com and you'll be in touch with a 'whack' of guy's who run these mills and can help you get the most out of them.

Good Luck!

Cheers,
Terry

 

[Capt.P]

Re: 3.7L Mercruiser Replacement

Well we bought the boat!Can't pick it up until about 10 boats are moved out of the way .Thanks all for your advise and input.Would anyone have an online manual for the 3.7L model mcm190 ser#6925608 and I forgot to check for sure if it is a alpha drive .I am trying to look up a number and price for bellows kit and gasket but not sure if this is ser #A309 167.
Once again thanks for all the info.

 

[Capt.P]

Re: 3.7L Mercruiser Replacement

Does anyone have a idea what manual would be best?

 

[Don S]

Re: 3.7L Mercruiser Replacement

The Merc OEM manual is best, you need book #8 for your engine. PN 90-44553. No online manual for the engine.

Your drive will be #6 or Click here for the online version.

 

[Capt.P]

Re: 3.7L Mercruiser Replacement

Thanks Don!The link you posted is for valve adjustment not a manual.

 

[Don S]

Re: 3.7L Mercruiser Replacement

Sorry bout that...... I fixed the link above also

http://www.boatfix.com/merc/Servmanl/6/6covr3.pdf