Yearly Maintenance- Impeller Changing


I've posted enough I should edit this section
Apr 22, 2013
Huntington Beach, ca, u.s.a.
Mako 192 cc
I have a 2008 Verado 150, and after listening before me nuts that hold the lower unit on, it still will not drop. Am I missing a nut or both somewhere? I can't seem to find anywhere where it tells me what to do...

Riding High

Professional Curmudgeon
Feb 11, 2010
La Cresta, CA
Parker 2120 - Riding High
I have a 2008 Verado 150, and after listening before me nuts that hold the lower unit on, it still will not drop. Am I missing a nut or both somewhere? I can't seem to find anywhere where it tells me what to do...
Did you get the "hidden bolt" under the anti-cavitation plate? You have to remove the zinc cavitation plate.

Miss Fitz

Call me Captain
Mar 4, 2013
26' TwinVee Pilot House
How do I remove that!!???
Take a picture of the underside lower assembly and post it. I originally wrote this tutorial for Suzuki 4 strokes because I had experience with those, but posting other manufacturers (Honda, Yam, etc) can be a great help to other DIY'ers.

My guess is you probably have one additional lower unit long bolt that's located underneath the skeg (it looks like a fin). Take the skeg off and I bet you see one last bolt you'll need to remove.


I've posted enough I should edit this section
Jul 4, 2015
Skipjack 24 Open
NIce tutorial. Is this the same for an I/O? I have a Mercruiser/Bravo 2.


Mike x 5
Dec 7, 2004
Somewhere n Vista
Blackman 23, 20 Skipjack, 15 Valco westcoaster
Can I suggest that you try replacing the never seize with marine bearing grease.
I use m- grease on my prop splines and all bolt/stud threads.
Problem with never sieze is that it creates electrolysis if boats are used in salt water.
No scientific data just my own experiences.


Sep 30, 2012
Oxnard /CA /USA
1995 Crestliner Eagle 225
yes, this is so easy that even a cave man can do it :D

You need some basic tools, some beer, and a small gauge hand gun if you fuck it up:shake:

Step 1: ID your engine, go to your dealer and pick up an Impeller kit. I have a Suzuki DF140 and my kit was $50. Also get some "anti seize" for your bolts- (this will be needed to close the patient) its about $4 a tube.

Step 2: Liquor store- 6 pack of your favorite

Step 3: assemble your tools (this includes one decent sized friend/moron to help you support the lower unit in a later step)

Step 4: Open beer and tilt the motor to about a 45 degree angle. Your gear shifter should be in the "Forward" position.

Step 5: Remove the cotter pin from the prop and back out the castle nut that holds the prop down. Gently tap the forward part of the prop to remove it from the lower unit. This is also a good time to clean up your prop and remove any salt deposits, dirt or grime from all visible surfaces.

Step 6: Begin removing the lower unit support bolts- there should be about 6 of them depending on the manufacturer

Step 7: I ALWAYS alternate putting screws in, or out using a "star" pattern. I NEVER remove or tighten bolts in a "straight line". LOOSEN BUT DO NOT REMOVE BOLTS YET!!

Step 8: The last bolt is actually hidden underneath the prop skeg. MARK THE SKEG position before you remove the skeg. Oncetheskeg is off, remove the last bolt to the lower unit completely and set it aside.

Step 9: Get your large pal now and have him help hold up the lower unit while you remove all the bolts. Once the last bolth is removed, gently remove the lower unit from the main part of the engine, and remove the waterline at the front of the lower unit-
(I was into beer #4 now, so insert picture here :D)
Step 9: After removing the waterline hose, gently remove the lower unit and set it on top of something that you can balance it on without damaging it.
Clean off the gear rods from dirt, debris and old grease and begin loosening the bolts around the impeller housing. Here is my Ghetto style work bench:

Step 10: After removing the impeller housing, note the position and "play" the old impeller has relative to the housing and impeller plate. It should have no interference and revolve easily.
Step 11: Gently pry the old impeller up and off of the main gear:

Step 12: Gently remove the old impeller lock key from the drive gear. A flat head screw driver and teeny tiny hammer are fine. BE GENTLE.

Step 13: remove the impeller housing, old impeller gasket and impeller plate. Ensure the new impeller plate, housing and friction spacer match the old ones BEFORE you toss the old ones away! Examine the inside of the impeller housing and remove grime, and dirt. It should be very clean before you put it back on.

Step 14: after cleaning all the parts up, begin by placing the new gasket down around the impeller housing, then place the impeller plate over the top of the gasket.
(insert pic here- beer #5)
Step 15: Install the small impeller key onto the drive gear where you had removed the old one. DO NOT FUCK THIS PART UP AND FORGET TO RE-INSTALL THIS THING-this tiny lock will prevent you from putting the impeller on upside down and also prevents the impeller from "free spinning" on the main shaft which will cause you some overheating problemo's. see repeat pic for position:

Step 16: gently tap the impeller key into position and slide the new impeller into position over it. Match the slot in the impeller to the vertical position of the friction tab, and into position over the impeller plate. The impeller should spin with little or no interference.
Step 17: Place the impeller housing over the top of the new impeller. CLEAN the old bolts with a wire brush and slather the tips with "Anti Seize". Screw the bolts in by hand initially to ensure you don't cross thread. Tighten the bolts in a criss-cross pattern to ensure the impeller housing is mounted straight:

Step 18: We are now ready to reinstall. (Unfortunately at this point, my patience with camera taking took its toll). Regrease the main gear and shift gear as instructed by your dealer manual.
Step 19: prior to lifting your heavy ass lower unit back into place, place a new zip tie over the air hose that still needs to be installed. Here is where the airhose (it's actually a water hose/speed sensor hose)belongs

Step 20: With the assistance of your pal, lift the lower unit into place and reconnect the airhose to the lower unit. Tighten the zip tie and cut the tag end. BE CAREFUL TO ENSURE YOU HAVE ALINGED THE MAIN SHAFT AND SHIFT ROD TO THEIR PROPER POSITION. The shaft and shift rod should slide into position easily, like butta.
Step 21: Coat the tips of the lower unit bolts with Anti seize and begin installing them in a "star" pattern. Don't forget to install the hidden bolt that lives under the prop skeg. Install all firmly (hand tight) or to your manufacturers specifications.
Step 22: install the prop skeg to its original position (which you had marked PRIOR to its removal....right?)
Stepp 23: Finish your last beer and install the prop to its freshly cleaned and lubed drive shaft. Install castle nut to manufacturers specs and insert NEW cotter pin.

Voy-lah. Not too bad huh??:food-smil

Anyone can add tips to this....I ain't no dad gum expert ya know?!?!

If your working on a Mercruiser Alpha I Out drive at step 20 and you do not carefully align the shaft you might damage the seal that it is sliding into "like butter" ,don't ask me why i say this, but suffice to say after step 23 it might be a good idea to pressure test the Drive. What is "Pressure Test " you ask ?
it's a test to find out weather or not you FUCKED THAT PART UP, if you did and You unknowingly take boat out you will then have water in your lube oil and drive WILL internally EXPLODE, DESTROYED.

Tip; if your Mercruiser gets water in drive lube like this Buy a Volvo Penta There's no pump, or impeller, down there ! , Its on front of engine, just say en I think there better.

tuna head

I've posted enough I should edit this section
Aug 13, 2008
watsonville Ca. usa
17ft aquasport cc ksea
mine was so easy i finished the job, couple weeks later my boy was looking at the kit cause his is the same and said dad this is a new impeller in this kit, must have put the old one back in or too many beers there was 1 beer left out of 20?


Condition One
Jun 13, 2008
Parker 2530 "WET-O's"
I do my own twin Yami's every other year. Yesterday the woodruff key on the starboard engine was stuck, and I mean STUCK. I finally resorted to taking the lower unit down to my shop and welding a plate to it to get it out. Worked like a charm. School of YouTube.


I've posted enough I should edit this section
Apr 28, 2010
Southern Maine Sure Its COLD, But Its a DAMP COLD!
Good Tutorial. Be sure to put your Gearshit in Reverse ( Both the ones in the Cabin and the ones on the Flybridge) and the Lower Unit shift in Reverse before you start so that it all sides back together correctly.

LUBE the Rubber Impeller with Silicone Grease or KY Jelly and gently spin ti in the direction of shaft rotation. Usually that is Anti Clockwize but may be backwards if your south of the Equator or some other special circumstance. Grease all the Zercs and the Engine shaft and snifter splines and prop shaft with proper attitude and. start up the engine and watch it spin. Mark your Props for multiple engines. I have on down a few thousads on these and in inadvertently swapped props on a Boston Whaler with twin 150s on day. the boat still ran OK but the owner asked me why it handled different and the wake was not the same. just had to swap the props. Always Make them with a CRAYON as to Port & Starboard and on Triple Engine boat you can write Middle Engine if your so inclined. Be Safe on the Water and Have Fun.



I've posted enough I should edit this section
Jul 24, 2017
San Diego, Calif
Joseph Gratteau
Valco Westcoaster
Thanks for the write up-it inspired me to do it on my 2003 40HP PTEFI 4 stroke. The only rub was disconnecting the shift linkage. See this utube video for the details, note the lower clip , on the front starboard side, tucked away towards the middle, just holds the hidden top clip from getting lost, flipping away to an area unseen. They cannot be on the shaft at the same time. Thanks for the help!!