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Mercury 525 Service

Motoxxxloak

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Either I am terrible at the search function (and Google) or there just isn’t much information on this.

I have a 525. Roughly 150hrs. I’d like to replace the water fuel separator (currently have Sierra 18-7844 installed) and the oil filter (Merc 35-866340K01 installed). I feel as if there is at least 1 or two more filters that should be replaced as I thought I saw what looked like a small fuel filter on back/top of the engine?

I had really good experience with Wix filters on my last big power motor and would like to use them again unless there is something better the brain trust recommends?

I also used to run Kendall GT-1 in that motor but am not finding any good suggestions to run in this motor? Boat never leaves havasu and might see 20hrs this season. Any input is greatly appreciated!


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BDMar

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I have the Wix Racing filter for that engine and also all the fuel filters.
 

port austin pirate

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Either I am terrible at the search function (and Google) or there just isn’t much information on this.

I have a 525. Roughly 150hrs. I’d like to replace the water fuel separator (currently have Sierra 18-7844 installed) and the oil filter (Merc 35-866340K01 installed). I feel as if there is at least 1 or two more filters that should be replaced as I thought I saw what looked like a small fuel filter on back/top of the engine?

I had really good experience with Wix filters on my last big power motor and would like to use them again unless there is something better the brain trust recommends?

I also used to run Kendall GT-1 in that motor but am not finding any good suggestions to run in this motor? Boat never leaves havasu and might see 20hrs this season. Any input is greatly appreciated!


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Book says replace oil en filter at 25 hours drive 50 hours or seasonal Merc recommends their 25/40 oil. I have run Merc oil now run 15/50 Amsoil dominater. seems to work well. Me and a lot of others change drive oil at 25 hours, A lot of the guys say Mobil 1 15/50 works well much better price all kinds of opiniuns on oil. the only other fuel filter is on the electric pump under the engine, But at 150 hrs it should be fine. ther is a small air filter at the back in top of the plenum have to look at manuel to get change hrs. Do you have the Merc manuel. can get online if not. I usually just use Merc filters. Others who are more knowledgeable than me will give you some input
 

02HoWaRd26

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Orielly’s was 60$ for 10q of Mobil 1 synthetic and the Wix filter for my 496 two weeks ago.
 

Fun Times

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525...I feel as if there is at least 1 or two more filters that should be replaced as I thought I saw what looked like a small fuel filter on back/top of the engine?
Do you have your engine serial number handy? as this engine does have an additional fuel filter up top / inline with the fuel injector rail but Merc had a few designs of filters so your engine serial number would be needed to help ensure you find the correct one/all your parts.
 

Runs2rch

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Fram Racing Filters are built better than the Wix Racing filters now. They filter better, and have a bypass.

HP4 Fram oil filter

Wix 33226 for water separating fuel filter.
 

hold_j

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Well shit, I Hope u put more then 20 hours this season you channel queen haha im at 12 already since the beginning of February lol

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Duck'ed_Up

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Well shit, I Hope u put more then 20 hours this season you channel queen haha im at 12 already since the beginning of February lol

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Hahahha you said “channel queen” I’m dead


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02HoWaRd26

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Do you have your engine serial number handy? as this engine does have an additional fuel filter up top / inline with the fuel injector rail but Merc had a few designs of filters so your engine serial number would be needed to help ensure you find the correct one/all your parts.
OM958384
Seems i have the spin on, on the starboard front corner and the canister on the port rear corner.

So what about plugs and what is the capacity of the oil do you know?
 

Fun Times

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OM958384
Seems i have the spin on, on the starboard front corner and the canister on the port rear corner.

So what about plugs and what is the capacity of the oil do you know?
OM958384 comes up as an RACE STERNDRIVE 2007 525 EFI HIGH PERFORMANCE 525EFI SGL PLUGIN WPS 525 EFI BRAVO Model Number 4WH2225WH 525.

Here's some parts catalogs for your engine,

Spark Plugs are new Merc part Number 33-8M0114747 (old number 810883) which comes out to be Mercury 810883 replacement spark plugs NGK part box # 7822 = Plug # NGK BPR6ES (NGK V-line-2), https://www.mercruiserparts.com/8m0114747-plug-bpr6es-4

See item number 48 for the plugs, https://www.mercruiserparts.com/bam/subassembly/31347/13369/40

Oil Capacity should either be 7 or 8 quarts of engine oil as it varies as you can see here if desired, https://www.mercruiserparts.com/hi-performance-engine-oil-chart

 
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fastenuff3

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Either I am terrible at the search function (and Google) or there just isn’t much information on this.

I have a 525. Roughly 150hrs. I’d like to replace the water fuel separator (currently have Sierra 18-7844 installed) and the oil filter (Merc 35-866340K01 installed). I feel as if there is at least 1 or two more filters that should be replaced as I thought I saw what looked like a small fuel filter on back/top of the engine?

I had really good experience with Wix filters on my last big power motor and would like to use them again unless there is something better the brain trust recommends?

I also used to run Kendall GT-1 in that motor but am not finding any good suggestions to run in this motor? Boat never leaves havasu and might see 20hrs this season. Any input is greatly appreciated!


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the small filter on back off engine you need to take apart there is a filter inside. i got a cleanable filter from teague. i use valvoline 20w50 vri and wix racing filters are good
 

02HoWaRd26

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the small filter on back off engine you need to take apart there is a filter inside. i got a cleanable filter from teague. i use valvoline 20w50 vri and wix racing filters are good
Any idea what you ordered for the cleanable filter? Also how often do you service that one?
 

Fun Times

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Any idea what you ordered for the cleanable filter?
For others with the 525 EFI's following along here, your design fuel filter at the fuel rail should be depended on what your engine serial number is as the earlier years had a different type/design than the newer 525's... [U]02HoWaRd26[/U] has the second design.

The first design injector fuel filter serial number range listed is 525 EFI - 0M900146 THRU 0M953619 , Fuel Rails And Injectors

The second design falls under the rest below,
525 EFI - 0M953620 THRU 0M956326 ..
525 EFI - 0M956327 THRU 0M962885 ..
525 EFI - 0M962886 & Up ..

First design item # 22,

2235-807174T FILTER, FuelACT$63.42$61.001
Second design # 27,

2735-8M0050994 --FILTER, Fuel848355SS/ACT
$35.97$35.321
 

02HoWaRd26

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yes the factory one is paper
I haven’t gotten back there but the new filter arrived today. Do i need any special tools? Any tips or tricks to this or once back there it’s obvious??
 

fastenuff3

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I haven’t gotten back there but the new filter arrived today. Do i need any special tools? Any tips or tricks to this or once back there it’s obvious??
use line wrenches and pull housing out and then pull housing apart on vice
 

02HoWaRd26

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use line wrenches and pull housing out and then pull housing apart on vice
Is this the same one??? Jesus Christ if so is it reverse threaded? Or is it mines never been opened since new? Cause this mother Fuq’r i cannot get opened.
DCC20329-E79A-469A-B940-282543DB2D7D.jpeg
837ED847-B3C5-4823-B1A3-FB07218C53C2.jpeg
117E229B-24E6-4CF8-954C-22EB23C26BBB.jpeg
 

02HoWaRd26

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yes that is it and it is not left hand thread. i have copper jaws in my vice so i put it in the vice alot easier to get apart
Yea i got it today, used vise with my an fitting clamp, but took a 3’ breaker bar. WTF lol.
added a tad of grease on the oring, but idk I’d that filter had ever been changed it was pretty gross.
 

evantwheeler

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aeromotive 100 micron p/n 12604. i check it yearly.make sure its the same because i have a 600sci it looks the same
I'm not up to speed with custom boats, but in sand cars, we put a 100 micron BEFORE the pump, and a 10 micron AFTER the pump. Are you sure that a 100 micron goes right there before the fuel rail, and not a 10 micron?
 

02HoWaRd26

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I'm not up to speed with custom boats, but in sand cars, we put a 100 micron BEFORE the pump, and a 10 micron AFTER the pump. Are you sure that a 100 micron goes right there before the fuel rail, and not a 10 micron?
It’s what Teague recommended him as well me when i ordered this one from them.
 

02HoWaRd26

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Any heads up on an impeller, now that I’ve officially taken over @Motoxxxloak ’s thread, since he’s afraid to get dirt under his nails and has a shop do his labor 🤣🤣🤣lol sorry buddy lol.
 

02HoWaRd26

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Other than it’s expensive, any reason not to use the case of Kendall GT1 i have sitting here for the oil change?
 

Fun Times

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Other than it’s expensive, any reason not to use the case of Kendall GT1 i have sitting here for the oil change? (impeller?)
Search online impeller kit part number 46-807151A14 for your preferred pricing options.. Item number 4, https://www.mercruiserparts.com/bam/subassembly/31347/13369/170

What's the engine oil weight of your GT1.

Quicksilver Marine Oil 25W40 or Quicksilver Synthetic Blend Marine Oil 25W40
Or,
Mercury High Performance 4-Stroke Synthetic Blend Oil 25W50 Recommended for use in all Mercury Racing four‑stroke engines including: FormulaRace and Verado outboards and 525 EFI through 1650 sterndrives.

Outside of oil preferences, 'These are some of the recommended weights to use.
 

Shlbyntro

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Merc 25w50
Or Castrol 20w50

I've had great results from both.

Delo 15w40 is also great but can have lower oil psi when returning to idle from hard running
 

Lavey 29

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I would use a racor or a FST spin on filters. I would use a Sierra fuel spin on filter before I would use a Merc fuel spin on filter. Wix fuel filters hugely over rated as they offer nothing great over any other fuel filter and they rust badly when water is in the fuel. Merc rust badly as well. I cut filters open 5 days a week to know the good - the bad and ugly. Just saying
 
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