new to inboards—a few questions!

[jimmwaller]

Hello,

I recently bought my first boat (1970 starcraft islander, i believe the motor is a pre-alpha mercruiser 165) and I have two questions about I/O engines. (okay, not super recently, but I've been fixing other stuff and haven't had it in the water yet :/) I've really only had outboards up until now and could use a little help!

Question one: I have two marine batteries on board. So far, even though I only start it up once every few weeks, they seems fine, but is there a recommended practice on how to keep the batteries in good condition? I was thinking like a solar trickle charger or something, but I don't know if there's one model that people love, or if there are certain features to avoid, etc. Or is it fine to just let them sit?

Question two: This is an older motor, and I'm going to be using it in a saltwater bay. I thought about putting closed cooling on it, but I got talked out of doing that because everyone said it would just clog and it wasn't really worth it unless I was going to completely disassemble and de-scale/de-rust the whole engine beforehand. So I'm just going to use it as-is, and flush it out every time.

Just to make sure I have the flushing process right: I pull it out of the salt water, and just run freshwater through it, just like an outboard? I was thinking, what if I filled a tub or something with fresh water, and ran the engine in the tub, and put in like a salt removing chemical every time? Would that help, or is that overkill? I'd like to do whatever I can to help keep this motor going for a long time to come, and will happily take any suggestions

Any thoughts on either would be appreciated,
thanks!

 

[alldodge]

Opinion: Most the solar charges will work to keep a fully charged bat charged, but most are of low quality.

Don't install closed cooling on an old motor

An I/O will not flush out like an outboard. You would need to run on muffs for a good amount of time so the thermostat will open/close a few times to add fresh water to the block. That said I would still recommend flushing. Use something like salt away can also help. Don't recommend using a bucket on an I/O

 

[Chris1956]

You can open the block and manifold drains and let the salt water out, then flush it like an outboard, w\using the 'muffs. After a few minutes, all the salt will be gone. I think the flusher products are unnecessary, and may not even work.

One more thing, The blocks are very robust, and hold up well to saltwater. The manifolds and risers need to be replaced, ideally before they rust thru and allow saltwater into the combustion chambers. I recommend you inspect the exhaust riser (inline 6 right?) and see if it is intact. They are usually the first to rust out, followed shortly after by the manifold.

 

[Scott Danforth]

use salt-away or other similar products with the muffs when you get home to keep salt-water corrosion to a minimum

 

[ahicks]

If this engine uses points, pull the distributor cap, grab the rotor, and give it a little shake. If you can feel slop the top bearing is shot, making anything close to accurate dwell/point setting pretty much impossible. This can leave you out on the water with very little noise coming from the engine compartment.

I used to replace the block and manifold drain plugs with brass radiator petcocks painted orange so they're easy to see. Made draining the engine a piece of cake. Just make sure something comes out when you open them. They will block with sand on occasion where they'll need some attention.

 

[Scott Danforth]

dizzy bushings are $4 at Napa if need be. knock the pin off the gear, pull the shaft, pull the bushing, drive in new bushing, install shaft, drive pin back in.... 15 minutes tops

points need filing every year. open your wifes purse and grab a nail file. run it thru the points 2-3 times before you set them

 

[jimmwaller]

Lots of good info here, thanks!

@chris1956: Yes, inline 6. Is riser inspection a DIY job for a home mechanic? I should also have noted, this motor has (apparently, assuming the PO was truthful) never been in salt water. Is rusting a concern even with fresh water use?

@ahicks: thanks. It uses points, I'll have to check the distributor cap. Just to verify that I'm getting that you're saying...

I'm basically just testing the top bearing in the distributor cap? Is this something worth keeping a spare of in a toolbox on the boat?

scott Danforth: Sorry for my ignorance, but I don't think I know what a dizzy bushing is. what part of the engine are we talking about here? Is that like...slang for a distributor, or something, that I've just never heard before? thanks!!

 

[Chris1956]

Riser inspection should be pretty easy. Both the exhaust manifold and the riser have water jackets over the exhaust passage. The terminal end of the riser is where the water mixes with the exhaust. That is where the rust should be the worst. You might take a look at a new riser on the web or someplace. Now pull off the rubber bellow and inspect the termina end of the riser for holes, missing sections, etc.

Manifolds and risers are good for 20+ years in frreshwater, but only 10 years in saltwater.

"dissy" is slang for Distributor.

 

[Scott Danforth]

dizzy = distributor
points = ignition contact point set
carb = carburetor

my last manifolds were nearly 30 years old when i sold them. 26 years in fresh water, 3 years in salt water.

 

[QBhoy]

Hi. My answers and thoughts.

Q1: a solar charger is a good idea, but make sure it’s a decent one. The cheap ones often bought for £20 or $20 are of no use at all for your batteries. If she is run every week they should last, if I’m good condition. Worth noting that deep cycle batteries (if used) don’t like being run flat. They never really recover. A smart charger is a good idea.

Q2: I’m not sure what old Merc you have. Some of that name are straight 4 cylinders and already have internal cooling. Other type is a 6 cylinder and likely hasn’t. The latter being the case, it is a great idea to flush the salt out when ever you can with muffs. Quite often the old big tub of water trick doesn’t work. It simply doesn’t allow enough head of static pressure to allow the impeller to lift the cooling water efficiently. It’s 50/50. It’s not the same as having the drive sat in 3ft of water and the pressure that brings. Good fitting flushing muffs are there answer.
During winter long term storage I like to fill with anti freeze to prevent corrosion too. Many will argue it’s not nessesary, but I do.

All the best.