New (Old) Boat

[cshirley]

I have a 14ft Jon Boat with a 25HP Mercury that is doing well but wanted to go bigger. I bought a 78' Wellcraft Air Slot 190. The hull and interior is in very good shape for the age of the boat. It has a Mercruiser 470 engine. The guy I bought it from owned a storage place and repo'ed it from a customer who wasn't paying to store it. He said that it had been sitting outside for a while but when the guy brought it in it had been running. It still has 07 tags so I am assuming why buy a tag if it doesn't run. So I bought it for $500, trailer, boat, everything. I have worked on V8s and V6s in vehicles but never a boat motor. Are there any diagrams for this engine? Or help with the general operation of an inboard marine engine. I'd like to get this thing running before the end of the summer.

Also, I pulled the fluid cap and the coolant is horrible, looks like it has almost become a paste. The first thing I would like to do is flush it out but I don't know how it works. I'd be looking for a radiator but I guess boats don't work that way.

Thanks for any help.

Curtis

 

[Dadicus]

Re: New (Old) Boat

Clymer makes a manual that is reasonably priced, and there are tons of posts on this discussion group. Some of these guys know more about this motor than the designers. Search the posts for "470," and "Mercruiser 470" and you will be amply rewarded.

 

[Maclin]

Re: New (Old) Boat

The barrel shaped outfit that you saw the coolant in is the heat exchanger or radiator. It has two compartments. Engine coolant is circulated thru the inside compartment coils and raw water from the lake is circulated around that compartment/coils and exits thru the exhaust. This type of system is called closed cooling or freshwater cooling. The engine will circulate an antifreeze mix and it will pressurize just like in a car engine. Comparatively, a raw water cooled engine does not have a heat exchanger, but rather raw water is made available to the engine's cooling system and excess and heated water is expelled thru the exhaust. There are advantages and disadvantages to either system. Typically salt water boats would have the closed system to cut down on corrosion in the cooling passages and cooling components.

That engine is specific to boats, there is no automotive equivalent.

Others will be along soon, just be ready for the good/bad news about your engine's characteristics.

 

[Dadicus]

Re: New (Old) Boat

CShirley,
If you live where it gets cold you'll want to make sure the boat was winterized before it was stored. The fresh water heat exchanger Maclin mentioned, as well as the fresh water pump, etc can be damaged if the fresh water was not flushed out of the system before it was stored.

There's a two foot long tube on the right hand side of the engine as you face aft. That's the heat exchanger. It has cover plates fore and aft that are held on by a single bolt each. Loosen one of those bolts. If water pours out that's kind of a bad sign, again assuming that you live where it freezes in the winter.

The boat has a fresh water pick up in the lower unit, just like your outboard, and pumps water through the heat exchanger as well as through the water cooled voltage regular that is right beside it (that's a story for another day). As Maclin mentioned, this engine also has a closed coolant system full of antifreeze/water mix. If you decide to flush the system make sure you flush the antifreeze system, not the freshwater system. I know that seems obvious, but there it is anyway. Be aware, also, that the block is aluminum. Again, I know it seems obvious, but make sure you have muffs on the lower unit if you start it.

I don't know too much about this engine/outdrive, but I've had one about a year and I'm starting to learn things the hard way. This site is a good place to look for information. You'll want to search the old posts about this engine system. The engine has plenty of horsepower (at least mine does), but it's prone to some specific kinds of failures. These guys can help a lot.

You may also want to check this site http://www.breezeworks.net/cgi-bin/...ics.asp?ForumID=1&PagePosition=1&ThreadPage=1

It's on a site called "Breezeworks.com" that specializes in this particular engine and outdrive system. It's not as well maintained as Iboats, but it's still useful and many of the parts you may need can be ordered on the site. Good luck.

 

[Coors]

Re: New (Old) Boat

Clymers doesn't even qualify as decent shat paper; you need factory manual.

 

[mainexile]

Re: New (Old) Boat

Clymers doesn't even qualify as decent shat paper; you need factory manual.

I agree with Coors 100%. I have the same engine on my '77 Grady White, and I bought the OEM manual after seeing what a joke the aftermarket versions were. It's a torquey little 4-cyl with enough power to pull skiers/tubers, etc. BUT it is unique with a set of possible problems that will turn your hair gray overnight (alternator, waterpump seals, etc.) as the veterans on this board can attest. Treated properly, however, you'll get good service from it. Good luck and welcome to iboats.
Steve

 

[cshirley]

Re: New (Old) Boat

Well, I have fixed many things that I have ran into so far. Someone sheered the top gears on the drive (MR) so I picked up a used alpha one I found for $100 and someone had drug it across pavement scraping a hole in the lower unit. The upper unit and gears looked great so I swapped it making sure all seals, etc. were good. I didn't know that the cooling system was closed. I assumed that the lake water ran through the engine to cool it. I pulled the heat exchanger off and cleaned it and resealed the caps because they were leaking. I've had it running for probably 15-20 min. once warmed up and it hasn't gotten over 160-170 degrees with earmuffs on. I'm not seeing any leaks from the front of the engine just a couple hoses needed cleaned and tightened. The engine has been painted and serviced pretty well it appears. It just has some vibration at certain rpms.

 

[Coors]

Re: New (Old) Boat

did you pressure/vacuum test it? Need to.