Tohatsu / Mercury 20HP Water Pump and Impeller - After one year of idle hose flushing method

[@bazbbeeb7226]

Just bought a 2023 Mariner 20hp for my 3.5m RIB, same motor as the Mercury and Tohatsu 20's. Thanks for the informative vid, subbed.

[@commonsensesolutions6662]

Thank you!! I’m sure you will be happy with it!

[@mikestevens2053]

Thanks for doing the follow up, I just bought the same motor and based on past experience with other motors would really favor doing a warm flush Versus just a cold flush. This gives me confidence to do so while idling. Too, I need to flush while the boat is still in the water, and access via the port is WAY easier than a motor muff would be.

[@gfiweb3]

Helped so much cheers, same for my Mercury 6hp 4 stroke. Perfect video

[@bowwave59]

I got Tohatsu 30hp 2022 year of manufacture. The instruction manual says not to run the engine when using the hose connection. Flush with engine running must be with the lower unit in a water butt / tank .

[@tonyt.5316]

Good to know. Not paying $300 for this easy job. Thank you for the video.

[@ozmenlevent]

I had the same concern. I'm relieved thanks to you, my friend. It's a nice experience and thank you so much for sharing it.

[@commonsensesolutions6662]

Thank you!

[@shannonyork5300]

Great follow-up and fine video. Thank you. Here's to a Wonderful Holiday Season for you and your Family. Cheers,

[@bagger2013jm]

Great video. So many time I hear people talking about a key and key way and they label the terminology wrong.

[@jimminniehan2548]

Thank you very much. I just bought the 2022 Tohatsu 15 Hp.

[@teeanahera8949]

It is the same motor as the 20hp. I was going for the 15ph but thought as both are the same weight why not pay $500 more to get the 20hp. Mine will be Mercury, same motor but I note the tiller is different. (Australia.)

[@wacpickleball]

Thanks for the following up video. I watched your previous video and was really curious about the flush port too. I have the same engine and will do the first oil change and lower oil soon. I may pull the impeller to look as well but I always been flushed with the muff. Now I can feel more confident to use the flush port.

[@roughas100]

Great video , the old impeller was in very good condition. Guessing you could stretch it out to 3 year change intervals.? Didn't change my impeller on my 50hp 4 stroke tiller Tohatsu until it was almost 6 years old..... no cracks or damage but it didn't look as good as your 1 yr old impeller...... Just on anti-sieze grease , I use copper on steel to steel fixings ( eg on trailer or vehcile bolts ) or even on electrical terminals but copper grease may not be good for aluminium castings ? Possible corrosion ? I've heard never use copper anti foul on aluminium hulls . Think I used a smear of lanolin grease on those leg bolts . Silver colour anti seize might be ok with SS bolts and aluminium but I'd read / check the label first.

[@commonsensesolutions6662]

Wow that’s a long time. I guess care and storage conditions affect how long they can go as well. Thanks for the anti-seize info. For high-torque fasteners using the exact anti-seize for the job is super important 👍🏻

[@rogerhill3984]

Good demo on changing Tohatsu water pump. Thank you.

[@commonsensesolutions6662]

Thank you!

[@northwestlife_9]

If I am ever brave enough to do this, I'm replacing the impeller regardless of the condition. If it looks good, I'll save it for the next pandemic part shortage. 😉

[@commonsensesolutions6662]

Once you do it and see how easy it is you’ll wonder why you ever paid someone else to do it 😂

[@jamesjaeger1976]

Can you share information on your jack plate . I had same problem you did. All I could find was a long shaft 20 hp. I’m shopping for a jack plate and since I have same motor and similar boat, I thought I might try the jack plate you have. If you have already covered this in previous video, please point me to the video.

[@commonsensesolutions6662]

I don’t think I covered it much yet but have had plans to do so. How soon do you need to do something?

[@colonelfustercluck486]

one thing I would worry about, is the use of copper 'non-seize' grease on the outboard. The outboard is mainly aluminum alloy, with zinc anodes. Copper grease would introduce another metallic element to the situation.... I think non-seize grease is a great idea, but I would be looking for a grease that is electrically non-conductive or at least neutral acting in the corrosion process. As I am no expert, I am not able to suggest a product, but there will be something out there.

[@michaelpalmer98]

Thanks for the info. I just found on page 62 of owners manual it says CAUTION “Do not operate the engine when flushing the outboard motor with a hose joint as this can cause damage to the outboard motor.” Maybe they’re just super cautious about impeller concerns? Im not sure there’s any real benefit to a warm flush if the hose is already putting water through the entire cooling system. Looks like yours is just fine but I might pass on starting it unless it’s in a bucket of water going forward

[@commonsensesolutions6662]

Thank you! The main benefit of the warm flush is to hopefully open the thermostat to flush salt deposits from the head. The original advice came from an engineer at Tohatsu so my video was really just to make sure it wasn’t causing damage in my engine. The designs may have changed since, but I doubt it. Bucket and muffs are always an option. It’s nice to have options. Thanks for watching and commenting 👍🏻

[@godslittleman5451]

Thanx for the video. My 20 horse merc is exactly the same motor, I think.🧐🧐

[@commonsensesolutions6662]

If it’s a newer one, yes, same motor 👍🏻👍🏻

[@garybelmore1691]

I own 2018 20hp owners Manual stated only backflush when outboard not Running I suggest you read your Manual again Good video how change a water pump must add some miss Leading information Regarding back flushing

[@commonsensesolutions6662]

Hi thanks for your comment! Seems the manual is really just to cover their rear ends for the ones that don’t follow the procedure correctly. 👍🏻

[@wacpickleball]

@@commonsensesolutions6662 I was looking at the 20C manual (Carb version) and on page 56, it actually says you can run engine idle when using the flush port. In the new manual, they removed this section. It could very well the reason you said, people didn't follow instruction and ruined it. www.tohatsu.com/marine/common/owners_manual/pdf/Toh_MFS15C_20C_003-11090-6.pdf

[@commonsensesolutions6662]

@@wacpickleball There it is! Thanks for this! I appreciate it. I believe we have found the deal. Appears when the port was low they needed to tape the inlets to ensure most of the water would be directed up to the pump. that need was solved by moving the port above the water pump where it is today. I’m sure the next step will be to idiot proof the engine in the next design update and remove the port entirely, but hopefully not…it’s so convenient and obviously works without damage when performed correctly. 👍🏻

[@wacpickleball]

@@commonsensesolutions6662 you may want to download this service and maintenance pdf. It’s for the Mercury 15/20 EFI but it’s almost the same as the current Tohatsu. Check out page 15 for flushing and page 21 for the oil filter drain hose. 😁. I’m going to use that hose for my next oil change. www.powerequipmentdirect.com/manuals/mercury-marine-7715b2c818cb0861bc499441cff4a390.pdf

[@alanmonroe6585]

Thank you for the informative video👍😀

[@commonsensesolutions6662]

Thanks for watching 👍🏻

[@sossmoss20]

Thank you

[@yusufk6109]

Hey thanks for the informative videos on this new tohatsu model! I've just ordered the mfs30d and can't wait to start using it here in Sydney, Australia. I'm wondering if you use a spray lube under the cowling to protect from water or corrosion? Maybe a silicone spray. Would love to hear some suggestions about how to properly protect a new outboard from corrosion.

[@commonsensesolutions6662]

Good luck with the 30! I’m sure you’ll enjoy it. I usually use WD-40 as it is really good for displacing water. They actually did a great job sealing the cowling and even after running in salt water it’s always spotless inside. Externally I really hose it down well with soapy water then hit everything below the cowling with the WD to protect.

[@yusufk6109]

Just did a major service at the tohatsu dealer after 80 hours of use and flushing through the hose port with the engine on idle. The dealer said the impeller and thermostats looked normal. Mine is the MFS30D

[@eddygoldman8811]

great video, thank you for your help with the tack and he meters install. if you don’t mind where did you get the new water pump please

[@commonsensesolutions6662]

Thank you! That one I picked up from www.tohatsu.us/home.php? Usually what I do is plug in the part number I’m looking for into a search engine and see who has the best deal going including shipping.

[@bobf.4523]

Very helpful video. The Tohatsu owners manual does not discuss AT ALL how to replace the impeller?? not helpful. I feel confident now that I can replace it with your guideance. I would like to ask that you hold your camera back about a foot. I would have liked to see the entire lower unit and crankshaft. Also, hold it a little stiller would be helpful. That said, good job!

[@commonsensesolutions6662]

Thanks! I’ll try!

[@shannonyork5300]

A comment below says this technique does not flush the "engine housing". Is that correct? I would assume that if you let the engine idle long enough with this technique so the thermostat opens, then water flow is 100% throughout the system. Perhaps I'm wrong.

[@commonsensesolutions6662]

I don’t agree with that comment either. It doesn’t matter if you use muffs, bucket, hose, or in the water if you bring the motor up to operating temp the thermostat will open. It might close again if the incoming water and ambient temp is such that conditions drop below the thermostat set point, but as the engine heats again it will again open. The frequency of this cycle is dependent upon conditions but for sure it opens at some point else the engine is not even reaching operational temperature. That’s my take.

[@shannonyork5300]

@@commonsensesolutions6662 I concur with you. I was curious, so I looked at the new 2022 version of the Owner's Manual for the 20hp like ours. It still says don't operate the motor when flushing using the hose flush input. The Tohatsu engineers I've talked with didn't say it, but my assumption is that the "official" statement to not run the engine when hose flushing is because they know there are a certain % of fools who would not flush it at the motor's idle speed, but would run it at higher rpms, thus running the risk of engine damage. Tohatsu doesn't want to be responsible for those fools' errors, so they dumb it down and just say don't run it while using the hose flush input.

[@BrandmeirZ1]

What type of damage do you think it would do to put it in gear but still maintain a low idle for short duration?... Asking for a friend :/

[@commonsensesolutions6662]

@@BrandmeirZ1 None. I do it all the time. Idle only for short durations. Probably more of a safety thing (stay away from prop) I’d think. Some people will probably say that the transmission will get hot since it’s not in the water…probably true if in gear for a long period.

[@wacpickleball]

@@shannonyork5300 Interestingly the manual (Page 56) for the 20C (the carb version prior to EFI) pretty much the same engine, specifies that you can run engine at idle using the port. They removed this in the new engine manual so it could be to prevent people from doing it wrong by not following procedures? www.tohatsu.com/marine/common/owners_manual/pdf/Toh_MFS15C_20C_003-11090-6.pdf

[@coryboyd7958]

I replace mine EVERY YEAR needed or not.

[@commonsensesolutions6662]

That’s a great strategy!

[@MrJameschance]

Could we look at your impeller a little while longer ?

[@stanRmeyer]

Use plumbers silicone grease which is good for rubber!

[@commonsensesolutions6662]

Excellent 👍🏻

[@Macberto]

Awesome! I've been waiting for this video since I own this same motor (year 2021). Does the water pressure make a difference? I would think using minimal water pressure would be best.

[@commonsensesolutions6662]

Hi Roberto, that’s a good question. I agree! Thanks for bringing that up! I usually open my hose valve a few turns but not all the way. High pressure would probably not be a good idea. 👍🏻

[@anatoliygusev]

Thank you friend for your work and for the video! I bought the same motor, only it has documents for 9.9 hp. We have a craftsman in Russia who flashes the ECU at 20 hp. I'll send it to the firmware soon. Can you tell me what year your motor is? Bottom damper no problem?

[@commonsensesolutions6662]

Hi, it’s a 2020 model. By Bottom damper do you mean the fin I installed?

[@eddygoldman8811]

which pitch prop did you use the most with your family with you

[@eighthnotch_]

I'm about to order a 20HP Tohatsu & using mine primarily in saltwater too so this is a great nugget of information. Do you ever flush yours with earmuffs? Or is that not even needed because of the freshwater flush port.

[@commonsensesolutions6662]

It’s a great motor! I’m glad I bought it. I only use the port. I’d stick it in a bucket from time to time but the fin I installed is in the way. Port works perfectly 👍🏻

[@wacpickleball]

I’ve been flushing mine with the muff and it works well too. Glad to know I can use both methods.

[@toddweltiable]

I know this is late but: does it matter if you are flushing IN water or OUT of water? I'm flushing mine in my slip at the marina.

[@commonsensesolutions6662]

If in water and on the hose it seems as long as there is good water pressure from the hose (more than the pressure the submerged water pump will create) it should work fine. At idle, the water pressure from the impeller is low so the hose should overcome it. 👍🏻

[@biglav6048]

Thanks for the video! Out of curiosity, do you know what the manufacturer specs are on compression? What's normal in your case?

[@commonsensesolutions6662]

That’s a good question. I figure when it comes time to check the valve lash adjustment at that service interval I need to grab a service manual and check the compression. What I will do in the interim is reach out to my contact at Tohatsu engineering and ask the question and then I’ll post it back up here 👍🏻

[@commonsensesolutions6662]

From Tohatsu via email: “The compression is 73 psi with the decompression on and 135psi when the decompression is off”

[@biglav6048]

@@commonsensesolutions6662 sounds great! Thank you! I did some more research and came up with the same 73PSI with decompression (prior to idling essentially) and it was closer to to the 180+ range without. Wonder if that was 2 stroke?

[@commonsensesolutions6662]

@@biglav6048 not sure. Let me know what you find 👍🏻

[@Hosstyuhin]

Do you buy only original impellers or aftermarket also?

[@commonsensesolutions6662]

I’ve had good luck with both. As long as you are changing them at regular intervals you are good to go so they don’t have time to sit and rot.

[@shannonyork5300]

Meant to ask: Is that hose coupler that attaches directly to your motor water hose in-take homemade or something you purchased?

[@commonsensesolutions6662]

Found it at the hardware store. Small hose extension. Easier than having to twist the hose around. I’ve seen them at Walmart as well.

[@shannonyork5300]

@@commonsensesolutions6662 Ok, thanks. Cheers,

[@kirkkohd4883]

so the flush port would theoretically be the same as putting muffs on and idling the motor to flush it?

[@commonsensesolutions6662]

Yes. Idle-only is the key.

[@johnholford4581]

If your tale tell was working fine after muff flushing there is no concern. If impeller had melted or had been damaged your tale tell is what tells you there in an issue. Impeller replacement should be done annually or at recommended hours per the manufacturer.

[@commonsensesolutions6662]

Agreed. The idea was just to determine if there was any early signs of damage from the process. I change annually regardless. It’s so quick and easy. Cheap insurance and opportunity for inspection. 👍🏻

[@homebrew.pinball]

Can you check the impellor without draai the gear ?

[@commonsensesolutions6662]

Yes, no need to drain the foot gear oil. But if you do drop the foot to check the impeller you might as well replace the impeller while it’s taken apart.

[@wittelarry1]

Great video

[@commonsensesolutions6662]

Thank you!

[@hermanstaavi7077]

Hey, i have the MFS 15, and the handbook says not to run the engine with the hose method, i tried but the engine whouldnt turn over, as soon as i disconnected the engine turned over with no problem, since then i have always used muffs to get the salt out of it, do you know why Tohatsu says it shouldnt be run with hose?

[@commonsensesolutions6662]

What year is yours?

[@hermanstaavi7077]

@@commonsensesolutions6662 2021

[@commonsensesolutions6662]

@@hermanstaavi7077 wow that is really strange. I will have to ask around and see what the story is with that.

[@hermanstaavi7077]

@@commonsensesolutions6662 Yes, i contacted my dealer and told them about the problem. They said that the engine is never meant to run with hose flush method. It doesn’t supply enough water, so the impeller will eventually burn up and your outboard will overheat, it is actually only made to flush salt or other substances out of the system. I also looked in to my manual and it says the same. The thing about my outboard not starting, they didn’t know. Maybe it just was a weird coincidence.

[@commonsensesolutions6662]

@@hermanstaavi7077 probably just coincidence. The evidence at least shows that the process works fine with my engine. If water is flowing out of the intake grates on yours then it’s getting water. Let the condition of your impeller and pump guide you when you change it at the next interval.

[@bigblockcutlass123]

How do you like your fin? Where did you get

[@commonsensesolutions6662]

I Love it for this boat. Provides rear lift without drag like some of the others. I talk about this in one of my other videos. The SE 200 is the one to get. Here are a few links to buy where I’ve bought mine: SE Sport 200 amzn.to/3iyelpG amzn.to/3ZxzAst

[@kinibowers7229]

I have the same motor, do you feel like that hydrofoil you have makes a big difference? Appreciate your videos, keep up the good work!

[@commonsensesolutions6662]

I think I talk a bit about it in another video, been a while…but the main reason I use it is because I felt this hull design has a bit more bow rise (bow rides high when on plane) than I’m used to with my other Jon boats. This hydrofoil lifts the rear up enough to make up for it without affecting performance (except in tight higher speed turns). 👍🏻

[@kinibowers7229]

@@commonsensesolutions6662 Good deal, thanks so much for the reply!!

[@kaavest]

Dont need to flush these engines, newer flushed a single engine in my life and the last impeller on a 3 sylindred 25 efi lasted 9 years of much saltwater use.The engine was in good shape and got stolen and drived drunk on the rocks at 12 years, then i used the insurance money and brought a 9,8 smaller 10 ft Pioner 10 boat to drive to my door through some shallow water in a lake. That engine also go out in saltwater and in 3 years ab 200 hours with no trouble.Only oil change. It take long time and if the impeller goes, it goes slowly, i drived the 25 a bit to long on the impeller(2years overtime) and it even started noise a little moore. But when changed it was no problem.

[@davehanna1557]

Car tires should get replaced ever 5-7 years according to the DOT, regardless of appearance. Rubber breaks down with time, so I’m guessing impellers should get changed out regardless of appearance…. How often? Not sure but…

[@commonsensesolutions6662]

I change the impellers in all of my boat engines each season. It’s easy to do and only takes a few minutes so why not? At the same time I’ll also change out the gear oil in the foot and the engine oil and inspect everything while I’m at it. It’s a good routine to follow. 👍🏻

[@richardkelly2047]

Good call on the BS. I don’t even see salt buildup

[@commonsensesolutions6662]

Same here, and Salt is mostly what I run in. 👍🏻

[@kentmere3560]

You’re not flushing the engine housing, just the lower part between the flushing port and the water intake.

[@AACnet1]

This debate is ongoing. Haha.. I think this.. Tohatsu say no, do not run it on hose - in my manual. I bought the outboard today. Some hoses/connections may not have the pressure, to go back against the system enough to flow into the pump and lubricate. If its lower pressure, then the wear and heat would be more evident on the pump. Even if you are on a marina, and someone else turns on a hose etc.. So if you dont touch the gears, stay in idle AND have enough water pressure, maybe its fine. I would like to damage a pump over time than damage an engine with corrosion and overheating over time? The pump is .. a pump! Could this be why its not recommended in my manual?.. Id love to flush this way.. Oh well, Ill say hi when I fall in the water putting muffs on! AARRGG!

[@commonsensesolutions6662]

Don’t fall in!! Pumps are cheap, thankfully. When you eventually change your pump, let it’s looks guide you. As long as you know the pump is in perfect new condition when you begin your process you will have a good read on how it’s working 👍🏻

[@colonelfustercluck486]

too remove all possibility of wrecking something, I prefer to use the large bucket / half barrel method. Then everything is imitating normal use. I can rev the engine etc. I can leave it for 5 or 10 minutes, and touch the engine to feel for heat. When it feels warm, you know for sure that your internal water passages are getting flushed.

[@shannonyork5300]

Totally Off-Topic, but has anyone tried to remove the cover to the 20 amp spade fuse on the port side of the Tohatsu 20hp? The cover, at least on my engine, is Yellow, but I'll be darned if I can get it off. And, I don't want to break it. Also, the Manual says there are spare fuses mounted in the engine. I don't see any. I'm leaving for a vacation with the boat and would love to know how to replace the fuse if necessary. Thanks.

[@commonsensesolutions6662]

Hi Shannon, good question. I don’t know the answer but I’ll take a look at it for you later today. I have spares in my power center (video coming soon) but would be a nice to know that Tohatsu already provided one for emergencies as well.

[@shannonyork5300]

@@commonsensesolutions6662 Thanks, I greatly appreciate it.

[@shannonyork5300]

OK, I pushed the Yellow square at one end of the black rubber housing and pushed the fuse assembly partially out. It is a very tight fit to get the whole yellow fuse assembly out and free, so I left it alone, pushing it back in. I didn't want to get distracted by whatever time it might take me to get it all the way free and pull it apart to see the fuse. So, I don't know if there's an extra fuse in there or not.

[@shannonyork5300]

Ok, just heard back from Tohatsu. There are two fuses within the Yellow plastic assembly. One that is being used and the other is the spare. I don't have time to mess with it right now, so I'll hope/trust the spare is there IF I need. it. And yes, I'll pick up an extra one, just in case.

[@commonsensesolutions6662]

@@shannonyork5300 I can confirm that’s correct info. I just checked mine. Just push the yellow “button” back through the rubber mount and the fuse holder comes right out, tight, but comes out. Next, just squeeze the clip like a pinch across the holder and gently pull the top off. Inside you will see two 20a fuses. The taller mounted one is connected, the lower one is the spare. I’ll do a quick vid on this. Good info for everyone to know. I had always wondered what the yellow button was myself 😂

[@markkus1134]

Well your water pump sucks in and up so no it’s not a good idea to hook up to a hose and run unless it’s on muffs, And doing that will not allow the t stat to open because it’s cold water Only way to get the thermostat to open is to put the Lower Unit in a bucket and let the water recirculate it will get hotter as a thermostat opens up in your motor will be completely flushed I’ve done it 1 million times

[@shannonyork5300]

Ok, understand your point. But when you're running the motor in actual water running conditions, the water going into the intake is not heated. The intake is constantly pulling in fresh "cold" water from the river, lake or estuary that you are operating in. Obviously, the thermostat opens under those "normal" operating conditions.

[@pawcrawlowens8730]

The engineer is wrong, been running outboards for 40 years and it won't be ok,

[@MrGeorgeSlash]

conclusion???do not listen to every idiot on youtube just listen only to the manufacturer I have the same machine and I only do what the manual says

[@commonsensesolutions6662]

Yes! I agree! If two different engineers at Tohatsu say it’s okay, it must be…and we proved it. 👍🏻

[@williamtukeyjr3661]

Yep, we're gonna call BS