HELP!!!!! Engine vibration!!!

[carlochik]

Hi guys,

I'm a newbie at this forum, Thank God their's a great site like this :oops:
Anyway. Need your help on this matter: my balancer shaft belt (the one that control the oil Pump arrgh!!!) broke off and it probably ran about 1 hour without oil pressure OUCH!!!, didn't know it coz the oil indicator light didn't light up. Because of this I was forced to rebuild me engine 4G63 SOHC. installed new pistons and rings, new con rod bearings, new crankshaft bearings, etc. I can still feel some vibration from the engine at 3000rpm.
What could this be? I'm going nuts becoz off this!!! HELP!!!

Before i rebuilt the engine, the vibration was already present. All of these happened after i replaced the balancer shaft belt when it broke.

[carlochik]

As i said, I'd really appreciate any inputs you guys may have regarding my dilemma Thanks

I can see inputs coming hurrah!!!

[Russian7G]

have you checked the engine mounts?

[ken inn]

well, i dont know anything about sohc, but on dohc, those symptoms are probably a mis aligned balance shaft belt, a common problem. there should be timing marks that you can see. manually turn the crank, and try to get them to line up. you will have to remove the timing belt cover to see, but i bet they are off.

[carlochik]

thanks for your inputs guys, yup all engine mounts are ok. all timing marks are aligned. Ill be doing a proceess of elimination thing here, starting at replacing the camshaft. I have a feeling that i may have a misaligned camshaft. AARRRGGGHHHH!!!

[dsmracer]

<div class='quotetop'>QUOTE(carlochik)</div><div class='quotemain'>thanks for your inputs guys, yup all engine mounts are ok. Â*all timing marks are aligned. Â*Ill be doing a proceess of elimination thing here, starting at replacing the camshaft. I have a feeling that i may have a misaligned camshaft. AARRRGGGHHHH!!!</div>

If it was a misaligned camshaft, you'd be rebuilding your motor again. How bad is this vibration? Can you compare it to something? When you rebuilt your motor you should have just removed the balance shaft. If the vibration is slight, it's possible that when you had your motor rebuilt, some of the parts weren't balanced or counter-balanced properly.

[carlochik]

I was really thinking of taking out the balance shaft when i was rebuilding the motor, was not just sure if there would be any effects on the motor in terms of power and performance. Did any of you guys tried removing the balance shaft???? hmmm

[manybrews]

<div class='quotetop'>QUOTE(carlochik)</div><div class='quotemain'>I was really thinking of taking out the balance shaft when i was rebuilding the motor, was not just sure if there would be any effects on the motor in terms of power and performance. Â*Did any of you guys tried removing the balance shaft???? hmmm</div>
all you will get is a substantial increase in vibration. you will detect no noticable increase in power. dont do it.
you probably have the oil pump/balance shaft out of phase, as it is geared on a 2 to 1 reduction; meaning you could have the marks lined up but actually have the sprocket a full turn off.

[dsmracer]

<div class='quotetop'>QUOTE(manybrews)</div><div class='quotemain'><div class='quotetop'>QUOTE(carlochik)</div><div class='quotemain'>I was really thinking of taking out the balance shaft when i was rebuilding the motor, was not just sure if there would be any effects on the motor in terms of power and performance. Â*Did any of you guys tried removing the balance shaft???? hmmm</div>
all you will get is a substantial increase in vibration. you will detect no noticable increase in power. dont do it.
you probably have the oil pump/balance shaft out of phase, as it is geared on a 2 to 1 reduction; meaning you could have the marks lined up but actually have the sprocket a full turn off.</div>

Okay, am I to believe that the SOHC differs from the DOHC in that there is only one timing belt, and not a seperate one for the balance shaft like on the DOHC. I haven't personally checked yet, but somehow I don't really believe it. You will get an increase in vibration, but not substantial. You will get an increase in HP, but the biggest benefit is an increase in oil pressure.

[Russian7G]

Both 4G64 SOHC & DOHC have a timing belt and a balance shaft belt.

[dsmracer]

<div class='quotetop'>QUOTE(Russian7G)</div><div class='quotemain'>Both 4G64 SOHC & DOHC have a timing belt and a balance shaft belt.</div>

That's what I was thinking. No reason the 4G63 would be different. I say Yank it.

[manybrews]

<div class='quotetop'>QUOTE(dsmracer)</div><div class='quotemain'>

Okay, am I to believe that the SOHC differs from the DOHC in that there is only one timing belt, and not a seperate one for the balance shaft like on the DOHC. Â*I haven't personally checked yet, but somehow I don't really believe it. Â*You will get an increase in vibration, but not substantial. Â*You will get an increase in HP, but the biggest benefit is an increase in oil pressure.</div>
the increase in vibration is very substantial, being as the engine is not internally balanced (to go along with an inline 4s natural inbalace to begin with).
you MAY get as much as a 2 HP gain.
and the increase in oil pressure is also pointless, as the cars do not have a shortage of it in the first place. the cars WERE built with the shafts for a simple reason; vibration fatigues everything, including the person driving. removing them is completely and utterly pointless.

[dsmracer]

<div class='quotetop'>QUOTE(manybrews)</div><div class='quotemain'><div class='quotetop'>QUOTE(dsmracer)</div><div class='quotemain'>

Okay, am I to believe that the SOHC differs from the DOHC in that there is only one timing belt, and not a seperate one for the balance shaft like on the DOHC. Â*I haven't personally checked yet, but somehow I don't really believe it. Â*You will get an increase in vibration, but not substantial. Â*You will get an increase in HP, but the biggest benefit is an increase in oil pressure.</div>
the increase in vibration is very substantial, being as the engine is not internally balanced (to go along with an inline 4s natural inbalace to begin with).
you MAY get as much as a 2 HP gain.
and the increase in oil pressure is also pointless, as the cars do not have a shortage of it in the first place. the cars WERE built with the shafts for a simple reason; vibration fatigues everything, including the person driving. removing them is completely and utterly pointless.</div>

That's completely false. There technically is no increase in vibration being made, just being felt. The motor is actually internally balanced, usually to within 0.5 gram of each other. We're talking about precision Japanese manufacturing here, not Detroit slap it together. The Japanese are very anal. Balance shafts were created by Mitsubishi to minimize the vibrations felt in order to provide a yuppie smooth ride. These motors do not make any more vibration than any other Japanese 4 cyl. HP gain isn't hugely substantial, but most shops estimate up to 10 HP can be netted.

The advantages are that YOU WILL get increased oil pressure AT IDLE, where you need it most. Top end remains unaffected for the most part since it's more than fine at stock. I should have specified earlier. Also, no chance the balance shaft bearings will fail and kill the rest of the motor. The other advantage is one less timing belt to replace or have break on you. Nothing like having the lousy Balance Shaft Belt break, go under the timing belt, and wreck your valves and worse.

[ken inn]

i still say it is the balance shaft being out of phase. and 3k is about where you will feel it. whether you remove the shaft or not, and whether it gives more hp or not, is debateable. i elected NOT to remove them from my modified vr4, and the one person i really trust also recommended against removing them(scott evans, forced performance). having ridden/driven several cars with no balance shafts, i prefer a smoother motor, and i got way more power than i need.

[dsmracer]

I guess it can boil down to a matter of preference. But to date I have yet to hear a horror story of motor problems from someone removing a balance shaft.

[manybrews]

<div class='quotetop'>QUOTE(dsmracer)</div><div class='quotemain'>
That's completely false. Â*There technically is no increase in vibration being made, just being felt. Â*The motor is actually internally balanced, usually to within 0.5 gram of each other. Â*We're talking about precision Japanese manufacturing here, not Detroit slap it together. Â*The Japanese are very anal. Â*Balance shafts were created by Mitsubishi to minimize the vibrations felt in order to provide a yuppie smooth ride. Â*These motors do not make any more vibration than any other Japanese 4 cyl. Â*HP gain isn't hugely substantial, but most shops estimate up to 10 HP can be netted.</div>
youre right.. they arent creating more vibration (unless they are out of phase).. theyre allowing the normal vibration of the engine to be felt. but the engines are not internally and externally balanced as a normal engine would be; they dont have to be.
I know balance shafts were created by mitsubishi; I have worked for them for more than 12 years now. EVERY other company on the planet has leased the engineering for balance shafts from them, because fatigue has no place on a modern car.
and the 10 HP estimation? pure crap. the shafts have no load on them other than their own intertia. theyre about 2.5 pounds each. no load, only the drag from 2 bearing surfaces. every other rotational componant will rob more power from the car, including the friction of the crankshaft itself.
<div class='quotetop'>QUOTE</div><div class='quotemain'>
The advantages are that YOU WILL get increased oil pressure AT IDLE, where you need it most. Â*Top end remains unaffected for the most part since it's more than fine at stock. Â*I should have specified earlier. Â*Also, no chance the balance shaft bearings will fail and kill the rest of the motor. Â*The other advantage is one less timing belt to replace or have break on you. Â*Nothing like having the lousy Balance Shaft Belt break, go under the timing belt, and wreck your valves and worse.</div>
at idle? sure. but who cares? there no load at idle anyway. idle is in no way the most important time to have high oil pressure. most auto engines could run at idle with almost no oil pressure. keeping in mind that people a lot smarter than you and I actually engineered these things to run, altering the oil pressure is pointless as the shafts were taking into consideration during the last 33 years of design.
failure of the balance shaft bearing? NOT going to happen unless you neglect your engine. Any of the other bearing are more likely to fail due to the simple fact that they are all loaded with more than their own weight.
and in regards to the last issue (the broken belt), i can only say one thing... if someone is stupid enough to neglect their timing belts, tough shit. the normal belt has a much greater chance of failing on its own, due to the far, far greater stresses placed on it (turning the cam(s), oil pump, balance shaft, etc. etc).

[manybrews]

<div class='quotetop'>QUOTE(ken inn)</div><div class='quotemain'>i still say it is the balance shaft being out of phase. Â*and 3k is about where you will feel it. Â*whether you remove the shaft or not, and whether it gives more hp or not, is debateable. Â*i elected NOT to remove them from my modified vr4, and the one person i really trust also recommended against removing them(scott evans, forced performance). Â*having ridden/driven several cars with no balance shafts, i prefer a smoother motor, and i got way more power than i need.</div>
youre completely correct. the oil pump/balance shaft IS out of phase, no doubt about it.
and I have built a 430 HP eclipse that also keeps the balance shafts in... for the simple reason that removing them is utterly pointless. If I wanted to drive a shitty, virbating piece of trash, Id pick a GM car. we do NOT have to compromise in this day and age.

[dsmracer]

I use to work for Mitsu too. The balance shaft was created simply for comfort, not to compensate for a poorly engineered and balanced motor. It's a preference thing, and coming from a racing perspective, less moving parts means less to worry about. Several shops say yank it, including RRE, and Mach V. I for one side with them and recommend the same to my customers, but to each his own. And how can you say it doesn't rob a significant amount of HP? Sure it's not like bolting on a turbo, but you're likely to feel the difference. You just said yourself the part is about 2.5 lbs. That's a big hunk of weight the motor is having to work to spin. It would net more power than removing the A/C or a similar accessory.

[manybrews]

<div class='quotetop'>QUOTE(dsmracer)</div><div class='quotemain'>I use to work for Mitsu too. Â*The balance shaft was created simply for comfort, not to compensate for a poorly engineered and balanced motor. Â*It's a preference thing, and coming from a racing perspective, less moving parts means less to worry about. Â*Several shops say yank it, including RRE, and Mach V. Â*I for one side with them and recommend the same to my customers, but to each his own. Â*And how can you say it doesn't rob a significant amount of HP? Â*Sure it's not like bolting on a turbo, but you're likely to feel the difference. Â*You just said yourself the part is about 2.5 lbs. Â*That's a big hunk of weight the motor is having to work to spin. Â*It would net more power than removing the A/C or a similar accessory.</div>
a 100 percent racing application would be the only time I would accept that as do-able, and even then its really not needed.
and Ive already described how it doesnt rob any significant power; its completely unloaded but for its own weight. ALL the other spinning accessories easily rob physical power, as they require torque to spin.. AC could be anywhere from 10 to 20HP, power steering 5-ish, even the alternator under heavy load will rob 5+ HP.
hell, the crankshaft alone weighs in at what, 30 pounds? complete with 9 large friction surfaces? and the cams have 4, plus the rollers and the friction required to open the valves against the spring pressure..
the balance shafts have to overcome only thier own inertia. nothing else. and their inertia is the smallest of all reciprocating engine parts. hell, the oil pump no doubt robs more power.
Youre right, theyre only for comfort. so why remove them? I garantee if we take the exact same motors, one with and one without balance shafts, the track times will be within .001 percent of each other. And if was an enduro, the car with balance shafts would no doubt win due to the less fatiguing nature of the diminished vibration.
one only has to look at a harley to realize why vibration is the antithesis of any motorized vehicle. ever drive a pre 2004 sportster? and then the new ones? the older ones are nearly unridable. pure shit. the japanese figured that out years ago, but the lazy americans decided that we didnt need comfort, so continued to sell us their crap until forced to quell vibration and noise.
there is absolutly no viable reason to worsen any driving experience, even when a car is sometimes raced.

by the way, i HAVE removed balance shafts for people before, and seen MANY engines with that done to it. there is no noticable power gain by any stretch of the imagination. you need approximatly a 10 percent power gain (no matter what power level youre currently at) to have a "seat of the pants" difference.
plus, only one person (out of possibly 2 dozen) doesnt regret it, because everyone else uses their cars daily, for more than justs a drag down the quarter.
yes, it is a preference thing. I just cant possibly understand how people could ever possibly prefer to have a loud, coarse, fatiguing car instead of the same car minus those things.

[dsmracer]

I understand what you're saying, but again you're acting like Mitsu engines are these horribly balanced pieces of machinery that NEED balance shafts, when in fact they don't. They don't produce any more vibration than any other Japanese motor without balance shafts. Honda's go 200k+ miles at much higher revs than Mitsu's and aren't necessarily better balanced motors.

As to enduro racing with balance shafts, I think not. Even in a class where you had to keep a the motor mostly stock. Come on many, you're a factory tech. Show some pride. I'm sure you know racing motors are precision built when they are Balanced and Blueprinted. This eliminates ANY need for a balance shaft. I agree that in enduro racing especially reliability is key, but that means keeping things simple and the less moving parts the better. That means no balance shaft. I am currently building a '94 Galant GS Touring Car for running NASA's 25 Hours of Thunder Hill, and my car will not have a balance shaft.