115 Mercury Optimax Impeller

Replacing the impeller (water pump) in a 2007 Mercury OptiMax 115 hp outboard (2-stroke)
Below is the link to the video I mentioned about building a lower unit service stand:
• Making a lower unit se...
Thanks for watching!

[@tuber5129]

I'm going to comment here so that another "home mechanic" researching this topic doesn't have to go through the pain that I did. First of all, thanks for making this video. I watched several videos before trying my impeller change for the first time. So long story short, nowhere in the the service manual or owner's manual does it say to drain the engine oil before dropping the lower unit. To my surprise, I had a flood of engine oil pouring out when I removed the shaft and dropped the gear box. I tried to research the problem on line and found a few people who had the same problem, but what they were being told was they had a costly engine oil leak and would need major repairs. This just didn't sound right to me, because I could see a hole at the top of the opening where the drive shaft stops, so I started to do more research. I won't go into detail, but the bottom line is that at least on my 2013 115EFI Four Stroke, you need to drain the engine oil before removing the gear case. I confirmed this with three different Mercury certified mechanics and called Mercury customer service. I realize the 115 two stroke is different than the Four Stroke, but I just wanted to mention this so someone else doesn't make a mess like I did.

[@TheAfterWorkGarage]

Thank you for your comment and the information! I have never worked on one of those motors, and likely would have had the same oily surprise on my hands. I'm surprised Mercury designed the motor that way, as I have seen the motors with the bottom crank seal ABOVE the splined socket for the drive shaft, and it seems far easier to service. Then again, it wouldn't be the first time engine designs seem to make no sense. If you have any further insight into why this is, I'd be interested to hear it!

[@tuber5129]

The After Work The only other info I got from Mercury is that the newer Four Strokes (at least 2013 and up) are the same powerhead as the Verado. If you look at a Verado owners manual it will tell you to drain the engine oil before servicing the impeller. It doesn’t say that anywhere in my manual. I was surprised how little info there was on line about the issue and even more surprised that I talked to one mechanic who knew nothing about draining the oil and told me no oil should be leaking out after dropping the lower unit. At $100 per hour in labor costs, that could have been a costly bit of misinformation.

[@azr2d1]

uhm, this is a 2 stroke. No engine oil. Does not apply here. Don't confuse people. The only oil is the tail oil which is below everything we see him service.

[@cbofresh861]

I just got a used boat with a 2006 Mercury EFI 90 4-Stroke and was really surprised and concerned to see a pool of oil in the transom area and on the floor. The oil appeared to be coming from the shaft area. All the videos I watched never mentioned draining the oil before changing impeller and not in the manual either.

[@brettprovost7650]

I was having problems getting mine to line up you just answered the question thank you for putting that video out

[@larrythompson5617]

As I was watching I was saying to myself, "secure the bottom end" then suddenly BANG, down goes the bottom end. Your not the first and won't be the last to have this happen. Glad there was no damage. Good video. Thanks for the refresher. One reason I leave the nuts partially attached. Try a ratchet wrench. Works great.

[@nelloagostini4389]

Ok so after seeing you remove the lower unit I just had to see you put back on and you did not disappoint. Entertaining to say the least.

[@reid092353]

Just a suggestion about installation of impeller: run it down on the driveshaft, engage the key, lubricate the top part of the impeller veins & rotate drive shaft as you apply pressure to the housing.

[@stuartbertles8721]

Great video! Thank you for your instruction! Entertaining and informative!

[@TheAfterWorkGarage]

Glad it was helpful!

[@mikesumner5129]

FYI, that second hard plastic round thing in the kit is the install tool for the black rubber seal that slides down the shaft. After you slide the rubber seal on untill it just touches the metal housing, put the plastic installer over it and push it down untill it stops. It sets that rubber seal at the correct height.

[@TheAfterWorkGarage]

Thanks for the info!

[@seanweng8674]

Thank you for the video, it gave me confidence to do it myself.

[@TheAfterWorkGarage]

Glad it helped!

[@TheFritz423]

Leave two of the nuts on but backed off almost all the way. Once you crack the lower unit loose (as you did) you can remove the remaining nuts by hand as you support the lower unit.

[@kristievanthul7086]

A tip for you,grab 2 6 mm bolts cut head off grind smooth,then insert for dowls to make it easy to put your layers together

[@teresatrembath754]

Great video

[@kiknbss14]

I have the same engine...went outside yesterday and the overheating alarm was going off (long constant beep). It was shooting out water and not smoking. I don't have any gauges to know of water temp. I was thinking of just changing the thermostat. Any other possibilities? Oil tank was also 3/4 full.

[@TheAfterWorkGarage]

Definitely check your poppet valve along with the thermostat (they're in the same housing) to make sure it's not suck in the close position. I would also run water from a hose back through the poppet valve hole, and any other coolant hole you can find. Often these overheads occur when debris gets lodged in one of the coolant passages and prevents cooling to part of the engine, while water is still able to come out of the telltale. One other note - I believe the system will also beep to alert you of a low temp situation if the engine is idling and the water temp is not coming up. This often happens when the poppet valve is stuck open (I had this happen to me).

[@kiknbss14]

@@TheAfterWorkGarage thanks yes that's what I am thinking a low temp because the water was 42*...I don't think the temps were hot...I ordered some parts for it...Thanks for your reply.

[@catfishstalkeroutdoorswith530]

Thanks for the video

[@alwayssharp]

Thank you

[@reid092353]

I was cringing once you started tapping the lower section. Glad you didn't injured. What position did you start at? Forward, neutral or reverse?

[@TheAfterWorkGarage]

In general I'll have it in neutral, but whatever position you chose, it's important that the shifter is in the same position as the lower unit (which is what gave me trouble at the end of this video)

[@zee-lv4jh]

FYI Teh gaskets are only capable of being installed in one direction. Hard to do it wrong

[@cbcb3661]

Nice video. When will you be making how to change your lower unit oil?

[@brycewilson8057]

Thank You for leaving the BS out ! The Job Is Done! Thank You !

[@TheAfterWorkGarage]

Thanks, it was my first video, so still had a little bit of improving to do!

[@davideason9343]

How did you make sure the lower unit is in gear if you forgot to do it ahead of time? I've tried turning the shift linkage clockwise and putting the throttle in gear but when I put it back together the gears didn't work.

[@TheAfterWorkGarage]

Hi, it's kind of trial and error. You can turn the shifter shaft on the lower unit and then spin the propeller by hand and see if the driveshaft is forward/neutral/reverse and then put the shifter at the console in the same position.

[@gassmank]

Hey, I noticed you’re running a 4 blade SS prop. What pitch did you run, and are you happy with it? I bought one with too shallow of a pitch, and it’s over spinning at high rpms.

[@TheAfterWorkGarage]

The prop on there (which I use most of the time) is a 17" Trophy Plus which I use 90% of the time. It's great for getting on plane quick (this boat is heavy), and still tops out around 40mph. I do also have a 21" stainless steel X7 Spitfire which really scoots, but is really only appropriate in a lightly loaded boat. I would probably rather have a 19" to the 21" on this boat, but it's what I have, and for my uses the 17" is what I run almost all the time anyways.

[@marcelobesen4067]

Hello Friend. makes a video on how to remove the thermostatic valve. there is no video talking about it. valve when the engine is heated. let the water pass, do you know what it is?

[@TheAfterWorkGarage]

There's actually two valves that regulate water flow. One is the thermostat (the smaller of the two) and the poppet valve (the larger one). The thermostat regulates temperature at idle/slow speed and allows cooling water to circulate once the engine is warm but at low speeds. The larger poppet valve is spring loaded, and regulated by water pressure, opening up a larger passage for cooling water when the engine is at a higher speed. Both sit in housings next to each other with one plate as the cover for both. Once this plate is removed, either valve can be removed and replaced. Unfortunately I didn't film unclogging my motor with sand, but if I have to replace either valve in the future, I'll be sure to make a video on it.

[@marcelobesen4067]

@@TheAfterWorkGarage tks !!!!!!

[@Agent0range67]

2:07 the thermostat/poppet valve is temperature controlled.

[@TheAfterWorkGarage]

In this and many engines, the thermostat is separate from the poppet valve. The thermostat controls the water flow via temperature sensitivity, and is primarily important during idle and engine warm up. The poppet valve is opened by water pressure through the engine (it is spring loaded), and ensures enough water flow during higher speed operation. Under these conditions the much smaller thermostat is much less important in controlling engine water flow

[@kimolsson3227]

can you please make a video how yo get the engine cover off i cant get my cover off

[@TheAfterWorkGarage]

I'll try to get something out this weekend, but in short, there's one handle in the back that pulls out, then lift from the back and rock it off the hooks on the front.

[@kimolsson3227]

@@TheAfterWorkGarage pls make One 👍

[@TheAfterWorkGarage]

@@kimolsson3227 Video posted - kzbin.info/www/bejne/amfEpalqbalgh5Y

[@melloreel]

Not to second guess but you installed the vanes backwards? They should press against housing with driveshaft rotation, not be cupped? Maybe I saw it wrong? Thanks for vid👍

[@azr2d1]

Don't think so. The vanes should follow, not lead.

[@kristievanthul7086]

Shawinggg dammit I’m rolling

[@colin_87]

what are the specs on the prop?

[@TheAfterWorkGarage]

I know this comment was a while back, but the prop is Mercury Trophy Plus 17" Stainless Steel that I use most of the time. Gets on plane really fast, and holds the water through turns amazingly well. A little under pitched when the wind is at my back, but flat out will still around 40mph (though I usually run it about 80%). I also have a Stainless SpitFire X7 21" that really flies if I'm alone in the boat with an empty livewell, but is really to much pitch for a boat this heavy w/115hp.

[@chrishussey1054]

A bit of grease on the spline ect helps next time you drop your leg. I'm glad you don't service mine.

[@TheAfterWorkGarage]

Thanks for the comment, and yes it was definitely my first video (seems so long ago), so you live and you learn!

[@marcelobesen4067]

friend makes video. to remove thermostatic valve

[@steveduncan131]

Where do i find you video cleaning the sand out ?

[@TheAfterWorkGarage]

Unfortunately I didn't film that. That happened shortly before I started making videos, and I was anxious to get my boat back on the water. If something similar happens again, I'll be sure to film it.

[@steveduncan131]

I put a new impeller on yesterday but I’m still getting A constant alarm I’m lost now don’t know what else to do

[@TheAfterWorkGarage]

@@steveduncan131 If you have the mercury smart craft gauge, look at the water pressure, it should be around 13-ish psi when running or 3-ish at idle (ballpark numbers) If it seems really low, then make sure you put all the parts back when re-installing the lower unit. I have in the past forgotten to install the small rubber connector that goes between the impeller housing and the water tube in the leg. This caused overheating due to insufficient water pressure. Also, make sure you put the woodruf key back in the impeller (without it, it won't be locked the the shaft and won't spin), and make sure all of the plates under the housing are in the correct orientation. I'm sure I'm missing something here, but good luck, and let me know if you're still having problems.

[@steveduncan131]

Thank you looks like I’ll take it back off to check the impeller goes on counter clockwise ?

[@TheAfterWorkGarage]

@@steveduncan131 The impeller turns the same way as the engine/driveshaft. This is clockwise looking down from the engine to the lower unit, but counterclockwise as you're pushing it into the impeller housing from the bottom.

[@dazmc8473]

Allowing unit to drop on ground...amateur

[@marcelobesen4067]

friend makes video. to remove thermostatic valve

[@marcelobesen4067]

friend makes video. to remove thermostatic valve