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still have an idle vibration Pages: 12

mhamilton on Mon January 09, 2006 9:50 PM User is offlineView users profile

Still working on my '80 229ci V6... I hope I can pick the brains of the experts some more.

Now that I've got the valvetrain replaced and working like new, the engine seems to run much smoother on the highway. Vacuum at idle looks good, over 20"hg, with just a very slight quiver of the needle. Unfortunately I still have a bad vibration at idle. Sitting in traffic, I can feel it strongly through the steering wheel and brake pedal, and also through the body. The engine does not seem to be running rough, I think it is more of a vibration.

So far I've replaced all motor mounts, ignition system, rebuilt the carb, eliminated all vacuum leaks, and disconnected all the accessories in an effort to isolate the problem. I can also feel some vibration (much less) at higher rpms with the trans in neutral, but it's not the same slow pulsing vibration as idle.

My thought at the moment is the torsional damper. I've noticed recently that my front seal has started leaking (after only 20k miles), and I recently noticed something odd with the belts. The a/c belt has a 2' span from the crank to the pulley, and the belt visibly shakes at all speeds. It's not the compressor pulley, that spins very smoothly by itself, and belts are tensioned properly. All the other belts have less than an 8" span, and I don't see the same shaking. Does that indicate anything? I hate to just throw parts at a problem without knowing the real cause.

Sorry for the long post, and thanks in advance for any suggestions.

-Michael

HECAT on Tue January 10, 2006 1:20 PM User is offline

Michael,

Not an expert, but I was working at a Chevy dealership in the early eighties and this allowed me to see a lot of these 229's with the same complaint you have. A Factory Service Advisor suggested we tell the customer it has a "hot" cam to improve power and the mild vibration at idle is normal. As the factory could provide no real answers and combined with the bad cam issue, it eventually must have contributed to its short life. Early Buick 231's had the same problem as did early runs of the 4.3. It was suspected that it is a torsional vibration due to the crankshaft design. Remember, engineering minds at that time trusted in their V-8 mindset. This has been somewhat validated by the fact that they have not abandon the 4.3 but have made improvements to the crank design to correct admitted torsional vibrations. I theorize but have no data to confirm that you may get some benefit from today's technology of an expensive fluid dampener that is if they even make one for this engine. At that time, we had some success at over tensioning the A/C belt, which seemed to be multiplying the torsional harmonics, because we saw what you have described. But we all know what negative effects this will have. Just a little tid bit from my memory of 25 years ago, sorry if it does not provide much help.




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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

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meaux on Tue January 10, 2006 3:19 PM User is offlineView users profile

HECAT says, "A Factory Service Advisor suggested we tell the customer it has a "hot" cam to improve power and the mild vibration at idle is normal. "

LMAO!!!

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Lazy bum who lives off his wife.

01 BMW 530i Sport, 92 Porsche 968, 85 F150, 72 911, 08 GM SUV, 01' Ford Lightnin'

HECAT on Tue January 10, 2006 3:39 PM User is offline

Yes, and it was real funny when the "soft" cams started taking a crap.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

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Edited: Tue January 10, 2006 at 3:40 PM by HECAT

mhamilton on Tue January 10, 2006 4:43 PM User is offlineView users profile

Quote
Just a little tid bit from my memory of 25 years ago, sorry if it does not provide much help.

It certainly does help... I might have gone on another 25 years searching for an answer to a problem with no solution!

Well, with the very likely possibility that a fluid damper is not available for a 229, do you think replacing the old damper would help any? I don't know if those "go bad" with the rubber in the middle, but after 25 years it's another possibility. Might also explain some of the highway vibrations (around 70 mph--2300rpm). I was reading in the factory manual that the dampers should not be hammered on, and I may have done that assembling the engine.

Indexing the torque converter was another though, but with the engine and trans being balanced, I don't think that would do much of anything. GM lists that as a last-resort type of solution to vibration complaints.

HECAT on Wed January 11, 2006 8:38 AM User is offline

The 25 year old dampener has been subjected to three issues that may warrant its replacement.

(1) The rubber deteriorates with time, ever seen the sidewall cracks in old tires?

(2) The rubber is of the same type as heater hoses and will deteriorate when exposed to engine oil.

(3) Hitting it with a hammer may have caused some minor distortion.

A stock replacement for $30 to $40 would not break the bank. I base that estimate on a new one for a 4.3 just cost one of my employees $35.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mhamilton on Wed January 11, 2006 11:17 AM User is offlineView users profile

Quote
A stock replacement for $30 to $40 would not break the bank. I base that estimate on a new one for a 4.3 just cost one of my employees $35.

That is certainly true, although the replacement I was looking at is $70 for a Pioneer brand (claims OE type). Was that 4.3 balancer from GM or from a chain store? It might just be a much different damper, I know it's a lot bigger than the damper on my old 283.

I think that I will end up replacing it, and I do want to replace the front seal. And I'll use the damper installation tool this time!

HECAT on Wed January 11, 2006 4:41 PM User is offline

Yes, he picked up a no name from a chain store for that price.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mhamilton on Thu January 12, 2006 9:46 PM User is offlineView users profile

Boy did I get a real winner today. I went to the local auto parts store, asked for a price on the torsional damper. The kid wearing a sleeveless undershirt and shorts (in January) says he "never heard of anything like a torsional damper..." like I give a fat rat's as# what he knows... so I tell him to look under harmonic balancers. "I don't think we sell anything like that." Then he goes and gets the owner, and she starts the whole "what? a torsional damper?" and I direct her to harmonic balancers. 5 more minutes of them searching catalogs, they come up with nothing. Good think I didn't ask for something difficult like a Thermac motor! I'll have to take a trip out to Advanced Auto parts for this piece.

Getting back to my highway vibration, I found something that I overlooked previously. I found that my mechanical advance is coming in way too early and too fast. I never suspected the springs when I rebuilt the dist. It's advancing almost 10 degrees before it hits 1000 rpm, not supposed to start even before 1400rpm, and get to the 10 degree mark at 3800rpm. I've ordered new springs and bushings from Summit.

Edited: Thu January 12, 2006 at 9:47 PM by mhamilton

HECAT on Fri January 13, 2006 8:41 AM User is offline

Seems like today's parts places should give up on the employees, turn the computers around so we can use them, walk down the isle, pick our part, a go out through self check out.

I do miss the day when the guy behind the parts counter did not even have to look in the "books" to know what you needed. 25 years ago the parts store guys were with us taking ASE cert tests, bet they don't do that today.



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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

Chick on Fri January 13, 2006 10:20 AM User is offlineView users profile

Today, they sometimes slip and ask if you want fries with that...Not all, but way to many....

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

mhamilton on Fri January 13, 2006 6:24 PM User is offlineView users profile

I've walked into chain stores with a part number in hand, after verrifying stock online, and the clerk could still not find the part.

Hecat, you've got something there with self checkout. We might finally be able to get the parts we need!

JJM on Sat January 14, 2006 1:45 PM User is offline

This is why you won't find me in an auto parts store for anything other than oil and cleaning supplies (which by the way are overpriced). Aside from the fact that most of the parts they sell are CRAP, the employees are totally clueless! For decades now, I only buy parts from the dealer or OEM parts jobber, i.e. AC/Delco, Motorcraft. Like Crunch over at BATAuto always says, "OEM parts hurt only once." Worst part is, aftermarket parts are often not much less than OEM parts from the dealer.

Another added bonus of buying parts from the dealer is the parts guys are usually much more experienced (actually know about cars) and really know the vehicles. This is how I learned that you need to replace the blower motor along with the blower control module on GM cars. When I went the Oldsmobile dealer to get a blower control module, the parts guy I've been dealing with for years, without even looking in the books or computer, goes in the back and comes out dropping a blower motor and hamster cage on the counter without saying anything, and continues back. I replied with a, "but I only need..." and he returns with the blower control module. I finish my sentance, "but I only the module, not the blower and cage, to which he replies as he's tallying up the bill, "Joe, if you wanna keep burnin' up modules, then keep your old motor. The motor almost always kills this things, so if you like spending your money... and since your changing the motor, you don't wanna make a trip back when you break the cage trying to get it off to save $9. What else do ya need?" That's what I like, someone who knows the job you're doing (especially if your unfamiliar with the vehicle) and can anticipate the parts you'll need. It's also good for the dealership too. I'd much rather that than someone who would've kept selling me modules.

Unfortunately, these type of folks are becoming a dying breed, as dealerships try cut costs and get "cheap" people to work. Happened to a good guy I dealt with for years at a local Ford dealership. He was there for a long time and making good money, but did he know his stuff. I went back to that dealership once since he left and dealt with the "new" employees there, and have never returned since. So I wonder about the "wisdom" of cutting costs, since I spent thousands of dollars there every year.

Joe

mhamilton on Sat January 14, 2006 8:51 PM User is offlineView users profile

Hecat,

I forgot to ask you in a previous post, were those owner complaints of idle vibration right off the dealer lot, or after some miles? I wonder if the engine ran smoothly with a brand new damper, and just got vibrational after the rubber aged a little? I can't imagine those cars leaving the factory with the vibration, especially with GM brochures claiming a new "smooth firing V6 engine."

HECAT on Mon January 16, 2006 9:50 AM User is offline

The headache I remember was that rough idle was often a complaint noted by the service writers when a new 229 powered car came in for its first service. It was so prevalent that we often did nothing about it until it became a repeated complaint by an insistent customer and then we found frustration in the fact that we were limited for a real solution.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mhamilton on Mon January 16, 2006 11:26 AM User is offlineView users profile

That's odd... I guess GM didn't think it was a big enough problem to fix during the engine's 4 year run. It does go away as soon as engine speed increases, just putting it in neutral stops most of the vibration (and that's only a 150rpm difference).

Aside from the belt tensions, was there anything else you did? I still intend to replace that damper, but at least now I won't be disappointed when the idle vibration is still there

HECAT on Mon January 16, 2006 2:00 PM User is offline

GM did not have the answer. They tried lame ones like....

Tel the customer it is a "hot" cam.
Tell the customer it is the best idle possible with a carburetor.

Over-tightening the A/C belt was the only thing that helped a little. Dampener failure or wear was not an issue with these cars at that time.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mhamilton on Mon January 16, 2006 9:49 PM User is offlineView users profile

I guess I'll have to see what happens with the new parts, if anything. I'm also intrigued that these problems go back to day 1. I'll have to ask my neighbor if she remembers it idling like that when new. I bought it from her quite a few years ago, but I can't remember what the idle was like with the original engine. The car had quite a few "issues" due to the neglect of the Chevy dealer in town (it's a real rinky-dink operation, and clearly took advantage of an old lady who had no way of knowing).

Thanks again for all the advice.

Edited: Mon January 16, 2006 at 9:50 PM by mhamilton

Gary Harrison on Sat February 04, 2006 10:16 AM User is offline

You might try some research on V6 engine history and development. It seems likely that balancing piston movements would be a challenge. I seem to remember reading long ago about challenges w/ designing a crankshaft to create acceptable balance and strength. Do later vintage V6's possibly use balance shafts such as used in many 4-cyl engines?

I was able to find a nice discussion on Wikipedia at following link.

V6 Engine Development History

good luck

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See you down the ROW.

mhamilton on Sat February 04, 2006 7:03 PM User is offlineView users profile

Thanks for that link, it's got some great information. Here's a quote regarding my V6: "In 1977, General Motors introduced a unique 'split-pin crankshaft' in the GM 3800 engine. Using a crankpin that is 'split' and offset by 30° of rotation results in smooth, even firing. Such a 'split' crankpin is weaker than a straight one, but modern materials and manufacturing produce a crankshaft that is strong enough."

The factory service manual says the same thing, that the 229 uses "splayed crankpins for a more even firing and smoother idle. A torsional damper on the forward end of the crankshaft dampens any engine torsional vibrations."

The article says V6s benefit a lot from dampers. With my idle vibration, a couple weeks ago I had time to index the torque converter 120 degrees, and surprisingly it cut down highway and idle vibrations. Idle vibration is still strong, but highway is better. I have been busy the past few weeks, I want to get to the store this week for the new damper. I hope that makes an even greater reduction in the problem.

But, as Hecat said this engine was not more than 305 V8 technology cut down, and knowing how things back then got rushed into production to meet CAFE and emissions requirements, it's quite likely this is just an imperfect design. I'm probably also being very picky about this--all my other cars are V8 and that's what I'm comparing this V6 with.

Edited: Sat February 04, 2006 at 7:16 PM by mhamilton

NickD on Mon February 06, 2006 7:20 AM User is offline

Is it worth the aggravation? Much easier to dump it and get something else. No matter how you slice the mustard, using a 90* block in a V-6 results in a non-symmetrical crankshaft. We had a 86 Maxima with a true 60* block V-6 that ran as smooth as silk. My old 89 Continental and our S-10 used the 90*block V-6 and even with the added counter balancing shaft would never idle as one would define as smooth as silk. While the counter balancing shaft would help with the feel of external vibrations, the internal stresses are still there plus you have a more complicated engine with more crap to go wrong. The timing of the counter-balancing shaft is very critical. Caddy, trying to come out with something to gain their lost prestige slapped in a V-8, now that idles and runs smooth over the rpm range and can set a wine glass on the air cleaner without it flying off after a great tuneup. But putting a V-8 in a FWD car is a maintenance nightmare.

Another advantage, if you want to call it that is that a 90* V-6 has a lower profile for a more aerodynamic hood, about a couple of inches shorter, using V-8 tooling may make the stockholders happy, but not ideal for the consumer. Since the degree of vibration increases by the square of engine speed, difficult to conceive how changing the damper pulley would improve that nasty vibration at idle, feel you have other misfiring problems. But if yours is out of balance, would help on the highway, but not at idle.

I just purchased an 82 454 CID powering a 27' motorhome, came with new brakes, exhaust, three brand new batteries, and six brand new tires, more than half the cost of the $4K I paid for it. Only 46K on the odometer and nice looking exterior and interior. Exhaust manifold problems with the 454 occur more in the 37' homes, really loading that same engine. No need for a scanner, and can't wait until the weather warms so I can dig out my fuel-air analyzer and actually do a real tuneup on it. And with an aluminum and fiberglass body with a undercoated frame, was pleases not to see any GM rust that was so common back then. But the trucks were immune from the passenger car madness going on at the time.

Being a strong GM fan for years after Henry Ford I, died and buying a 49 Olds Rocket V-8 got totally disgusted with GM passenger cars in the late 70's, not only the usual GM rust, but loaded with mechanical problems as well, screw them, went with the Japanese.

Do recall working on a friends 85 Buick V-6 that was totally screwed up by his dealer, took a couple of days to get it back to original so troubleshooting could begin, wouldn't idle worth a darn and rough on the highway. The real problem with his was the EGR valve, a double acting device depended on venturi vacuum to operate the top half and intake vacuum to operate the bottom half, his ran super lean at idle and super rich on the highway. Not really complicated, replaced the thermal switch and EGR with factory units, always seem to get better prices from my dealer than these aftermarket places, cleaned the venturi and the EGR passages, then it ran purred like a kitten, well as good as you can expect from a 90* block V-6. His mechanics cure was to set the idle at 2,200 rpm, kind of mean on the AT when shifting gears.

But is it really worth your time and money on a vehicle designed to make the stockholders happy?

mhamilton on Mon February 06, 2006 3:05 PM User is offlineView users profile

A hobby is largely uneconomical and inefficient. This is not my only car, nor is it my newest. I have already spent many more thousands of dollars on this auto than anyone would consider economical at this point, so a new damper will not hurt anything. I was more interested in solving the highway vibrations, which are very tiny at this point. If it helps the idle, that's all the better, but I hardly ever sit in traffic where it would matter that much. It's really not as bad as a misfire... like I said I'm always comparing it to smoother V8s. Besides all of that, I like my Malibu. I can actually access the spark plugs to service them (this is rear drive, BTW), and not one piece of solid state technology beyond the stereo radio. The most complex electrical connection on the engine is the electric choke coil.

I drove a brand new 1997 El Dorado with the Northstar, and there was a definite idle vibration in that car. Would never spend money for that, I get a smoother idle from a '97 Ford F150 V8 with 100k miles.

Years ago my father owned a '86 LeSabre with the 231--nothing but trouble with that car. But that 231 was always a 60 degree engine... what was in the '85 Buick?

NickD on Tue February 07, 2006 6:22 AM User is offline

231 sounds about right, but I don't recall if it was a 60 or a 90*, do remember having problems learning which cylinder was number one, even my dealer didn't know for sure and wasn't even in the shop manual, something as basic as that. Did have TBI that was troublesome, but my friend didn't keep that car very long, he was just ordained a priest and had to get down to Florida for his first assignment, car was only a couple of years old and was given to him, even the Holy Spirit and prayers couldn't help with that one. His mechanic had the TBI so screwed up and actually hit it with a hammer breaking it, insisted a new one had to be installed, it was way out of calibration. Price for a new one back then was an outrageous $460.00, but his dad, a doctor picked up the tab on that. I argued with his mechanic for breaking it, but my friend didn't want to pursue it, but did get it running nice with the idle back in the 600 range rather than at 2,200.

My ex-father-in-law purchased a new 86 Chrysler New Yorker with a turbo, what a bucket of bolts that was with constant problems, he laid out more than $2,000 on electronic dashes when I found his ignition switch was bad, so much for Detroit back then.

Against all my principles I went Japanese, but didn't really see significant gains in fuel economy, had to buy two Japanese cars, one for each foot.

Having fun with my 82 motorhome, got the factory service manuals both from Chevy and Pace Arrow, a makeshift electrician made a mess out of it, but simple enough to correct, engine has 12 volts coming from the generator, and 12 volts going to the HEI and choke, I can deal with three wires, LOL.

CorvairGeek on Tue February 07, 2006 7:52 AM User is offline

The 231/3800 is a 90 degree engine. The later versions are considered an even fire 90 degree. It's origin is the Buick 225 odd fire which was a cut down Buick 300. "Here's a quote regarding my V6: "In 1977, General Motors introduced a unique 'split-pin crankshaft' in the GM 3800 engine. Using a crankpin that is 'split' and offset by 30° of rotation results in smooth, even firing. Such a 'split' crankpin is weaker than a straight one, but modern materials and manufacturing produce a crankshaft that is strong enough." The 3800 reference is only used with the Buick engine. It was also sold in 196? and 252 cid versions.

The Chevy V6 (200, 229, 262) is actually considered an odd/even fire to keep a stronger crankshaft (note the difference between split-pin and splayed). "The factory service manual says the same thing, that the 229 uses "splayed crankpins for a more even firing and smoother idle. A torsional damper on the forward end of the crankshaft dampens any engine torsional vibrations."

Ford's V10 is of the odd/even fire design as I recall.

The 90 degree Chevy V6s are rough. The earliest carburated ones are the worst.

Jerry


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Jerry

mhamilton on Tue February 07, 2006 6:30 PM User is offlineView users profile

Wow, I would have sworn anything that the 231 was a 60 degree engine. Just looked it up, it certainly is 90 degree. I have no idea why I ever thought that. Jerry, you're right--I was not paying attention to the details in that article... now that I look back I should have at least realized the 200ci was for the '78 Chevy model year, not '77.

Nick, I never did any major work under the hood of that '86 Buick, but I'm surprised to hear the cylinder numbers were not cast into the intake manifold along with the firing order. I know my father had nothing but trouble with that front drive automatic trans from day one. Had it completely replaced at one time, and it was not a high mileage vehicle. I also seem to remember some major engine overhaul before he got rid of it, it couldn't have had even 75k miles on it.

As far as the 229 idle vibration, I'm going to have to see what happens with the new damper. The idle vibration is worse at times, maybe when the engine is not at full operating temp. I'm going to check on the carb adjustment. Off idle it runs very smoothly. I think the highway vibration may be from the suspension, I just found a sagging rear coil spring (new spring set on order), I suspect that's where most of the body vibration was coming from.

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