inline six cylinder question..

[double vanos]

I was having lunch today when a fellow car enthusiast (his deal is old Jags and other British sports cars)told me that all inline sixes will stop in the exact same place when you cut them off.

He claims that because inline 6's always stop in the same place, they eventually wear out the ring gear because the starter always engages in the same place everytime you start it.

He says he read this somewhere and it is due to dynamics found only in inline sixes.

I told him he needs to cut his scotch consumption because I had never heard of such nonsense.

Am I missing something here or do I go ahead with my plans to buy him a season ticket to AA? Cheers DV

 

[Earl Filter]

That's a load of Bu...

That's incorrect information.

By the way, pass this on to him:

http://www.kitcar.com/articles-kitcar/humordept/lucas-prince.html

Among my favorites is a bumper sticker in my local Jag shop stating, "All of the parts falling off of this car are of the finest British craftsmanship."

 

[d00df00d]

If that were the case, you'd have to imagine that there would be something about that particular place that makes everything want to end up there in the absence of force. It'd be easier to move into that spot than to move out of it, and even if that difference were barely enough to make itself known it still would have a tangible effect on the smoothness of the engine....

 

[Earl Filter]

To further insult him, show him my 1989 Jaguar XJ6. I threw the 6-cylinder in the trash, and put an injected Chevrolet LT1 in it, along with some Corvette wheels. That should make him faint.

 

[Kestas]

In your friend's defense, I remember seeing a ring gear in our lab that had heavy wear at two places, 180° from each other. I believe it came from a 4-cylinder engine, though I'm not sure. It wasn't my project.

So why would this be bull? Anybody that's worked on lawnmower engines knows that the crank likes to relax at certain positions. Why couldn't the cylinder pressures and valving nudge an automotive engine into certain spots during shutoff?

 

[rpn453]

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To further insult him, show him my 1989 Jaguar XJ6. I threw the 6-cylinder in the trash, and put an injected Chevrolet LT1 in it, along with some Corvette wheels. That should make him faint.

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Nice ride; nothing beats a Frankenstein sleeper!

What do you have for the rest of the drivetrain?

 

[TallPaul]

So when you change the clutch, you rotate the flywheel to expose fresh areas to the starter, or is that not possible because of balancing?

 

[Steve S]

A 4 cyl stops at the same 2 places a 6 cyl stops at the same 3 places and an 8 stops at the same 4 places due to hhw the pistons go up and down in pairs. Odd fire engines ,I am not positive about.

 

[Master ACiD]

when i use to mess with glo fuel r/c airplanes it was common practice to set the prop on the crankshaft in such an orientation that when the engine stops the prop was horizontal. this was done so that you wouldnt break a prop in the event of a harsh landing. seemed that those single cylinder 2 strokes awalys stopped in the same place. i would have to imagine a multi cylinder 4 stroke would atleast have a tendency to stop in the same places as well.

 

[tom slick]

I don't know about an I-6 stopping in one spot but I have certainly seen flywheel gears with wear in only a couple of spots.

 

[fillitup]

I remember my auto teacher in high school talking about this.

 

[mechtech2]

Of course engines stop at the same few spots if given the chance.
Slight differences in compression, balancing, and valve spring pressure [cams] are some of the obvious reasons.
I've noticed this on my own cars - V8s and fours in particular.

 

[Earl Filter]

Quote:

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Quote:

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To further insult him, show him my 1989 Jaguar XJ6. I threw the 6-cylinder in the trash, and put an injected Chevrolet LT1 in it, along with some Corvette wheels. That should make him faint.

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Nice ride; nothing beats a Frankenstein sleeper!

What do you have for the rest of the drivetrain?

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I sold the car, but it was an LT1 350 (iron heads out of a Buick Roadmaster) with a 4L60E trans, custom driveshaft, and stock Jaguar 3.54 rear end. All of the factory gauges worked, with a few mods on the engine side of the harness. I ran dual electric fans from a TransAm, controlled by the PCM. The factory PCM and wiring harness from the LT1 were used, with all of the unnecessary stuff deleted. The engine was stock except for headers and exhaust, but the LT1 was good for 140mph in an Impala SS that weighed about 500 lbs more.

 

[JTK]

The inline 6 in my trailblazer likes to stop at gas stations?! Actually, it's no worse than any other similar truck. Mid teen MPG's to low 20's on straight hyway runs. It is the smoothest engine i've ever owned.

Joel

 

[Shannow]

Steve S is spot on.

 

[TheLoneRanger]

Quote:

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A 4 cyl stops at the same 2 places a 6 cyl stops at the same 3 places and an 8 stops at the same 4 places due to hhw the pistons go up and down in pairs. Odd fire engines ,I am not positive about.

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Steve is indeed correct about this. The cylinder compression 'brakes' the engine on the compression stroke, and the spot is determined by where the crank is positioned when the ignition is turned off.

I would think this effect would be more pronounced for an engine with the fewer number of cylinders.....

 

[alreadygone]

Not sure how many "stops" each # of cylinders has, but any used flywheel you observe will have definite wear marking. As stated by Steve.

Bob

 

[Gary Allan]

I've never reasoned it soundly in my head ..but all inline 6 cylinders have the same firing order ..unlike any V or other inline application.

How this relates to this alleged tendency has got me swinging ..but I would imagine that at any point in rotation you're going to be 60° from a compression event ...but that would be the same for a V6 as well

 

[Tracker8]

It is a given that the 4, 6 and 8 cyl engines do this but now the question is what do the 3 and 5 cyl engines do?

 

[oldmaninsc]

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The inline 6 in my trailblazer likes to stop at gas stations?!
Joel

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Hee - hee Good one Joel.

I have the same problem with my Trailblazer I6 - 25 gallon tank!

Seriously I've heard this about the 6 cylinder engines before, but I have no clue if it's true or not.