replacing an 82' 470 merc

ProudFather1215 · #1 01-27-2009, 11:37 AM

i have an 82 mercruiser 3.7/470 in my V20. as is common with the engines ive heard, my head gasket blew on me, and im not too thrilled about the prospect of throwing another 470 in there. especially considering i could get half way down my canal on the first trip, and have another gasket blow on me with my luck

are there any other engines that will be a direct replacement for the 470 that may not be plagued with as many issues, without having to do any extensive refitting/glassing of the hull or anything of the like. or am i pretty much looking at alot of time and $$ to install anything but another 470?

spareparts · #2 01-27-2009, 12:30 PM

un furtunatly, there is not a direct replacement for the 470. The 4.3 V6 is the most common replaceemnt for the 470, but it will require building up motor mounts to the stringers. Its not that big of a job. Depending on which drive/transom plate you have( 82 was a change over year) you may not have to change anything on it to install a complete V6 engine. None of the accesories on the 470 will work on the V6, so you will have to get a complete engine. The biggest issue with the V6 is cost, some times its not that much more to put a V8 in there instead, its not that much weight difference, and it flat haul butt with a V8. I poersonally like the 470, but parts are getting harder and harder to find for them. What caused the head gasket to go( they don't blow out for no reason)

ProudFather1215 · #3 01-27-2009, 02:36 PM

im guessing i blew the gasket when the motor overheated. theres an engine alarm on there, but dident go off for some reason when the temp was rising. ended up smoking the engine real bad. was paying more attention to a snotty inlet, than my guages at the time. i also dont know the original cause of the overheat.

the mechanic i had check said its not worth replacing, since i have fairly crappy compression. if i remember,#1/2 were at around 140 my #3 was at 120 and #4 at 150. based on that, he said it may not be a healthy engine to consider cracking open.

Skools Out · #4 01-27-2009, 02:50 PM

hang a bracket and put an outboard on the boat sell the out drive and blown motor for parts on ebay should get enough out of the out drive to buy a good used bracket.

ProudFather1215 · #5 01-27-2009, 02:55 PM

yea, the outdrive is about worthless. its been leaking gear oil for quite sometime, and from what i was told, was NEVER serviced by the original owner. im partial to my i/o set up however. had an i/o on all 3 boats ive owned, and wish to stick with them

can we say i got screwed on this deal?

spareparts · #6 01-27-2009, 03:50 PM

with the outdrive needing work, then you may need to rethink your repower. A bracketed outboard is an excellent way to go if you have the ability. If you have to pay for everything, then its going to get expensive. be patient, look around and see if you run accross a deal on anything. There aer a lot of boats that are going to get repoed in the next couple of months, keep an eye out on the salvage and auction sites. You could find a deal on a crappy boat with a good outdrive package, or a good OB set up that coule be bracketed to your boat. Whats teh transom on your boat look like now. If its bad or in need of repair, its hard to justify going back I/O.

ProudFather1215 · #7 01-27-2009, 09:03 PM

the boats transom is actually extremely strong i was told. this was the first season the boat has ever been left in water. it was trailered and used in freshwater until i bought it.

like i said, im extremely partial to my i/o set-ups. ive ran several boats with OB's before, and maybe im just a creature of habit, but i like my IO much better.

so since im dead set on an i/o, would the 4.3 v6 be the best solution otherwise?? or would any of you guys chance rebuilding or looking for a decent 470 again, since when they are running, you cant beat the bang for the buck they put out.

THEFERMANATOR · #8 01-27-2009, 09:16 PM

If speed isn't a major concern, maybe a repower to the new 3.0L would be feaseable. With this market you may be able to get one heck of a deal on a new unit witrh a warranty.

spareparts · #9 01-27-2009, 09:47 PM

the compresion on your engine isn't that bad, what worries me is the drive, I'd hate for you to rebuild the engine and then the drive and transom plate goes to crap, then you end up with about 10,000 more than the boat is worth. Keep your eye open on craigs list or local sites around large fresh water lakes. I've run across complete boats with Alpha 1 gen II drives, 4.3 engine for sale because the floor was bad or the traielr and interior went to crap. I've seen boats like that for $2500, just ignore everything but the drive line. Alpha ! Gen II ( 1991 and newer will get you the latest stuff. MAke sure you don't buy a motor thats been under water. Check with banks and wet slip/dry stack marinas that don't offer service. There is no way around the fact that its going to cost you money, but at least you've got a decent boat to work with. You may want to have an expert check out the transon, just to make sure you're not throwing good money after bad.

spareparts · #10 01-28-2009, 06:27 PM

Proud Father, I think I may have found you a doner boat. What part of the country are you in.