30hp, 4 stroke, Tohatsu Maint.

[Wee Hooker]

Just ordered a new Tohatsu 30hp 4 stroke. Wondering what the flushing procedure is for this motor? Does it use a flushing special fixture /attachment?

Also, does anybody know what plugs it uses? Like to order a new back-up set before it gets here.

Thanks in adance.

 

[pvanv]

Re: 30hp, 4 stroke, Tohatsu Maint.

The 30B four stroke can use the flushing adapter 336-60007-0, but earmuffs work just as well. If you use the adapter, you need to tape off the water inlet strainers during flushing.

Standard spark plug is NGK DCPR6E.

A copy of the parts catalog is available at http://www.internetoutboards.com/PartsCatalogMenu.htm

I would run a good stabilizer, such as K100-MG, in the gas, particularly if you have E10 as we do here, to reduce the possibility of phase separation. I would also avoid synthetic crankcase oil, especially during break-in -- and then only if you run the motor hard. Synthetics seem to be prone to "making oil" in these four strokes, unless you get the motor really warm.

 

[TOHATSU GURU]

Re: 30hp, 4 stroke, Tohatsu Maint.

What he said, but with a lot more emphasis on not using synthetic oil in your outboard. Also, your dealer is responsible for test running this model engine prior to letting you take possession of it. If they are shipping it to you, be aware that it takes some cranking on the initial test run to prime the fuel system as it was completely drained at the factory.

 

[Wee Hooker]

Re: 30hp, 4 stroke, Tohatsu Maint.

Thanks much for the expert advice gents!

The synthetic oil thing really caught me buy surprise. I would ahve likely switched it over after (20hr?) break-in as I'm pretty sold on synthetics in my truck. I will be sure to stick with Nissan/Tohatsu dinosaur oil for this motor then. I figure, after break-in, I'll change the oil every spring as I don't expect to put more than 20-30 hrs /year on it for the near future.
I'll also look up that brand of stabilizer as we are limited to the E10 here as well. Always use SeaFoam in my 2 strokes but had a nightmare experience with Stabil one year (as did the local marina) and will never use that brand again.)

For the record, the shop I'm buying the new(mirrocraft 1615-O) boat from is ordering the motor for me. He is installing and test running the motor (including prop selection) as part of the cost. I won't be picking up the package till March (it's 24deg here today :-( ) but I wanted to have all my maintenance/support stuff in place well befor then.
I'm pretty particular about maintaining my stuff in top order and teh fact that this motor cost more than my last boat, motor and trailer package combined will keep me that way too!

p.s. What's your thoughts on 87 vs 93 octane for these engines? I've read that higher octane can cause excess carbon build-up.

Thanks again for the info and links!
Dave

 

[pvanv]

Re: 30hp, 4 stroke, Tohatsu Maint.

In my experience, higher octanes don't usually cause carbon build-up. Some premium fuels can contain more additives, and -- theoretically -- might give a hair better economy -- but since you should be using a good stabilizer anyway, that's not much of a factor.

Most OB factories note that 87 is OK, but they often recommend 89 for the 4-strokes. Personally, I have been running regular 87 "land fuel" (with K100), with no issues for years, both in old 2-strokes (some of which only required 67 octane!), and my new Nissan 4-strokes.

In automobiles, the rule of thumb was always to use fuel with an octane of at least 10 times the compression ratio. So 8.5 to 1 compression motors needed at least 85 octane to avoid preignition (which is what we're trying to avoid). With different cam profiles (more overlap, etc), this isn't 100% true any more, but still a good starting point.

The usual root causes of carbon build-up are running too cool, too rich, or too much oil (in a 2-stroke). 4-stroke OB's do tend to run cooler than their land-based cousins, and stay cleanest when run hard -- over 50% throttle, but the fuel injection system is pretty good on the Tohatsu/Nissan 30. When operating correctly, they don't usually run too rich. So I wouldn't worry about running any good, clean, fresh, fuel that is at least 87 octane.

 

[Wee Hooker]

Re: 30hp, 4 stroke, Tohatsu Maint.

Thanks again, I'll likely run 89 as that's what I feed the truck. that keeps everything simple. Besides @ 10-15 gal/year consumption in ALL my boats combined, fuel costs have never been a big issue. I LOVE small outboards!