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Author Topic:   Mercury Air Filter for 90-HP FOURSTROKE Disintegrates
bben posted 04-22-2011 02:25 PM ET (US)   Profile for bben  
This will be the second time that I have to replace my air filter [on a Mercury 90-HP FOURSTROKE that apparently was manufactured in calendar year 2008] due to it coming apart. The first time, the dealer noticed it on my 20-hour service and sent it to Mercury because it was very unusual. This will be the second time with the motor now having about 50 hours. Ever since new, I have complained that the motor idles roughly and carbon comes out the propeller after starting when warm. Now the filter has been chewed up. I am starting to think the two [problems] could be related but my dealer thought the engine ran fine and that carbon is natural due to ethanol in the gas. What could be causing the filter be be chewed up? Is [the filter deterioration] related to my other [engine problems?] I use the boat in the Florida Keys and when it is stored, it is inside. There is no evidence of any bugs or animals getting to it. The guy at the marina said it likely is from using ethanol fuel--that sounds like a possibility. Any thoughts would be welcome and any thought on whether I may have caused permanent damage. Thanks, again
Buckda posted 04-22-2011 07:59 PM ET (US)     Profile for Buckda  Send Email to Buckda     
I'm curious how ethanol extended fuel would affect an AIR filter? Or are you talking about the fuel filter? I know that ethanol extended fuel is a relatively new item down in Florida, and it's the "mechanic's designated whipping boy" du jour, but we've had ethanol in our fuel for about a decade in the Midwest, and I've not heard of this problem.

Besides that, he would have to explain to me how fuel is getting into the air filter, and why that is normal.

Otherwise, I'd call him Uncle B.S.

fno posted 04-23-2011 08:52 AM ET (US)     Profile for fno  Send Email to fno     
Funny, I never found an air filter on my Mercury 90-HP FOURSTROKE. Maybe he means the fuel filter.
boatdryver posted 04-23-2011 09:41 AM ET (US)     Profile for boatdryver  Send Email to boatdryver     
[M]aybe [bben] will come back to his thread, but in [2008] wasn't a FOURSTOKE a Veradito and not a Mercaha?


bben posted 04-23-2011 01:48 PM ET (US)     Profile for bben    
Thanks for the replies. It definitely is the air filter and not one of the two fuel filters. The motor is a 90 EFI FOURSTROKE. The filter sits vertically on the front right side of the motor looking from back to fron of the motor, just above the low pressure fuel filter. It attaches to the intake and has a purge vent tube and a breather tube attached to it. I have a picture but don't know how to attach. It is on page 65 of the owner's manual. The theory is that it is backfiring through the intake causing the filter material to shred. The service guy said that the Verado uses the same filter but it sits on top of the motor, horizontally. He has never seen one of those fail but doesn't attribute it to the position, rather to the ethanol because Verado engines on the bigger boats that generally go to marinas to fill, as opposed to me who takes my tanks out to the local shell station. I am not sure I completely buy it but it does sound plausible and may account for the get carbon deposits on warm starts. I am going to run a few tank fulls of non-ethanol and see, although I have to wait until the new filter comes in on Tuesday. By the way, should I try changing my fuel filter, at least the low pressure one - the motor only has about 50 hours? Thanks again.
bben posted 04-23-2011 02:01 PM ET (US)     Profile for bben    
[H]ere is a link to a picture that I found; this is really a picture of the low pressure fuel filter but you can see a portion of the air filter just above it; it is the black mess-type looking thing

davej14 posted 04-23-2011 04:34 PM ET (US)     Profile for davej14  Send Email to davej14
Buckda posted 04-23-2011 05:07 PM ET (US)     Profile for Buckda  Send Email to Buckda     
Ethanol is not causing your motor to backfire. Your car, lawnmower, etc runs on the stuff just fine. If you are having backfiring problems, it's unlikely because you buy your gasoline at the Shell station.

Let me be clear, I am NO fan of ethanol "enhanced" fuels. Quite the opposite, in fact. But I just don't see how ethanol is the cause of a problem with your AIR filter.

I'd be rather incredulous if my mechanic tried to say that ethanol was to blame for shredding TWO air filters in 50 hours of operation.

It's likely something else...if it isn't, please post a follow up here, because I'm currently unconvinced and will be very interested in the rationale.

I am not a mechanic, so if this were my motor, I'd be visiting another shop for a second opinion. Why do you have carbon problems after only 50 hours of operation on an EFI 4-stroke engine? I'd be looking for problems with spark, engine lugging (too aggressive of a prop), or something else...perhaps a thermostat is not letting the engine come to temperature...something other than ethanol in the FUEL somehow destroying and AIR filter. The only place air and fuel is supposed to mix is in the combustion chamber, right?

dbrown posted 04-23-2011 10:36 PM ET (US)     Profile for dbrown  Send Email to dbrown     
In the link below is a picture of the air filter on my (Manufactured 2007) Mercury 90 HP FourStroke "Veradito" taken when the engine had approximately 50 hours on it. Mine was self destructing by the 100 hour mark. I have since replaced the filter media with another type and I have had no further problems. This is not an isolated problem with these filters. I have read many reports of the same type failure. In most cases the filter turns to "goo" and disintegrates in small pieces, which are then ingested into the engines intake. I was fortunate enough to catch this at an early stage and no harm appeared to be done to my motor. But I would not use another of the same type media material, which is all Mercury offers at this time.

ktm3ten posted 04-24-2011 12:20 AM ET (US)     Profile for ktm3ten  Send Email to ktm3ten     
Another owner here with the disintegrating air filter. Not sure if it's hours or just time since these things seem to just shrivel up and die after so many hours. These motors are on tons of pontoons around here (midwest, USA) and seems like most of 'em I've seen lately have just taken the filter off. How necessary is an air filter on a marine outboard?
bben posted 04-24-2011 07:09 AM ET (US)     Profile for bben    
Thank you. That at least makes me feel like it is not just me! I emailed Mercury Marine on Friday and will resport back. Dbrown, your set up looks exactly like mine. What type of material did you use and did you just shape it around the housing of the old filter? I am not sure about running it without the filter since it has the two other hoses attached to it. I am hoping that my carbon deposits out the exhaust on warm starts will be fixed once I get the filter issue resolved. Maybe it's not related but we will see. Thanks again.
dbrown posted 04-24-2011 11:31 AM ET (US)     Profile for dbrown  Send Email to dbrown     
I used the filter material in the link below at the recommendation of another owner with the same type motor and problem. I cut it to fit the filter housing and used "Hot Glue" to seal the seam where it came together. I'm now have 237 hours on my motor and the filter still looks fine. leafCatId=11102&skuId=305376&productId=p301500&mmyId=

bben posted 04-24-2011 02:04 PM ET (US)     Profile for bben    
Dbrown, thanks, again. Two more questions. First, did your old filter look and feel oily and sticky? Second, before modifying your filter , did your motor shoot out black carbon soot on warm start ups? I just cleaned my intake throttle body and noticed it had a sticky goo film, so I cleaned it in the hope that will cure the black soot issue. Ben
dbrown posted 04-24-2011 08:19 PM ET (US)     Profile for dbrown  Send Email to dbrown     
Yes, the filter was beginning to get darker and sticky, but I can't say it was necessarily oily. The filter just starting to get the "goo" appearance and feel that is often described by other owners of the same motor. I did notice that, on occasion, I would see what appeared to be some small particles of carbon and unburned fuel that discharged from the propeller exhaust on start up. I could see the "carbon" specks floating on the water and a small sheen of unburned fuel very clearly. If I recall correctly, this was before I changed the filter. I have put an additional 130+ hours on the motor since changing to the above mentioned filter material and I have not noticed this happen since then. I also never had the rough idle problem that you were describing, although the motor never did sit absolutely still when idling in neutral. In my opinion, Mercury knows there is a problem with those filters but is failing to own up to it. I also find it ridiculous that you cannot buy just the replacement filter media, but must buy the entire filter assembly for the outrageous price of $87.00.
bben posted 04-24-2011 08:32 PM ET (US)     Profile for bben    
Thanks again; I emailed [Mercury] and asked a local [Mercury] service center for the name of a regional manager...I will report back if and when I get a hold of someone. You are so right about the cost of the filter and what they can sell material like you used to wrap the housing with. My motor is still under warranty and I am going to try to get them to pay for the filter but I am sure I will have to front end the payment, which makes getting reimbursed highly doubtful. Today, I ran the motor with not of the material in the filter - I removed all of the gooey junk and the motor ran better than ever, faster and hitting higher RPM. I still had the black carbon on warm starts, however. Thanks again and I will report back if I get anywhere with [Mercury].
dbrown posted 04-25-2011 12:15 AM ET (US)     Profile for dbrown  Send Email to dbrown     
Hope you have better luck than I did when I contacted Mercury. The reply I received was that it was a maintenance item and was not covered under warranty, even though I explained it was literally falling apart and not just dirty. Dealer was not much help either, although he did submit it to Mercury and received the same answer I did. Hopefully your dealer will have more success and come through with a replacement. But like I said, it will be the same material and it will do it again.
jimh posted 04-25-2011 11:43 PM ET (US)     Profile for jimh  Send Email to jimh     
Many thanks to dbrown for the clear photograph of the air filter on the Mercury VERADITO or FOURSTROKE 90-HP which is a source of problems.

There are millions of automobiles running on ethanol-gasoline blended fuels that have air filters which do not disintegrate in 100-hours of operation.

How much is an OEM Mercury replacement filter? $87? That is crazy-expensive.

chuck21401 posted 04-27-2011 02:22 PM ET (US)     Profile for chuck21401  Send Email to chuck21401     
Interesting thread. I have a 2008 170 Montauk with the 90 FourStroke engine. I will check the air filter on my engine and report back.


chuck21401 posted 04-28-2011 07:23 AM ET (US)     Profile for chuck21401  Send Email to chuck21401     
I checked the air filter on my 90 FourStroke. The filter looks OK, but upon closer inspection it is starting to disintegrate. The filter feels sticky and oily.

The part number for the OEM filter that I've found is
35-897575T02 and the lowest price I've found online is $60.

Rick U posted 04-28-2011 01:39 PM ET (US)     Profile for Rick U  Send Email to Rick U     
Would this be the same air filter on the Mercury VERADITO 115 ?
bben posted 04-28-2011 03:08 PM ET (US)     Profile for bben    
I had some success with Mercury. I recievd a telephone call after filing out a very detailed report using the online contact us email. The Mercury woman asked for the dealer and then the dealer contacted her and they replaced the filter under warranty (I am going on 4 years under a 5 year warranty). They clearly recognized the issue and asked that the dealer send the filter back for their engineers to examine. We will see if they modify the material. The new filter unfortunately is exactly the same and I have NO confidence that it wont eventually break down but I will keep a much closer eye on it. I plan to call Mercury after a couple weeks and follow up. I want to know what they plan to do for long term solution. The dealer claims that the motor runs fine - they hooked it up to the computer and it didnt throw any abnormal readings - I wish they pulled the plugs. I still get black soot (I assume it is carbon) out the prop exhaust on warm starts, sometime very heavy. I had the dealer replace both fuel filters and I will run it fo a bit and see if that issue clears up. I was using ethanol for some time before recently switching to non-ethanol. Maybe it will take a while for all carbon build up to get cleaned up. I also swapped out the stainless prop for an aluminum one after getting a bent prop shaft as a result of running through some very shallow water down in the Keys. Supposedly, the performance of the aluminum prop will be the same but we will see...I will report backon all these issues. I would encourage anyone having the air filter issue to contact Mercury.
dbrown posted 04-28-2011 03:40 PM ET (US)     Profile for dbrown  Send Email to dbrown     
Thanks for the filter update. Good to hear they took care of you. I think at this point I will keep the aftermarket filter material I have on there now, since I have seen no degradation so far. I'd also be curious to the outcome of your running problems and carbon deposits. The 115 HP (Veradito) also uses the same filter.
sapple posted 04-28-2011 07:24 PM ET (US)     Profile for sapple  Send Email to sapple     
chuck21401, where can one go to purchase the air filter for this engine? I assume I could go to a Mercury dealer but that would be the most expensive route. When I go to web sites, including Mercury Marine's site, I can't seem to find air filters. Is there a particular web site that you can recommend?
bben posted 04-28-2011 08:17 PM ET (US)     Profile for bben    
Chuck posted the part number in this thread and you can buy it from here (I think it will be expensive no matter where you go; I dont thinlk there is an aftermarket version):,12586-50.aspx

dbrown posted 04-29-2011 12:24 AM ET (US)     Profile for dbrown  Send Email to dbrown     
Another source: 1B366823%20%26%20Up/Integrated%20Air%20Fuel%20Module/parts.html

Rick U posted 04-29-2011 07:44 PM ET (US)     Profile for Rick U  Send Email to Rick U     
It does appear to be the same filter used in the following motors:

Integrated Air Fuel Module is a part of the following model(s):
75 EFI (4-STROKE) 100 EFI (4-STROKE)
115 EFI (4-STROKE)

sapple posted 05-02-2011 06:54 PM ET (US)     Profile for sapple  Send Email to sapple     
FYI, here is part of an email Mercury sent me.

Thank you for contacting Mercury Marine in regards to your Mercury 90 EFI 4 stroke outboard motor, serial number 1B367060, we appreciate the opportunity to assist you.

The part number for the air filter you are inquiring upon is 35-897575T01.

skinnywater posted 05-03-2011 01:17 PM ET (US)     Profile for skinnywater    
After reading this thread and getting my boat out on the water again this weekend I want to Thank You all for posting (and to jimh for hosting). Upon reading this thread I immediately recognized the "gooey" condition you all refer to - I have a 2007 170 Montauk and this has been a source of consternation to me for awhile. I had noticed this condition starting by the end of the first season but have not used the boat very much each season since first getting it (maybe 30 hrs max per - We are now entering our 4th season). We have the boat winterized and made ready for season at the dealer but they had never mentioned the air filter.

I took pictures today:

90 EFI Cowling:

90 ELPT Data Plate:

90 EFI Air Filter:

I will contact Mercury and see what can be done, or if this is "the new normal" to be expected.


skinnywater posted 05-03-2011 01:24 PM ET (US)     Profile for skinnywater    
Left out from above: if you notice in the Air Filter 3 picture there seems to be a greasy/oily substance on the filter's rubber outer shell (and my air line has obviously popped off).
bben posted 05-06-2011 09:55 PM ET (US)     Profile for bben    
Max, I too had the oily substance. I wonder if the fact that the hose has popped off is consistent with the theory that the motor is backfiring through the air intake, which is what one mechanic told me could be causing the filter element to break down. Have you been running ethanol gas (regular gas that you get at any gas station) or marine gas without ethanol (that you can generally only get at a marina)? Also, have you had any carbon soot come out the prop exhaust on warm starts? Ben
sapple posted 05-13-2011 06:13 PM ET (US)     Profile for sapple  Send Email to sapple     
I ordered this filter assembly and just received it. The filter fabric material is black, unlike, the tan color in some of the pictures posted above. Maybe Mercury is using a different material now.
Sixer posted 05-20-2011 09:01 PM ET (US)     Profile for Sixer    
Glad I found this post. I was a poster here about 8 years ago until I sold my Outrage. Just picked up a 2007 Montauk with the 90 4-stroke a month ago. First thing tomorrow I will be checking the filter. It appears that the foam of the filter is dissolving, as if some sort of solvent has come in contact with it. Not sure of where the hoses on the filter come/go from/to, but if they are for emissions it is possible fuel fumes could be the problem. The dealer I bought the boat from swapped out the aftermarket fiberglass tank the Montauk had and put in an aluminum one at no cost to me because of the problems with ethanol and fiberglass.
Sixer posted 05-24-2011 03:18 PM ET (US)     Profile for Sixer    
Checked the air filter; it is brown and tacky to the touch. Spoke with 2 Merc service reps at 2 separate dealers, one eing my regular rep, and both say this is not a problem. Both also said it is not really a filter but a silencer for the intake and if it deteriorates with age to replace it. I ordered a new one and will keep check on it based on the coditions of my use.
ktm3ten posted 05-24-2011 09:11 PM ET (US)     Profile for ktm3ten  Send Email to ktm3ten     
so again...what would be the consequence of simply removing said filter? Lots of older outboards had no filters, right?
Sixer posted 05-25-2011 09:44 AM ET (US)     Profile for Sixer    
As it was explained to me, there would be an increase in noise from the air entering the intake. I would still want some sort of screen covering the intake.
sloppyrudder posted 06-11-2011 09:20 PM ET (US)     Profile for sloppyrudder  Send Email to sloppyrudder     
Has anyone found a solution to this? I just noticed the carbon looking discharge on the water behind my outboard. I got home, looked online and found the thread. After taking the cowling off, about 40% of the filter is gone and the entire filter is gooey / sticky. I've just ordered a replacement, which I'm assuming is the same cheap foam media. I'm concerned about how much of this media my motor has ingested.
Jefecinco posted 06-12-2011 11:01 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
An air filter which disintegrates allows filter media to enter the engine. IMO, that is worse than no filter at all.

A screen is probably not necessary but would do no harm. Intake noise may increase but I doubt it would be very noticeable when on plane nor very objectionable at slow or idle speeds. If you use a screen inspect it often. it may become corroded faster than you would think particularly around salt water.


sloppyrudder posted 06-15-2011 05:43 PM ET (US)     Profile for sloppyrudder  Send Email to sloppyrudder     
I emailed Mercury about the problem, and they told me to take it to a dealer. I've ordered a new element, something I will have to keep an eye on I suppose. I'm a little disappointed that Mercury is not more responsive to what appears to be a common issue with these motors.
chuck21401 posted 06-16-2011 01:05 PM ET (US)     Profile for chuck21401  Send Email to chuck21401     
>> I emailed Mercury about the problem, and they told me to take it to a dealer.

I just decided to be buy a new filter and be done with it. The effort involved in taking the boat, motor, trailer to the dealer and leaving it their for a service appointment is entirely too involved.

Mercury needs to evaluate the problem and come out with a revised part. They are aware of the problem.

Alphonse posted 10-27-2012 06:51 PM ET (US)     Profile for Alphonse    
Just discovered a gooey filter/silencer as described here on my 2009 Montauk (90 hp)

Wondering if anyone has had any luck with Mercury on this issue?

Kelry posted 11-06-2012 02:26 PM ET (US)     Profile for Kelry  Send Email to Kelry     
Is there such a thing as a Veradito? I have a Mercury Four Stroke engine, but it is called a Verado. I have searched the internet, and have not found a Veradito model. Is that what they call a Four Stroke model less than 100HP?
bben posted 11-07-2012 07:01 PM ET (US)     Profile for bben    
hey guys, since I started this post, I wanted to chime in and let you know that I did NOT get any response from Mercury. The dealer repaced it under warranty and so far, for the past 25-30 hours, no issue. I haven't seen my boat in 3 months though. I am heading south to get it ready for the season down there and will check it. Ben
boatdryver posted 11-10-2012 08:44 AM ET (US)     Profile for boatdryver  Send Email to boatdryver     
Kelry, "Veradito" is a term coined by jimh, moderator of this site to denote a four stroke Mercury outboard motor based on the four cylinder Verado block but normally aspirated. I think this includes the 90 and 115 hp models.

Do a search for Veradito on this site and you'll get a lot of information.

bben posted 01-01-2013 06:55 PM ET (US)     Profile for bben    
Well...I have another one that I just noticed is deteriorating. This is really frustrating. I had no carbon ou the exhaust the last several hours and I noticed the varbon yesterday and I decided to check the filter and sure enough the filter is about 1/3 gone. My motor is now out of warranty but I am going to try to contact mercury and see if they will send another repalcement. I fear that I need to add this to my annual maintenance. I will let you all know how I make out.
Jefecinco posted 01-01-2013 08:04 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
What is the down side of eliminating a filter that ultimately does not filter. I would think a screen would catch almost anything you would expect the engine to ingest while running on the water. A deteriorating foam filter would seem to me to be virtually useless at filtering dust. What is the value of this thing?


fishinchips posted 04-23-2014 12:44 AM ET (US)     Profile for fishinchips  Send Email to fishinchips     
I think merc changed the filter media. Also the part number to 358-M0082911
fishinchips posted 05-11-2014 10:43 AM ET (US)     Profile for fishinchips  Send Email to fishinchips     
mercury changed the part.
first it was 35-897575t01 (disintegrating filters)
then changed to 35-897575t02 (don't know what changed?)
then changed again to 358-M0082911 (the last change the element is different)


deltateachingsupply posted 06-04-2014 11:30 AM ET (US)     Profile for deltateachingsupply  Send Email to deltateachingsupply     
i have 2008 mercury 75 horse that the filter has detonated. i saw a part# 358-M0082911, has anyone tried the new part, and does it work. do i even need an air filter?

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