Question for diesel engine experts

[Delfin]

I have a Puradyn by pass filter that when saturated probably holds about 3/4 of a gallon of oil. The oil supplied to this filter is from the pressure side of the system, pushed up through the inside of the filter, passing through to the outside and then gravity fed back to the sump.

This creates a situation where the oil level can be full when the engine is off, but low when the engine is running at idle and the filter is saturated. It isn't below the add oil mark when running, but my question is whether I can safely overfill the level when the engine is off so it is full when running without putting stress on the seals, since there is a path for the excess pressure on startup to presumably go via being pumped through the bypass filter?

Hopefully the question is clear....

 

[C lectric]

Question since I don't know the Puradyn in particular.
Where is the output line back to the engine attached to the Puradyn?

If the output line is at the Puradyn top or near it the oil, once in the filter, will remain in the filter at shutdown time. The bulk of the oil won't drain back to the engine sump except the minimal amount in the final line or any that is above the return oil line attachment point.

The only time you would need to add more oil to take care of the Puradyn volume is at the initial filling or oil change interval.

I do not have a Puradyn but do have a bypass filter, Cummins, which holds approx 5 litres of oil. I fill it directly as best I can , then run the oil pump untill the alarm quits, start the engine to run for a couple minutes to pressurize the entire system, shut down, allow time for drain back, and then recheck the sump level and adjust as needed.

Next oil change time I drain out about 4L of oil from the bypass filter into a pan. Some oil is trapped in the element itself and will not drain to the pan. It is a whole lot heavier at change time than when I installed it.

So based on my own experience the oil does not drain back to the pan assuming the return line is at or near the top of, in your case, the Puradyn.

The oil is trapped in the Puradyn if my question above is correct.

No, I would not add extra oil to "take into account" the Puradyn volume as I think you will overfill it.

 

[psneeld]

Can you ask the engine manufacturer whether 3 quarts overfill is a problem? Even in n a heavy seaway?

Some engines can take low oil pretty well, but some can't take excess oil hardly at all....

Try to find out what you have.

 

[Ski in NC]

What engine?

 

[Lepke]

I have old Detroits that have bypass filters, not full flow filters. They hold about 3 quarts. As C lectric says, when changing oil, either start with extra oil or run the engine and add oil after shutdown. Depends on the engine make if you can have extra oil in the pan. I could probably put two extra gallons in the Detroits.

I don't change my filters very often because now I centrifuge the oil below what the filters can catch. I only change the oil if it fails a test. So far that's never. Makeup oil seems to keep enough additives.

 

[Delfin]

Question since I don't know the Puradyn in particular.
Where is the output line back to the engine attached to the Puradyn?

If the output line is at the Puradyn top or near it the oil, once in the filter, will remain in the filter at shutdown time. The bulk of the oil won't drain back to the engine sump except the minimal amount in the final line or any that is above the return oil line attachment point.

The only time you would need to add more oil to take care of the Puradyn volume is at the initial filling or oil change interval.

I do not have a Puradyn but do have a bypass filter, Cummins, which holds approx 5 litres of oil. I fill it directly as best I can , then run the oil pump untill the alarm quits, start the engine to run for a couple minutes to pressurize the entire system, shut down, allow time for drain back, and then recheck the sump level and adjust as needed.

Next oil change time I drain out about 4L of oil from the bypass filter into a pan. Some oil is trapped in the element itself and will not drain to the pan. It is a whole lot heavier at change time than when I installed it.

So based on my own experience the oil does not drain back to the pan assuming the return line is at or near the top of, in your case, the Puradyn.

The oil is trapped in the Puradyn if my question above is correct.

No, I would not add extra oil to "take into account" the Puradyn volume as I think you will overfill it.

When the engine is off, the oil just gravity drains back into the sump because the return line is at the bottom of the cannister. Some oil certainly stays in the filter, but quite a bit drains back to the sump. It is that amount that means that if the system is "full" when running, it is overfilled when off.

 

[Delfin]

What engine?

It's a CAT 3306. The dipstick says "Do Not Overfill".

 

[Delfin]

I have old Detroits that have bypass filters, not full flow filters. They hold about 3 quarts. As C lectric says, when changing oil, either start with extra oil or run the engine and add oil after shutdown. Depends on the engine make if you can have extra oil in the pan. I could probably put two extra gallons in the Detroits.

I don't change my filters very often because now I centrifuge the oil below what the filters can catch. I only change the oil if it fails a test. So far that's never. Makeup oil seems to keep enough additives.

I believe I could do the same thing, but for the cost of an annual oil change, I just go ahead and do it.

 

[Delfin]

The cure could be just to install a shut off valve on the return line from the Puradyn to the sump, and close it when the engine is turned off. That isn't hard to do, but adds some complexity I'd as soon avoid if it turns out that an overfilled sump isn't a problem as long as their is someplace for the excess oil to go after startup, which in this case would be in filling the filter. That is what I'm not too sure about, but I would assume that having an outlet for excess oil is a very different set of conditions than starting the engine up with no place for the oil to go other than circulate.

 

[Ski in NC]

What matters is not the oil level when sitting, but the oil level when running. Presumably the bypass filter is full when running, but empties when sitting. Then fills right up on startup. So it is ok for it to be a little over the full mark with filter drained. You could check it right after shutdown while filter is full, if above the add mark it is ok.

 

[Delfin]

What matters is not the oil level when sitting, but the oil level when running. Presumably the bypass filter is full when running, but empties when sitting. Then fills right up on startup. So it is ok for it to be a little over the full mark with filter drained. You could check it right after shutdown while filter is full, if above the add mark it is ok.

Thanks Ski, that is what I hoped, and it makes sense. Besides, I will usually run the engine for 10 minutes or so at idle before powering up (pulling anchor, motoring out of a marina), so the oil pressure isn't at the high end before the excess oil is pumped into the Puradyn cannister/filter.

 

[Capitaine R]

Loop it

Would this work?... Put a longer hose on the drain side of the filter and loop it higher than the top of the filter and then it would not drain back into the sump. When it is time for an oil change you could release the loop and let the oil from the canister drain down to the sump making the oil filter change much easier. ???

 

[Delfin]

Would this work?... Put a longer hose on the drain side of the filter and loop it higher than the top of the filter and then it would not drain back into the sump. When it is time for an oil change you could release the loop and let the oil from the canister drain down to the sump making the oil filter change much easier. ???

That's actually brilliant, and it seems like it would work fine. The oil pressure would push the oil up the loop and into the sump when the engine was running, but not when it wasn't. Very clever, mon Capitaine....

 

[Capitaine R]

Merci Beaucoup, let me know if it works for you.

 

[Taras]

I have Puradyn external oil filtration on my Cat 3406’s. Original owner put them on after 500 hours. Boat now has 5500 hours and the motors hardly smoke at all and burn very very little oil. Seems to have been a good investment.
Regarding the draining of the oil back into the crankcase, I didn’t think about that and appreciate you bringing this up.
I’ll be sure to check the level right as I shut down the motors after a trip.

 

[Coalman]

Cummins 6bta 5.9 m3 335hp

Anyone have a good fuel burn rate at cruise speed (say 8-9 knots) Cummins 6bta 5.9L M3 335 hp. I’m looking at economy. Not sure if this is the engine. Any help is appreciated

 

[C lectric]

Coalman,

Far too open ended a question. A huge amount depends upon the boat, how the hull loads the engines and how YOU run it, not the specific engine.

The hull may be quite good at 7 - 8 knots but if you insist on running faster by even , to you , a small amount more speed the engine may use a disproportionate amount more fuel.

The engine you asked about can be very good on fuel, it's all how you run it.

Need more info such as the boat, hull type, boat length to even start.

Also not trying to be snarky but this should have been in a separate thread so the original thread is not hijacked..

 

[DDW]

Not sure the hose idea would work as (without a siphon break) it is likely to siphon back. You might be able to arrange the hose to enter the engine above the filter, and create the siphon break.

However, I would not be worried about it. On a cold engine, if you look at the oil level at startup, first it goes way down as the cold oil is pumped up into the rocker box and elsewhere, and is slow returning as it is cold. Then the level comes up as the oil warms and drains better. It takes only a few seconds to pump quite a bit of oil out of the pan, it's hard to imagine some extra oil in there causing a problem in that few seconds, even if the crank is churning it. Overfilling while in normal operation will cause foaming due to crank windage, not a good thing, but not a problem in a very temporary startup situation.

 

[garycasey]

Engine oil level

There might be a lot of overthinking going on. I'm certainly not an expert on much of anything, but here are my opinions: First, don't check the oil with the engine running. The fill level was set by the manufacturer assuming the engine is shut off, not running. Also, I wouldn't worry about the filter draining in any reasonable time. To drain, there has to be a way for air to get into the filter housing, and there isn't an easy way for this to happen. Where would it come from? Sure, after a long time sitting (months), the filter might drain down. I would fill to the mark after an oil change, start the engine and then measure again after shutting it off. Fill it back up to the mark and forget about it. Whether the oil level is somewhat higher or lower than the mark there will be no effect on oil pressure. When too full the oil might be aerated if it gets up to the crankshaft, but that won't have much effect. And it has to get really low before the pump will start picking up air.

 

[Delfin]

I have Puradyn external oil filtration on my Cat 3406’s. Original owner put them on after 500 hours. Boat now has 5500 hours and the motors hardly smoke at all and burn very very little oil. Seems to have been a good investment.
Regarding the draining of the oil back into the crankcase, I didn’t think about that and appreciate you bringing this up.
I’ll be sure to check the level right as I shut down the motors after a trip.

I decided the simplest thing to do was add a ball valve at the bottom of the unit that can be turned off when the engine is shut down. This will trap the excess oil in the cannister. I like the design C Lectric described, where the return to the sump is at the top of the cannister. Except, I suppose, when it comes time to change the filter, but I doubt that is much of a bother dealing with the excess oil.

 

[Brooksie]

A little check or relief valve, set to open at 10-20 psi, in the drain line would do the job automatically. Not a check valve from HD plumbing but a proper small valve from Grainger or McMaster Carr.

 

[Delfin]

There might be a lot of overthinking going on. I'm certainly not an expert on much of anything, but here are my opinions: First, don't check the oil with the engine running. The fill level was set by the manufacturer assuming the engine is shut off, not running. Also, I wouldn't worry about the filter draining in any reasonable time. To drain, there has to be a way for air to get into the filter housing, and there isn't an easy way for this to happen. Where would it come from? Sure, after a long time sitting (months), the filter might drain down. I would fill to the mark after an oil change, start the engine and then measure again after shutting it off. Fill it back up to the mark and forget about it. Whether the oil level is somewhat higher or lower than the mark there will be no effect on oil pressure. When too full the oil might be aerated if it gets up to the crankshaft, but that won't have much effect. And it has to get really low before the pump will start picking up air.

Well....the CAT has a two sided dip stick - one marked for engine not running and one marked for when it is, at idle. They do this because this 3306 engine was designed for the North Slope and they never turned them off. It is also handy for a trans oceanic crossing of weeks since being able to check the oil when underway at idle but in gear is a blessing rather than waiting for it to drain into the sump while bobbing around like a demented cork. Oil drains within 10 minutes or so from the filter and cannister if it is hot oil, and the air you mentioned is coming from the supply line from the motor, which when the engine is off is just an empty channel.

As mentioned above, I put a valve on to prevent the oil that saturates the Puradyn filter - which is about the size of a gallon and a half - from draining back into the sump when the engine is off. Peace of mind since in addition to the marking for "Oil Level Engine Stopped" is the message, in CAPS, "DO NOT OVERFILL".

 

[Delfin]

A little check or relief valve, set to open at 10-20 psi, in the drain line would do the job automatically. Not a check valve from HD plumbing but a proper small valve from Grainger or McMaster Carr.

You're right, Brooksie, that would have worked. I just looked at one at it opens at 3.5# psi, which would be strong enough, I presume, to block the flow when the system is depressurized after shutting down the engine. One advantage of the ball valve I did install is that when I change the oil, I can open it to drain the oil out of the cannister into the sump for removal. A bit cleaner, methinks.

 

[catalinajack]

I have old Detroits that have bypass filters, not full flow filters. They hold about 3 quarts. As C lectric says, when changing oil, either start with extra oil or run the engine and add oil after shutdown. Depends on the engine make if you can have extra oil in the pan. I could probably put two extra gallons in the Detroits.

I don't change my filters very often because now I centrifuge the oil below what the filters can catch. I only change the oil if it fails a test. So far that's never. Makeup oil seems to keep enough additives.

Finally, someone who understands that, with good filtration, oil almost never needs to be changed. I assume you test your oil to ensure that the TBN is suffiently high enough for continued use and soot levels are okay as well. Even without by-pass filtration oil lasts a very long time. IMHO, most boaters throw away good oil every season. Cheap insurance, I guess. I do not have by-pass filtration. I change my oil when testing says it is time just as the military and large fleet (truck) owners do. Remember when the oil industry had us all convinced that auto oil just MUST be changed every 3,000 miles lest our engines would fail prematurely?

 

[Ski in NC]

Delphin- just read that you have the two sided stick, one side for running, one side for shut down. Nice feature, lots of Cats have that. Just use the stick with engine idling warmed up and use the "running" side. Don't worry if it is high on the shutdown side of the stick when filter drains. What matters is oil level with engine running and you can tell that with your stick.

 

[Delfin]

Delphin- just read that you have the two sided stick, one side for running, one side for shut down. Nice feature, lots of Cats have that. Just use the stick with engine idling warmed up and use the "running" side. Don't worry if it is high on the shutdown side of the stick when filter drains. What matters is oil level with engine running and you can tell that with your stick.

Thanks Ski, I'll take that advice. As I mentioned, I installed a valve on the return line from the bypass filter, so I'll top it up after running for a bit, to be full at idle. Turn off the engine, close the valve. Start the engine, open the valve. There's stuff I have to do in the ER before starting and after stopping, so the valve presents no burden.

 

[stubones99]

I change my oil when testing says it is time just as the military and large fleet (truck) owners do. Remember when the oil industry had us all convinced that auto oil just MUST be changed every 3,000 miles lest our engines would fail prematurely?

Many new cars have an oil change schedule from 8,000-16,000 miles between oil changes. Part of the reason for an oil change is to remove the moisture and acids that build up in the oil over time.

There are oil recyclers that can filter the oil and replace the detergents in the oil to be re-used again, underscoring the oil not wearing out, but becoming contaminated.

 

[catalinajack]

Many new cars have an oil change schedule from 8,000-16,000 miles between oil changes. Part of the reason for an oil change is to remove the moisture and acids that build up in the oil over time.

There are oil recyclers that can filter the oil and replace the detergents in the oil to be re-used again, underscoring the oil not wearing out, but becoming contaminated.

Remove acids? Again, another misunderstanding of oil attributes. With much respect, do some self-education around TBN (Total Base Number). The TBN is an indicator of the oil's ability to NEUTRALIZE residual acids. As long as the TBN is sufficiently high, the oil is NOT acidic. Oil anysis will show the TBN and the analyzing house will tell you if you need to change the oil. As I opined earlier, many, if not most, boaters throw away good oil. The idea that oil must be changed before winter layup to avoid internals from sitting in acidic oil is preposterous regardless of what any "experienced" mechanics postulates.

 

[sunchaser]

Jack
An oil change on engines like ours (I do every 300 to 400 hours or at least annually totaling 9 gallons for 3 engines) is hardly expensive nor inconvenient. Since this is the wrong forum for 24/7 engines, easy to argue any combination of regular changes, additive packages etc will work. Once into old Detroits or bigger engines the costs go up as pan capacity increases.

As you suggest, routine oil analysis programs are how the tugs, mine equipment, truckers, gensets etc operate. That is not us, but of course analyzing your oil does no harm.

 

[catalinajack]

Jack
An oil change on engines like ours (I do every 300 to 400 hours or at least annually totaling 9 gallons for 3 engines) is hardly expensive nor inconvenient. Since this is the wrong forum for 24/7 engines, easy to argue any combination of regular changes, additive packages etc will work. Once into old Detroits or bigger engines the costs go up as pan capacity increases.

As you suggest, routine oil analysis programs are how the tugs, mine equipment, truckers, gensets etc operate. That is not us, but of course analyzing your oil does no harm.

Four hundred hours is not bad but some guys change oil in the fall without even 100 hours - the acid fear. Yes, an oil change after 400 hours is not terribly expensive but for some boaters, unlike you, an oil change is not so easy or convenient. I do not agree that oil analysis is not "us". It is not "us" only because boaters somehow think their diesel engines are different than those in fishing boats, over-the-road trucks, etc.