A few critical suggestions

[Don Moyer]

The buzzing sound around our Community Forum at moyermarine.com and the large number of new owners calling in for technical service are both clear indications that the Atomic 4 fleet is continuing to expand. The technical service requirement is more and more being served by a huge body of technical information from myriad sources on the Internet which augments our own collection of videos, manuals and tech tips. The only problem with this rosy picture is that this mountain of technical information is threatening to bury a few critical suggestions that have served us well in the past. This gap in our collective memory at times results in our learning lessons over again and spending a lot of money and time in the process.

Experience has taught our senior members that the engine itself is only one of five major sub-systems within your boat’s total power system. For this newsletter, I’ve tried to select the single most important action you can take (many times at little or no cost) to improve engine reliability in each of the four sub-systems that are mostly external to the engine: ignition, fuel, exhaust and cooling (the engine being the fifth sub-system within this context).

I’ll also try to provide rationale for each of the suggestions for those of you who like more detail on these kinds of things, but please don’t get bogged down in the rationale. If you only follow through with the suggestions themselves, you should improve your chances for getting through the season with fewer problems.

IGNITION SYSTEM: Install a permanent back-up ignition switch in the engine compartment to connect the big battery terminal on the starter solenoid directly to the primary terminal of the coil to be used any time a failure of the ignition system is suspected.

Rationale: Our technical service experience indicates that approximately 75% of all ignition problems occur within the 12 volt primary ignition system, and 95% of the primary ignition system lives within the wiring harness between the engine and the cockpit. Symptoms of a breakdown in this primary ignition sub-system include intermittent random shutdowns, as though someone accidentally turned off the ignition switch in the cockpit. The engine will frequently restart almost immediately. In worse case failures of this primary ignition circuit, the engine may simply fail to start.

With the installation of this back-up ignition switch in the engine compartment, you can bypass 95% of the things that could be causing an ignition problem by virtue of a faulty connection. It’s interesting that one of the frequent claims of diesel advocates is that they get away from unreliable ignition systems. Installation of this back-up ignition switch eliminates most of this perceived diesel advantage.

This back-up ignition circuit will not protect you in the unlikely event of a short circuit or other cause of high current draw in your primary ignition circuit. Therefore, even after installing this simple back-up ignition switch, it would be a good idea to follow up and investigate literally everything connected to the “Ign” terminal of your existing ignition switch. Power to the field excitation circuit for the alternator, power for an electric fuel pump and power to cockpit gauges are usually the only things you should see coming from the “Ign” terminal of the ignition switch. Things like bilge pumps, and even tachometers, are prone to develop shorts which will take out your ignition system. If you suspect this kind of problem within your primary ignition system, you should disconnect everything from the coil except for your back-up ignition circuit before turning it on in an emergency. After starting, you can momentarily connect the field exciting lead from your alternator to get it started but you can then leave it disconnected and the alternator should continue operating. After arriving at a safe port, you can reconnect other wires one at a time to diagnose where the specific problem is located.

You should also be skeptical of little mystery modules connected within the primary ignition system, as shown here.

One of the two pink wires coming into the back of the tachometer from below (light green gauge on left) is from the “Ign” terminal of the ignition switch. The pink wire leaving in an upward direction from that terminal goes to power the rest of the gauges. Both of these wires are OK. The third pink wire from the lower terminal of the tachometer connects to an unidentified black module, the output of which ran all the way to an unidentified location in the engine compartment (it was naturally disconnected when we picked up the engine). This wire had an un-insulated set of male/female quick disconnects half way along its length and a large area of missing insulation at another location. This wire was definitely not OK. I can’t say with certainty that this wire or the mystery module contributed to this prior owner’s intermittent shutdowns, but it would certainly be consistent with such symptoms.

In case you wonder where the other 5% percent of the primary ignition system is located, it is the short black wire from the negative terminal of the coil to the points (or Ignitor module) in the distributor.

FUEL SYSTEM: Remove the ½” hex-headed main passage plug from the bottom of the carburetor and pump a couple pints of fuel into a clean glass jar.

Rationale: Carburetors really have no inherent ability of their own to produce dirt. Virtually all dirt moves into the carburetor from the boat’s fuel supply system. Flushing the fuel system as in this suggestion moves fuel through the entire fuel system at a much faster rate than it ever does during normal engine operation, and any dirt lurking anywhere in the system will (hopefully) flush into your jar. Any visible particulate that shows up in your jar during this flushing operation would be a genuine smoking gun potential that you caught before the fact of a breakdown.

As a follow-up suggestion, you could install a rubber priming bulb between the fuel tank and everything else in the fuel supply system (see our tech tip entitled “Fuel-Related Shutdowns” at moyermarine.com.

These suggestions more or less assume that you already have a good primary filter (10 micron) between the tank and pump, and an inline filter (5 to 7 micron) between the fuel pump and carburetor.

EXHAUST SYSTEM: Install a 1/8” pipe tap in your exhaust manifold outlet flange to enable measuring exhaust system back pressure.

Rationale: The Atomic 4 likes a quite low exhaust back pressure of 1 to 1-¼ psi. Our tech service experience indicates that much of the Atomic 4 fleet (my guess would be at least 70%) is suffering some impairment in performance or reliability due to some amount of elevated exhaust backpressure. Symptoms include chronic sootiness of all four spark plugs, one or two cylinders failing to work with otherwise good compression, engine refusing to accelerate accompanied by a “gagging” sound from the carburetor, engine running better with any one of the four plug leads removed (yes, believe it or not), and eventually failing to start.

Being able to read your exhaust back pressure won’t in and of itself cure the problem but given the difficulty of working on the exhaust system, it would be good to know before starting that gruesome work that you do indeed have a blockage. Difficult access on some boats can make even this suggestion a bit difficult, but the reward will be worth the effort.

In the event that you can remove the two bolts retaining the exhaust flange, some folks have diagnosed elevated back pressure by removing the bolts, propping the flange away from the manifold a fraction of an inch and running the engine for a few seconds. If your symptoms are quite profound, you should notice a definite improvement in running for just a few seconds.

If you can remove the two flange bolts, you may also be able to remove the entire hot section of the exhaust and replace it as a preventative maintenance measure without ever testing the back pressure.

Back to measuring the back pressure, you can check the custom exhaust flange in our online catalog to see what a flange looks like with a 1/8” pipe plug installed.

We’ve been installing these pipe plugs for several years to facilitate checking back pressure, and we’ve recently added two other kits to assist in the process as well. You can check here to see what the gauge assembly looks like, and if you have space to get a drill over your existing exhaust flange, you can drill and tap an 1/8” pipe-threaded hole rather easily with the tools pictured here.

COOLING SYSTEM: Remove the engine cooling water outlet fitting at the rear of the manifold (the fitting leading to the exhaust system, if you have a V-drive) and remove any build-up of crud from that end of the manifold that you can reach through the ½” pipe-threaded hole. Click here for a good example of what you might find.

Rationale: There are, of course, other specific locations within the cooling system where restrictions can occur, but for some reason, this fitting and the area directly below the ½” hole in the cooling jacket of the manifold are currently causing many of our overheating problems. The photo in the above link was from an engine we recently bought for the price of a rebuildable core that had been replaced due to “frustrating chronic overheating problems”. While it’s usually best to eventually remove a manifold in this condition for professional cleaning by a local machine shop, you can usually remediate the immediate problem by using coat hanger material and simply cleaning the area of the manifold within reach of the ½” threaded hole.

Don

[Kelly]

Don,

Once again you show us why so many people (myself included) say that you are the best.

Thank you for spelling it out clearly, concisely- and in a language we can all understand.

Kelly

[Don Moyer]

Kelly,

Thanks for the kind words. I'd like to thank you as well for your profound comments on our Community Forum on a variety of subjects. You have helped a great number of fraternity brothers with your technical insights to their problems.

Don

[rigspelt]

Don - Thanks from me too. I added all your points to my refit checklist. Excellent guidance.

[P30_889]

You 'Reader's Digest' version of suggestions are a great addition to an already exhaustive set of information about these engines. I am now to the point where I have to quickly decide on the best course of action for my engine that was running fine for the first 1+ years that I had it but now is starting to show signs of the need for some help. All good advice.

[Chris T]

Originally Posted by Don Moyer

The buzzing sound around our Community Forum at moyermarine.com and the large number of new owners calling in for technical service are both clear indications that the Atomic 4 fleet is continuing to expand. The technical service requirement is more and more being served by a huge body of technical information from myriad sources on the Internet which augments our own collection of videos, manuals and tech tips. The only problem with this rosy picture is that this mountain of technical information is threatening to bury a few critical suggestions that have served us well in the past. This gap in our collective memory at times results in our learning lessons over again and spending a lot of money and time in the process.

Experience has taught our senior members that the engine itself is only one of five major sub-systems within your boat’s total power system. For this newsletter, I’ve tried to select the single most important action you can take (many times at little or no cost) to improve engine reliability in each of the four sub-systems that are mostly external to the engine: ignition, fuel, exhaust and cooling (the engine being the fifth sub-system within this context).

I’ll also try to provide rationale for each of the suggestions for those of you who like more detail on these kinds of things, but please don’t get bogged down in the rationale. If you only follow through with the suggestions themselves, you should improve your chances for getting through the season with fewer problems.

IGNITION SYSTEM: Install a permanent back-up ignition switch in the engine compartment to connect the big battery terminal on the starter solenoid directly to the primary terminal of the coil to be used any time a failure of the ignition system is suspected.

Rationale: Our technical service experience indicates that approximately 75% of all ignition problems occur within the 12 volt primary ignition system, and 95% of the primary ignition system lives within the wiring harness between the engine and the cockpit. Symptoms of a breakdown in this primary ignition sub-system include intermittent random shutdowns, as though someone accidentally turned off the ignition switch in the cockpit. The engine will frequently restart almost immediately. In worse case failures of this primary ignition circuit, the engine may simply fail to start.

With the installation of this back-up ignition switch in the engine compartment, you can bypass 95% of the things that could be causing an ignition problem by virtue of a faulty connection. It’s interesting that one of the frequent claims of diesel advocates is that they get away from unreliable ignition systems. Installation of this back-up ignition switch eliminates most of this perceived diesel advantage.

This back-up ignition circuit will not protect you in the unlikely event of a short circuit or other cause of high current draw in your primary ignition circuit. Therefore, even after installing this simple back-up ignition switch, it would be a good idea to follow up and investigate literally everything connected to the “Ign” terminal of your existing ignition switch. Power to the field excitation circuit for the alternator, power for an electric fuel pump and power to cockpit gauges are usually the only things you should see coming from the “Ign” terminal of the ignition switch. Things like bilge pumps, and even tachometers, are prone to develop shorts which will take out your ignition system. If you suspect this kind of problem within your primary ignition system, you should disconnect everything from the coil except for your back-up ignition circuit before turning it on in an emergency. After starting, you can momentarily connect the field exciting lead from your alternator to get it started but you can then leave it disconnected and the alternator should continue operating. After arriving at a safe port, you can reconnect other wires one at a time to diagnose where the specific problem is located.

You should also be skeptical of little mystery modules connected within the primary ignition system, as shown here.

One of the two pink wires coming into the back of the tachometer from below (light green gauge on left) is from the “Ign” terminal of the ignition switch. The pink wire leaving in an upward direction from that terminal goes to power the rest of the gauges. Both of these wires are OK. The third pink wire from the lower terminal of the tachometer connects to an unidentified black module, the output of which ran all the way to an unidentified location in the engine compartment (it was naturally disconnected when we picked up the engine). This wire had an un-insulated set of male/female quick disconnects half way along its length and a large area of missing insulation at another location. This wire was definitely not OK. I can’t say with certainty that this wire or the mystery module contributed to this prior owner’s intermittent shutdowns, but it would certainly be consistent with such symptoms.

In case you wonder where the other 5% percent of the primary ignition system is located, it is the short black wire from the negative terminal of the coil to the points (or Ignitor module) in the distributor.

FUEL SYSTEM: Remove the ½” hex-headed main passage plug from the bottom of the carburetor and pump a couple pints of fuel into a clean glass jar.

Rationale: Carburetors really have no inherent ability of their own to produce dirt. Virtually all dirt moves into the carburetor from the boat’s fuel supply system. Flushing the fuel system as in this suggestion moves fuel through the entire fuel system at a much faster rate than it ever does during normal engine operation, and any dirt lurking anywhere in the system will (hopefully) flush into your jar. Any visible particulate that shows up in your jar during this flushing operation would be a genuine smoking gun potential that you caught before the fact of a breakdown.

As a follow-up suggestion, you could install a rubber priming bulb between the fuel tank and everything else in the fuel supply system (see our tech tip entitled “Fuel-Related Shutdowns” at moyermarine.com.

These suggestions more or less assume that you already have a good primary filter (10 micron) between the tank and pump, and an inline filter (5 to 7 micron) between the fuel pump and carburetor.

EXHAUST SYSTEM: Install a 1/8” pipe tap in your exhaust manifold outlet flange to enable measuring exhaust system back pressure.

Rationale: The Atomic 4 likes a quite low exhaust back pressure of 1 to 1-¼ psi. Our tech service experience indicates that much of the Atomic 4 fleet (my guess would be at least 70%) is suffering some impairment in performance or reliability due to some amount of elevated exhaust backpressure. Symptoms include chronic sootiness of all four spark plugs, one or two cylinders failing to work with otherwise good compression, engine refusing to accelerate accompanied by a “gagging” sound from the carburetor, engine running better with any one of the four plug leads removed (yes, believe it or not), and eventually failing to start.

Being able to read your exhaust back pressure won’t in and of itself cure the problem but given the difficulty of working on the exhaust system, it would be good to know before starting that gruesome work that you do indeed have a blockage. Difficult access on some boats can make even this suggestion a bit difficult, but the reward will be worth the effort.

In the event that you can remove the two bolts retaining the exhaust flange, some folks have diagnosed elevated back pressure by removing the bolts, propping the flange away from the manifold a fraction of an inch and running the engine for a few seconds. If your symptoms are quite profound, you should notice a definite improvement in running for just a few seconds.

If you can remove the two flange bolts, you may also be able to remove the entire hot section of the exhaust and replace it as a preventative maintenance measure without ever testing the back pressure.

Back to measuring the back pressure, you can check the custom exhaust flange in our online catalog to see what a flange looks like with a 1/8” pipe plug installed.

We’ve been installing these pipe plugs for several years to facilitate checking back pressure, and we’ve recently added two other kits to assist in the process as well. You can check here to see what the gauge assembly looks like, and if you have space to get a drill over your existing exhaust flange, you can drill and tap an 1/8” pipe-threaded hole rather easily with the tools pictured here.

COOLING SYSTEM: Remove the engine cooling water outlet fitting at the rear of the manifold (the fitting leading to the exhaust system, if you have a V-drive) and remove any build-up of crud from that end of the manifold that you can reach through the ½” pipe-threaded hole. Click here for a good example of what you might find.

Rationale: There are, of course, other specific locations within the cooling system where restrictions can occur, but for some reason, this fitting and the area directly below the ½” hole in the cooling jacket of the manifold are currently causing many of our overheating problems. The photo in the above link was from an engine we recently bought for the price of a rebuildable core that had been replaced due to “frustrating chronic overheating problems”. While it’s usually best to eventually remove a manifold in this condition for professional cleaning by a local machine shop, you can usually remediate the immediate problem by using coat hanger material and simply cleaning the area of the manifold within reach of the ½” threaded hole.

Don

Don how about a schematic for the back-up ignition switch. A picture is worth a 10000 words as they say. Chris Tacoma Washington

[lhbradley]

Don:

Be REALLY careful about using a priming bulb. In my original A4, which had a mechanical fuel pump, in installed one, and it worked like a charm. When I got a rebuilt engine with an electric fuel pump, I left it in the fuel line.

Later on that summer, the engine would die suddenly (as if it were an ignition problem - no sputtering out like I would have expected with fuel issues).

After getting towed in to the marina by a friendly power boater, I eliminated the ignition system as the source. The engine finally started and away we went. The next time it happened, I squeezed the priming bulb (I've no idea why I did this), and the engine started OK. This happened several times that summer. Priming solved the problem. After one failure, when I was at a dock, I took out the carb drain plug - no fuel. Took fuel line off, put into a jar, tried to start: no fuel from the pump. Assumed bad pump. But since the problem was intermittent, and I could always start after squeezing the priming bulb, I figured I'd wait until haulout to try and fix it.

Well, to make a long story short, I ran a temp fuel line from the tank to the pump, immediately after a failure, and all was well. Put the old line, with the bulb back - engine died. Removed the bulb from the old line, all was well.

Moral of the story: priming bulb valves can stick. If you do install one, I recommend taking it apart every spring and cleaning everything, or perhaps even replace it each spring.

By the way, "Lady Di"'s replacement A4 we got from you last August still purrs like a kitten. Love it!

Larry Bradley
C/C Corvette "Lady Di"
Gananoque, ON, Canada
(The Thousand Islands)

[Don Moyer]

Larry,

So good to hear that your MMI rebuild is serving you well after your long saga with previous troublesome engines.

Don

[williamg]

Don --
Thanks for the great advice. I stuck my head down in the engine hole today to follow your directions.
Most interesting, for me, at least, is that there is a 1/8" pipe thread hole in the exhaust manifold -- just before the flange. Looks as if it's been there for a long time. Is this anything to worry about, or just another way to do the job?
Thanks
Bill

[Don Moyer]

Bill,

The 1/8" pipe-threaded hole just ahead of the exhaust flange is no doubt the
drain for the water jacket in the manifold. If there is no plug in the hole,
it's apparently clogged.

Don

[Richard Gressle]

Two questions: 1] recently installed the fresh water cooling system, retaining the preferential bypass to the block. Replaced the thermostat but A-4 then expressed water through the #1 cylinder spark plug. Removed thermostat and engine runs fine at 180. Do I have an issue here? 2] fuel economy: we are running at 2 gals an hour at 5 kts of hull speed. What's up? :My previous Tartan 27 ran 1 gal per hour at 5 kts: this is a C&C 29 but 1000 lbs less weight.
Thanks all, and thanks Mr. Moyer for the fresh water system and tech support getting it in!

[rigspelt]

Originally Posted by Chris T

Don how about a schematic for the back-up ignition switch. A picture is worth a 10000 words as they say. Chris Tacoma Washington

I'm no Don, but I am working on a schematic for my ignition wiring and will post a diagram when I get it done. I'm doing it for myself just to document how the ignition electricity works, but others may find it useful.

[Don Moyer]

Fr. Gressle,

I see no connection between a thermostat and water getting into one of the
combustion chambers. I suspect that you might be reporting that you
observed water in the recessed area around the base of the spark plug of the
first cylinder. If this is a correct assumption, I would then make a second
which is that the gasket leaked a bit around the base of the thermostat
housing on the first installation and found its way into the first spark
plug recess.

Your fuel consumption is a much bigger issue. Two gallons per hour is way
too much fuel to be burning in an Atomic 4 and should be resulting in quick
fouling of the plugs, rings, and valves. The first thing I would check is
the choke for proper adjustment. Be sure it is completely open after the
starting sequence is complete. If the choke is proper, I would check the
float valve next to be sure it is not allowing an overfilled float chamber.
The easiest way to check float valve function is to remove the flame
arrestor housing and look into the intake throat of the carburetor while the
engine is running. If you see raw fuel trickling down from above, it would
confirm a defective (or dirty) float valve.

Don

[rigspelt]

Originally Posted by Chris T

Don how about a schematic for the back-up ignition switch. A picture is worth a 10000 words as they say. Chris Tacoma Washington

Originally Posted by rigspelt

I'm no Don, but I am working on a schematic for my ignition wiring and will post a diagram when I get it done. I'm doing it for myself just to document how the ignition electricity works, but others may find it useful.

This schematic here might help, if I got it right.

[fvigeant]

Don (or anyone else) is there any reason to preserve the wrieing harnesses? It seems the MMI wiring kit eliminates them... and they are the source of so many issues... i noticed this year that water from a bad seal on one of my instrument gauges worked its way down to the wiring harnesses and has since caused corrosion on both harnesses (leading to instrument panel and engine) to the point the corossion has caused enough resistance thet there is evidence of melting on on of the harnesses. Now.... it seems the easiest thing is to cut out both harnesses and splice all the wires together and shrink wrap them so everything is Kosher. It seems liek the wiring harness is useless unless you are removing the engine and the harness leading to the instruments seems equally useless given the frequency of removing the entire instrument panel. Is eliminating these harnesses an issue?

[rigspelt]

As far as I know (amateur who rewired whole boat recently), there is no reason a person cannot rewire from instrument panel to engine with direct wires instead of a plug-in harness, if that's what you meant. Probably a good idea, if the wires are old.

[sastanley]

rigs, good point.. There is also no reason why if you think you need to do so, you can't build a junction or plug to accommodate the re-wire.

I recently (this past winter) pulled my rig and replaced all of the wires. Based on the beautiful & functional work that Neil Dutton did, I chose to follow his path and add a junction box for all the wires where they come in the boat from the mast into the head. When I finish the project, I am sure it will be great, but right now I have random wires flowing out of the head, but I am working on it.

My point is, it isn't rocket science, but having a contingency plan with a junction area of some sort (maybe pulling the motor some day) may be a good idea.

[rigspelt]

Originally Posted by sastanley

Based on the beautiful & functional work that Neil Dutton did, I chose to follow his path and add a junction box for all the wires where they come in the boat from the mast into the head.

Shawn, can you point me to that thread? I can't find it. I just installed a cable clam that beautifully solved my problem with getting the mast wires through the deck, but now I have a junction wire mess hanging down in the cabin.

Awesome sail yesterday, started and ended with our restored orange-red A4.

[ndutton]

Originally Posted by rigspelt

Shawn, can you point me to that thread? I can't find it. I just installed a cable clam that beautifully solved my problem with getting the mast wires through the deck, but now I have a junction wire mess hanging down in the cabin.

First I'd like to thank Shawn for the compliment, made my day.

Rigs,
There's no thread to find because Shawn and I discussed it off list, not being A-4 related. Would be happy to do the same w/ you. I can't attach pics via PM's so please send me your email and I can describe.

fvigeant,
If your electrical experience is of concern, Nigel Calder's book is the boat electrical bible. Here are a few basic practices you should consider:
1. The fewer connections, splices and plugs, the better. Less to go wrong.
2. Avoid wiring through the bilge.
3. Pay attention to wire gauge, within reason bigger is better, more important with our DC systems.
4. Don't lay wire on the hull, tie it up.
5. Pay attention to potential chafe.
6. Spend a little on tinned wire, it's worth it.

[Al Schober]

Much too complicated. How about: Alligator clip - wire - Alligator clip. One end to battery +, other end to coil +. Length? Well, it's gotta reach..

Al

[Esgbradford]

I realize this is an old thread, but it has such good information in it, I thought I'm reply to bump it TTT, and to say...

Thank You Don for posting this. Excellent stuff. I love your newsletters. This one be being printed and added to my copy of the Moyer A4 manual.