Why is the Merc 470 a bad motor choice?

[Nandy]

In another post a member mentinoned the Merc 470 as a non desirable motor to buy. I read the reasons why OMC might be a bad reason. Some mention that it is a discontinued motor with hard to find parts and little support. Some argued that point.
So anyone wants to share why would a 470 be a bad motor to buy? C'mon, no opinion is wrong, right?

Thanks!

 

[Haut Medoc]

Re: Why is the Merc 470 a bad motor choice?

Funky water pump seal & water cooled voltage regulator, are two....
Let the others add to the list......

 

[Nandy]

Re: Why is the Merc 470 a bad motor choice?

Are any of those 2 issues fixable with an aftermarket part? Or is it economically prohibitive?

 

[mkast]

Re: Why is the Merc 470 a bad motor choice?

Let's restore an Edsel, after a bunch of money, it's still an Edsel!

 

[Haut Medoc]

Re: Why is the Merc 470 a bad motor choice?

Are any of those 2 issues fixable with an aftermarket part? Or is it economically prohibitive?

They sell an aftermarket alternator kit for about $400.....
Don't know about the water pump/cam seal.....

 

[tommays]

Re: Why is the Merc 470 a bad motor choice?

While i am sure there are happy owners of most everything ever made

Why do you think Merc abandoned ship after spending so much money on R&D and went back to using GM and Ford production blocks


And the open deck cylinder design seems to a weak point also



Tommays

 

[ziggy]

Re: Why is the Merc 470 a bad motor choice?

i've never seen one. but understand another reason would be alum. block w/ iron head.........dissimilar metels...

originaly i believe they came w/ 3" heat exchangers which apperently wasn't adiquite. they then went to 4"...upgradable.

there are plenty other engines that don't have these issues. if ya don't have one. why get the pain.........boats are hard enough to keep running in proper shipshape w/o adding design flaws into the picture

 

[180shabah]

Re: Why is the Merc 470 a bad motor choice?

they can be upgraded to a standard alternator, kits cost $600-1000 depending on what is included and where you shop.

That funky water pump seal, if not replaced before it goes bad can wreck cam bearings.

 

[DHPMARINE]

Re: Why is the Merc 470 a bad motor choice?

I would think any good running 3.7 generation motor still in service would be a decent purchase.Note I said STILL GOOD running.

The worst problem (I think) was the elbow/riser/resevoir putting antifreeze down into #3 or #4 cylinder.

The charging system was a nightmare,until they got rid of the amp meters in the dash,but not all that bad.We just remember the stator and regulator were $500.00 in parts.Belt driven alternators were around $125.00 then.And if you didn't do a regular water pump service,yes YOU ruined the regulator.

As to the water circulation pump ..... ya you can't just bolt on a new pump. But it took many years for those seals to leak,and Jiffy Sleeves will probably work well even longer.

This motor would not scare me away from a boat I liked,but as others are saying don't go out of your way to buy a boat BECAUSE it has this motor.

DHP

 

[rodbolt]

Re: Why is the Merc 470 a bad motor choice?

open deck block was simply **** poor. the altenator while a good excersise in theory never worked. the starters tended to get wet and fail, rather expensive. the original cast iron manifold is now a kit with AL.
was a very poor excuse for a marine powerplant that merc gave up on rapidly as most the isues simply could not be economically engineered away.
if ya ever replace the cyl head gasket or do a valve job on one you will see what a pain lash checking is. if you misalign the cyl head to block by more than about .020" you will either have intake leaks or an unsolvable oil leak.
I I had a good running 3.7 given to me I doubt I would run it but no way would I buy one.
like I say, it was not a stellar performer 20 years or so ago when the last one was built. its not a fine wine.

 

[Nandy]

Re: Why is the Merc 470 a bad motor choice?

The alternator on this motor looks like any other alternator. I could not see any water hose going to it. I follow all the cables and could not see the water cooled voltge regulator. I will think that someone upgraded that. How can I be sure? I mean, Was I looking in the right place trying to find a water hose conected to the alternator? If not where is that voltage regulator? The current owner was telling me that this motor was work on extensevily by the previous owner and had a lots of upgrades including the cylinders bored to make it into a 140 hp. Anyone heard of that? Any help will be appreciated. Im still offering him 250 for it. His battery was dead and it did turn once, but I could not check for sparks or anything like that...
Thanks.

 

[Don S]

Re: Why is the Merc 470 a bad motor choice?

The 470 models didn't come with alternators. They used the crankshaft pulley as a flywheel with magnets in it and a stator under that flywheel, like an outboard. The regulator was bolted to the port side of the block and was water cooled.
If you have a standard looking alternator, then it has been upgraded.

 

[Nandy]

Re: Why is the Merc 470 a bad motor choice?

The 470 models didn't come with alternators. They used the crankshaft pulley as a flywheel with magnets in it and a stator under that flywheel, like an outboard. The regulator was bolted to the port side of the block and was water cooled.
If you have a standard looking alternator, then it has been upgraded.

Great, now how do I know if the water pump has been upgraded as well. Anyone has a hint?

 

[Don S]

Re: Why is the Merc 470 a bad motor choice?

The current owner was telling me that this motor was work on extensevily by the previous owner and had a lots of upgrades including the cylinders bored to make it into a 140 hp.

OK, what engine do you REALLY have???? The 470's originally had 170hp right out of the box, so how would the previous owner bore it to 140 hp. Besides that, you bore to cu. in. not HP.

Please answer both questions below.

First question.
What side of your engine is the starter on? Port or Starboard.

Second question.
Is your carb and exhaust both on the same side of the engine?

 

[Nandy]

Re: Why is the Merc 470 a bad motor choice?

OK, what engine do you REALLY have???? The 470's originally had 170hp right out of the box, so how would the previous owner bore it to 140 hp. Besides that, you bore to cu. in. not HP.

Please answer both questions below.

First question.
What side of your engine is the starter on? Port or Starboard.

Second question.
Is your carb and exhaust both on the same side of the engine?

I guess what the guy meant is that the motor was bored to a cu in size that will give him 140 hp. I posted a few days ago one of the members told it it was a 470. He also gave me a link to download a manual and it looks pretty much the same motor. This is what I posted initially:
Serial is 5037133
4 cylinder.
The model number it says MCM something in the valve cover but could not see the rest as the label is damaged. It did had clearly it was a 120 hp in that lablel.
The starter is in the starboard.
I dont remember the exhaust. the carb is to the port side.
Does that helps?
Thanks for your help.

 

[Don S]

Re: Why is the Merc 470 a bad motor choice?

Well, that SN may be in the range of SN's for the 470, but it ISN'T a 470 engine. It's a 120, now bored out to be the size of a 140.
The 120/140 is a Chevy engine originally used in the Chevy II's back in the early 70's. Then they became industrial engines and marine engines by using the same block, crank, & head.
Even Mercury doesn't list what motor it is by SN, either on Merc net (Dealers site) or Merc Parts Express (Merc parts lookup online)

So all this talk about 470 style engines is a waste of time for you, cause that boat doesn't have one........... And that's a good thing

 

[Nandy]

Re: Why is the Merc 470 a bad motor choice?

Oh my... Where do I go from here now?! LOL! The stern is a mercury, I did not check the s/n. How do I find out what motor I have for real?

Thanks!

 

[Don S]

Re: Why is the Merc 470 a bad motor choice?

Post some pictures of the engine.

 

[Big Boat Bay Buster]

Re: Why is the Merc 470 a bad motor choice?

I know its a moot point, but I own a 470 and I like it. Alot of torque, and Great on gas! I'm aware of its problems, thanks to the internet, and I keep an eye on those items. Check out this ad, selling points still hold true today.
Chris
http://www.members.aol.com/cdrr61/470.jpg

 

[JoChek219]

Re: Why is the Merc 470 a bad motor choice?

I have a 3.7L in an 87 Thompson Cutglass 18.5ft Deep V hull... Its a powerful 4banger...You can buy an alt. kit for about $200 at www.breezeworks.net I Put one on mine last summer and have had no problems. That motor had power curves similar to the 4.3 and the gearing in the drive is perfect if you ever wanted to drop in a 4.3.