For The Mechanical Engineer/Machinists Out There

Rocky · Post by **Rocky** » Feb 5th, '12, 09:12

So, this has been a discussion and a challenge for me with our Toyota FTS
(field technical specialist) on counter balance shafts. We have a failed engine in the shop in which the FTS says is because of loss of lubrication to the mains,rods, and countershaft bearings. This I agree with, for the mains/rods and balance shaft bearings are dry/spun. BUT he condemned the engine because the nylon driven counter balance shaft was off time, putting excessive wear on IT'S bearings causing overheating of the countershaft therefore melting the nylon gear putting debri into the pickup then main oil galley getting plugged. This is were I disagree with the cause.
In my way of thinking and correct me if I'm wrong, the counter balance shaft is ALWAYS weighted offset and out of balance with those sideloads no matter what relation or "phase" it has to another shaft or harmonic and resonant noise/vibration engine is producing. It is ALWAYS out of balance within itself. As long as this shaft has proper oil film psi at all times of engine operation, it will keep turning unbalanced for the life of the engine. If this shaft loses that film psi, of course the bearing surface of the shaft will centrifugally fail on the weighted side.
So, what do you think?

Bruce · Post by **Bruce** » Feb 5th, '12, 09:50

Given that the eccentric weights on these counter balance shafts are designed to run 180 out of phase to cancel out the vibration inherent to the popular 4 banger, an out of time problem would only make the engine run rough or really rough depending on how out of time it is.

All these increased forces can enhance wear internally causing parts to wear faster.

In an all timed engine, the counter balanced shaft does run out of balanced all the time but all of the forces are canceled out which is why 4 bangers will run smoother.

Parts like nylon could in fact wear quicker in an engine not balanced and cause a part failure.

If this counter balance shaft was out of time or phase as is the correct term, a rough running engine should have been suspect.

Remember the shafts are there to balance the engine for smoother operation especially those 4 cylinders with long strokes for increased displacement. They can be run without the shafts as many racers do.

I see both sides of the point but look at it from a complete running engine and not individual components.

Now not seeing the aftermath of parts I can't determine if there was a specific part failure that Toyo knows about and is trying to get out of a factory fix and put it on the consumer.

Having worked with engine manufacturers and seen first hand what they hide, don't trust any of em.

If your looking at a big enough repair bill, bring in an independent to look over the aftermath and render an opinion.

Rocky · Post by **Rocky** » Feb 5th, '12, 11:10

Bruce, thank you for the perspective. BTW this engine was replaced as a shortblock about a month ago for an oil leak through "porous casting" of block. With no vibrations evident to either myself when I replaced it or the customer. The FTS admitted if it was out of time even one tooth, at 2500rpm there would have been a noticable vibration none of which was evident for the month of customer driving or me before it left. To find the root cause, I will be carefully disassembling this and possibly getting that independent opinion. Also to note, the upper end has lubrication, as do the under piston skirt jets, and no pieces of "nylon" in or through the pickup screen.

Carl · Post by **Carl** » Feb 5th, '12, 11:47

New short block, did that include a new counterbalance and nylon gear?

If using the old gear, is it possible the Gear Ran Warm and or Tight. It don't take much to degrade the Nylon to the point it prematurely fails. It looks great at the moment but heat and stress do something to the material where you'll see cracking and brittleness develop not long after.

If you get to the bottom of this, let us know.

Bruce · Post by **Bruce** » Feb 5th, '12, 12:54

You can bet a customer would complain about vibration. Doubt it was out of phase with the counter balance shaft and more likely a part failure of the nylon gear.
That replacement short block should have had the counter shaft and gear with it as my definition of a short block goes.
Was it a new or reman short block? Reman possible oil gallery blockage?

Rocky · Post by **Rocky** » Feb 5th, '12, 14:43

Bruce it was a Toyo new through extended warranty, but that doesn't eliminate possibility. The oil passage through the mains into the counter shaft assy was my intention to see if blocked from the factory somehow. I'm trying to find an oil passage routing schematic to see flow direction, I do know the head is the last place oil psi hits and it was getting it at time of failure, freeze frame data indicates vvti controller up there was O.K.

Harry Babb · Post by **Harry Babb** » Feb 5th, '12, 22:18

Rocky

I see your point.

We can discuss the dynamics of balance and how it applys to your engine but in the end it all comes down to the fact that you are being bull shitted by an FTS.

Where I come from and the day in which I grew up we did not talk to an "FTS". We talked to the Service Manager and was eventually refered to the Factory Rep.....names that described exactly who and what we were talking to. But back then we bought a "Used Car" not a "Certified Preowned Automobile"

I would tell the "FTS" that I am calling "BS".

hb

Rocky · Post by **Rocky** » Feb 6th, '12, 00:26

Harry I know it's like beating a dead horse on trying to have the FTS change his mind, kind of like seeing a judge for a traffic ticket- they want there revenue. But he did say " prove me wrong" so If I do perhaps Toyo will learn of a defect on " there end" and rectify it. I"ll keep you guys updated on my findings this week.
Carl no the short block was no counter included, I agree should have been too. If the factory can leave a $.25 hose clamp off a new part they will..!!

Rocky · Post by **Rocky** » Feb 11th, '12, 00:09

So as promised I've got an update on the countershaft challenge. Here are some pics of the engine, as you may be able to see the rear bearing assy of the driven countershaft is destroyed with all the damage of course on the centrificaly weighted side. The sequence of events is still what I and now our top machinist who stopped by is oil psi loss first, not bearing failure first. I took our smoke machine and inserted it into the main oil pump output port, all ports in block get smoke out of them readily. I will be making a product report even though the catastrophic damage is too great to pinpoint, but in that report the request of the stiffening plate that houses the shafts along with shafts and cap to be included in a short block. Funny thing , the newer model replacement engine for 2009 and up does not use countershafts anymore... Wonder why.

Bruce · Post by **Bruce** » Feb 11th, '12, 16:09

I can't tell from the pics but anyway the bearing with the non hole to the oil groove got 180'd with mating half on assembly on that failed assembly?

Rocky · Post by **Rocky** » Feb 12th, '12, 00:57

Bruce the way the shafts are timed correctly look just like they are sitting in cap in relation to each other, and spin in opposite directions. I actually took pics of external timing marks before disassembly of original engine. TDC of crank, cam marks, and countershafts.These marks done by repair manual were confirmed by my pics landing in the same spots right down to outer shaft's mark slightly lower, inner shafts slightly higher than mating surface.
All of which was shown to the FTS when inspected to no avail.

P.S.- I apologize for this rambling on of non bertram related subject!

Rocky · Post by **Rocky** » Mar 3rd, '12, 21:17

So just a quick update on the balance shaft status for those interested- Toyota had a field rep come in. He then had me, without intervention set all three components up. TDC, first and second countershafts timed, and stiffening plate that houses them onto block. He then said to the three techs along with myself, "Well , I don't see anything you did wrong here, all the marks line up according to the manual."
So, that satisfied Toyota's question if it was something on the dealership's part or a bad shortblock. But it did not satisfy me. I told him the shortblock and the description of a shortblock should include the balance shafts as one unit- always. I also filed a DPR( dealer product report) and hopefully this will change the way the manufacturer sends shortblocks with fiber reinforced phenolic gears.
We are still trying to get Toyota to pay for the shortblock that failed. I'd imagine that would be like pulling teeth, I'm not holding my breath!
Anyways, back to Bertram stuff..Thanks guys for your inputs.

Here is the new setup, and below is the original. Each tooth is 14.4 degrees,so any deviation would be a dramatic change to timing. Also, the final timing marks are actually the bottom "alignment holes" of shafts and should be pointing inward 0-5 degrees, 0 degrees being an imaginary line 90 degrees in relation to the mating surface of cap. The stamped "circles" are just a crude reference pointing toward each other.

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Carl · Post by **Carl** » Mar 4th, '12, 11:53

So after all that you found out what you already knew...that you set it up right.

Rocky · Post by **Rocky** » Mar 4th, '12, 17:27

Carl, yep. And hopefully they're money won't get in the way of reason.

Bruce · Post by **Bruce** » Mar 5th, '12, 07:25

Rocky,

You or the owner would have noticed right away an off timing issue with the balance shafts anyways as we said. I guess they didn't grasp that concept except hoping you would make a mistake on his test so he could negate the whole claim.

I started to run into this with every engine company I dealt with. Distrust of the dealers and argument of every part failure in the field as being installed wrong.

Carl · Post by **Carl** » Mar 5th, '12, 11:07

Rocky wrote:Carl, yep. And hopefully they're money won't get in the way of reason.

Unfortunately money always seems to get into the way of reason.

Rocky · Post by **Rocky** » Mar 5th, '12, 18:21

Bruce wrote:
I started to run into this with every engine company I dealt with. Distrust of the dealers and argument of every part failure in the field as being installed wrong.

And I thought for eleven years now Toyota and the dealership worked as a team. Silly me.

Bruce · Post by **Bruce** » Mar 6th, '12, 08:48

Team sports has gone the way of the DO DO bird.

That is except for the "mean team" who are always ready to fight and run rough shod over anyone that gets in their way........Their leader is brutal.

TailhookTom · Post by **TailhookTom** » Mar 6th, '12, 09:33

Based on recent postings, I'm not sure the Mean Team Leader isn't eating gumdrops and sunshine -- the level of meanness has noticably deminished.

Bruce · Post by **Bruce** » Mar 6th, '12, 11:16

Like a trap door spider luring in it's prey, ignore the pretty shiney exterior cause your about to get eaten.

Rocky · Post by **Rocky** » Mar 7th, '12, 10:00

I guess "corporate headquarters" didn't get where they are by not eating a few "little ones" along the way! Hopefully the efforts of this DPR will save a few victims of the trap door spider. My intentions anyway.
Thanks again guys for the honest opinions. Helped me put myself out there to drive the point home.

Bruce · Post by **Bruce** » Mar 8th, '12, 06:32

When Yanmar thru me under the bus on my last warrantee job, that was my clue to retirement.

25 years of trouble free, zero complaint work even sending people to me from outside my service area due to the incompetent work of other Yanmar dealers.

Watch your back, there is no loyalty anymore.

Rocky · Post by **Rocky** » Mar 8th, '12, 20:08

Wow Bruce,
I would never have thought Yanmar would pull such a thing.
It seems with all your customer loyalty they should have recognized who
not to throw under. Not that Yanmar and Toyota are not great products, it just seems it would be of there best interest to protect there loyal people even if you or I are not directly there employee.

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For The Mechanical Engineer/Machinists Out There

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