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Tohatsu 6hp Alternator install (flywheel issues)

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DavidBuoy
Admiral

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USA
707 Posts

Initially Posted - 12/30/2014 : 16:20:58

So the spare bedroom workshop is open for business. Nothing like the smell of oil and dirty cat litter. Im installing an alternator/rectifier kit on my 2004 Tohatsu 6hp (MFS6A2) and am trying to figure out how to get the flywheel off.

I am following this helping "tutorial" from a guy who previously did the install but am running into an issue.

http://killintimesailing.blogspot.com/2010/04/tohatsu-6hp-alternator-install-document.html

I can't get the flywheel off because unlike in the blog noted above, there are no holes all the way through the flywheel that I can put a screwdriver to stop it from spinning. I have a buddy who is going to lend me his gear puller to actually pull the thing off but I just can figure out how to lock the motor.

Has anyone else had this issue and dealt with it?

Thanks!

Edited by - on

islander
Master Marine Consultant

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3992 Posts

Response Posted - 12/30/2014 : 19:16:47

I did this with my Honda 9.9 when I first got my boat. I Upped the 6amp alt to a 12 amp and also put on a new timing belt. You don't need to lock the motor. You need a gear puller to pull the flywheel. The gear puller has three claws that you hook on the outside of the flywheel where the teeth are. You remove the center bolt or nut that holds the flywheel to the shaft with an impact gun. If you don't have a gun you can put a wrench or 1/2" drive socket on the bolt and smack it hard with a hand sledge hammer. You will probably have to hit it many times before the bolt/nut will come loose. You are trying to imitate a quick slamming action of an impact gun. Once the bolt/nut is out the gear puller has a center bolt with a point on the end that will sit in the bolt hole or on top of the shaft if it was a nut.If you have a nut put it back on the shaft a few turns so the point of the gear puller has a place to sit in and not slide off the

shaft. You then tighten that bolt and it will start to pull up the flywheel. The process is that you tighten the bolt then tap on the flywheel then tighten some more and tap the flywheel again. You keep doing this until the flywheel pops loose from the shaft. There will be a key-way on that shaft, Don't loose it.

PS Love the use of the room..A true sailor. I had a friend that built a chopper in his bedroom..True story.

Edited by - islander on 12/30/2014 20:00:51

islander
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Response Posted - 12/31/2014 : 06:15:57

If you still need to lock the engine just put it in gear and put a block of wood between the prop and the cavitation plate to keep the prop from turning. Also make sure the kill switch is on.

Edited by - on

islander
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Response Posted - 01/08/2015 : 09:08:51

Did you get the flywheel off?

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DavidBuoy
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Response Posted - 01/08/2015 : 09:30:57

quote:
Originally posted by islander

Did you get the flywheel off?

Not yet. Im going to bring it over to my buddy's who has an impact gun/air compressor and a gear puller. Problem is its been either rainy or damn frigid each weekend. Im also gone this weekend and the next going skiing, so hopefully stars align and that next weekend works out. Not in a huge rush anyways.

Edited by - on

islander
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3992 Posts

Response Posted - 01/08/2015 : 10:25:32

Just a heads up. When you go to test it after the install, Do it with a battery connected and measure the voltage at the battery terminals. If it's working the voltage will jump up when the engine is running. If you just try to test it at the plug without the battery you might not get a reading. The rectifier needs to sense a resistance(Battery)and a need to send out the current. Without the battery it senses nothing so no current.

Edited by - islander on 01/08/2015 10:26:19

OJ
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4382 Posts

Response Posted - 01/08/2015 : 11:26:07

quote:
Originally posted by DavidBuoy

So the spare bedroom workshop is open for business. Nothing like the smell of oil and dirty cat litter . . .

Gee, suddenly I don't feel so bad about the spinnaker and whisker poles I have stored behind the couch in the living room!

Edited by - on

Akenumber
Navigator

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USA
247 Posts

Response Posted - 01/08/2015 : 16:39:41

I have never had one that tight. I have always just put some torque on the puller and then tap the top of the main threaded bolt on the puller with a hammer and it usually pops off. Maybe this helps if you have not already tried it.

Edited by - on

DavidBuoy
Admiral

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707 Posts

Response Posted - 01/28/2015 : 18:50:28

So I'm just wondering what people have done about the wiring to the battery...
The PO had installed wiring for either a previous electric start or alternator engine and the gauge is massive. It is basically the same as the primary battery wires. The kit from tohatsu has the wiring from the alternator at like 16 gauge max. I was planning to install like a trailer style connector or something but am just not sure about the huge gauge change in wire gauge. Should I just replace all the existing wires with something smaller or what?

Thanks!

Captain Rob & Admiral Alyson
"David Buoy"-1985 C25 SK/SR #5053

Dave5041
Former Mainsheet Editor

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3754 Posts

Response Posted - 01/28/2015 : 19:19:04

The bigger gauge won't hurt, so I would just connect to it. It was probably for electric start, around a 30 amp load. I use a trolling motor plug and receptacle. See my Pearl Bits and Pieces album.

edited for brain dead autocorrect

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

Edited by - Dave5041 on 01/29/2015 07:16:11

awetmore
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1144 Posts

Response Posted - 01/29/2015 : 06:53:33

The alternator on those things is tiny, somewhere around 6 amps. You can use the calculator at BlueSea.com to determine the minimum safe wire gauge. It looks like 14 AWG would be good for 20', which is probably about the length of that run (remember that you need to measure the round trip length, not the one way length).

Alex W
Seattle, WA
Express 37 "re-Quest"
previously owned 1984 Catalina 25 "Lutra"

islander
Master Marine Consultant

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3992 Posts

Response Posted - 01/29/2015 : 07:07:02

I believe I have 14 gauge (maybe 12) duplex (Marine) from the engine to the batt. for the charge wire. This is for my 10 amp charge circuit. There is a dedicated plug connector on the side of the engine. Battery side has two ring connectors. The 14 gauge is good for up to 15 amps and is still flexible enough to handle the repeated turning and lifting/tilting of the motor. It would be very rare that your alt/rectifier would put out the maximum amps as in full throttle and a totally dead battery situation. I'm surprised they didn't include a plug connector with the charge kit. Maybe its sold separately. This is mine on my Honda but there should be one sold similar for your engine.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 01/29/2015 07:46:28

DavidBuoy
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Response Posted - 01/29/2015 : 09:41:02

quote:
Originally posted by awetmore

The alternator on those things is tiny, somewhere around 6 amps. You can use the calculator at BlueSea.com to determine the minimum safe wire gauge. It looks like 14 AWG would be good for 20', which is probably about the length of that run (remember that you need to measure the round trip length, not the one way length).

I don't think the existing wires with a the alternator are 14, maybe 16. Should I keep the existing 8 or 10 gauge to the switch and ground? I don't know if I can get a connector to go from 8 to 16 gauge.

Captain Rob & Admiral Alyson
"David Buoy"-1985 C25 SK/SR #5053

Dave5041
Former Mainsheet Editor

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3754 Posts

Response Posted - 01/29/2015 : 10:21:32

just run the heavy gauge to a receptacle on the stern and the smaller gauge from the motor to a plug.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

islander
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Response Posted - 01/29/2015 : 11:22:09

I would ditch the heavy gauge wiring,Your PO really did an overkill. Maybe he had it laying around or thought he was working with a 110 amp alt. but your 6amp rectifier(You don't really have an alt.) Doesn't need 8-10 gauge wire. Sometimes its just better to start fresh with the proper size wire and terminals rather than trying to work with the heavy gauge. Like you said fitting terminals to it. Wiring is only as good as the weakest link. If you put a 16 gauge fitting on to 8-10 gauge wire then the whole assembly is now 16 gauge. My wire runs straight from the engine to the battery with a fuse at the battery end. It might not even need that fuse because there is a fuse in the circuit under the engine hood but I put it in anyway. Simple with less connections to fail or corrode.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 01/29/2015 11:32:36

DavidBuoy
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Response Posted - 01/29/2015 : 14:48:10

quote:
Originally posted by islander

I would ditch the heavy gauge wiring

That's honestly what I was thinking

Captain Rob & Admiral Alyson
"David Buoy"-1985 C25 SK/SR #5053

Dave5041
Former Mainsheet Editor

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Response Posted - 01/30/2015 : 16:04:06

My thought is that should you go for electric star at some point you will go back to the heavier gauge, so why do the work. Do what makes you happy.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

islander
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3992 Posts

Response Posted - 01/31/2015 : 09:11:08

I don't think the 6HP has an electric start option but I looked at the schematic for your engine and there is a 10 amp fuse in the charge circuit so based on that I think you will be fine using 15amp wire (14/2 duplex marine). Its a 12V, 60W, 5A charge kit that you are using. (its what they show) Boy I really like the Sailpro model.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 01/31/2015 10:08:50

DavidBuoy
Admiral

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USA
707 Posts

Response Posted - 01/31/2015 : 16:38:49

quote:
Originally posted by islander

I would ditch the heavy gauge wiring

That's honestly what I was thinking

Captain Rob & Admiral Alyson
"David Buoy"-1985 C25 SK/SR #5053

Voyager
Master Marine Consultant

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5231 Posts

Response Posted - 01/31/2015 : 20:55:43

Agreed - without an electric start, you're talking about small currents between the alternator and the battery. Let's assume the entire cable run is 15 ft (the round trip is 30 ft), and if we assume a worst case max current of 15Amps, 14 AWG is probably enough. Double check it using the Don Casey book or your favourite website. I have 6 or 8 AWG for Passage, as I do have an electric start. My in line fuse handles 30 or 40 A. I'm happy to have an electric starter, BTW.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

DavidBuoy
Admiral

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USA
707 Posts

Response Posted - 02/02/2015 : 05:51:57

So I think I am going to leave the existing 8 or 10 gauge wiring from the hull exit to the battery and switch intact. Couple reasons.. easier to switch to electric start down the road, quality marine wire and it is less work.

I picked up a trolling motor connection that I believe is 14 gauge to bridge the two. I do plan on shrink wrapping everything, even the connector as it will be a once a year install and can cut it after.

With the larger gauge going to the battery will I loose some of the capacity of the alternator?

Here is a picture of the connector next to the alternator wiring...

Captain Rob & Admiral Alyson
"David Buoy"-1985 C25 SK/SR #5053

islander
Master Marine Consultant

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Response Posted - 02/02/2015 : 08:51:04

quote:
With the larger gauge going to the battery will I loose some of the capacity of the alternator?

No, Keeping the larger gauge wire is fine if that is what you want to do. Actually the larger gauge will have less resistance, Like a river, The wider it is the more water flows down it.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

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