To fuel filter or not. 3.0

Lou C · Apr 30, 2022

And you only need a 10 micron for EFI engines; for carbed 20 is fine. Don’t overthink this

nola mike · Apr 30, 2022

Lou C said:
If that’s the case the cause was probably not changing the oil. Look at the spec on some of those filters. A Racor flows 90 gallons per hour!

Yeah, running lean isn't the cause of cylinder scoring.

Mercperk · Apr 30, 2022

nola mike said:
Yes, until it gets saturated
Most/all newer Merc engines came with the screw on filter I believe.

I think we're done with this ... Either use it or don't. There has never been a post here --ever-- where someone has added a filter and had problems. Do what you will with that.

Well experience might be able the answer these questions and I don't know about you but I prefer to operate in manner that doesn't require major repairs frequently.

I'm sorry you lack the knowledge

Mercperk · Apr 30, 2022

He probably has 5 inline filters.....

nola mike · Apr 30, 2022

Mercperk said:
Well experience might be able the answer these questions and I don't know about you but I prefer to operate in manner that doesn't require major repairs frequently.

I'm sorry you lack the knowledge

What knowledge do I lack exactly?

Mercperk · Apr 30, 2022

nola mike said:
Yeah, running lean isn't the cause of cylinder scoring.

Gasoline is a lubricant

Mercperk · Apr 30, 2022

nola mike said:
What knowledge do I lack exactly?

Why the 3.0l doesn't come standard like the rest with a H20 separator

nola mike · Apr 30, 2022

Mercperk said:
Gasoline is a lubricant

No it isn't. In a 2 stroke engine it's mixed with oil and lubricates the cylinders. In a 4 stroke, not so much

Mercperk · Apr 30, 2022

Mercperk said:
Why the 3.0l doesn't come standard like the rest with a H20 separator

And why the mercruiser repower book says not to add a filter

nola mike · Apr 30, 2022

Mercperk said:
Why the 3.0l doesn't come standard like the rest with a H20 separator

Because Merc was cutting costs. Already been answered.

Lou C · Apr 30, 2022

With the same base engine Volvo Penta used a spin on canister filter. The confusion might be from the fact that older versions of the mechanical pump did have a smaller filter built in; the V6/V8s did not.

nola mike · Apr 30, 2022

Lou C said:
With the same base engine Volvo Penta used a spin on canister filter. The confusion might be from the fact that older versions of the mechanical pump did have a smaller filter built in; the V6/V8s did not.

Good point. The mechanical pumps had the built in filter, the electrics didn't.

Lou C · Apr 30, 2022

Correct and the only pump I have ever seen that used a built in filter was on the 3.0. None of the others to my knowledge had that built into their pumps. Probably because the marine pumps for the V6 & V8s were based on automotive pumps, that were modified for marine use so had to use the add on cannister filter. However the 3.0 was not used in vehicles so the pump was different and incorporated the smaller version of a cannister filter. Is that filter all by itself adequate? It might be depending on your conditions. If in a dry climate with clean fuel maybe it is. In a damp climate with your only choice being E-10 fuel, it might not be. Having said that, whenever I dump out my cannister filter it is usually clean gas, no water on the bottom, but some people have a big problem with this.
examples:

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www.volvopentastore.com

later model Volvo Penta 3.0 with mechanical pump that does not have the intergral filter, and has the cannister.

this is the style of pump used by both OMC and Merc that had the integral filter:

Sierra Marine 18-7282 - Fuel Pump, 8M0073435, See Detail Page for Important Info

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www.marineengine.com

if you have that style pump and you don't have problems with the smaller filter, then no worries. But if you have a water in the fuel problem, then adding a cannister style filter I don't think is going to cause a problem, and they can hold a lot more water. Just change both filters regularly, to prevent restrictions.

Lou C · Apr 30, 2022

Mercperk said:
Why the 3.0l doesn't come standard like the rest with a H20 separator

see my post on the 2 different pumps used on the 3.0. One had an integral filter (used by OMC and Merc) the other did not (used by Volvo Penta).
The integral filter may, or may not be adequate for your conditions. If in a damp climate and forced to use E-10 fuel like we are, I would use a cannister filter. In a dry climate with straight gas it might be fine.

Mercperk · Apr 30, 2022

nola mike said:
Because Merc was cutting costs. Already been answered.

So why are you answering again?
It's just that this agro bullshit detracts from actual information trying to be gleaned from the conversation.
Just because you think you have a full understanding of something doesn't mean someone else doesn't want understand more......

Mercperk · Apr 30, 2022

Thanks iboats folks I appreciate your time and consideration

achris · May 1, 2022

Mercperk said:
Says
2. Should I as a fine-micron filter to the system to prevent debris from entering the engine?
No. .....
Talks about fuel starvation

Merc 3Litre engines don't come standard with a spin-on water sep fuel filter. This is a 'budget' engine, and by not adding a $50 filter kit it kept the sale price down by $50. Apparently people like that

I was a Mercruiser dealer in the 90s, and I did not let a boat out of our shop with a new engine that didn't have a spin-on water sep filter on it. All the V6s and V8s came with one bolted on as standard, usually near the stbd engine mount, so we didn't add another, but every 3L got one.

My own boat has a V6, with the ascribed spin-on. I have added a fuel flow meter to the system and the first flow sensor I installed crapped out, because it caught some dirt. I decided that I either need to install it between engine mounted filter and fuel pump (not really an option as it's a hard pipe), or in the same place as before (before the engine mounted spin-on) and I'd add another filter to the system. As those horrid little plastic filters are an absolute 'no-no' on a boat it had to be another Merc spin-on...

And that's what I have, 2 spin-on filters, and no starvation problems.. Here's the photo.

Scott Danforth · May 1, 2022

Mercperk said:
Why the 3.0l doesn't come standard like the rest with a H20 separator

Answered in first line of post #4

nola mike · May 1, 2022

Lou C said:
Correct and the only pump I have ever seen that used a built in filter was on the 3.0. None of the others to my knowledge had that built into their pumps.

The 4.3's had them until they had electric pumps, as did the 470's. 4.3s also had a brief spell with some inline filters. I think the v8s were always (?) canister type.

Lou C · May 1, 2022

nola mike said:
The 4.3's had them until they had electric pumps, as did the 470's. 4.3s also had a brief spell with some inline filters. I think the v8s were always (?) canister type.

I don't think you're right about that, I have a pic here to show you what a 4.3 marine mechanical pump looks like, just like the V8 pump but mounted upside down. Old one is OE Carter, new is Sierra aftermarket, I also have a new Carter one, looks exactly the same. So no integral filter on these they all had cannister filters added on.

However, there is one other engine that DID have that style pump, the old GM inline six (250 and 292 cu in) engines did use that same style of pump with the integral filters.
250 cu in: