150 HP 4 Stroke Counterbalance Gear Failure

[ausnoelm]

This is a common issue, the balancer sounds like a slight whirring sound before it falls to bits, there has been a couple of upgrades to the balancer, so hopefully the new ones will be OK, there is stories of people simply removing the balancer and running the motor without it, no one has come back and said it blew up.....yet! here is a picture of a good balancer, and a not so good one.

[rodbolt17]

so far, most all balancers manufactured before 2010 its a 100% failure item.
I understand there is a class action lawsuit.
my F150 has 240 hrs or so. its had 2 balancers.

[boscoe99]

If you have fiber gear parts in the oil pan then you likely have them in the oil pump, the heads, the block and goodness knows where else. The engine should be completely torn down, inspected for dwarf and swill, repaired as necessary and then reassembled. Otherwise, it is a crap shoot.

Why did you not have the balancer replaced a long time ago as a preventative measure?

As the man says, pay a little bit now or pay a lot more later. You now get to pay a lot more since later is here now.

[TownsendsFJR1300]

I have a 2007 Scout Costa 190 with an fl150txr Yamaha .At 1045 hrs I came off of plane after a wot run and noticed a shake or vibration in my motor .i was close to the ramp and on my way in and when I docked I ran it up in neutral and it was still there.I had read online about the counterbalance drive gear failure so I took it to Seagate marine in Stuart Fl and asked Carl if I had a problem with mine.When I picked up the boat he charged me for de-car boning the engine and assured me I had no failure.20 hours later my low oil pressure indicator sounded and the led bar lit.When I got home I removed the oil pressure switch and took the oil pressure.It was in fact low,12psi cold idle and 35 @ 1500.I removed the oil filter,cut it open and found green fiber looking stuff in the filter.I removed the counterbalance assembly (which only took about 20 minutes)and found that the plastic drive gear had failed.I removed the powerhead,then removed the lower unit casing which houses the oil sump.It was quite clogged.Next is to purchase a new counterbalance assy.,oil pump and pressure regulator ,and gaskets,and give it a try.No sign of metal in the sump so I"m hoping that the low oil pressure did not hurt anything.Of course it would have been better to do it 20 hrs.earlier!Maybe Carl at Seagate marine will feel bad enough to give me a discount on my parts.Knowing how easy the fix is before failure I don't understand why Yamaha didn't recall these.They sure left a bad taste in my mouth.I am definitely not happy with their "Not so Bulletproof 150 Four Stroke"

They have been replacing them on a regular basis, no charge either and even if its out of warranty. They updated the balancer several times as well.

I had my 06 F150 done a couple of years ago. Watched the mechanic do it as well.

Yamaha probably would have done the full fix for free as it is a KNOWN issue. My dealer keeps the balancers in stock as it is a known issue and a freebie fix..

I didn't know about the balancer issue, the dealer told me about it. Set up an appointment and had it swapped before any damage occurred..

You might want to look for another dealer..

[ausnoelm]

Rodbolt... Do you know how the motor will go (long term) without the balancer fitted? I know of a couple of guys that have (supposedly) removed all the internals and just refitted the cover and the motors are still running, but then, if the motor can run OK without it, wouldn't this be a pretty simple fix for Yamaha?

[boscoe99]

The motor can run until hell freezes over with the balancer removed.

Yamaha offers the F150C model without a balancer in some markets. See illustrations below. One with the balancer and the other without the balancer. A different crankshaft is used that does not have the balancer drive gear installed.

[ausnoelm]

yep, that maybe the case, BUT... maybe (somehow) the crank is different, not just the gear missing? I really have no idea, just guessing of course, just seems feasible if the motor will function perfectly without it, why would Yamaha go to the expense of fitting one in the first place? unless of course the balancer fitted motor has a much higher RPM recommendation?

[boscoe99]

Perfectly may be in the eye of the beholder. A crusty old crab boat captain is not going to give a crap about vibration.

I suspect it is more of a customer satisfaction issue. People are used to the smoothness of a Mercedes or Lexus. They get in a I4 motor and complain about the vibration. So, Yam does what they can to keep the vibration to a minimum through the use of a balancing device.

Little do those customers know how unhappy they will be if and when the balancer gear lets go. It is no mere act of coincidence that Mercury Marine touts their 150 four stroke as having all steel gears for their balancer.

[TownsendsFJR1300]

Besides NO gear on the different crank, its very possible its (the crank) is weighted differently to compensate for lack of counter balancers.


IMO, with the upgraded /repaired part installed, its now a non issue.

Besides having a smoother running engine, its going to last longer over all.

Many V8's (automotive engines) have internally balanced cranks, some have flex plates that are balanced. Thus the term, blue printed and "balanced" (Balancing the rotating mass) for better performance.

[99yam40]

IMO, with the upgraded /repaired part installed, its now a non issue.

Rodbolt said he has had to replace more than once, so not sure replacing with new part is the final fix.

But if you pay attention and replace before they go too bad it is a much easier repair

[TownsendsFJR1300]

Rodbolt said he has had to replace more than once, so not sure replacing with new part is the final fix.

But if you pay attention and replace before they go too bad it is a much easier repair

They updated the same part, I believe 3 or 4 times, that's per the dealer.

The balancer in its entirety is a VERY heavy built unit. Each shaft is damn near as heavy as the crank shaft between the weights and the shafts themselves. I watched as the mechainic did mine and got to peek at both units. Took maybe 1/2 hour, boat still in the water..

The mass of those weights is substantial. Running without them, IMO, would not be the smartest thing you can do. Your pretty much unbalancing a balanced engine.

If Rodbolt got the first version updated one, yes, they updated that one and several after (per my dealer).

Rodbolt being in the shop, I'm sure would have the latest balancer.

Per Rodbolts post, #17, since 2010 they were all bad. The problem was apparently finally fixed after that. Getting a new unit manufactured after 2010, you should be good...

[boscoe99]

Don't go confusing the balancing of a crankshaft with the reason for using a balancer in an I4 configuration piston engine.

Balance shaft - Wikipedia, the free encyclopedia

The I4 F150A and B models and I4 F200 are the only Yamaha models that use a balancer. All other I4 Yamaha models such as the F115, F100, F90, F80, F75, F70, F60, including the commercial F150C model, do not use balancers.

Many, many, many commercial F150 users down in Louisiana have removed their balancers. They are putting thousands of hours on their motors. More hours than Joe Schmo will ever see on his F150 with a balancer installed, assuming the balancer does not let go and take the motor out. Plus, they may get a few more extra HP out of the motor since work is not having to be done to turn the darn thing.

[TownsendsFJR1300]

I'm very familar with balancers. My last single cylinder 250cc motorcycle had two balancer shafts running thru the block, chain driven, with weights on the other side of the block to smooth out the vibs of a single:



My current I4 600cc and last I4, 1300 cc Yamaha, 145 HP, were/are both balanced for smoother performance.


Re the other Yamaha engines, I believe you.

However, if Yamaha designed this particular engine with a balancer, if they could get by without it and save $500 to put in their pocket, why wouldn't they??

That balancer runs on 4 roller bearings total, if anything, its acting /performing as additional flywheel effect.

The Op can pull those balancers if he wants, its his engine.

I have to believe the Yamaha designers had a reason to put it there, at least in those particular models...

[boscoe99]

Absolutely positively they put it there for a reason.

Is it critical to the life of the motor or if removed is it in any way detrimental to the life of the motor? Apparently not according to those that have removed it. And apparently not for those F150 models that come from the factory sans balancer.

Of those that have had their motors destroyed due to the fiber gears failing, and who are outside of the warranty period or Yamaha US goodwill period, I am betting they wish that their motors had had the balancer removed.

[99yam40]

think about the old auto motors that had to have the timing chain and gear changed at about 70,000 miles.
plastic coated gear so it would run quieter.
We always put a metal gear back in, and never noticed any more noise.

Failure built in to them just like the light bulbs, so some one could sell more