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Tohatsu Mega 25hp

  • Thread starter John C. Arceneaux
  • Start date
J

John C. Arceneaux

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"My Tohatsu Mega has recently

"My Tohatsu Mega has recently began one major problem, it doesn't accelerate like it once did. I put fresh gas in the fuel tank, this didn't solve the problem, remove all carbs and cleaned all the jets, bowls,body, still no power, anyone have any info they can share."
 
"Check compression, check spar

"Check compression, check spark. Then clean the carbs by dipping them in carb cleaner for three hours."
 
"Elvin, it has very good compr

"Elvin, it has very good compression, also while running we checked each cylinder by removing the spark plug wire on each and the motor stayed running, my brother who is a small engine mechanic did mention soaking the carbs in carb cleaner, thanks. We'll give that a try"
 
"john did ya get it running ye

"john did ya get it running yet ,,,im looking for a mega 25 for my jon boat ..thanx randal phone # 309 822 9911 leave a message"
 
"The Mega's and all 3 cyli

"The Mega's and all 3 cylinder Tohatsu's have an inherent problem. The crankshaft is pressed together with no spline nor key to hold them in place. Under stress, the crank will spin out of time. Motor will run great, just lacks acceleration and top end. I have repaired several hundred since 1993 with this problem.
D"
 
You mean that when the engine

You mean that when the engine is operated at RPMs above what it is designed to run you can spin a crank....Just like any other engine that uses a multi-piece crankshaft. You mean that if you hit an unforgiving object in the water that causes the engine to stop suddenly you can spin a crank....Just like any other outboard that uses a multi-piece crank shaft. The only people that spin cranks are boat racers and stump jumpers who operate their engines in hazardous environments. And the Danny Thibodeaux that I know knows that.
 
"I worked on hundreds that had

"I worked on hundreds that had the rev limiter connected, with spun cranks. And as much as I love Tohatsu's, I also know that Yamaha uses a splined crankshaft, as does Mercury, E-Tec, all the old OMC's. Tohatsu would not recognize it as a "prevalent" problem, less than 5% failure rate. So to say "The only people that spin cranks are boat racers and stump jumpers who operate their engines in hazardous environments." would not be entirely true. That may be Tohatsu's point of view????, they still paid the warranty claims.
I am not sure if this is the Danny Thibodeaux you know. I have touched a few Tohatsu's in my 35 years as an Outboard Tech. Touched a few Mercs, OMC's, Yammies, and various and assorted other brands.
D"
 
"And you probably knew the old

"And you probably knew the old Danny Thibodeaux, the unsaved one. You knew the one that would say nothing but good things about whomever sponsored his race program, whether they were true or not. Nah, you don't know THIS Danny Thibodeaux, the old one died. The new Danny Thibodeaux will not lie, won't even stretch the truth, regardless of who it is for or against.
D"
 
"Well Danny, I don't know

"Well Danny, I don't know what to say to you except being saved or not does not make your view of reality right or wrong. I disagree with your idea that there is/was a problem with the pressed crankshaft. The only way the crankshaft would spin is from excessive RPM or an impact... That's science, not religion. Your version of the Truth isn't any different than anyone else's who believes what they say, but I think your limited(limited meaning primary) experience with Tohatsu's in racing has undoubtedly caused you to think that crank shaft failure was some sort of wide spread phenomenon when it was not. And for the record, I won't lie or stretch the truth either...And I have been "saved" a lot longer than you have
"
 
"Only took the time to view re

"Only took the time to view records from 93-97. My view of reality, and my records show that from 1993-1997, I reindexed and welded the crankshaafts on 121 Tohatsu 3 cylinders. And my shop did not close in 1997, I still work on them today. I'm not sure about your thinking that I had "limited" experience with Tohatsu motors, I sold and warranted Tohatsu outboards for 5 years. As for you being saved, great brother, hope to turn wrenches with you in Heaven. I did not come here to argue with you. I came here to simply give unbiased advice. I do not sell any brand of outboard, so I have no vested interest. I still repair a few. I have two 3 cylinder Tohatsu's in my shop now with spun cranks. It is a very prevalent problem. That is the reason that for the year of 1995, Ken Scoville suggested Tohatsu not warranty their outboards on our marsh tunnel boats.
Bless You
Danny"
 
"Danny,

This is a perspecti

"Danny,

This is a perspective issue. Engines used in racing and in the swamps have a much higher incidence of failure due to consumer "abuse". That's your bailiwick and it makes sense that you would see that type of problem with increased numbers. But, that does not mean you are correct in making a blanket statement about a model engine that does not have that problem outside of that application and environment. My viewpoint is national in nature and there just weren't twisted cranks then or now other than in areas where people were hitting stumps and racers... That's why you don't see people complaining about it on the web and when it is brought up its always by a racer or someone who admits they hit something in the water.

On a side note, back when I worked for NIMAC, I didn't find Scoville to be friendly to any warranty claim
I think his practices were based on how Tohatsu Japan was compensating him...I might be wrong though, it may just have been his nature."
 
"danny thibodeaux if you happe

"danny thibodeaux if you happen to se this please contact me [email protected] i have a 40 tohatsu iwant to rebuild i want to make sure she last duck season is close ready to jump a few stumps"
 
Re: "danny thibodeaux if you happe

I have a Mega that I just changed the head gasket on, and I am still getting water in the bottom cylinder. I need any advice as to where I need to be looking now. The cylinder did not show any signs of a broken ring or damage, but reading about a "spun crank" has got my attention. Am I looking at a crank problem or a block problem, any advice would help. I am looking for a block, but if this is a crank issue, would that cause my water intrusion?? I am not expert, but I am willing to work, thanks to anyone who has time to reply,
 
pvanv said:
Do a compression test and a leakdown test. That may reveal the source of the water leak.
Click to expand...
I am getting compression gauge for this now, also found out the cooling plate on the side is another possible point of water intrusion, will take apart to inspect today. I know understand it is not the crank, motor runs too good, so if not the cooling plate it will most likely be the block, but to access it will have to be torn down. Thanks for the reply, will post what I find,
 
What's plugs are you running I have been running b8hs-10 and a buddy told me I needed to try b7hs-10 since they were hotter I'm illiterate when it comes to this stuff and don't want to mess anything up
 
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