How many owners have noticed engine vibration (around 2500 rpms)?

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Originally Posted by RamAirZ

Well also a vibration to one person might not be one at all to another. So it's hard to say. But it's very easy for any engine to vibrate when mounts go bad, which they can/will do over time. Like you said, should be able to be corrected. I'm thinking mounts or balancer, I know the earlier 3.2 had balancer issues.

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I agree this is a DIFFICULT topic to talk about/solve -- as one man's vibration might be another's soothing back rub! LOL

The vibration I'm talking about is definitely more than you could sell a new car with (and enough so that I can comfortably classify it as an "issue"). It's also enough that it would drive me toward a solution (or sale if never corrected). It's one that creates cabin resonance at hwy speed where passengers are annoyed (mainly in the back seat). But, it's definitely coming from the motor (since it is present when parked).

After reading Jerry's response, I tend to think this is a motor mount issue. Plus, the current owner had the belt removed, checked for balancer play, and if the vibration still existed w/o the belt. It does and there's no play.

That pretty much means it's the mounts (or the motor). When/if I can confirm the mounts, I'd like to purchase the VX in question.

The downside is the same shop said they did not see a problem with the mounts either. But that's probably harder for the average mom/pop wrench-turning shop to determine. It's one of those areas where a (dealership that's seen more specimens) might better diagnose. OTOH, lots of dealers have seen very few of these!

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Originally Posted by 89Vette

The vibration I'm talking about is definitely more than you could sell a new car with (and enough so that I can comfortably classify it as an "issue"). It's also enough that it would drive me toward a solution (or sale if never corrected). It's one that creates cabin resonance at hwy speed where passengers are annoyed (mainly in the back seat). But, it's definitely coming from the motor (since it is present when parked).

After reading Jerry's response, I tend to think this is a motor mount issue. Plus, the current owner had the belt removed, checked for balancer play, and if the vibration still existed w/o the belt. It does and there's no play.

That pretty much means it's the mounts (or the motor). When/if I can confirm the mounts, I'd like to purchase the VX in question.

The downside is the same shop said they did not see a problem with the mounts either. But that's probably harder for the average mom/pop wrench-turning shop to determine. It's one of those areas where a (dealership that's seen more specimens) might better diagnose. OTOH, lots of dealers have seen very few of these!

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Maybe this 6VE1 really isn't very smooth. I saw another 3.5L motor today. I went back/forth between both motors. They had (close) to the same vibration/harmonics around 2500rpms. Both smoothed out between 3500-4000rpms though one motor was noticeably smoother than the other. (Not a lot, just noticeable.)

Maybe this really is a combination of the motor's "character" -- plus a bit of mount vibration. It might also be that one needs plugs and/or injector cleaning to recover maximum smoothness.

Has anyone ever looked into installing new mounts and/or trying the heater hose trick relayed by Jerry?

I think this is a car that you can find any number of things that shoulda woulda coulda.

Like I've said before it was never a secret that this car was a short run and essentially a prototype that was pushed to a short labored manufacturing run.

I previously owned a Trooper and an original model Amigo, every single Isuzu I have ever owned or ridden in had a certain "truth" about it for lack of a better term. They are robust and well built but there isn't much of an attempt made to mask every vibration, noise and such and there is always a certain lack of detail when it came to nonessential things such as window tracks.

I obviously can't drive the particular vehicle you are interviewing, but even if it did have an issue that can be remedied I can tell you at some point there will be another one. There is a passion for this vehicle that has to be had. I went into it knowing about the engine issues, the window issues, etc, but I also knew I had never seen anything I had wanted so badly and that it used a standard Isuzu powerplant for the most part. I resolved myself to the fact I was going to own this car forever and that if the engine goes that I would, in fact, replace it. Yes, I take it in and try to find resolve to some issues, but for others, it runs like a beast and I love driving it. It's loud, it's rough, but that's what I bought.

I just think that if you are already finding issues every which way you should either not settle with this particular VX if it's really an abnormal vibration, or it's possible that you may just not want to get a VX. There are features and characteristics that have been mulled over and over and over again on these forums.

Like you said, one man's vibration is another man's backrub, but I really honestly think that these "issues" (all relative right?) are standard on this model.

You are right, you couldn't sell the roughness of this engine today. Of course, you probably couldn't work on an engine in most of the cars today in your average garage either. But this car isn't being sold today, it was being sold 11 years ago and it was never a Honda Civic or Ford Ranger. There are less than 10,000 of these unicorns. They were hand assembled and it is essentially a short run prototype.

You may prove me wrong, but you aren't going to find a perfect VX. They are only perfect to the people who love them above and beyond all the little bits and annoyances.

Just my two cents, again, hahaha. I really do hope you get in one, it's exciting to still have the VehiCross getting people riled up, but it isn't for everyone. I can tell you now, if you do decide to stick with one, I have NEVER encountered a better support group and honest group of mutual fanatics as those here on this site.

Cheers.

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Originally Posted by technocoy

I think this is a car that you can find any number of things that shoulda woulda coulda.

Like I've said before it was never a secret that this car was a short run and essentially a prototype that was pushed to a short labored manufacturing run.

I previously owned a Trooper and an original model Amigo, every single Isuzu I have ever owned or ridden in had a certain "truth" about it for lack of a better term. They are robust and well built but there isn't much of an attempt made to mask every vibration, noise and such and there is always a certain lack of detail when it came to nonessential things such as window tracks.

I obviously can't drive the particular vehicle you are interviewing, but even if it did have an issue that can be remedied I can tell you at some point there will be another one. There is a passion for this vehicle that has to be had. I went into it knowing about the engine issues, the window issues, etc, but I also knew I had never seen anything I had wanted so badly and that it used a standard Isuzu powerplant for the most part. I resolved myself to the fact I was going to own this car forever and that if the engine goes that I would, in fact, replace it. Yes, I take it in and try to find resolve to some issues, but for others, it runs like a beast and I love driving it. It's loud, it's rough, but that's what I bought.

I just think that if you are already finding issues every which way you should either not settle with this particular VX if it's really an abnormal vibration, or it's possible that you may just not want to get a VX. There are features and characteristics that have been mulled over and over and over again on these forums.

Like you said, one man's vibration is another man's backrub, but I really honestly think that these "issues" (all relative right?) are standard on this model.

You are right, you couldn't sell the roughness of this engine today. Of course, you probably couldn't work on an engine in most of the cars today in your average garage either. But this car isn't being sold today, it was being sold 11 years ago and it was never a Honda Civic or Ford Ranger. There are less than 10,000 of these unicorns. They were hand assembled and it is essentially a short run prototype.

You may prove me wrong, but you aren't going to find a perfect VX. They are only perfect to the people who love them above and beyond all the little bits and annoyances.

Just my two cents, again, hahaha. I really do hope you get in one, it's exciting to still have the VehiCross getting people riled up, but it isn't for everyone. I can tell you know, if you do decide to stick with one, I have NEVER encountered a better support group and honest group of mutual fanatics as those here on this site.

Cheers.

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Well said...:thumbup:

Any problems I've ever had with my VX has been more than made up for by the stares I get every time I drive it. Oh, and the great gas mileage. :winko:

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Originally Posted by deermagnet

I don't believe it's normal for this engine to vibrate at all. In over ten years on the Vehicross forums this is the first time I've heard about any engine vibration. Mine is so smooth with 218,000 miles and at 80 mph my whole vehicle doesn't have even the slightest vibration.

Engine vibration on this 3.5L should be something that can be corrected, IF the problem can be found.

Mark Griffin

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Haha! Mark your VX has been rockin' along for 218K and you didn't even know it! The vibration I was talking about that is inherent in our 3.5 is not something you'll feel when you're going down the road. Put it in Park and play with the loud pedal a bit and you will feel it between 2400 and 2800 though. Also at around 1300-1400 but it's really hard to hold it steady at those low rpms. It's not bad at all and you may not even notice it if you're used to riding a Jackhammer Davidson like RamAirZ is - but go from something that has a straight six to the VX and you will feel it!

89Vette I am fully aware that the crankshaft is weighted but those weights are not for your comfort, they are there to offset the mass of the pistons and rods and thus keep the crankshaft from self destructing - as is the harmonic damper at the end of the crankshaft. Even though the rotating parts within the engine are balanced, the engine itself - as a unit - can and will vibrate however - and some configurations are worse than others. The L6 and V12 are naturally smooth whereas the V6 is not - a result of having three cylinders per side. The only way to cancel the rocking couple of our V6 is with a counter-rotating balance shaft like what is seen in the picture of the GM 4.3. That balance shaft isn't "needed" to prevent the engine from self destructing - it's there for human comfort - to keep the engine from rocking along its length which is felt as vibration. But that adds extra weight/complexity/rotating mass. The designers of the GM 4.3 thought it was worth the extra weight, etc to include a balance shaft and they were probably right since it's a 90 degree engine. A lot of sixty degree V-6s don't have one since the more shallow V means less vibration. They make do with some squishy motor mounts that turn the rocking motion into heat (and break down eventually because of it) and call it good. I guess the Isuzu engineers thought our 75 degree V6 was close enough to 60 to go "au natural" as well and for most people it is.

Bottom line is if you're looking for something that's silky smooth when revved in the driveway - from idle to redline - don't go for a V6 with no balance shaft - you need a BMW L6 or better yet a Jag V12. This "cabin resonance" at highway speeds you speak of is NOT caused by the normal amount of engine vibration of the VX though. The normal VX engine vibration isn't noticeable when driving.

Did the vehicle in question have a roof rack?

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Originally Posted by SlowPro48

Haha! Mark your VX has been rockin' along for 218K and you didn't even know it! The vibration I was talking about that is inherent in our 3.5 is not something you'll feel when you're going down the road. Put it in Park and play with the loud pedal a bit and you will feel it between 2400 and 2800 though. Also at around 1300-1400 but it's really hard to hold it steady at those low rpms. It's not bad at all and you may not even notice it if you're used to riding a Jackhammer Davidson like RamAirZ is - but go from something that has a straight six to the VX and you will feel it!

89Vette I am fully aware that the crankshaft is weighted but those weights are not for your comfort, they are there to offset the mass of the pistons and rods and thus keep the crankshaft from self destructing - as is the harmonic damper at the end of the crankshaft. Even though the rotating parts within the engine are balanced, the engine itself - as a unit - can and will vibrate however - and some configurations are worse than others. The L6 and V12 are naturally smooth whereas the V6 is not - a result of having three cylinders per side. The only way to cancel the rocking couple of our V6 is with a counter-rotating balance shaft like what is seen in the picture of the GM 4.3. That balance shaft isn't "needed" to prevent the engine from self destructing - it's there for human comfort - to keep the engine from rocking along its length which is felt as vibration. But that adds extra weight/complexity/rotating mass. The designers of the GM 4.3 thought it was worth the extra weight, etc to include a balance shaft and they were probably right since it's a 90 degree engine. A lot of sixty degree V-6s don't have one since the more shallow V means less vibration. They make do with some squishy motor mounts that turn the rocking motion into heat (and break down eventually because of it) and call it good. I guess the Isuzu engineers thought our 75 degree V6 was close enough to 60 to go "au natural" as well and for most people it is.

Bottom line is if you're looking for something that's silky smooth when revved in the driveway - from idle to redline - don't go for a V6 with no balance shaft - you need a BMW L6 or better yet a Jag V12. This "cabin resonance" at highway speeds you speak of is NOT caused by the normal amount of engine vibration of the VX though. The normal VX engine vibration isn't noticeable when driving.

Did the vehicle in question have a roof rack?

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Thanks for the reply! This is the kind of feedback I was looking for. It's thought-filled, detailed, and makes a genuine attempt to explain the dynamics of what's happening.

[No offense, but blind acceptance of a vehicle as a halo project is short-sided. The motor's character was my question -- which was used in other non-concept projects. As such, it shouldn't be doled off as half-hearted by Isuzu.]

I agree the motor seems to have some inherent vibration. Surprisingly, the only other motors I've noticed this on (in my 37yrs of driving) is a 2-cylinder motorcycle. OTOH, this is the first V6 I've driven with the intent of ownership. (My father has a V6 Buick which is also smooth -- but that's in the cabin. Maybe it has a balance shaft too?)

To determine whats "normal", I placed my hand directly ON the 3.5L motor. I repeated this for another 3.5L motor from 2001. With the isolation of the mounts removed from my perception, I could feel the similarity in cylinder pulses, variances at rpm, and stubbling during decel. With everything I felt, the character was the same. The only difference was that the strength of vibrations were approximately double in the newer 76k mile engine. (The other had 120k on the clock.)

Though it's possible that the lower mileage vehicle also transmits more vibration thru the mounts (to the vehicle), it seems more like the character of the motor itself.

Obviously, part/weight tolerances from the factory could make a difference, or these a specific action that could smooth the vehicle. Since air, fuel, and compression (plus timing) all play a part in the strength of an indidual cylinder pulse, this particular motor might see improvement thru: 1) spark plug inspection/replacement, 2) injector service/replacement, 3) coil replacement?, or 4) cylinder compression check. But I haven't gone so far as to do those myself. But, the owner was KIND enough to send it to a mechanic for the "once over". I have no idea if any of these individual points were examined.

That said, the mechanic gave his thumbs up. Though he also drove it, felt the vibration, and acknowledged it, his final judgement was to categorize it as a typical 9-yr-old vehicle. My problem with that assessment is the vibration CAN be felt and acknowledged, but an explanation could only be found thru my efforts here. (Thanks btw for that!)

I can feel the vibration on the hwy around those rpms. Because it can also be heard, one logical conclusion is the vibration is being transmitted to the frame via hardened/touching motor mounts. Just as an exhaust pipe can create exponential noise when touching a car's frame/body, so could an engine.

So, it would seem like the mounts might be the culprit. OTOH, because it's vibration does feel somewhat stronger than another 6VE1 specimen, maybe there's a tune-up issue that could affect improvement.

The issue is not resolved IMO, though I've gotten alot closer to determining the issue. Because there are SO many other GOOD things about the unit in question, I'm not so eager to assume it's just the nature of the beast or that a VX just isn't the vehicle for me. That approach just doesn't provide enough investigation/thought IMO. If you can't tell, I'm more eager to make this work than to give up!

Happy Memorial Day to Everyone!!!

gp

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Originally Posted by navistar

Any problems I've ever had with my VX has been more than made up for by the stares I get every time I drive it. Oh, and the great gas mileage. :winko:

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This is my "Man of the Hour". Navi is the one who personally visited and introduced me to the VX concept. Before he was nice enough to visit, I was only able to view/judge from afar. If was his congeniality that helped me move from intrigue to infatuation. At this point, I'm hoping to continue until I hit satisfaction!

I can't get no..., I can't get no...., satisfaction. Cause I've tried...and I've tried...and I've tried.

R. Stones
:dance:

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Originally Posted by navistar

Any problems I've ever had with my VX has been more than made up for by the stares I get every time I drive it. Oh, and the great gas mileage. :winko:

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Oh, I don't know. Eighteen highway is pretty thrifty compared to a bench stock 454, which gets 12 highway, 14 if you baby it!

I tell everyone that you have to remember, when the vx came out, gas was 1.12 a gallon. Who cared about mileage?! Its getting better than 1 hp per cubic inch of displacement, which is the bare minimum of acceptable performance in my mind (an I mean Bare! If honda and ferrari can get 100+ hp per liter and make it last, why can't someone else?) on a vehicle that's pushing 4000 pounds of steel and rubber. :yeso:

In that view, 18 doesn't seem so bad!

I avg. about 17 with my lift and tires and what not, I'm pretty happy with that