Suggestions on looking for corrosion inside engine

[accentphoto]

I have a 1984 90hp Mercury that I am getting ready to replace all of the electrical components on and I thought that before I committed to actually putting them on I would open the motor somewhere to see if the aluminum block had corroded badly from salt water use and the PO not flushing properly.

Any suggestions on where I should check? Which side to open? I have the electrical mounting bracket that holds the switch boxes and coils already off and the frame that goes around the top of the engine is off. I have about 90% access to the starboard motor side bolts and 95% on the port side. Since I can't find my Mercury repair book I thought I'd ask. I just want to make sure the insides are not corroded away.

So I think I am looking at removing either the exhaust cover, cylinder block cover or the (for lack of better words) starboard side behind the electrical mounting plate side.

Also, how do you get to the lowest engine cover bolts if they are in the bottom recesses of the bottom cowl? Does the cowl somehow slip over the motor and if so, what needs to come off?

 

[accentphoto]

Re: Suggestions on looking for corrosion inside engine

I forgot to mention that the main reason why I am concerned about internal engine damage is because it appears that every cover plate that goes over a gasket and gets mounted to the block has a light corrosion characteristic. The PO left the engine uncovered for about six months or more so I am not sure if this is from being uncovered or put in salt water. You can see the whitish corrosion where the exhaust gasket meets the exhaust cover and engine block in the attached photos. I do live near the beach and I am thinking that since the boat originally hailed from NJ that maybe the owners way back then also put it in salt water.

 

[Mi duckdown]

Re: Suggestions on looking for corrosion inside engine

does it run? That motor looks pretty clean.
Changing electrics is pretty exspensive for no reason.

 

[Mi duckdown]

Re: Suggestions on looking for corrosion inside engine

compression would be my first concern.?

 

[accentphoto]

Re: Suggestions on looking for corrosion inside engine

As far as clean, its one of those kind where if you saw it in person you may doubt the condition based on a photo (like buying a beautiful car on Ebay only to see the flaws when it arrives).

Compression was good ... maybe too good (my gauge is new but accurate?). I was getting no less than 151 and no more than 155 on the cylinders. Thought that was pretty good.

On the electronic end of it, the stator had one pair of wires that tested bad on the ohms. Basically like a open circuit. The trigger may be original so for $105.00 I think I can get a few years out of it. The switch packs were mixed and they recommend changing them every seven years. One may be only three years old but I don't want to have to worry about that out in the ocean so for $105.00 each its a lot less than a tow charge. The rectifier seems to be bad on one side so replace it. All in all I got 2 CDI switch packs, 1 CDI stator, 1 CDI trigger, 3 Sierra carb kits, 1 Sierra Impeller kit, 1 Sierra fuel pump kit and some water proof grease for $575.00 shipped. I just want peace of mind.

 

[Chris1956]

Re: Suggestions on looking for corrosion inside engine

If the compression is good, you are ready to run it. Nothing else makes sense to inspect at this time, IMHO. If you pull the transfer covers you will see clean non-rusty cylinder walls, or the compression would be bad. If you pull the exhaust cover, you will break all or most of the bolts. You can inspect the inner exhaust cover and baffle, but at too high a price, IMHO.

Change and inspect the gear oil. I would clean and rebuild the carbs as they look weathered. After that take it on a short run and inspect the plugs. If any are steam-cleaned, you likely have water intrusion from bad crankseals, leaky baffle or exhaust inner cover.

 

[accentphoto]

Re: Suggestions on looking for corrosion inside engine

Thanks for the great detail. Thats what I am looking for. My biggest worry was putting on all of the new electronics only to find the motor didn't work if it were due to corroded passageways or worse the eaten away interior cooling system that is beyond repair. I am attaching a photo of what I don't want to see. Don't worry, its NOT my motor.

 

[Mi duckdown]

Re: Suggestions on looking for corrosion inside engine

Why would you post that? it only confuses people.
Thinking it is your motor.

 

[accentphoto]

Re: Suggestions on looking for corrosion inside engine

I was hoping that someone would way ... "yes there is a easy access point on a certain part of the motor for you to check" but that didn't happen. I plan on posting a couple of cell phone pics of the areas that concern me. Basically, the port, stern and starboard side of the motors gasket areas have a whitish corrosion on the motor near the gaskets that appears to be in the metal now. I realize that the model of Mariner I have is for salt water but I hope this is not a sign of improper flushing and care by the PO.

 

[accentphoto]

Re: Suggestions on looking for corrosion inside engine

So here are some photos of the corrosion I mentioned around the gaskets. Please let me know if anyone thinks this is a warning sign before I commit to buy this boat. I hope the photos help.

 

[CDT]

Re: Suggestions on looking for corrosion inside engine

All i can suggest is run water thru the water lines on the motor, But as for that corrosion it looks fine to me, Nothing that i would be concerned about.

 

[Chris1956]

Re: Suggestions on looking for corrosion inside engine

Accent, the first phots is of the transfer cover. All corrosion is from the outside, as it does not have contact with any of the cooling passages. The second photo is of the water jacket cover over the block. It doesn't look too bad. I would think the motor was left outside uncovered for a number of years. Check the wiring and plastic pieces for degradation.

 

[accentphoto]

Re: Suggestions on looking for corrosion inside engine

CDT and Chris1956 I appreciate the advice and vote of confidence in the motor. Yes, it seems the PO had it "open" to the weather since he got discouraged trying to start it. Being this is a "Marine" engine, I have high hopes that the inside fairs much better.

CDT, run water thru the water lines? Can that be done without the motor running?

Chris1956, the stator wires, trigger wires and switch box to coil wires all suffered from age and environment. I replaced all of the electrical from the motors harness to the coil packs. Check out this link .... I am a little proud: http://forums.iboats.com/showthread.php?t=481366&p=3264408#post3264408