My '87 DV18 thread...

[CobaltRick]

You’re correct Mike.. I believe a PO just attached it to keep it front blowing around and making noise.. I’ll need to make a proper fix at some point here..

[Macarokks]

Ok.. After looking at some of the older threads I decided to not have a pile of separate threads, but instead create a single thread to follow whatever it is I'm trying to fix/upgrade,etc.. If I could I'd merge my separate seat thread here but waited too long and couldn't rename the thread. Oh well..

So, my first question revolves around the dash switches..

Here's the overall dash cluster..
IMG_6011.jpg

Here's the switch cluster for the left side..
IMG_7711.jpg

And the right side..
IMG_6435.jpg

My question is what are all of these aux switches connected to? Seems like a lot of spare switches and I've got NO idea what (if anything) they're connected to. Some of these switches light up and others appear to be dead -- perhaps the switch or circuit breaker is DOA. I thought that perhaps the 12V outlets were switched but that isn't the case. Thoughts?

Also, in the right side of the dash, the switch for the dash lights doesn't appear to work -- no lights come on (the two black ones I gather) and the red lamp next to the switch doesn't light. Any thoughts on what typically fails with these circuits?

My ‘79 and ‘84 both have extra Aux switches that don’t “do anything”. Essentially they put the switch in whether the boat had the feature or not. I.e. captains calls, spot light, docking lights, etc. however, one of my aux switches turns the cigarette lighters on and off. Hope this helps.

[CobaltRick]

Hi all.. It's been a few months.. lol..

The boat sat in my garage since last August.. I was just too busy to get out and put the boat to use. Fast forward, I filled the gas tank with 30 gallons the other day and couldn't get it to start. It would crank ok -- but it was obvious that the 8 year old battery is a bit tired from not being charged for a bunch of time. So.. I charged the battery with a battery tender I just bought and watered it (the water was pathetically low on the cells). Anyway, in re-installing the battery (I couldn't access the battery in its location enough to fill the cells with water so I had removed it), I apparently hooked it up backwards. Doh!!!

About 10 seconds later, the fire in the alternator started. Thankfully I was down there and hit the battery switch right away.. I checked the wires and no issues there -- I'm sure I cooked the diodes in the alternator. I've changed TONS of vehicle batteries but this is a first for me!!

Anyway, I can't fix what is already done.. Mark that off as something to NEVER do again. I'm thankful there aren't any computers or anything on this old of a boat.

So.. To my question.. Can the Mercruiser alternator be swapped with a standard Chevy part instead of an expensive boat part? Thx in advance!!

[Big Block Power]

No what ever you do don't use a automotive alt. Get a marine one. The price won't be that much diff. That sucks about tn he battery cables. Your not the first one. Check the points in the dist. You might have fried them.

[CobaltRick]

thanks for the tip.. This one doesn't have points.. It's got some sort of "thunderbolt"?? electronic ignition.. I'd hope that IF the key wasn't in the ON position that it would not have power applied..?? It seemed to crank over light it was trying to start and in fact burped out the tail pipe (or the boat equiv) once or twice after my fiasco..

[Bfun220]

Simply put,
Automotive alternator = BOOM !!!
What are the big differences between a marine alternator versus one purchased from an auto parts store like advanced or autozone. ... A marine alternator is ignition protected so that you don't blow up your boat. ... USCG requires ignition protection on inboard boats.

[CobaltRick]

wow.. I had no idea! thx!!

[Big Block Power]

Most of the time it will pop the 50 amp breaker back by the engine. Did you perform any wire magic and let the smoke out of any? The fusible link could be fried going to the alt as well.

[CobaltRick]

I saw the breaker on the left side of the engine.. Everything was around the alternator -- I believe the 3-4" flame was coming out of one of its vents.

[Big Block Power]

I saw the breaker on the left side of the engine.. Everything was around the alternator -- I believe the 3-4" flame was coming out of one of its vents.

I guess they should have added a flame arrestor on alternators..

[akorcovelos]

Common failure point on the Thunderbolt ignition is the module under the cap. Cheap part, but when it fails you got no spark.

[CobaltRick]

Hmm.. I’m pretty sure I’ve got spark as I occasionally hear a sound from the exhaust every so often while turning the engine over. I think I’m going to replace the 8yo battery and the now cooked alternator and go from there. I noticed that the thunderbolt system seems to still use a coil.. interesting..

[Big Block Power]

Yes they use a coil. It's a primitive set up but not as bad as points. Yes get the alternator changed and check the wiring going to it. Correct if the thunderbolt took a hit you won't have spark. I'm just giving things to double check that are easy to see ahead of time.

[CobaltRick]

Thanks!! I’ll check those areas..

On a different thought.. I believe I’ve also got an issue with the throttle/drive shifter. On it is a “throttle only” button that I believe your supposed to be able to press to allow the outboard to be disengaged but the throttle enabled. That doesn’t appear to do anything in my case. I’ve not yet taken it apart and don’t know if it’s a mechanical lockout or electronic lockout. If I push it and try to throttle up, then the starter is locked out.. so if I want to throttle the engine just a bit while starting, I can’t.

Thoughts on this would be great. Perhaps my notion of how it’s supposed to work are wrong or something. If it sounds as though it’s not working, is this a common issue, and are there replacement parts or is the fit to replace the entire assembly..?

Thx!

[Big Block Power]

Yes it's Mechanical and of course has a stick in there. Is it a mercury 3000 shifter? What model?
Everyone I had were touchy though. But yes you should be able to push it on and just get throttle and no drive engagement.