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Warning! New filter system on new Yanmar engines is Bad!

14164 Views 60 Replies 19 Participants Last post by  gibbo90909
Hi folks,

I got into a very serious problem the other day.
I have a new Yanmar 4JH57 the new common rail engine. 300 hours on the clock. It has a new pre-filter replacing the Racor 500. The inlet on the new Yanmar pre-filter has a Banjo bolt where the fuel must turn at 90 degrees and go through a hole in the bolt about 1mm wide.

This turn gunked up and the engine stopped.... in a remarkably difficult and dangerous location with a contrary current of 5 knots and me being only able to sail at 1.3 knots - directly towards the rocks!!! With another 6 hours of current sucking me into the infamous Alderney race with currents up to 9 knots.

If it had stopped 15 minutes later there is no way I could have turned around and been able to sail into the current.

So I had a fun few hours trying to sail and locate the fuel fault.
Also the filter needs a spanner/wrench far larger than I have so I couldn't change the filter at sea!

On a brand new engine its not expected to stop!
Anyway I finally traced it back to the Banjo Bolt and its tiny hole. A tiny piece of orange plastic has gummed it up then crap built up around it.
I though a pre-filter was meant to suck anything out of the tank and filter it before the primary fuel filter mounted on the engine.

I do not want / and will not have this possible situation again. Cruising boats can often pick up dirty fuel (I've fuelled in Venezuela, Egypt, Oman, Indonesia, Malaysia etc) or some goop can get in or grow, no matter the additives etc.

My solution is to buy a new Racor 500 as a pre-pre-filter and to mount it in the aft cabin on the external riser for the bunk, adjacent but on the outside wall to the Yanmar filter. Thus I will be able to ensure gunk the size that blocked the Banjo Bolt will not cause a problem, and that I can visually see the Racor from the Saloon, and change that Racor filter in less than 1 minute.

I found the problem and cleaned the Banjo Bolt and was able to get back to harbour no problems... but by then another bit of gunk was in the bolt.
I pumped out the whole tank and filtered the fuel and its clean as a whistle.

I will upload a pic of the problem off my phone in a few moments... but heres a location snap of exactly where you do NOT wanna have the engine clag up.

Your comments appreciated.



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1 - 8 of 61 Posts
So these new fangled Yanmars come with both an engine mounted and remote pre-filter?

Sounds like I'd lose the Yanmar pre-filter altogether and replace with a Racor. Intuitively, those bango fitting are not the best inlet for a fuel filter.

I'm not a fan of dual 2 micron filters in series. That means that everything clogs the first filter and nothing ever gets to the second. If you had real sediment, I think that shuts off the fuel sooner.

I use a 30 micron Racor and a 2 micron engine mounted. The big stuff is caught first, as well as the Racor separating any water, then the 2 micron gets anything left over. Change them both on schedule, which is annual for my use. I would change every 6 months, if I was full time and taking on suspect fuel.
Fuel line going INTO the pre-filter has a right angle turn into this tiny hole in the Banjo Bolt.

Crazy is right. I'd remove the whole thing and replace it with the Racor, rather than just add a Racor.
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You can get a water alarm for a Racor as well. I'm not sure, but suspect it would be the same wiring. If not, I doubt the boat stops working, if the alarm is inop. YMMV.
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One thing I substantially prefer about the Racor 500, over the Yanmar filter in your pic, is the clear bowl. You can visually see sediment and water.

You probably know this, but the 500 comes with and without a metal cup under the clear plastic bowl. I understand the metal cup is necessary, if mounted in the engine compartment. I'm really not sure if it's to deflect heat or catch a drip. It's nearly impossible to ignite dripping diesel fuel, unless a fire is already raging, in which case, I don't see the cup helping. :eek
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Almost unheard of to pump bad fuel in New England. Water maybe, but still uncommon.

I've been in third world countries, where fuel has been hand cranked out of 55 gallon barrels off a flat bed truck. Into an aircraft! Guess how long you sit there on the ramp, running up the engines to insure the fuel isn't contaminated. :eek
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Another thought is to use a pre-fill filter. I read in PS that the West Marine pre-fill rated best. I have that one and don't like it. Takes forever. I think they all might. The Baja filter is popular and expensive, but I've never tried it. Also gets good ratings. Says 2 gallons per minute filtration rate. We can easily take on 60 gallons (we hold 110). That's a half hour. I suppose, if cruising the islands, it's just part of the deal.
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.....Every trawler I've been on has a for real polishing system and a day tank. You could have dead bodies floating in the fuel tank(s) and the engine would be fine. Has anyone here done something similar on their boat?
Good point. No way one is prefiltering at 2gal/min, when taking on 1000+ gallons. Not humanly possible.

Best I can tell, polishing systems are nothing more than a couple of filters in series that recirculate the fuel. Probably a 10 mic and 2 mic in series, with water separating filters.

They would be a great idea, if one has the space, power and money. 2 Racors, a pump and all the supplies and fittings is probably running north of a boat buck, before all is done. I wonder if one could rig a dual R500 system to do double duty. If each filter went to/from a mainfold, some valving might do the job. Motor away from the dock, drop the hook, turn some valves and power up the polisher, while one cracks a cold one or makes a meal. Interesting thought.
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I don’t have heat shields on mine either, but they are in a cabinet outside the engine room. Does that ABYC quote apply regardless of where they are installed?
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