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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
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
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