posted 06-26-2003 08:45 AM ET (US)        

So, Sal, Bigshot, et al, am I witnessing something that is just how it is, or is this diagnostic of something I should be concerned about?

posted 06-26-2003 09:59 PM ET (US)            

I'm on the project of checking out the starboard t-stat and/or blockage; once I get that licked I'll almost be back to where I'm trying to track down the intermittent missing problem. First thing I've got to do though is replace my VRO tank; I took it too far apart out of curiosity when I was making sure of the tightness of all my fuel and oil line connections, screwed up an electrical connection in the sending unit, and now the low oil horn beeps every time after I've run the motor for a few minutes.

Trader Bill's in Hot Springs Arkansas sent me a new old stock replacement VRO tank with all fittings and lines that has never been used for 45 bucks. Recommend them highly, lots of OMC stuff, helpful and quick!

So hopefully I'm close to getting back to the original problem...

posted 06-27-2003 08:49 AM ET (US)            

It took me a while to get it through my thick scull why Sal had made that point; finally dawned on me that it was in response to my description of trying to run down a problem I was having at medium and high RPM. (Duh!)

I wasn't running the motor at high RPM on muffs though, just out in the open water. Now I will be particularly careful, and I appreciate the warning from both of you-

John

posted 06-27-2003 10:53 PM ET (US)            

New VRO tank fixed the low oil beeping; took the opportunity to re-arrange the fuel line and oil line more to my liking as well as to relocate the bulbs for both in more sensible spots.

Took both t-stats out, ran motor without either one and both banks stayed cool; took the stats inside and warmed them up in a pan of water, they both opened around 170 to 180 degrees, so I put them both back in and now both banks only get warm. I think I've got (or had) a sticky stat. They're kind of goofy looking plastic things, and I think they're supposed to open closer to 160 degrees. As easy as they are to r&r and as cheap as they are to buy, I'm going to order new ones for both sides. 11 years is probably enough to expect out of them.

Ran a good slug of Techron through and let it sit over night. Now my tach is coming and going on me. I've read somewhere that weird tach readings *can* portend some electric problem or another, like stator as lhg suggested, or power pack or coil or something; can't remember what. I'm heading over to Lake Michigan in the morning and intend to pick uo a new tach on the way; hopefully that is all that's wrong, but by sometime tomorrow I'll know.

Downloaded a bunch of data on troubleshooting electric problems like failing stator, power pack, coils, etc. and intend to bone up, particularly if I find tomorrow that I've still got intermittent missing at medium and high RPM and/or the new tach doesn't give me consistent readings.

Thanks for the help-

posted 06-28-2003 09:52 AM ET (US)            

Can a failing rectifier cause intermittent medium and high RPM missing?? (Say, "yes".)

posted 06-28-2003 04:56 PM ET (US)            

Didn't mean to be obtuse - I attached the red lead of a voltage tester to the terminal on the end of the gray wire once I removed it from the back of the tach, and attached the black lead to ground, then started the motor; the volt meter read 5 volts and change. I presumed that meant the rectifier was going bad, so I ordered a new one.

I did then take the boat over to Lake Michigan for a test run (with an extra battery considering my presumption that I'm not getting good charge from the rectifier/regulator), and strangely enough, it ran real well as I started it and idled about a mile down the river to the lake and ran real well for a couple of miles at about half throttle. Then it overheated (first time this has *ever* happened). I wound up removing the thermostats to get back to the ramp. I had reinstalled them exactly as I found them when I inspected them yesterday, so I'm not ready to believe I had them in wrong in some way. It's like they both just chose now to quit working, but I can't believe the coincidemce. The motor was showing a good telltale stream and good pressure (above 20# at half-throttle) on the pressure gauge.

It seems really weird that a seeming host of things are happening all at once like this...

posted 06-29-2003 06:06 PM ET (US)            

Well, I think I’m on to something-

I bought a gear puller and a 1-7/16 socket (that I had to grind down because the OD was too big to fit down inside the recess in the flywheel), and pulled the flywheel.

Two little pieces of beat up sheet metal fell out when I took the flywheel off. (I’m thinking, “Hmm; I’ll bet that’s not a good deal…”) For the life of me, I couldn’t find where they might have come from or where they belonged.

I don’t know what a bright shiny new stator looks like, but this one doesn’t really look burned up, it just looks, well, kind of worn and cruddy. After disconnecting the leads from the terminal strip under the power pack cover, and cutting a half dozen cable ties that I don’t know how OMC *ever* installed, and even more to the point, I know even less about how I’m going to reinstall new ones in their place, I got the stator off and was able to take a good look at it. VOILA!! I found where the little sheet metal pieces once belonged.

My stator has one power coil and two charge coils; all three of these look basically the same except for the number and color of wires coming from them. Looking at these coils from the radial side, each one has a vertically oriented laminated metal contact that the flywheel magnets spin around, and each one has about a 1-1/2” h x 2” w sheet metal “shield” that surrounds the contact and is kind of bent slightly back towards the crankshaft on each side, and the “contact” protrudes through these shields. When you look at the top or bottom of the coils, it turns out that these “shields” are actually three separate, thin, individual pieces of sheet metal, glued together or something. Well on one of the two charge coils, right in line with one edge of the laminated contact, about 1/3 of the outermost layer of the “shield” had snapped off and broken away somehow and had been turned into the two beat up pieces of sheet metal that fell out when I removed the flywheel. I have to presume that’s not good...

I’m going to attempt to test the stator, if I have the right kind of multimeters and if the stator can be comprehensively tested. Any and all input would be more than welcome here…

Additionally, if I find like I think I will that this stator is shongo (credit: Bigshot), is it possible that the low voltage in the gray wire going to the tach, and the erratic tach behavior could be caused by something here in the stator?? That could mean that I only have to replace the stator and not the stator and the rectifier??

Thanks-

posted 06-30-2003 09:27 AM ET (US)            

There is hard "pinkish" looking stuff around the three coils on the stator; I take it that is OK and that is not evidence that the potting compound is or has been leaking? I have read references to the potting compound appearing like "honey" if it is showing up where it shouldn't be; is that an accurate description? There is evedence of stuff that looks like varnish on the stator, but again, not knowing what a bright shiny new stator looks like, I don't know if this is a bad thing or not.

Thanks,

posted 06-30-2003 04:14 PM ET (US)         

All kidding aside, I believe tach problems are usually rectifier problems. Also, as JimH taught me, fiddle with the pole selector on the back of the tach.
They can get corroded up a little and need to be rotated a couple of times. This worked for me just recently.

However, I had a bad tach signal about 2 years ago on one of my EFI's. So the Mercury mechanic replaced the rectifier.
Tach still erratic. Finally found it to be a stator, even though engine was running fine. Go figure.

You're a lot braver than I would be tackling that big 'ole V-6. For me, it would be off to the dealer, since I would not trust my own work! All I do is change plugs and gear oil.

posted 06-30-2003 04:48 PM ET (US)            

Right you are about the "shongo" credit - there is something about the feel of that word and the condition it denotes that just rubs me the right way...

lhg-

Thanks for the words of encouragement - I have, at the suggestion of the local OMC dealer, fiddled with the pole selector, but the big deal is that there's only 5 volts getting to the tach via the gray wire when there should be 12. Everything else being equal, I guess that would indicate a bad rectifier/regulator. My dilemma now though is that my stator may be bad, and my rectifier may not be, but at the moment I haven't yet developed a strategy to determine whether one or both of them are bad, and if only one, which one. $200 for one and $300 for the other; my front mount Teleflex cylinder budget is currently in negative territory.

posted 06-30-2003 07:45 PM ET (US)            

I've just sent you a couple of digital photos of the charge coils on my stator, in hopes that you can diagnose whether they look like they should, or if that "pink" stuff is a bummer...

Thanks-