Mercury Compressor Strainer

FlatsBoyFlatsBoy Posts: 1,376 Officer
There has been some questions about Mercury's clogging up while running in the Keys or any shallow muddy sandy bottom!

Well first hand knowledge is when you run the motor threw sand shell and mud your going to have a problem! It will clog up the inlet strainer to the compressor which exits the back of the motor threw the pee port! When you run the motor threw lots of silt,weeds,sand or shell the strainer will build up and not let the bigger media pass threw restricting water flow to the compressor which will cause premature failure do to heat build up from not cooling properly. Yes you will get little pieces stuck in the pee hole port and it will need to be cleared. But the real problem is the inlet screen on the port side of the power head needs to be removed and cleaned along with hooking the motor up to the flush port and back flushing the motor to remove all the sediment that is trapped in the lower block!

You must remove the side panels to gain access to the strainer which is on the port side toward the bottom rear. It is a plastic fitting screwed into the side with a hose that cools the compressor then exits the motor. Here are a few pics below of the location and part number. You can see the weeds and shell stuck to it along with that is inside the block. It is imperative that you back flush the motor with the strainer out so you can clear all the debris settled in the bottom of the power head which can't be seen other than what is right at the hole. Once flushed wrap some teflon tape around the treads and re install and re attach the hose. You may want to order a back up strainer because it is made of plastic and I've seen them crack when taking them out or strip while re installing just saving! Hope this helps anyone with a Mercury!

Part is the same for all 115 150 175 250 Mercury Pro XS engines Part # 8348084

This is normal maintenance you must do and should be done at every 100 hours or when you know you ran your motor threw the ****!:grin

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Replies

  • mbowersmbowers Posts: 496 Deckhand
    That looks a little bit easier to get to than the Hull Truth description which seems to indicate trimming off hose clamps and having to buy factory replacements for the clamps. I guess no reason you can't keep the older strainer to use as a replacement in case you break one.

    It would be REALLY valuable to Merc owners who run in shallow water if Merc could at least move that strainer to somewhere it can be cleaned by just removing the cowling and not having to open up the side panels...

    While that strainer might be the real problem, for me clearing the pee hole made the huge difference between coming back 5 miles on the trolling motor versus getting the Opti to run again for more than 60 seconds at a time.
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    mbowers wrote: »
    That looks a little bit easier to get to than the Hull Truth description which seems to indicate trimming off hose clamps and having to buy factory replacements for the clamps. I guess no reason you can't keep the older strainer to use as a replacement in case you break one.

    It would be REALLY valuable to Merc owners who run in shallow water if Merc could at least move that strainer to somewhere it can be cleaned by just removing the cowling and not having to open up the side panels...

    While that strainer might be the real problem, for me clearing the pee hole made the huge difference between coming back 5 miles on the trolling motor versus getting the Opti to run again for more than 60 seconds at a time.

    The strainer or location is not the problem it is there to prevent you getting to much big debris in the compressor which you will not be able to clear with a piece of wire threw the pee hole. The real problem is running our motors threw the Mud and Sand! lol :shrug
  • rocketman1rocketman1 Posts: 187 Deckhand
    While you are at it, check the thermostats. Easy to clean em out, but may have some debris in them too.
    NO HABITAT = NO FISH
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    rocketman1 wrote: »
    While you are at it, check the thermostats. Easy to clean em out, but may have some debris in them too.

    Absolutely check the thermostats any time you suck up debris. You may want to also pull the pop it valve on the opposite side (starboard) of the strainer to see if there is anything in there also.

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  • FishinMcNutFishinMcNut Posts: 536 Officer
    I carry a swivel head ratchet with 5/8's deep socket on the boat for this very reason. Have only had to use it once!
  • Renagade69Renagade69 Posts: 1,232 Officer
    This strainer should be in an easier place to access. Can you drill an access hole in the cowling and add a grommet to make it look factory?
    Hells Bay Estero Bay Boat and Hells Bay Marquesas
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    Good idea but since the side panel is curved there. It would be hard to find plug that would look good easier to take the side panel off. Four screws and 10 minutes of time!
  • FishinMcNutFishinMcNut Posts: 536 Officer
    Five minute operation with a swivel ratchet :wink
  • mbowersmbowers Posts: 496 Deckhand
    FlatsBoy wrote: »
    The strainer or location is not the problem it is there to prevent you getting to much big debris in the compressor which you will not be able to clear with a piece of wire threw the pee hole. The real problem is running our motors threw the Mud and Sand! lol :shrug

    Well running through some mud and sand is in the mission statement for my boat and I expect to do it on nearly every trip. Most motors run forever if you just run them in a tub of fresh, clean water but that's not the real world of a shallow water fishing boat. I appreciate that it's a more sophisticated motor which needs that strainer and that strainer can get clogged but they should make the strainer easily maintainable FROM the boat if they want repeat business from shallow water boaters IMHO.

    It does appear to me that running the motor in reverse when it touches mud is much worse for causing an overheat issue than in forward. I imagine the prop is throwing the muddy water forward over the water intakes when running in reverse so more sediment is ingested. When the motor is in forward gear at least the water intakes see the water before the prop has disturbed it..
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    Everything is a trade off. Can't say i disagree with you on making it easier to get to. But if you want that type of motor you need to live with the manufactures design and take care and do basic maintenance on it. If you want to run in real shallow water and kick up bottom any motor is going to get clogged up eventually Some easier than others. The Yamaha's and Etecs get clogged even easier with their screens on the sides of the lower units. I couldn't run threw any grassy or turned up water without overheating my Etec when i had it. I even installed the larger screens they offered. Maybe a mud motor or jet drive would work better for mud bogging!
  • Renagade69Renagade69 Posts: 1,232 Officer
    Mercs the only motor that comes with a filter for the cooling water. To me that is a flawed design.
    Hells Bay Estero Bay Boat and Hells Bay Marquesas
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    Renagade69 wrote: »
    Mercs the only motor that comes with a filter for the cooling water. To me that is a flawed design.

    Not a flawed design at all. The strainer is only one part of the cooling system and prevent debris to large to enter the Air Compressor which is part of the fuel deliver system. The strainer does not restrict the main water flow threw the block or cylinder heads.
  • Egrets LandingEgrets Landing Posts: 949 Officer
    FlatsBoy wrote: »
    Not a flawed design at all. The strainer is only one part of the cooling system and prevent debris to large to enter the Air Compressor which is part of the fuel deliver system. The strainer does not restrict the main water flow threw the block or cylinder heads.

    It seems to me the pro xs overheat alarm due to a clogged up pee hole is a design problem. It seems to happen to me almost every day and sometimes two or three times. Granted, I run through lots of shallow areas and do very long runs as well and some mud gets kicked up sometimes but it seems it only takes the very smallest amount of debris to clog the hole and prevent circulation. I am talking a few large grains of sand or a tiny pebble will do it. I was thinking of widening the hole some but not sure if that will create another issue. I need to discuss with my mechanic. My old EFI never did that even once. And it could happen at the most inopportune time. Last year on the Marquesas run we got caught coming back in a big storm with a waterspout nearby and were running back and I had to shut it down due to a few grains of sand in 30 kt winds, some larger seas, a downpour and a tornado nearby. If it happened running in an area where you need to stay on plane or stay for 8 more hours (like maybe the inner narrows at dead low tide at 9 pm) until the tide turns it could be a real hassle.
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    You can enlarge the holes on the plastic output. That will pass larger debris getting stuck behind it because there is a separator in there. If it causes a loss of back pressure which i can't see being a problems you can buy a new piece and install. It just pops out of the rubber boot and is connected with a zip tie! The Yamahas have even a smaller output for water than the Mercs. Once again if you run your motor threw enough mud and sand what do you expect is going to happen!

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  • Renagade69Renagade69 Posts: 1,232 Officer
    FlatsBoy. I don't know if you read the post but the shallow water of the keys is loaded with sand. Mercury should have built the motor to be less temperamental. Larger passages through that compressor would have been ideal. Sometimes the genius engineers lack common sense.
    Hells Bay Estero Bay Boat and Hells Bay Marquesas
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    FlatsBoy wrote: »
    You can enlarge the holes on the plastic output. That will pass larger debris getting stuck behind it because there is a separator in there. If it causes a loss of back pressure which i can't see being a problems you can buy a new piece and install. It just pops out of the rubber boot and is connected with a zip tie! The Yamahas have even a smaller output for water than the Mercs. Once again if you run your motor threw enough mud and sand what do you expect is going to happen!

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    Here is the response from a Mercury mechanic. So there is a back pressure engineered into the fitting for water pressure so i stand corrected on that.

    I've seen this done. More of using the same diameter drill bit, and "straightening" the angle of the flow (not so much enlarging the opening). You have to be careful... opening it up too much will result in low water pressure (potentially).

    Not really specific to just those two engines- most all of the V-6 Optimax engines use the same fitting. It's much more specific to the "trash" the engines are running through (keep in mind, this same debris WENT THROUGH WATER PUMP, can be in STRAINER, in THERMOSTATS, and in Poppet Valve).


    So i guess every engine manufacture needs to engineer there motors to run threw sand mud and shell and never have a problem according to some!
  • Renagade69Renagade69 Posts: 1,232 Officer
    Apparently the other Manufactures have done that already.
    Hells Bay Estero Bay Boat and Hells Bay Marquesas
  • FlatsBoyFlatsBoy Posts: 1,376 Officer
    Renagade69 wrote: »
    Sometimes the genius engineers lack common sense.

    You said it best!:funnypost
  • mbowersmbowers Posts: 496 Deckhand
    That first trip to the Marquesas, the Etec and the Yamaha overheated with weed debris while the two Merc EFIs ran like champs through the surface weed.. :)
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