Single vs Twin (fuel filters)

[Mark P]

So in looking at two different boats by the same manufacturer, I came across these two pictures. The one with what appears to me to be dual engine filters is about 10 years old, and the one with the single engine filter is about 17 years old, both have about the same engine and transmission set up, and 6KW genny.

I really don't know how the two system set up works - is it a step filtration so that first filter takes out larger contaminants, and the second smaller items? Or is it just more maintenance. As always, I appreciate the education!! Thanks, Mark P.

 

[mvweebles]

On the dual filter, the handle is pointed towards the left filter, so it's the one providing filtration. If it were to become clogged, the vacuum gauge on the central manifold would show increased vacuum, and the operator could shift the source to the other filter by just turning the valve without interrupting engine operation. If both become clogged, you could get by for a while longer by rotating the handle to point down so flow is through both filters. On the single filter, there is no standby - if the filter gets clogged, you must shut-down and replace the filter element. There is often a vacuum gauge on the T-Handle at top of the housing, but the picture is cut-off so not sure if it's there.

The dual-Racor setup is pretty expensive - the 900 series (which I think those are) are well over $1000 plus install. It's a highly desirable feature. You may find other places where the owner of the single-filter boat may not have added other upgrades. I also see the owner of the dual-filter boat has clearly labeled the filters and marked them with when the elements were changed - a good practice. The single-filter owner did not. Might be a hint about how the boat was cared for and the owner's approach/knowledge.

Good luck boat shopping!

Peter

 

[jgwinks]

On the setup with two large filters, only one of them is on line at a time. If it gets clogged, you throw the yellow valve to select the other one. Saves you having to change a filter in rough conditions, which is when they're most likely to clog due to the tanks getting stirred up. It is a great safety feature.

 

[sunchaser]

Either will do the job. Pick the vessel that most suits your needs in all respects. Previous owner loving attention should be high up on your choice list. You can easily alter the fuel filter setup at a later date.

BTW, our vessel does not have a dual filter setup. Generally we cover a few thousand miles per year. Due to clean fuel availability in the PNW we've never had a filter blockage since the vessel was new. If traveling out of NA clean fuel areas, dual primary filters would be added to our vessel.

Forward a few pictures of the two ERs if you have a chance. Those would prove equally interesting.

 

[Mark P]

Thanks for the education on filters. I will send ER pics in the morning. If I went after older boat which I believe has a mechanical as opposed to an electronically controlled engine in the newer boat, I would invest in upgrading the filtration system.

 

[Comodave]

We have single Racor 900s on our boat. We have owned it for 5 years so far and never had an issue. Of course if you are getting fuel from questionable sources then it can be a problem but most marinas have good fuel now. In the old days not as reliable sources were available so filtration was more of a requirement. I would buy the boat in the best condition all other things being equal.

 

[Mark P]

Okay, so this may be a bit of a thread drift from the fuel filter question (hope the forum moderator is asleep at the helm), but here are the two engine pics. I think I may have been wrong on the description of the engines when I said one was a mechanically controlled engine, both appear to be 380 Cummins Common Rails, not mechanicals. Do these pics looks typical of what is to be expected in a 9 or so year old and 16 year old boat?? Any thoughts on what you see would be appreciated.

Thanks,

 

[jleonard]

First impression is they look unusually clean.

 

[Ski in NC]

Yep, those are both QSB of some rating. Common rail. At rating of 380, they are a very nice engine.

Twin filters are nice to have. Easy switch if one gets cloggy. On my personal boat I run a single and it has not caused me any issues. I can hear the engine rpm wavering a tiny bit when it gets cloggy, I can run over an hour and it only gets a tiny bit worse. So gives me plenty of time to get to a good spot to change it.

 

[High Wire]

The larger filters are Racor 900's and the smaller on the right are Racor 500's for the generator.
The ERs look great.

 

[firehoser75]

I agree with Ski about these engines. At first look, they look good (cared for?).

Be aware, that 2 things to check out are the aftercooler maintenance records, and the exhaust system (particularly the elbow).
If the aftercooler has not been maintained properly, it may end up needing replacement and they are not cheap. If the exhaust elbow is what Tony Athen's calls "doomed to fail", then it should be investigated and probably replaced with a better design. The "doomed to fail" designs, when they fail, can allow saltwater to enter the turbo and/or the exhaust side of the engine. That is very bad news were that to happen.

 

[rgano]

Do I assume correctly that the vessels under consideration are single engine? I can see the appeal of a nice dual filter setup, but rather than remove a functioning single filter and going to the expense of a massively expensive twin setup, you can with judicious valving add another single. My current single engine boat came with a single Racor 500 for the main engine, and as you can see in the photo, there are now two. I can feed the engine from either or both, and even change the filter in a clogged one without shutting down. Downstream of these filters is a tee to a remote vacuum gauge at the helm.

If you are looking at single Racors supplying twin engines You can do as I did on my twin engined boat which was to provide valved crossover lines downstream to the single Racors to allow both engines to continue running while changing out the clogged filter.

Those big thousand-dollar rigs are nice, but I found other things I wanted to spend my dollars on.

 

[Mark P]

Both boats are single engines. Firehoser75 - can you give me a bit more info on the what you describe as the exhaust elbow "doomed to fail design"? Regardless of boat, I intend to service the aftercooler to make sure its in good shape. But I don't understand the exhaust elbow issue - what would I be looking for - or should I play it safe and just replace the exhaust?? Thanks,

 

[firehoser75]

Mark,
There is a large amount of info available on marine engines in general and Cummins specifically on Tony Athen's website sbmar.com under Tony's Tips and/or his various forums.
I have attached a photo of a OEM SS exhaust that Tony calls "doomed to fail" and a photo of a much better exhaust elbow. No matter how well built, any exhaust elbow will eventually corrode through. When one like the photo does, it can allow saltwater to flow into the turbo or even the engine!!
While on Tony's site, check out his info on servicing the aftercooler. A lot of mechanics do not (and even Cummins) do it using the best methods. Even if you don't do the work yourself (I do), you will be able to ensure the mechanic "learns something" and does yours correctly.

 

[Ski in NC]

Mark- Post some photos of the exhaust system at the turbo outlet. From a few different angles. With those may be able to tell if it is a risky system or not.

 

[FF]

"Racors to allow both engines to continue running while changing out the clogged filter."

The safe way is to locate the fuel filters is out of the hell hole.

Then changing out plugged filters is not attempting the task with a couple of hot operating lumps of iron operating in a small space that might be 120F..

 

[rgano]

"Racors to allow both engines to continue running while changing out the clogged filter."

The safe way is to locate the fuel filters is out of the hell hole.

Then changing out plugged filters is not attempting the task with a couple of hot operating lumps of iron operating in a small space that might be 120F..

Some engine rooms are so arranged that there is plenty of distance between filters and engines. There was 4-5 feet clearance in my trawler, but your point is taken. Remotely mounted filters are certainly more easily monitored, but since mine weren't, I did this which allowed me to keep a remote eye on the vacuum for the two mains and the genny as well as the polisher which ran underway sometimes.

 

[boating rich]

I am buying some Racor filter replacements and the choice is between 2, 10 and 30 microns. What is the difference and which do most people run?

 

[rgano]

I am buying some Racor filter replacements and the choice is between 2, 10 and 30 microns. What is the difference and which do most people run?

Whoa, now there's a topic fraught with all sort of implications and resulting discussion. Lots in the archives if you do a search. However, I will tell you that I currently have a 2- and a 10-mic filter in the two Racor 500s feeding my single engle. 2-mic on, 10-mic off until I see a rise on my remote reading vac gauge - nothing so far after a couple of years running 9 GPH. On my trawler I never ran anything but 2-mic - it had a very low fuel flow rate.

Rationale? Engine-mounted filters are harder to replace, more expensive and engine must be stopped. I can swap filters in the Racors without stopping the engine.

 

[Comodave]

I am buying some Racor filter replacements and the choice is between 2, 10 and 30 microns. What is the difference and which do most people run?

The difference is the size of particles that the filters will generally stop. The smaller the number the finer filtration. I have Racor 900s for my engine that are easier to replace the elements than the secondary filters, the filter(s) on the engine, so I run 10 micron in the Racor so I don’t have to change the secondary elements as often. There are a lot of people that run 30 micron elements in the primaries, the Racors.

 

[firehoser75]

I am buying some Racor filter replacements and the choice is between 2, 10 and 30 microns. What is the difference and which do most people run?

Most of the experts like Tony Athens and Steve D state that a progressive series of filtration is "best". So, in a perfect world you would start with a "mud" filter of say 30 microns, followed by a second off engine filter of say 10 microns, followed by an on engine filter of say 2 microns. Filtering to the smaller number is even more important for "common rail" electronically controlled engines. My mechanical engine (2002) does not require such "fine" filtration. I have a double Racor off engine where I run 10 micron filters and have an on engine filter as specced by the OEM. I think it is 10 microns as well.
The main thing is to supply your engine with clean fuel that is free from water flltered to at least the level specified by the OEM.

 

[T210DRVR]

Chinese copies of the dual Racor filters are now selling on EBay for $350.00. I have one tank that sips a bit of water while under way. I’m considering the dual so I’m not slumping a racor in the middle of a passage.

https://www.ebay.com/itm/1000FH-360...893269?hash=item5240b48f55:g:O70AAOSwcHhdJp~i

 

[Salish Nomad]

Nice clean engine room photos. Looks identical to my 34 American Tug???

 

[Mark P]

Salish Nomad, yes, those two engine rooms pictures I posted are American Tugs. Super boats IMO. Trying to decide how much boat I can handle - really like the 41 but may only be able manage the 34-36 sized boats.

 

[Salish Nomad]

Salish Nomad, yes, those two engine rooms pictures I posted are American Tugs. Super boats IMO. Trying to decide how much boat I can handle - really like the 41 but may only be able manage the 34-36 sized boats.

Yes, love ours. 400+ hours per year, including trip to AK in 2019. Let me know if you have questions.

 

[Bkay]

Most of the experts like Tony Athens and Steve D state that a progressive series of filtration is "best". So, in a perfect world you would start with a "mud" filter of say 30 microns, followed by a second off engine filter of say 10 microns, followed by an on engine filter of say 2 microns. Filtering to the smaller number is even more important for "common rail" electronically controlled engines. My mechanical engine (2002) does not require such "fine" filtration. I have a double Racor off engine where I run 10 micron filters and have an on engine filter as specced by the OEM. I think it is 10 microns as well.
The main thing is to supply your engine with clean fuel that is free from water flltered to at least the level specified by the OEM.

I subscribe to this philosophy (mostly). My current engines are John Deere and they have two on engine filters, a 10 micron primary and a 2 micron secondary on the engine. So for my off engine Racor I have an oversized filter and run 30 micron elements. So I have multi-stage 30 - 10 - 2.

But when I only had one on-engine secondary in my Yanmar, I decided to run 10 micron in my dual, switchable Racor. So I had 10 - 4 (or 5 - Yanmar said their secondary filter is around a 4 or 5 micron). Personally, I wouldn't go from 30 primary to a 2-5 micron secondary. I'd go with a finer primary.

 

[rgano]

The micron rating for most engine-mounted fuel filters I have personally encountered, including my own 315 HP Yanmar is 12 or so microns. Have not been able to find finer, and since these are not something I can change underway anyhow, I filter finer, down to 2 microns at the Racor. I suppose my engine-mounted filter is there for nothing more that chunks of the 2-micron breaking off.

 

[Mark P]

So in either case of single or twin filters, and whether equipped with step-up filtration - at how many engine hours should the filter element be changed? Change only when vacuum starts going up?? Also, another question, if vacuum starts going up and you are using a multi-step filter system, do you change all filters, or is it obvious which one is clogging?? (Apologies if these questions are obvious!) Mark P.