Nissan/Tohatsu 4-stroke 18 hp o/b vibration

[FlyBoyMark]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

20" transom IS a long shaft....15" transom is standard or "short". Put a 1" square block under the clamps and retighten and remove block. I WOULD advise you to bolt lower part of bracket.<br /><br />...Unless you got the EXTRA LONG 25"?

 

[bbutturff]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

I have one of these outboards, an NSF18B2 short shaft purchased in April 2002 from Cabela's and delivered to my home (I live about 60 miles from the nearest dealer). I set it up on my boat per the manual, ran it for about 10 minutes, pulled the dipstick, and discovered that there was water in the crankcase oil. A bad head gasket I was told and I chalked it up to bad luck. So, I returned motor #1 to Cabela’s for exchange and two weeks later was in possession of motor #2. Motor #2 ran well the first year but I did notice an annoying vibration at idle. Adjusting the idle speed helped a little but the vibration remains. I logged about 200 hours on the motor in 2002 and at that point I was pretty happy. The motor was quiet (off idle), fuel efficient, and powerful. In May 2003 I noticed a small trace of oil in the water behind the boat. Although I wasn’t seeing the crankcase oil level drop at the time it was cause for concern considering my experience with motor #1. I called my dealer and he felt it might have been some residual oil spillage from a recent oil change that I had done and assured me there was no reason to be concerned. As 2003 progressed so did the leak and I was noticing that the crankcase would lose about 250ml of oil during a day of fishing/trolling. So, I called the dealer again and he had me bring the motor over (120 miles round trip) for a look. After running it for over an hour he could not detect any oil loss and refused to tear into the motor for fear of not being reimbursed by Nissan. After another 120-mile round trip to pick up the motor I called Nissan and they said, “Sorry, seals aren’t covered under the 3-year limited warranty”. They told me I was on my own. At this point I had no choice but to order a powerhead gasket set ($100.00), an outboard repair manual ($25.00), and tear into the motor myself. My initial inspection lead me to believe the powerhead base gasket had been over torqued at the factory because it was crushed and appeared to be causing the leak. After replacing it, I found out that it wasn’t the culprit because the motor was still leaking oil from somewhere. So I tore it down again (BTW if anybody wants to know how to take one of these apart, I’m your guy) and replaced both the powerhead base gasket and the cylinder head gasket. I’ll know this weekend if the problem is fixed. Also, these motors DO fire both spark plugs at the same time. There’s no power or economy reason for this, it just makes for a simpler ignition system and is commonly called a “waste spark” ignition system. Even if my problems are over, it probably goes without saying that I’ll never buy another Nissan outboard. Even if I had purchased a Mercury (Tohatsu powerhead also), at least I would have parts and a dealer about 6 miles away.<br /><br />Regards and good luck,<br />Bruce<br />

 

[SeaDawg]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Yea, sorry to hear about your motor probs. I'll be keeping an eye on mine now, especially for oil leaks. I just put 10 running hours on it, and the oil level was fine.<br /><br />Just changed the oil, and I'm going to change the lower unit too, before the next trip out.<br /><br />I did raise the motor, and it helped - got the motor to the correct height. I could not raise the motor without attaching something for the motor to clamp too, due to the design of the bracket.<br /><br />Anyway, it is still running well, I'll update as time goes on.<br /><br />Ron

 

[bbutturff]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Well, I got everything hooked back up again and ran it for about an hour in my driveway last Sunday. No oil loss from the motor, no water in the oil. So it looks like it really was the head gasket leaking. We’re going on a 4 day fishing trip over the 4th of July weekend so that will be the real test. <br /><br />Later,<br />Bruce

 

[bbutturff]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

It's fixed! Four days on the water and not a trace of oil in the lake! (At least not from my motor).<br /><br />Bruce

 

[DJ]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

B Butturff,<br /><br />You may want to re-torque that head.

 

[bbutturff]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Although the book didn’t recommend it, that’s an excellent suggestion. I’ll do it this weekend.<br />Thanks.<br /><br />Bruce

 

[TOHATSU GURU]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Bruce,<br /><br />The problem that you have run into with oil loss is directly related to the operating temp of the engine. In the north, in cold water, with a thick oil, the engine never reaches operating temp. The fuel blows past the piston rings directly into the fuel. This never was an issue when the largest four-stroke was a ten hp, but now that all brands of outboards are offering larger sizes all manufacturers are having the same problem in your type of application. The solution is to run the engine with 10-30 or even straight 30, change the oil every 40 hours and to rev the engine up every so often if you are trolling at an idle(to bring the temp back up).

 

[bbutturff]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Elvin,<br /><br />If I understand you correctly you're saying that the fuel gets past the rings and into the oil? The oil level rises to above full and then.........? How does the oil get out of the crankcase and into the exhaust housing? Is there a crankcase vent? Couldn't this also happen if the crankcase was slightly overfilled from the beginning? I've always used 10w-30 like the manual says and troll at about 1200 RPM. The lake temps are around 65 degrees right now. I'd really like to understand this better but am puzzled why this didn't happen the first year, especially during break-in.<br /><br />Thanks,<br />Bruce

 

[TOHATSU GURU]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

As the crancase fills beyond capacity the overpressure allows it to vent through the relief valve in the engine and it could happen if you just added to much oil to begin with. Thats the reason all the manufacturers have those warnings about overfilling. As to way id didn't happen the first year...The water may have been a couple of degrees warmer, you may have had a little less oil in to begin with and maybe you ran it a little bit more RPM. One probably would not have done, but all three and some bad luck....and there you are. It's also possible that there really might be something wrong with the engine. It might have a seal or gasket that allows some blowby. As you already found out, outboard warranties do not cover seals or gaskets. Unless you get a dealer to say that the seal or gasket was/is defective. A friendly understanding dealer can make or break your happiness if you have a problem.<br /><br />Elvin<br />InternetOutboards<br />AvalonProGrp

 

[SeaDawg]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Back on "vibration". I just went out with a friend who just bought a 2004 Yamaha 25 HP 4-stroke on his new J14 Carolina Skiff, and it "vibrates" about the same as my 18 HP Nissan on my J12 skiff.<br /><br />His is remote steering, but you can feel the engine in the floor of the boat. Not objectionable, but "some" vibration.<br /><br />I continue to have no problems with my Nissan 18 HP 4-stroke, and I will periodically update here, relating to engine vibration.<br /><br />Ron

 

[TOHATSU GURU]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

You might be able to dampen the vibration by placing a piece of sheet rubber or even carpet over the transom, then placing the engine over that.

 

[phatmanmike]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

i just wanted to add that i own and have owned several small toe-what-sue's... between 5 and 10 hp. all 2 strokes. and they were by far the best running and longest lasting motors ive ever had. not to mention this by FAR makes the my FAVORITE motors ive ever owned, and iive owned more than a few.<br /><br />but heres a quastion, do the bigger tohatsu's run just as easy and are they built as "simply" as the little ones do? cause id buy another ina heartbeat

 

[TOHATSU GURU]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

With the imposition of the the EPA NAZI guidelines Tohatsu was forced to develop new designs. Those designs are very advanced, but they are far, far, far(and still farther) more complicated than the simple(think gentle rolling pastures with peaceful farm animals) engines of just five years ago. They now use 4-stroke designs for the 30hp and down(except for the 2.5-3.5) and the 40 and up are all TLDI( Except for the 115 and 140). F-strokes have more moving parts...ergo more complicated. The TLDI 2-stks are just as complicated as the F-strokes, but at least they have better fuel economy and a lot more low-in power than F-strokes. It's to the point now that people are no longer trusted to install their own engines. There are no warranty failures....yet. The TLDI's are the only direct injected outboards that have not had problems. But, I long for the days of simple points and condenser engines. Anyone could fix the engines of the 60's.

 

[interceptor]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Geez guys, I'm getting a little weepy over all the Nissan/Tohatzu chat. I'm planning on buying a used Nissan 70 to replace my not so beloved Force 50, and feel like I'm being accepted into a familiy. Have been lurking on different forums for some time now, and I'm surprised at how much support there is out there for Nissan's. Thanks for all the input!!!

 

[SeaDawg]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Any more, with companies making engines for each other, a lot of the time the name on the cowling does not mean anything. For instance, Nissan makes a lot of the smaller Mercury 4-strokes, the same way that MTD makes lawn mowers for Sears.<br /><br />The global economy at work........<br /><br />And Elvin, I do have a rubber mat on my transom. And, still no problems with my Nissan (smile).<br /><br />Ron

 

[MOTION LINE]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

The most common reason for an vibrating 18 2- or 4-stroke is the original
propeller, try for example SOLAS props very good lately.
Have a look at the leading edge of the prop, you will find that
it is pretty thick, despite all 3 blades are of different thickness.
The new Tohatsu (2008) 9,9 - 15 - 20 series props are most likely much
better since the factory was well aware of the problem and fixed it.

 

[TOHATSU GURU]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

Really? They fixed a non existent problem?

 

[mickjetblue]

Re: Nissan/Tohatsu 4-stroke 18 hp o/b vibration

I have the 18hp 4 stroke, and I bought it online about 7 years ago.
That motor runs smooth through the full power cycle, including idling.
I think it's important to use a fuel stabilizer in the gas as standard procedure
to keep the smoothness in the engine. Anyway, it works. Aside from oil
changes, oil filter, gear lube changes, and spark plugs, the
motor has not needed any other maintenance. Never been to the shop.

I wish I could buy a 30 or 40hp the same way, but policies have changed,
and that can't be done. Tohatsu/Nissan quality and dependability has become recognized, so
their prices have come up closer to the other outboad makers.

I'd recommend buying online if you are looking for a smaller motor that is still
available that way. Right now, the economy is so bad that very few dealers are stocking outboards in the small to medium range. Good luck!