A lot of sailors are running older engines with unknown amount of hours. Performing a compression test on diesel engines requires specialized tools. A simple test can give you an idea of your engine's condition. Start the engine and get it up to operating temperature, remove the oil fill cap and place the palm of your hand against the opening, you will feel air pushing against it; that is compression blow-by. Compression gases which escape the combustion chamber and flow into the crankcase. A small amount is normal but a strong flow is an indication of worn piston rings or thin diluted oil. Once a fair amount of compression blow-by is detected you may extend the life and performance of the engine by going to a thicker oil. Some additives or restorers likes STP can be used. That 30W oil recommended when the engine was new may not be the best for it now. A good multigrade oil with a restore additive can make an oldie purr a little longer.
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C
CalebD
Benny, does this advice hold true for my Atomic (4) bomb?
I would guess that the blow by compression test with the oil fill cap may not be as reliable as both the oil fill and the dip stick may allow pressure to flow this way and that. I am wondering if a 10W-40 oil and the STP additive make sense on this old gas engine? The usual life support oil that Don Moyer recommends is MMO which is something like a 5W oil.
What you mentioned makes sense for diesels though and I will try it on my friends Universal when I get down to MD next week.
I would also assume that a 'good multigrade oil' might be Rotella 'T'?
Thanks for the insight and input.
I would guess that the blow by compression test with the oil fill cap may not be as reliable as both the oil fill and the dip stick may allow pressure to flow this way and that. I am wondering if a 10W-40 oil and the STP additive make sense on this old gas engine? The usual life support oil that Don Moyer recommends is MMO which is something like a 5W oil.
What you mentioned makes sense for diesels though and I will try it on my friends Universal when I get down to MD next week.
I would also assume that a 'good multigrade oil' might be Rotella 'T'?
Thanks for the insight and input.
W
William
Compression tester
It is a handy trick but a compression tester is not that expensive and a much more accurate way to know the condition of your motor. When blow by is bad enough you will actually smell the gas in your oil. Old when talking sailboat motors is a funny thing...an Atomic 4 in a 25 year old 35 foot boat will probally be in rougher shape than one in a 25 foot sailboat the same age and hours just due to the fact that it has to run at higher rpms to push the boat.
We swear by STP in everything we have. It is a LOT thicker than the MMO that Moyers recommends but it seems odd to use 40w oil then add a thinner to it.
Caleb, love that old Atomic 4...they are good engines..old but good at least in my opinion. They are simple to work on and make run. They are cheap to get parts for and a lot cheaper than swapping it out for a new diesel engine (but if you can talk the admiral in a new diesel attached to the new boat then swap out). Also The nick name ATOMIC BOMB I think was started by companies trying to sell diesels to unsuspecting atomic 4 owners. With 10s of thousands of A$s out there there is not one documented case of an A4 exploding.
If you have a crap A4 then by all means swap it out but if yours runs good the the song says "love the one your with"
here's to wind in your sails and keeping the heavy part down
It is a handy trick but a compression tester is not that expensive and a much more accurate way to know the condition of your motor. When blow by is bad enough you will actually smell the gas in your oil. Old when talking sailboat motors is a funny thing...an Atomic 4 in a 25 year old 35 foot boat will probally be in rougher shape than one in a 25 foot sailboat the same age and hours just due to the fact that it has to run at higher rpms to push the boat.
We swear by STP in everything we have. It is a LOT thicker than the MMO that Moyers recommends but it seems odd to use 40w oil then add a thinner to it.
Caleb, love that old Atomic 4...they are good engines..old but good at least in my opinion. They are simple to work on and make run. They are cheap to get parts for and a lot cheaper than swapping it out for a new diesel engine (but if you can talk the admiral in a new diesel attached to the new boat then swap out). Also The nick name ATOMIC BOMB I think was started by companies trying to sell diesels to unsuspecting atomic 4 owners. With 10s of thousands of A$s out there there is not one documented case of an A4 exploding.
If you have a crap A4 then by all means swap it out but if yours runs good the the song says "love the one your with"
here's to wind in your sails and keeping the heavy part down
C
CalebD
William, thanks for your A4 adulations.
And yes, my A4 is from 1967 and still ticking. It has taken me many miles that I might not have made without it but it is still an old engine that bears listening to and doing a good bit of TLC for. Frequent oil changes and new spark plugs are the norm for me. I guess I haven't mastered this engine that many disparage because it is gas and lacks a middle shaft support or bearing (where is Fred?).
I only used the term Atomic Bomb because many people as well as myself know that a good, working diesel is probably the best bet for use on a boat. And no, I do not plan on swapping out the A4 for a diesel because of the cost at the moment. I will baby my engine until I am in dire straights.
I also know that A4s where installed in many boats including my Tartan 27' as well as Tartan 30' and many other brands. My guess is that our engine is miraculously in good shape because it did not have to work so hard as if it had been installed in a larger boat. I have learned a lot with my old work horse that needs constant tending. It is quieter than most diesels I have experienced as well and therefore needs more attuned listening to.
I am interested to hear that you use the STP oil treatment (thickener) with your A4 as Don Moyer's advice has helped me through some rough scrapes (eg, water in the oil reservoir due to cabin flooding from a loose stuffing box). Do you use the STP treatment on top of the recommended 30W oil or some other weight oil?
Perhaps it is time to purchase a compression tester.
I always try to keep the pointy part of the boat positioned into the waves and the heavy part seems to stay down if reefed well enough.
Pray for wind as it is summer.
And yes, my A4 is from 1967 and still ticking. It has taken me many miles that I might not have made without it but it is still an old engine that bears listening to and doing a good bit of TLC for. Frequent oil changes and new spark plugs are the norm for me. I guess I haven't mastered this engine that many disparage because it is gas and lacks a middle shaft support or bearing (where is Fred?).
I only used the term Atomic Bomb because many people as well as myself know that a good, working diesel is probably the best bet for use on a boat. And no, I do not plan on swapping out the A4 for a diesel because of the cost at the moment. I will baby my engine until I am in dire straights.
I also know that A4s where installed in many boats including my Tartan 27' as well as Tartan 30' and many other brands. My guess is that our engine is miraculously in good shape because it did not have to work so hard as if it had been installed in a larger boat. I have learned a lot with my old work horse that needs constant tending. It is quieter than most diesels I have experienced as well and therefore needs more attuned listening to.
I am interested to hear that you use the STP oil treatment (thickener) with your A4 as Don Moyer's advice has helped me through some rough scrapes (eg, water in the oil reservoir due to cabin flooding from a loose stuffing box). Do you use the STP treatment on top of the recommended 30W oil or some other weight oil?
Perhaps it is time to purchase a compression tester.
I always try to keep the pointy part of the boat positioned into the waves and the heavy part seems to stay down if reefed well enough.
Pray for wind as it is summer.
W
William
Size Matters
Yes I do believe that boat size has a lot to do with life span. Mine was in a C&C 27. I know the motor has it's problems but which one doesn't. We are playing with a design that is a half century old. I know that in my boat I never have to get above half throttle and I am doing hull speed. I friend of mine has a C&C 35 and he has a hard time getting to hull speed.
I think we all would agree that a new diesel is a better engine than our old A4's. But trying to recoup the cost on the sale of one of our boats won't even come close.
The one thing I did to my A4 that made the greatest improvement and was cost effective was to add the electronic ignition that Moyer sells. The boat starts better, runs smoother and gets better fuel economy. I did save the points and plate. Leave the points on the plate and they are set if you ever have to use them in an emergency
Yes I do believe that boat size has a lot to do with life span. Mine was in a C&C 27. I know the motor has it's problems but which one doesn't. We are playing with a design that is a half century old. I know that in my boat I never have to get above half throttle and I am doing hull speed. I friend of mine has a C&C 35 and he has a hard time getting to hull speed.
I think we all would agree that a new diesel is a better engine than our old A4's. But trying to recoup the cost on the sale of one of our boats won't even come close.
The one thing I did to my A4 that made the greatest improvement and was cost effective was to add the electronic ignition that Moyer sells. The boat starts better, runs smoother and gets better fuel economy. I did save the points and plate. Leave the points on the plate and they are set if you ever have to use them in an emergency
E
Eddie
Generally, introducing oil additives to the
existing oil package is not a good idea. There is one exeption and that is where an engine is old and showing signs of severe wear. In that case, you should try go to straight 30 weight oil if you are using a multi-viscosity oil. In your case you're all ready there. In your situation you might get a hold of straight 40 weight oil if you can. Then you might add a viscosity enhancer (STP). This is yhe only time you would ever need to inroduce an additional oil additive. Over the years that has been a good way of milking some extra life out of a tired engine. Frequent oil changes will also prolong your engine life.
existing oil package is not a good idea. There is one exeption and that is where an engine is old and showing signs of severe wear. In that case, you should try go to straight 30 weight oil if you are using a multi-viscosity oil. In your case you're all ready there. In your situation you might get a hold of straight 40 weight oil if you can. Then you might add a viscosity enhancer (STP). This is yhe only time you would ever need to inroduce an additional oil additive. Over the years that has been a good way of milking some extra life out of a tired engine. Frequent oil changes will also prolong your engine life.
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