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Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Dec 29th, '20, 21:27
by zebedee
The Tohatsu MFS6C SailPro has a flushing port on the underside of the motor pan at the rear; it's the 13mm hex head (eg: 13mm or 1/2" AF spanner) M8x1.25 thread plug between the 10mm hex head bolts holding the motor into the pan. Most if not all Tohatsu/Mercury/Mariner small outboards including 2 strokes appear to have the same flushing port.

The Tohatsu part number for the adapter is 336-60007-0; the Mercury/Quicksilver part number for the same part is 16841Q02:
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Tohatsu flush adapter.jpg
They are made for a 5/8" ID hose, which appears to be the standard size for garden hose in North America, but which isn't dreadfully useful here in 1/2" / 12mm Australia! They're also expensive.

The threaded end is not BSP nor NPT, as an engineer would expect; it's M8x1.25

Today I bought three sets of M8x1.25 male to 1/4" BSP female and 1/4" BSP male to 1/2" hose barb from Enzed (a national hydraulic component supplier) in Moorabbin for just under $30 total; $9.90 each set. I could also have bought 1/4"BSP male to female 90degree elbows, but it didn't occur to me.

One set is destined for Jim's Tohatsu Sailpro at Wyndham harbour, another is destined for Adrians Tohatsu 4 stroke 9.8 short shaft in the bowels of his Noelex (not an easy job to extract it!).

The instructions in the manual for the SailPro say to only run the motor at idle, elsewhere instructions say not to run the motor at all, as the water is supplied above (after) the water pump, so it's not a replacement for a drum for tuning, etc, but it is an easy fresh water flush with a garden hose. Because it is after the pump, there should be positive pressure when running, so a short hose with a female click-fit hose fitting with a valve should prevent water leaking out and allow the adapter to be left in place. We'll report back when we have tested this!

If you buy the same parts, use teflon tape between the two parts and between the brass and the aluminium motor, and fit a fibre washer at the motor. This will:
  • Seal the joins
  • Protect against electrolysis
  • If you manage to break anything, ensure the broken thread left in the motor comes out easily with an Ezi-out!

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Dec 29th, '20, 23:22
by JimJ
zebedee
Do you have a Enzed catalogue number for the two fittings?

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Dec 30th, '20, 00:30
by zebedee
Invoice was still on the passenger seat of my car!

Verbatem from the invoice:
Item No. ... Description
P3-0804 ... 1/2 H/TAIL x 1/4 BSPT (1/2" barb, aka hose tail, for garden hose to 1/4" BSPT male)
72-04M08D ... 1/4 BSP F x M8 (8x1.25) MALE (1/4" BSP Female to M8 male to screw into motor)

BSPT is tapered, eg: slightly conical, to seal in the parallel threaded matching female part. Use teflon tape of course!

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Dec 30th, '20, 07:51
by Tezza
Same procedure for Suzuki 4st ob

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Dec 30th, '20, 14:25
by Furstin
https://www.ebay.com.au/itm/Boat-Outboa ... 890.l49292



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Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Dec 30th, '20, 15:53
by Johny
The only thing that makes me not bother and use the "earmuffs" is that you still have to block thet water inlets - the manual says with duct tape. That seems a bit difficult when the motor has just been wet. Is that just my understanding?

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Jan 1st, '21, 01:50
by zebedee
If you want a male hose connector end, such an animal is readily available with 1/4" BSP to suit sprinklers, etc, eg:

Image

One benefit of using a hose barb is that you can use a "stop" connector which won't allow water out and leave the hose in place all the time.

If just rinsing the motor, I can't see that plugging the intake would be necessary, as long as you get enough fresh water flow to come out the telltail. I would be reluctant to run the motor on the hose, since the water pump has no supply on the suction side.

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Jan 5th, '21, 19:35
by zebedee
And confirmation that, as expected, the flush port is under positive water pressure when the motor is running; not unexpected since it is right next to the telltale. I didn't know where the telltale was until I ran the motor for the first time yesterday.
The decompression system (Tohatsu MFS6CSUL Sailpro 6hp 4 stroke single cylinder) works brilliantly, it is so easy to start!
The day after I picked it up from IanB in Sydney (got out of there just in time too!), I noticed the new "D" model is now out overseas - and it is still carby! It has a new lid to look more modern, but no efi, so I'm very happy with my new motor. Tohatsu MFS6DSSPUL.

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Jan 6th, '21, 00:28
by JimJ
Sailpro 6hp 4 stroke single cylinder
I bought the same 2 years ago.
So far so good.
Be careful pulling the motor through before starting as mine has started on a gentle pull.

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Jan 16th, '21, 17:51
by bachus
zebedee wrote: Jan 5th, '21, 19:35 And confirmation that, as expected, the flush port is under positive water pressure when the motor is running; not unexpected since it is right next to the telltale. I didn't know where the telltale was until I ran the motor for the first time yesterday.
The decompression system (Tohatsu MFS6CSUL Sailpro 6hp 4 stroke single cylinder) works brilliantly, it is so easy to start!
The day after I picked it up from IanB in Sydney (got out of there just in time too!), I noticed the new "D" model is now out overseas - and it is still carby! It has a new lid to look more modern, but no efi, so I'm very happy with my new motor. Tohatsu MFS6DSSPUL.
Did my first flush (using the flushing adapter). Motor not running. Water came out the pee hole and everywhere in the leg. So it seems the water pump will be flushed too.

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Feb 24th, '21, 19:57
by fritzelhund
While no doubt a convenience it must be remembered that some models have thermostats ( I suspect mainly the clean running 4 strokes .. all in an attempt to keep pollution levels low ).Thermostats also function to send the cooling water in a certain direction and need some time to ensure that they DO open. Insufficient time with a hose flusher may not give 100% flushing. The tell tale can be seen to vary its output as the thermostat opens and closes.
I still prefer to bucker flush as that was the prop shaft and all the prop surrounds get a good wash too. Years ago my Mariner had a sliding spline that drove the prop..in reverse the prop would slip on the spline and cover exhaust ports. One good reason to flush in a bin.

Re: Flushing adaptor for Tohatsu/Mercury/Mariner motors

Posted: Feb 27th, '21, 11:08
by bachus
fritzelhund wrote: Feb 24th, '21, 19:57 While no doubt a convenience it must be remembered that some models have thermostats ( I suspect mainly the clean running 4 strokes .. all in an attempt to keep pollution levels low ).Thermostats also function to send the cooling water in a certain direction and need some time to ensure that they DO open. Insufficient time with a hose flusher may not give 100% flushing. The tell tale can be seen to vary its output as the thermostat opens and closes.
I still prefer to bucker flush as that was the prop shaft and all the prop surrounds get a good wash too. Years ago my Mariner had a sliding spline that drove the prop..in reverse the prop would slip on the spline and cover exhaust ports. One good reason to flush in a bin.
Yes I did wonder about the thermostat as well.