Reply to safe operating temperature

[ArtJ]

From the way you describe your fancey temperature control I suspect
that you may have a Indigo regulator valve installed. If the valve is
overheated from lack of cooling water to boiling point, it can melt internally per Tom Stevens of indigo. I suggest contacting Indigo Electronics to determine if this is the case, as well as obtaining a installation procedure
for the valve. This valve works great if used properly.

Regards

Art

[hanleyclifford]

To answer one of your questions; an engine running at 130 degrees could not generate enough heat to fry the coil. The coil problem is not related to engine heat. Do you have the electronic ignition or points and condenser? This subject of coils is being exhaustively discussed on this forum. Please give us the particulars of your ignition system.

[ndutton]

Wonder why the original thread is closed? Thanks Art for continuing on here.

Paul,

The highest temp you report is 190. That doesn't seem off the scale to me for a FWC engine and I wouldn't expect it to be the root of your performance/running problems. That's not to say you shouldn't chase down the fluctuating temperature. In my experience, the A4 operating temp is rock steady. My raw water cooled engine operates within a 10 degree range depending on RPM and that's on its own, no manual bypass valve.

Then why the performance issue? The coil's been replaced and it still gets hot, way hot. I'm immediately drawn to what type of ignition you have and a potential mismatch of the coil. You report the engine was well maintained and it has FWC. I think any owner that goes the FWC route likely also has electronic ignition.

Do you?

If so, not just any coil will do. It needs a coil with 3 ohm internal resistance. Without the proper coil you risk damaging it and the electronic ignition.

Edit: I see Hanley was typing at the same time as me, albeit faster.

[Paul Clarke]

Not sure where my original post went, because it had diagnostic info.

Art: Thanks for your educated guess! You're right. Some previous owner installed the Indigo fresh water cooled system, including the Temperature Control Valve. I only know that because of your tip here. I've gone to the Indigo Electronics web site and confirmed it. I'll take a look at their documentation. (The first thing I noticed is that there is a sacrificial pencil zinc that is supposed to be replaced yearly; I bet it hasn't been changed in several years!); so thanks for that insightful lead. Is the "Tom Stevens" you mention someone I should contact?

Hanley: To paraphrase, you say that the heat generated by an engine running at 130 F couldn't overheat the coil. Thanks for that; it's good to know. For clarity, here's the sequence of events again:

1) Engine operated at whatever RPMs gave me about 5 knots of cruising speed in flat water for about 3 hours. Smooth operation. Temperature as measured by gauge in cockpit steady at about 130 F. Because I am nervous about this first extended outing with this new-to-me engine, I am regularly monitoring (and writing down) oil pressure, temp, amp output, and fuel levels. As it happened, I had checked temp within about 10 minutes of the onset of our troubles, and the temp was steady at 130 F.

2) Suddenly the engine revs drop (as if someone had just accidentally hit the throttle... though no one did), and then recovers to normal RPM.

3) 15 seconds later, while I am staring at the instrument panel in an ineffectual way, the engine cuts out altogether, and we are surrounded by silence as we glide to a stop.

4) In the course of checking the fuel system (tank, shut-off valve, separator, lines, etc), I opened the starboard cockpit locker and left it open.

5) Ten minutes after shut down, with the engine still stopped, my wife reports the water temp gauge is now reading about 190 F. The ignition switch is therefore still in the "on" position in order for the gauge to function, although the engine is not running.

6) A few minutes after that, a geyser of ?? steam ?? erupts from the starboard cockpit locker.

Hanley, is it possible that as the temp of the stopped engine rose to say 180 or 190 F that that temp could have caused problems?

ndutton: In the half-dozen or so short outings I've done over the last month, the engine temp has been rock steady, as you say, varying only slightly with RPM. This engine has points and condenser, not the electronic ignition.

As mentioned in my original post, the mechanic this week thought the ruptured coil was suspect. I had kept its original box it came in, and although it was labeled as a Mercury part, the mechanic said he'd never seen one that colour (red, instead of black), nor had he ever seen "Made in China" printed on the body of the coil. The ignition coil he installed states plainly on its body that no external resistor is required as it is fitted with an internal resistor. Is the mechanic right... is an internal resistor required when the ignition is by points and condenser?

In retrospect, the geyser of steam must have been from the ruptured coil. The mechanic said he'd never seen one with the internal elements rattling around like that.

-Paul

[ArtJ]

Tom Stevens is the owner and chief engineer of Indigo.

His website is atomic4.com which will give you his phone number.

The heat exchanger probably was made by Moyer Marine.

Regareds

[ArtJ]

Be careful when removing any parts or zincs from the heat exchanger.
You must use two wrenches, else you can damage the exchanger fittings.
Get a manual for the indigo unit from Tom.

Regards

Art.

[hanleyclifford]

First of all an engine temp of 180 or 190 is STILL not hot enough to harm a coil. In fact 180/190 is ok running temp for a FW cooled A4. Your problem is in the primary ignition circuit. You may also have the wrong high voltage wires. Neil has specifications for these items which he has previously posted. Also you could check the Moyer Marine on line catalog. BTW, since you are new to this engine, get yourself a copy of the Moyer Marine Overhaul and Service Manual. It is the A4 "101" for us.

[ArtJ]

Please be aware that there are two distinct version of the mixing thermostatic
control with diferent connections. There is also a bleeding sequence that
must be done properly.Make sure and get the correct manual that applies
to your valve.

Art

[Administrator]

Wonder why the original thread is closed?

Neil:

Which thread?

Bill

[rigspelt]

Not sure where my original post went, because it had diagnostic info.

Wierd. It was on the form earlier today when I checked it quickly on a break, and then when I got home I can't find it either. I had wanted to sit and read through your initial post carefully.

5) Ten minutes after shut down, with the engine still stopped, my wife reports the water temp gauge is now reading about 190 F. The ignition switch is therefore still in the "on" position in order for the gauge to function, although the engine is not running.
6) A few minutes after that, a geyser of ?? steam ?? erupts from the starboard cockpit locker.

Once the engine stops, I would expect the temperature at the sender to rise, because antifreeze is no longer circulating. I note that the ignition key was set to "run" for 10 minutes, so the ignition circuit would be hot. Could the coil have overheated? Was it steam or oil? I don't see how steam would have come out of a coil. Puzzler.

[hanleyclifford]

When you shut an engine down the ignition circuit should be off. If you leave the key on in order to read a temp gauge, you are in effect leaving the primary circuit hot - if the points are closed they can get plenty hot and if you do this too long you can fry a coil. Forget the cooling system - you have an ignition problem. I think you just got the wrong coil. Do not assume the mechanic put in the right coil. Neil, help us out with that specification!

[rigspelt]

From my notes, scavenged from somewhere in the archives: Don wrote, "Our experience also suggests that heat buildup is the most tangible threat to coil life, so the coils that we have been using and marketing for over 8 years are metal-jacketed oil-filled coils with 4 ohms of resistance within the primary circuit. They have been extremely reliable, in both conventional and electronic ignition systems, with a failure rate so low as to never have made it to our radar screen of concern."

[ndutton]

Neil:

Which thread?

Bill

This one:

http://www.moyermarine.com/forums/showthread.php?t=4313

[Paul Clarke]

Art: Thanks for the advice on the Indigo unit. I'll proceed slowly, and with the documentation in hand.

Hanley: I'll look into the specs for the ignition coil, and high voltage wires. I was concerned that the newest coil installed just a few days ago still got hot enough after several hours running to be too hot to hang onto. That bit of evidence might be important... on the other hand, not much of anything in that tiny engine space is cool enough to hang onto after 2-3 hours of running, so I'm not sure if the coil should be or not. Thanks for the tip on the Overhaul & Service Manual... I bought one a month or so ago when I was working my way through carb issues.

rigspelt: Thanks for looking up that quote re the reliability of Moyer ignition coils. It makes me think twice about the source for my spare parts.

On that note, is the electronic ignition conversion (such as the one offered for sale by Indigo) a good thing? Would you recommend it?

-Paul

C&C 27
Canvasback
North Vancouver, BC

[rigspelt]

is the electronic ignition conversion (such as the one offered for sale by Indigo) a good thing? Would you recommend it?

I'm no mechanic, but this is my second boat and the first thing I did after buying both was to switch to electronic ignition -- no more fussing with points and condensor. I think I got the EIM kit for our A4 from MMI.

Never leave the key on "run" without the engine running with EIM, or that expensive EIM will burn out. Should carry a spare EIM kit, but I never had a problem with the ones in our boats. Keep the old points and condensor on the boat: there are a number of threads here where operators were able to decide whether the EIM was faulty by swapping for the original points/condensor to see if whatever problem went away or persisted.