CAUTION: Removing the engine balance shaft and belt

Hey everyone,

I couldn't help but read on this forum that a few members advise removing the harmonic balancer belt and balance shaft from the engine, in order to decrease the rotating mass. And/or if the belt breaks, to not worry about replacing it.

I strongly caution you against doing this. The belt and shaft were intentionally placed in the block by Mitsubishi engineers, because of the very nature of four-cylinder engines.

It is difficult to produce a self-balanced 4-cylinder engine. Mitsubishi knew this, and placed the balance shaft there to prevent the gradual internal engine damage that would result without it. While your Galant may run just fine for several tens of thousands of miles without the shaft, prolonged unbalance will almost guarantee a warped/bent crankshaft and bent connecting rods. These problems will continue to get worse and worse the more you drive it, eventually causing catastrophic engine damage and failure.

In addition to shortening your engine lifespan, removing the balance shaft is hard on your engine mounts.

I was told by an ASE certified mechanic that engine destruction could occur after about 50,000 miles of unbalanced driving.

If someone can prove me wrong on this (if you've driven at least that far without it), let me know! This is just what I've been told about it. Be safe and take good care of your Galants everyone! :smile:

EDIT: Disregard all of my warning woes here, It seems that I have in fact been proven wrong with this particular engine setup. It seems there are drivers out there with over 100K+ miles on their cars without balance shafts. While my car has gone 127,000 miles without ever breaking a balance belt, others have gone through 4 in the span of 5K miles. So, do what you like. I sort of missed my mark with this thread, I really intended to ask for your opinions on it, as I have heard both sides of it. After hearing that the engine is not at all adversely affected if the elimination is performed correctly, I've decided that I might even end up taking mine out. :109:

I'm torn on the argument. The only real upside to deleting the shaft is that the infamous balance-shaft belt won't break...because it's not there anymore. And that thing loves to break....

Removing rotational mass is kind of whatever in my opinion, it's not going to make any real noticeable difference.

The only drawback that everyone can agree upon to an extent is there is slight to moderate increase in engine vibration. My car already feels like a tractor with the vibrations from the prothane motor mounts so this is yet another reason I've kept my balance shaft belt.

I always knew there were more reasons, even more critical reasons, to keep the balance shaft belt, such as the ones you outlined. Until I'm building race motors that are only planned to last 10K miles, I will keep all my balance shaft belts, as much as I hate having the potential of them breaking (AGAIN) and forcing an entire timing belt job.

^^^Exactly. On another note, think of it way:
"If it's there, it must've been put there for a reason."

Especially since it's inside the block itself. Not a very common place for designers to throw in random, useless parts for the heck of it.

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Originally Posted by mygalantwasfree

Hey everyone,

I couldn't help but read on this forum that a few members advise removing the harmonic balancer belt and balance shaft from the engine, in order to decrease the rotating mass. And/or if the belt breaks, to not worry about replacing it.

I strongly caution you against doing this. The belt and shaft were intentionally placed in the block by Mitsubishi engineers, because of the very nature of four-cylinder engines.

It is difficult to produce a self-balanced 4-cylinder engine. Mitsubishi knew this, and placed the balance shaft there to prevent the gradual internal engine damage that would result without it. While your Galant may run just fine for several tens of thousands of miles without the shaft, prolonged unbalance will almost guarantee a warped/bent crankshaft and bent connecting rods. These problems will continue to get worse and worse the more you drive it, eventually causing catastrophic engine damage and failure.

In addition to shortening your engine lifespan, removing the balance shaft is hard on your engine mounts.

I was told by an ASE certified mechanic that engine destruction could occur after about 50,000 miles of unbalanced driving.

If someone can prove me wrong on this (if you've driven at least that far without it), let me know! This is just what I've been told about it. Be safe and take good care of your Galants everyone! :smile:

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No offense but you jump in the ring with 7 posts under your belt and your giving us advice on engine harmonics based on what an ASE mechanic told you. No offense but becoming an ASE mechanic in this day in age is a damn joke, any kid who can read, write and isnt a total moron can become certified.

With that being said, you have a valid arguement to a point. This topic has been debated since I was in 4th grade (I kid you not) People have been removing balance shafts from DSMs since the early 90's. I know of several people with built race motors that have anywhere from 60-75,000 daily driven and track miles with no balance shafts and no problems. A big part of this is having your rotating assembly balanced properly and having the motor assembled correctly in the first place and maintaining your setup properly. You have to also consider most people building engines and doing this mod dont expect their engines to last 100k. The reason mitsu did it was because they had to make sure the engine doesnt die before the warranty is up, because then the repair is on their dime.

In regards to being hard on the engine mounts, it is, but most people doing this type of mod are using urethane mounts which can take the abuse with no problem. Not alot of people are doing the balance shaft eliminator to free up rotating mass and gain 4 horsepower, they are doing it to eliminate that damn belt that ALWAYS breaks. Just like Peano said above, that belt is a real problem.

In closing, an ASE mechanic told me I couldnt convert my car to 5 speed, I did it about 3 weeks after he told me I couldnt, a bunch of certified mechanics told me I couldnt put an EVO motor in my car because it wouldnt fit and the wiring and ECU were different it would never run, I did that too. So have many other people, part of being a "tuner" is doing what people say cant be done and thats how this whole culture evolves.

The moral of the story is, dont believe everything someone tells you.

newbie-> :062: <-brian

Haha Chris <3

I just think that for the average driver who keeps his Galant stock and just uses it to go to work and back every day (that's me!), following proper maintenance, as described in the repair manual, is the key to a long-lasting engine. :cool:
Choosing to ignore a broken balance belt without making any other compensating modifications to the car (upgraded mounts, installing a better-balanced after-market crankshaft) is asking for trouble in the long run, in my opinion. (just my 2 cents)

How often does that harmonic balancer belt break? Should I be worried? I just follow the replacement interval as described in the Haynes repair manual. Is this belt notorious for breaking prematurely before the interval is up? If so, is an improper installation of the belt (too tight, too loose) to blame? or does this engine just break belts easily?

BTW I know I'm a noob on this forum, but I've been working on cars for about 7 years now, and my own car repair company for the past 2 :smile: I'm by no means an expert, but I'm not a noob when it comes to working under the hood!

the belt goes a lot and the location of it is easy to not notice and very hard to get to. many people dont even realize its broken until the whole motor goes

I disagree 100%. I went through 2 enines because of that damn balance shaft. That fucking belt snapped and destroyed all my valves, lost compression in 3 cyls....and for what? Because mitsubishi thought it should be there? Fuck that. And before anyone says anything about it being my fault and I should have taken better care of my car....I am more picky about my car than anything else. I had constant maintenance work done, belts checked regularly and it still happened. Ask Peano, I take extremely good care of my car. With that said I had an engine built without the balance shaft and I have had no issues (knock on wood). My car idles smoothly...when its running you cant tell its on. My car runs better without it, revs a little quicker, and I have the added security that that damn belt wont snap and cost me ANOTHER freaking engine. So the whole warning thing is just pointless in my opinion. Most of the people on this site know the risks of whatever mod they may do to their cars so....

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Originally Posted by mygalantwasfree

I just think that for the average driver who keeps his Galant stock and just uses it to go to work and back every day (that's me!), following proper maintenance, as described in the repair manual, is the key to a long-lasting engine. :cool:
Choosing to ignore a broken balance belt without making any other compensating modifications to the car (upgraded mounts, installing a better-balanced after-market crankshaft) is asking for trouble in the long run, in my opinion. (just my 2 cents)

How often does that harmonic balancer belt break? Should I be worried? I just follow the replacement interval as described in the Haynes repair manual. Is this belt notorious for breaking prematurely before the interval is up? If so, is an improper installation of the belt (too tight, too loose) to blame? or does this engine just break belts easily?

BTW I know I'm a noob on this forum, but I've been working on cars for about 7 years now, and my own car repair company for the past 2 :smile: I'm by no means an expert, but I'm not a noob when it comes to working under the hood!

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and how long have you been working on mitsu's?

^^lol

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Originally Posted by evil-G-nius

I disagree 100%. I went through 2 enines because of that damn balance shaft. That fucking belt snapped and destroyed all my valves, lost compression in 3 cyls....and for what? Because mitsubishi thought it should be there? Fuck that. And before anyone says anything about it being my fault and I should have taken better care of my car....I am more picky about my car than anything else. I had constant maintenance work done, belts checked regularly and it still happened. Ask Peano, I take extremely good care of my car. With that said I had an engine built without the balance shaft and I have had no issues (knock on wood). My car idles smoothly...when its running you cant tell its on. My car runs better without it, revs a little quicker, and I have the added security that that damn belt wont snap and cost me ANOTHER freaking engine. So the whole warning thing is just pointless in my opinion. Most of the people on this site know the risks of whatever mod they may do to their cars so....

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Were the belts just examined or were they actually replaced? I believe you that you take care of your car, I'm not trying to cast doubt on that, I'm just wondering if I should be concerned that mine will just snap one day for no reason. BTW I got my car for free cuz it was totaled. If if lasts another 50k with this rebuilt A/T then I'll be damned. It is for this reason only (it has 127k on the odo) that I might actually consider removing my balance shaft, I don't have much to loose, it looks like.

I just generally think that most engine parts are there for a reason. If you guys claim that my car's engine won't be adversely affected 50k down the road from this mod, then I'm all for it. It's better than shattered valves and cracked pistons...

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Originally Posted by Cali

and how long have you been working on mitsu's?

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around 7 years as well.

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Originally Posted by mygalantwasfree

Were the belts just examined or were they actually replaced? I believe you that you take care of your car, I'm not trying to cast doubt on that, I'm just wondering if I should be concerned that mine will just snap one day for no reason. BTW I got my car for free cuz it was totaled. If if lasts another 50k with this rebuilt A/T then I'll be damned. It is for this reason only (it has 127k on the odo) that I might actually consider removing my balance shaft, I don't have much to loose, it looks like.

I just generally think that most engine parts are there for a reason. If you guys claim that my car's engine won't be adversely affected 50k down the road from this mod, then I'm all for it. It's better than shattered valves and cracked pistons...

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Nope...regularly checked and the second engine had all new belts put it and it still happened. I have no faith in that thing so i'd get rid of it. You can smooth out the vibration by adjusting your idle just a touch. Thats what I did and it is as smooth as it was when it was in there. No adverse effects

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Originally Posted by evil-G-nius

Nope...regularly checked and the second engine had all new belts put it and it still happened. I have no faith in that thing so i'd get rid of it. You can smooth out the vibration by adjusting your idle just a touch. Thats what I did and it is as smooth as it was when it was in there. No adverse effects

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It says in the mod how-to that there are 2 balance shafts, one in front and one in back. It says that the back balance shaft is driven via sprocket from the oil pump.

Couldn't I simply just cut the harmonic balancer belt (to stop the front balance shaft), and then just remove the rear balance shaft sprocket? Doing this would result in neither shaft spinning, and would require no extra parts. Is this possible to do?

by any chance does this pertain to why my engine mounts keep going bad? Im getting sick and tired of changing them, they go bad within 3-6 months. Im just gonna install the prothane kit, as of tomorrow

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Originally Posted by mygalantwasfree

It says in the mod how-to that there are 2 balance shafts, one in front and one in back. It says that the back balance shaft is driven via sprocket from the oil pump.

Couldn't I simply just cut the harmonic balancer belt (to stop the front balance shaft), and then just remove the rear balance shaft sprocket? Doing this would result in neither shaft spinning, and would require no extra parts. Is this possible to do?

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No. Again not trying to start a shit fight, but you just asked if you could cut the balancer belt to stop the front shaft and remove the sprocket to stop the shafts from spinning, this just furthermore proves you dont understand how it works, yet you offer advice on the topic. Now I will answer your question....

The "lower" balance shaft is the one driven by the oil pump. The one thats higher up is driven by the balancer belt which is driven from the crank. The reason you cant just remove the belt and leave the shafts in is because the shafts receive oil and without knowing which point of rotation the shaft is at when it stops, the oil passages could be lined up which would mean constant oil pressure being released thru the shafts oiling hole and causing a lack of pressure in other parts of the engine. Also since the shafts arent spinning they are just dead weight, you wont know how they are oriented inside, this may cause more vibration and inbalance than removing them all together.

Typically in a balance shaft failure the shaft will either sieze up and/or spin the bearing which will cause the belt to jump from the sprocket or flat out break, then the real carnage happens when the belt comes off and gets caught in the gear on the crank for the timing belt, it ends up breaking the timing belt or causing it to jump which results in bent valves, cracked pistons, etc.

Also removing the balance shafts with the engine still in the car should not be taken lightly, especially if your not doing it on the lift. If you do end up removing them, its the ideal time to replace the water pump, oil pump and timing belt, since you'll have all the stuff taken apart to get to them.

Brian, are you balance shaft belts removed?

think about the question you just asked about just cutting the belt.. if we could do that and get away with it then the belt breaking wouldnt be a big deal and no1 would have the belt on there.

i personally am keeping mine on my current motor as like brian said its a bitch to remove it correctly with the motor in the car, but the new motor will have no balance shafts

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Originally Posted by qnz

Brian, are you balance shaft belts removed?

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Yes Sir.