Engine shakes when turned off, sometimes

According to the Chircoe website dieseling can be caused by the following:

Engine diesels (continues to run) after switching it off.

The idle speed is too high.

The engine operating temperature is excessive.

The pilot jet cutoff valve is defective.

And here's a thread on The Samba that covers it as well:

http://www.thesamba.com/vw/for...wtopic.php?p=5674191

Good luck.

Ryan:  

Do you have or can get a timing light?

Your engine is "dieseling" due to a combination of the octane of whatever gas you are using and the amount of timing advance your engine is running.

You need to reduce (retard) your timing 1-2 degrees from where it is currently to account for the gas you're using.  Just re-set the timing back from where it is.

Back in the 1970's - '80's, Toyota (on the 8R series engines) actually had an adjuster on the side of the distributor that let you do this with the twist of a knob, +/- 4 degrees from your baseline.  On our cars you have to loosen and rotate the distributor body just a little.

THAT should stop your dieseling.

All engines will move around more as they spin down from running, but if you are getting excessive shaking (that is not from dieseling), it could be due to bad transmission mounts.

While bad transmission mounts certainly could contribute, the statement that he doesn't see it every time (see way above) leads me towards dieseling.

Also, Ryan, this sequence is a little funky;

Is there a best practice in turning it off? Here's what I do:

1) clutch in

2) neutral

3) turn off (cross fingers for no shake)

4) parking break

5) first

6) clutch out

Should I be doing something different?

Yeah, try;

1) Clutch in

2. 1'st gear

3.) Set parking brake

4.) Turn engine off while gently letting the clutch out - trust me, the engine will stop

While this should work well, it is no replacement for retarding your spark a degree or two to really fix the problem.

Of course the last 3 times it shut off just fine. Fingers crossed it fixed itself. 

They don't fix themselves...get a timing light and do it right!

Maybe had some weak gas?

Is it shaking or continues to run shaking then shutting its self down?

It doesn't continue to run. It just shakes the last cycle or two before stopping. Enough to be noticeable.

I assume there's enough inertia in the motor to keep going a cycle or two after power is cut.

I know they don't fix themselves. But I can't get it to happen again for video.

Ryan, the best way to get this to happen on cue is to list the car for sale and invite someone to take a test drive.

That's funny Mitch.

Ryan, check all your mounts and make sure your engine bolts are tight.

My neighbor is helping me install seat belts for the rear bench and has a lift. When I throw it up on the lift I'll have him look it over. It's really driving smooth otherwise. I've noticed the shakes maybe 3-4 times. But it hasn't happened in the past 3-4 times.

Shake it once or twice when you are done. Anything more and you are just playing with it...

TRP posted:

Shake it once or twice when you are done. Anything more and you are just playing with it...

A friend of my dad's said that to me when I was 8 or so (he, of course, needed to get into the bathroom). Took years to figure out what he was talking about....

Finally happened again. It was happening 1/2 times. Now it's happening 1/10+.

I think there's something to turning it off in first though. I tried to duplicate right after it happened again and couldn't.

I know these sorts of things don't fix themselves. But the sporadic nature of this "bug" is perplexing.

Ryan, did you contact Theron to ask him if he ever had this happen to him?

Hey just saw this thread.  Remember you can always page another member now by added typing the @ symbol like  @Theron

Anyway, Ryan what you describe is called dieseling.  It never happened on that car.  It could be a couple of things.  1) Could be cured by going to a slightly higher fuel octane since you live in a much warmer climate than the car came from.  The fuel could still be igniting when the engine is hot.  Higher octane will diminish the chance of detonation.  2) Could be caused by the carbs or timing falling out of adjustment and should be correctable with a tune-up.

-=theron

Theron posted:

Hey just saw this thread.  Remember you can always page another member now by added typing the @ symbol like  @Theron

Anyway, Ryan what you describe is called dieseling.  It never happened on that car.  It could be a couple of things.  1) Could be cured by going to a slightly higher fuel octane since you live in a much warmer climate than the car came from.  The fuel could still be igniting when the engine is hot.  Higher octane will diminish the chance of detonation.  2) Could be caused by the carbs or timing falling out of adjustment and should be correctable with a tune-up.

-=theron

@Theron, I'm surprised at this! I mean really?

You should have started your reply with...@Ryan

Advanced timing and hot weather can cause this also, mark exactly where your timing is now and back off 1-2 degrees and try that , if no difference return the timing and look elsewhere.

Since timing has come up a few times, it's time for a timing light (tired of borrowing my friends). Any suggestions? To many to try and choose from...

Thanks @Theron