Moderated Discussion Areas
  ContinuousWave: Whaler Performance
  inline water separating filter

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   inline water separating filter
alvispollard posted 02-28-2001 10:13 PM ET (US)   Profile for alvispollard   Send Email to alvispollard  
What inline water separating filter is best for a mariner 100 (montauk)? Brands? Price? Source?
Dick posted 02-28-2001 10:49 PM ET (US)     Profile for Dick  Send Email to Dick     
Available from Mercury part #35-604944A4 or aftermarket from Sierra part #18-7852. Both run $32 to $40 and well worth the money.
Change the filter element a couple times a year, around $7.00. Racor also makes a very good one.
stagalv posted 03-01-2001 11:30 AM ET (US)     Profile for stagalv  Send Email to stagalv     
I would love to have one of these on my Montauk but where do you put it?? Does it have to be exposed back aft or have you guys located the filter in a more secure place? I sure would love some kind of a locker or thwart seat back aft where I could mount the filter and a VRO tank underneath it? Any ideas?? Rex
compounder posted 03-01-2001 06:55 PM ET (US)     Profile for compounder  Send Email to compounder     
Rex, my Racor unit fits nicely mounted just above the small bilge opening. It is mounted with screws (large, SS) to the engine well. The filter holder has two inlets and two outlets which is neat because I can run one fuel line out to the main engine and one out to the kicker and have filtered fuel for both.
lhg posted 03-02-2001 04:03 PM ET (US)     Profile for lhg    
I have never thought a water separating fuel filter is necessary on a boat with conventional on-deck fiberglass/plastic tanks. I ran a 13 and Nauset for 20 years without one, and never a problem. I think they are only recommended with built-in tanks, when water condensation in a tank becomes a problem. Unless you're buying really terrible gas, most fuel today would normally be free of water. Even then, a little of the MDR WaterZorb added to the fuel would solve the problem much easier.

BW is not factory rigging the Montauk with these filters, but they are using them in the models with built-in aluminium tanks.

Mize Johnson posted 03-02-2001 08:06 PM ET (US)     Profile for Mize Johnson  Send Email to Mize Johnson     
I found a great fuel filter/water separator that Racor makes for PWC. Its rated at 25 gph which should be more than adequate for your engine. It is only about 3"x4" so I mounted mine inside the engine well right below the engine to keep it out of the way (it's al and plastic so not as much problem with corrosion as the steel filter elements). I like the fact that it has a clear bowl so you can see if there is any water or dirt and I don't have to change the element unless it needs it. The local West Marine special ordered it for me last year when it first came out. I think the number was Racor 25-02.
Bullbay posted 03-02-2001 09:59 PM ET (US)     Profile for Bullbay  Send Email to Bullbay     
I had a fuel filter mounted on stern of my 89 Montauk after I remotered. The first time I tried to change the filter I pulled the bolts out. I have permanetly removed it now and redid my gas line and gel coated the holes were it was. My son's 87 Montauk with Yamaha never had a filter on it. He uses the Yamaha fuel treatment and I am now using the OMC. He has the Pate fiberglass tank and I have two 14 gallon plastics on mine. If you keep them full and use the fuel additive I understand that you will not have a problem. On his Revenge he has two filters and I think they are needed because of the large capacity aluminum tank under the deck.
stagalv posted 03-02-2001 11:59 PM ET (US)     Profile for stagalv  Send Email to stagalv     
Thanks for the info. What about the oil injection tanks on a Montauk? Are you placing them in the console? Rex
andygere posted 03-05-2001 01:00 AM ET (US)     Profile for andygere  Send Email to andygere     
There is no magic to portable tanks; condensation does not know the difference. Unless you are able to keep your tanks full all the time, or live in a climate with zero humidity, a water separating filter is a good idea. I mounted mine on the motorwell of my Montauk, and it always seems to have some water in it when I change it! Filters are cheap, motors are not.
triblet posted 03-05-2001 01:04 AM ET (US)     Profile for triblet  Send Email to triblet     
Then why don't I need a racor on my truck?


dgp posted 03-05-2001 12:29 PM ET (US)     Profile for dgp  Send Email to dgp     
Chuck, any internal combustion engine could benefit from a fuel/water seperator/filter. The car/light truck mfrs are too cheap to install these, besides the consumer would not pay for them. Don
triblet posted 03-05-2001 02:44 PM ET (US)     Profile for triblet  Send Email to triblet     
Please back up your "any internal compbustion
engine could use one" statement?

If they were necessary on a truck,
there would be big
display at the local NAPA auto parts store.
There isn't.


dgp posted 03-05-2001 03:32 PM ET (US)     Profile for dgp  Send Email to dgp     
Water in fuel, whether gas, diesel, jet fuel, etc. is not supposed to be there and if it is, it causes poor performance, unnecessary wear and corrosion, can cause things to break and in some cases can leave you stranded on the road or in the middle of the ocean.
Water in your carb will cause corrosion of the aluminum if allowed to sit overwinter. Too much water there and the engine just won't run. On fuel injected engines it causes wear of the nozzles and can blow the tips off if the water flashes into steam.
If the water freezes in the fuel hose no fuel will flow to the engine. Expanding freezing water can break/crack engine metal components.
triblet posted 03-05-2001 09:49 PM ET (US)     Profile for triblet  Send Email to triblet     
You didn't address why there isn't a big
market for water separators for cars and

Consider this: My whaler gets used darn near
every weekend. I go through a tank of gas
a month, and keep it reasonably full because
I never know where I'm going until I'm five
miles from the launch ramp. It gets used
all winter (well, sometimes it's sits for
two or three weeks in the winter -- the
weather is fine, but it blows a whole gale).
My boat never gets exposed to freezing
temps (it's in a California garage -- sorry
if that doesn't go over to well back east

I don't think the water is getting in there.
Now, tell me why I need the filter.


Russ posted 03-06-2001 02:45 AM ET (US)     Profile for Russ  Send Email to Russ     
Water isn't the only fuel contamination problem. If you fuel your boat at out-of-the-way fuel docks, where the tanks are old, and not a whole lot of fuel is sold, it's quite likely that they are contaminated with rust as well as water. That rust, and water, will be pumped into your tank. Those little in-line filters used on outboards are not adequate to filter it out. Full sized fuel filters, such as those described in the above posts, are. Of course, if you only fuel up at modern, busy, stations and docks, you probably have very little to worry about. By the way, my pickup does have a fuel filter. (Diesel, y'know.)
dgp posted 03-06-2001 08:04 AM ET (US)     Profile for dgp  Send Email to dgp     
Chuck, if don't think your boat will catch on fire, why do you have a fire extinguisher? If you don't think your engine will overheat, why does your engine have a high temperature warning device?
A fuel/water seperator/filter is just another safety device so that in the event you get a dose of bad gas it won't leave you stranded. Don
bigz posted 03-06-2001 08:13 AM ET (US)     Profile for bigz    
Hey Don and Russ fine explanations.

Sorry Chuck had to ask you in such a "polite" manner Don, on a topic that frankly common sense (maybe not as technical) would tell you that it is beneficial for the small amount it cost compared to the investment it is protecting!!

This topic has been covered numerous times in the past! Regardless, I believe you are a foolish person not to spend the money and install a water and contaminate fuel filter --- as I mentioned above common sense dictates here, some folks have more of it than others! --- That's my opinion on both subjects and ain't going to change it either so don't even bother trying.

Clark Roberts posted 03-06-2001 10:22 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
I have "water separating" filters on all my boats regardless of engine size or fuel tank particulars. Just a matter of personal choice and the fact that I have had several bad experiences with water in fuel, not a pleasant thing! Also, as mentioned, other forign materials are filtered. Interesting to note that my new Merc 135 Optimax has a water separating filter (canister type) under the cowling and there is a sensor built in which alarms (light and buzzer) if water ever gets trapped in filter! And the manual warns to use no other fuel filters! So, I removed the existing Racor filter and now have only the under cowling stock filter. Reason for no other filters is the added restriction to fuel flow. My engine is a 2000 model with analog gage package and the 2001 models are all digital gage (smart-craft) which also monitor fuel flow.etc..etc...etc... May be too much info for this old Florida Cracker... heh, heh.. happy Whalin'... Clark... The Old Man and the Sea
Orca posted 03-07-2001 02:54 AM ET (US)     Profile for Orca  Send Email to Orca     
Should I post my Racor comments in the tow insurance posts?
JAC posted 03-09-2001 02:19 PM ET (US)     Profile for JAC  Send Email to JAC     
OK, the filter people win. So where is the best place to install a RACOR type filter on an 18 OUTRAGE ? I hate to use my best "dryland" judgement only to find out the placement doesn't work well when on the water.
Also, are two filters needed when a kicker is installed or are the two exit ports on a single filter OK ?
Please hurry with your comments , I have only a half tank of gas and thunderstorms are forecast for this weekend !!!
Tom W Clark posted 03-09-2001 02:46 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I mounted mine under the gunnel board just aft of the tunnel exit (i.e. where the fuel line comes out at the starboard rear corner of the cockpit. Thi way the fuel hose makes a straight run to the intake bard of the filter. It's perfectly fine to use the two outlets for both the main motor and the kicker. Just make sure the filter flow capacity of the filter you choose is sufficient for your motor.
lhg posted 03-09-2001 02:50 PM ET (US)     Profile for lhg    
With an 18 Outrage, and built in tank, you definitely need one. One will suffice, as a Mercury engineer told me I could run twin in-line 6 115's using just one. Plenty of fuel flow volume through the filter.

I installed mine, as high as possible, on the inner hull sidewall, just underneath the starboard gunwale, forward of the fuel manifold. This would be immediately above the floor sump cover, and keeps it dry, easy to reach and change, and out of the way. Since the 18 Outrage has two fuel line take-offs, besides running the two lines FROM the filter, you can also run two lines INTO it if you feel the need. But with just a kicker, this may not be necessary.

dgp posted 03-09-2001 05:09 PM ET (US)     Profile for dgp  Send Email to dgp     
For flow rates, fitting sizes and OA dimensions go to
dgp posted 03-09-2001 05:14 PM ET (US)     Profile for dgp  Send Email to dgp     
Damn, forgot the "L"
andygere posted 03-12-2001 01:46 AM ET (US)     Profile for andygere  Send Email to andygere     
A few reasons boats need water separating filters "more" than cars. 1) They are used on the water, a place where local humidity is always high. 2) Fuel turnover in cars is typically higher than boats simply from frequency of use. Small quantities of water are burned off in the fuel, but since the car tank is emptied and filled often, a large quantity of water does not accumulate. The small amount of water burned (volatilized actually) does affect performance. Trailered boats that get used frequently are probably less suceptable to large quantities of water in the fuel tanks than infrequently used boats or those berthed at a marina. 3)Marina fuel is notoriously "wet" for the same reason as 1 above.

A secondary reason for using the spin-on filters is the significant filter area they offer compared to the small built-in filters on an outboard. These are easily plugged with a slug of rust from the bottom of a tank, while the spin-ons can handle significant mass loading. For me, it is just an extra bit of insurance.

LarrySherman posted 04-11-2001 12:59 PM ET (US)     Profile for LarrySherman  Send Email to LarrySherman     
Does anyone know which model filter has 2 outlets to accomodate the main/kicker config discussed above? Thanks, Larry
compounder posted 04-11-2001 04:40 PM ET (US)     Profile for compounder  Send Email to compounder     
Larry, I've seen (though not lately) filter mounts sold by Mercury, OMC, and Racor and they all had two inlets and two outlets. I assume they are all supplied with two brass plugs and two brass barbs, as most applications will only consist of one inlet and one outlet being used.

I own three but they are all more than 10 years old, so I'm not sure that the current configurations are the same.


lhg posted 04-11-2001 07:51 PM ET (US)     Profile for lhg    
From what I have seen, all major brands have the two inlet, two outlet configuration.
See my new thread on these water separating filters.
LarrySherman posted 04-12-2001 12:39 PM ET (US)     Profile for LarrySherman  Send Email to LarrySherman     
Thanks, perfect.

Post New Topic  Post Reply
Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.