What to check when buying a boat with an old MERCRUISER 470

[alesserfate]

Hey Fellows,

I've owned two boats previously (14ft larson and 13ft zodiac) and now onto the next.. going to look at a 17ft fiberglass with a Mercruiser 470 in it... I know the motor basics from cars so I'm going to pull the plugs and look at their condition, maybe do a compression test if my gauge fits. The owner agreed to take me out on the water with it so a test drive should be in order as well.

What can I check on the motor/leg etc or look for to find any potential problems with this setup ? Should I look for cracks on the intake/exhaust manifold ?

Any further advice would be appreciated.

 

[Don S]

Re: What to check when buying a boat with an old MERCRUISER 470

Don't buy into a 470 unless you really like spending money on your engine and working on it a lot.
1. Open deck design. no support for cylinders with an overheat. Replacing a head gasket is normal after an overheat.
2. Aluminum block (Mercruiser design, not automotive), iron head (Ford 460).
3. Cam seals that leak antifreeze into the oil.
4. Known cooling problems with 3" heat exchangers.
5. Charging system like an outboard :facepalm: Didn't work well, and many parts are NLA Most replace with an expensive alternator replacement kit.

 

[HT32BSX115]

Re: What to check when buying a boat with an old MERCRUISER 470

What can I check on the motor/leg etc or look for to find any potential problems with this setup ?
Any further advice would be appreciated.

Do a search on this site and others for problems with the 470.

Then do the safest maneuver in Aviation. The 180 degree turn!!

AND FLY AWAY!

 

[alesserfate]

Re: What to check when buying a boat with an old MERCRUISER 470

Ah.. that bad huh ?

 

[Don S]

Re: What to check when buying a boat with an old MERCRUISER 470

I did this screen shot a day ago in the Mercruiser repair forum. I Highlighted the 470 threads in yellow.

 

[alesserfate]

Re: What to check when buying a boat with an old MERCRUISER 470

Hmm thanks for the advice. I'm going to look at it tonight and I'll judge it for myself. I think if it was maintained well it could be fine. Regardless now that you've guys brought this up I'll be much more careful.

 

[1st things 1st]

Re: What to check when buying a boat with an old MERCRUISER 470

My '89 3.7 (470) has much power and has ran like a dream for years. Ask if the speedi sleeves were already put on. Mine were. Did the alternator conversion and it has performed flawlessly.

 

[Don S]

Re: What to check when buying a boat with an old MERCRUISER 470

My '89 3.7 (470) has much power and has ran like a dream for years. Ask if the speedi sleeves were already put on. Mine were. Did the alternator conversion and it has performed flawlessly.

There is always the lucky few.

 

[HT32BSX115]

Re: What to check when buying a boat with an old MERCRUISER 470

Hmm thanks for the advice. I'm going to look at it tonight and I'll judge it for myself. I think if it was maintained well it could be fine. Regardless now that you've guys brought this up I'll be much more careful.

Misery ALWAYS loves company............

There'll be a whole bunch of good and absolutely sincere guys jump in here and tell you their good experience with the engine.

I thought the same thing about the boat I bought from my brother with an OMC 460 King Cobra under the hood!!

In good running condition, they run well..........

But there's a LOT of other choices of engines that are still in production, and/or still supported for nearly the same money with none of the parts procurement headaches

 

[lakeerienewbie]

Re: What to check when buying a boat with an old MERCRUISER 470

Thanks to this thread, I just narrowly escaped a mercuiser 470 myself! Thanks for the head's up!

I did this screen shot a day ago in the Mercruiser repair forum. I Highlighted the 470 threads in yellow.

 

[alesserfate]

Re: What to check when buying a boat with an old MERCRUISER 470

Took her for a spin with the original owner and I was sold, she runs like a clock. I replaced exhaust bellows on it since old one was cracked (alpha 1, managed to get it on without taking the drive off), that's all it needed and now she's docked. Thanks again for all the help fellows!

 

[HT32BSX115]

Re: What to check when buying a boat with an old MERCRUISER 470

Took her for a spin with the original owner and I was sold, she runs like a clock. I replaced exhaust bellows on it since old one was cracked (alpha 1, managed to get it on without taking the drive off), that's all it needed and now she's docked. Thanks again for all the help fellows!

Good luck! You're gonna need it. There's a LOT of people here that have had a plethora of problems with the 470. So if you have one of them, there'll be someone here with the same experience to help you!


Cheers,


Rick

 

[Jlawsen]

Re: What to check when buying a boat with an old MERCRUISER 470

What to check when buying a boat with an old MERCRUISER 470

Your wallet. Sorry, just had to chime in. It didn't really need reinforcement but I couldn't resist... Slap myself:facepalm:

 

[Bondo]

Re: What to check when buying a boat with an old MERCRUISER 470

What to check when buying a boat with an old MERCRUISER 470

Your wallet. Sorry, just had to chime in. It didn't really need reinforcement but I couldn't resist... Slap myself:facepalm:

Ayuh,... I disagree,... If ya buy a 470, ya need yer Head examined, as it's probably Empty....

 

[HT32BSX115]

Re: What to check when buying a boat with an old MERCRUISER 470

Now come on guys! Be nice!

 

[alesserfate]

Re: What to check when buying a boat with an old MERCRUISER 470

No big deal this is cake, spent 10 years on car forums people ripping each other apart.

Anyway so far so good, been out 4 times, threw in a new bilge pump and redid wiring for the lights. Also drained the bilge of the grime it had in it, been sitting in the water for a week and no water in the bilge yet.

I was reading about how the alpha 1 exhaust bellows can get stretch out and crack if you leave the outdrive in the up position so I leave mine down, this also prevents the green seaweed slime (saltwater) from growing on the trim cylinder shafts and ruining the seals - anyone have any input on this ? Do I ever have to clean that **** off or is it okay if I just run the boat once a week to blast most of it off and then clean it at the end of the season (end of october here). I'll post some pics when she's all done.

 

[HT32BSX115]

Re: What to check when buying a boat with an old MERCRUISER 470

In good condition and properly maintained, the 470 will run fine and work well.
The problems are well documented..... Learn to deal with them and it will probably work for you.

 

[alesserfate]

Re: What to check when buying a boat with an old MERCRUISER 470

Did the alternator kit, some pics for you guys that still have to do it eventually.

BEFORE:


AFTER:


DISCONNECT THE VOLTAGE REGULATOR AND HOOK UP ALTERNATOR CHARGE AS WELL AS CLUSTER POWER/ACC TO BATTERY SIDE OF STARTER SOLENOID:


ISOLATE OLD MAGNETO WIRES INDIVIDUALLY:


RELOCATE COOLANT TANK:


I also had to shift the doghouse an inch forward to clear alternator pulley and what not.

Been out about 6 times already no problems. I run it around 3500rpm most of the time, but I've tried it to about 4700rpm and still have some throttle to go. What is a max safe rpm for the motor ? I've tried to find a PDF operating handbook but wasn't successful so if anyone knows that would be great. I feel like 4000rpm for it is the highest safe power setting I'd use judging by sound.

 

[achris]

Re: What to check when buying a boat with an old MERCRUISER 470

What is the serial number of the engine and I'll post up a link to a service manual for you... Revs at wide open throttle should be between 4200 and 4600...

Chris........

 

[boltonranger]

Re: What to check when buying a boat with an old MERCRUISER 470

I had no idea of the 470's pifall's when I bought my boat. I've learned a lot here and yes it has needed upgrades. Forum and it's members have been invaluable. Good luck with it. -Br