Re: [Catalina 355:4567] Digest for catalina355@googlegroups.com - 9 updates in 1 topic

[David Everett]

Those symptoms may be your exhaust elbow where the sea water enters - once it’s clogged to a tiny internal diameter it will run at low revs but not higher and hunts up and down. Engine strangled from exhaust end, not fuel end. 

If elbow not been taken off and checked in last 3-4 years then suggest it may be your issue. 

I learnt the hard way. 

David - #62

On Fri, 27 May 2022 at 7:40 am, <catal...@googlegroups.com> wrote:

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• Fuel filters - 9 Updates

Fuel filters

Ernie Bubb <erni...@gmail.com>: May 26 02:17PM -0400 First some context. Having some difficulties with the Yanmar 3YM30 engine on my 2011 Catalina 355 — engine RPMs fluctuation. Yard maintenance assessed problem as injector pump, which I have had rebuilt. Still having difficulties which occur mostly at higher RPM (2500) but not at lower RPMs (1500). New primary and secondary fuel filters. Fuel appears clean in bowl of filter.   I am using a Racor R20T primary fuel filter which was the type installed when I bought the boat last July. I understand that filters to 10 microns. I have seen information on web that Yanmar recommends the primary filter to 30 microns. Can anyone tell me what is standard on the C 355s and whether a 10 micron primary could cause some loss of RPMs at higher engine levels?   Regards,   Ernie Bubb   Sent from my iPad

Ken Kloeber <KWKl...@aol.com>: May 26 02:43PM -0400 The problem about fine primary filtering is that it will clog up before the secondary fiikter. In essence OEM filtering on a boat is a$$ backward. The first filter should be coarser than the final filter and most secondary filters (using published tested beta ratios) are rated at 20u - 30u “absolute”; lower values “nominal” efficiency.   See this info (which is for our Universals but points out the range of efficiencies.) https://c34.org/wiki/index.php?title=Replacement_Filters,_Belts,_and_Lubricants#Diesel_Fuel_Filters       Ken K   Sent from my pad

Ernie Bubb <erni...@gmail.com>: May 26 02:58PM -0400 Thanks Ken - So I infer from your comments that I should use a primary filter rated at 30 microns. Is that correct? Do you know what the original equipment filter is on C355s?   Thanks   Sent from my iPad

Juan Galan <miaj...@gmail.com>: May 26 03:11PM -0400 Using a 10 micron on a primary should not cause the problem you are describing. If you changed both primary & secondary filters and are having a problem at higher RPM, it is either fuel flow or air flow. Have you removed air filter to see how clean it is? If it just came out of storage during winter, you might even have some cobweb or similar, blocking air flow needed for higher RPM use! If air filter is clean then it is possible that something in your fuel pump has reduced fuel flow at higher RPM[i.e., fuel flow restriction]. I have run larger diesel engines than a Yanmar 30hp with 10 micron primaries- no problem!   On Thu, May 26, 2022 at 2:43 PM 'Ken Kloeber' via Catalina355 <

Ken Kloeber <KWKl...@aol.com>: May 26 03:37PM -0400 Ernie   I'm not qualified to speak to yanmar and what they recommend. That said I've not seen a recommendation from Parker-Racor about any issue using a 20u on the primary. Their warning was more related to finer filtering (4u and 10u) on the primary.   What filter number is OEM?   The **proper** filtering would be to reverse the filters, which we can do on our Universals. I may eventually bolt the secondary filter bracket off-engine and plumb to it first. Then I can filter 25u ~> 10u or 4u, which is admittedly overkill.   Filters shouldn't be on-engine because the rated efficiency depends on developing a filter cake and engine vibration hurts that process!   Ken K   Sent from my phone

Michael <michael.h...@gmail.com>: May 26 12:54PM -0700 Ernie,   Do you hear the engine change RPM and / or notice the tach fluctuate? Do lower RPMs last or does it recover? Does it do in neutral at the dock?   -Michael   On Thursday, May 26, 2022 at 2:12:01 PM UTC-5 miajag44 wrote:

george johnson <george.wan...@gmail.com>: May 26 05:18PM -0400 I’ve been running a Racor R20P 30 micron filter for 6 years on my 2014 C355 with Yanmar 3YM 30 engine…….no problems……   On Thu, May 26, 2022 at 3:37 PM 'Ken Kloeber' via Catalina355 <

Ernie Bubb <erni...@gmail.com>: May 26 05:34PM -0400 Thanks for answering. I hear the engine drop and also see the tack go down. At 2500 it drops maybe 300-400 RPMs then will recover then repeat a couple minutes later. It has never happened in neutral if I drop to 1500 then it is stable Since the injector pump was rebuilt it has only happened on the water under load, but I haven’t tested it at dock tied up under load. Planning to do that this weekend.   Sent from my iPhone

Ernie Bubb <erni...@gmail.com>: May 26 05:35PM -0400 George - thanks   Sent from my iPhone

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[Jon Vez]

Great point David. A restricted exhaust does match the symptoms…

Sent from my iPad

On May 27, 2022, at 1:03 AM, David Everett <davidse...@gmail.com> wrote:



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