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  #46 (permalink)  
Old 10-03-2010, 08:20 AM
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Quote:
Originally Posted by kyle86
Now that I think of it, the car has been using oil. I havn't been able to figure out where the heck it's going since the car doesn't smoke. I would loose about a quart every 1000 miles. It doesn't drip either. Reading around, someone said this is a symptom of an internal vacuum leak.

As I said, pull the inatke and reseal it.

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  #47 (permalink)  
Old 10-03-2010, 09:47 AM
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Quote:
Originally Posted by kyle86
I missed this post. I will try this when I get the chance Cobalt thanks.
You're welcome, although this was mentioned (but more in passing, not in any detail) earlier.

This fix assumes you have no internal or external vacuum loss, but I'm sure you realize that the engine would need to be otherwise correct- and STILL dieseling- before using the solenoid.

Good luck.
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  #48 (permalink)  
Old 10-03-2010, 03:42 PM
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Quote:
Originally Posted by adantessr
Cobalt, I believe is right on the point there as ignition timing has nothing to do with dieseling once the key is turned off . As for having to back off the timing more than before to avoid pre-ignition, I'm not sure on that . I wish I could remember the application on the electric idle solenoid, but I do remember GM ran a lot of them .
LOL . Even as I was typing this I thought I might be getting myself in trouble . I was also thinking how retarded timing does make the engine run hotter and require more throttle opening . I don't mind a bit in being called on my goof ups . It just helps to keep me on my toes for the next time . Thanks, Seriously :-)
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  #49 (permalink)  
Old 10-03-2010, 03:48 PM
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You think that maybe an internal leak on the intake manifold could be sucking oil and causing carbon build up on the valves? That could be the cause of your dieseling problem Greg T mentioned. Something inside the chamber has to be getting red hot to keep igniting the next cyl. after the key is shut off.
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  #50 (permalink)  
Old 10-03-2010, 04:16 PM
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Quote:
Originally Posted by sqzbox
You think that maybe an internal leak on the intake manifold could be sucking oil and causing carbon build up on the valves? That could be the cause of your dieseling problem Greg T mentioned. Something inside the chamber has to be getting red hot to keep igniting the next cyl. after the key is shut off.
Oil from bad guide seals or from bad intake gaskets tend to carbon up the back sides of the valves, not nearly as much on the chamber side- although there could be any number of things that would act as a glow plug in the chamber.

The head gasket and intake gaskets would have been changed, from the "before" engine that didn't run on, to this "after" engine that DOES. If the head gasket has an overhung flame ring, or the intake gasket is leaking, either could account for the chances of having dieseling- but for a chamber hot spot causing dieseling, the chamber hot spot would also be causing preignition.

I would suggest looking carefully at the plugs to see if any look lean, or oiled more than the others.
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  #51 (permalink)  
Old 10-04-2010, 11:37 AM
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Quote:
Originally Posted by kyle86
Is there any way to diagnose it?
You could see if there is excessive vauum in the crank case. Unhook and block pcv valve. You could then either hook a vacuum guage up to crank case via the breather hole, or dipstick tube, depending on how its layout or put a very thin nitrile work glove over the opening and see if it pulls on it. You could have the tail pipe emissions checked. Another way of diagnosing, is to use a smoke machine. You pressure up either the intake or crank case side, to see if smoke bleeds over to other system. There is another tool called the First Look Sensor also, That uses an Oscope to measure the pulses either in the intake, crank case or exhaust, to isolate a leak ...But these are shop tools usually Silver bullets are hard to come by in many instances.
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  #52 (permalink)  
Old 10-06-2010, 12:49 PM
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The spark plugs are very oily. Especially the threads. These are from the passenger head, I havn't pulled the driver head yet.







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Old 10-07-2010, 04:13 AM
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Quote:
Originally Posted by adantessr
Cobalt, I believe is right on the point there as ignition timing has nothing to do with dieseling once the key is turned off . As for having to back off the timing more than before to avoid pre-ignition, I'm not sure on that . I wish I could remember the application on the electric idle solenoid, but I do remember GM ran a lot of them .
They are still running them with all of the "fly by wire" throttles. When shutting turning the key on you hear the throttle plates open and when turning key off, you hear it slap closed. My '05 Silverado does this...

Yumm... Oil! Cuz she's definitely eating it!

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  #54 (permalink)  
Old 10-07-2010, 06:46 AM
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Besides for anti dieseling, the same type solenoid was used as a 'kicker' for the AC. When the AC would be engaged, the solenoid would energize and kick the idle speed up to compensate for the drag of the compressor.

These were mainly on the '80-back GM's w/small engines, V6 and such, especially those that used the loaf-of-bread shaped A-6 axial AC compressor.

If an application was needed to get one from the parts house, ask for a 1980 Malibu w/the 229 cid V6. They used an AC idle speed kicker solenoid. It's adjustable and has enough strength to move the throttle by itself when it's energized, in other words, you do not have to depress the throttle to "set" it, like a choke- it sets itself.
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  #55 (permalink)  
Old 10-07-2010, 11:13 AM
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After looking at those plugs Cobalt, do you still think that the solinoid might be his problem? I can just imagine what the valves look like. Nothing like oily carbon to get yer motor turning when the key is shut off. If not a leaky intake gasket, he has a major problem elsewhere.
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  #56 (permalink)  
Old 10-07-2010, 11:24 AM
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Quote:
Originally Posted by sqzbox
After looking at those plugs Cobalt, do you still think that the solinoid might be his problem? I can just imagine what the valves look like. Nothing like oily carbon to get yer motor turning when the key is shut off. If not a leaky intake gasket, he has a major problem elsewhere.
All the solenoid might do, is help the symptom, but would not be a cure- that's for sure. As I said earlier,
Quote:
Originally Posted by c327
This fix assumes you have no internal or external vacuum loss, but I'm sure you realize that the engine would need to be otherwise correct- and STILL dieseling- before using the solenoid.
Those plugs sure aren't extended tips, are they?

But yeah- there's oil coming from somewhere, MUCH more than normal.
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  #57 (permalink)  
Old 10-07-2010, 12:56 PM
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They look like the equivalent of AC 44T's or 45T's.
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  #58 (permalink)  
Old 10-07-2010, 02:10 PM
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I think I would start with a blowby test just to get that out of the way first . That would be the easiest thing to check, just in case .
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Old 10-07-2010, 05:01 PM
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Quote:
Originally Posted by adantessr
I think I would start with a blowby test just to get that out of the way first . That would be the easiest thing to check, just in case .
How would I perform a blowby test? compression gauge?

The spark plugs are NGK BR6FS with non-projected tip. I switched from projected to non-projected after noticing some funny burn marks on the insulators.

EDIT: Oh yea, and those plugs have less than 2000 miles on them. I pulled them out in the morning after the car sat overnight.
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Old 10-08-2010, 10:15 AM
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Okay, I'm guessing my next step is to pull the heads and intake? Take the valves out and brush all the carbon off the tops?

Just to make sure it's intake leak, if I were to put a vac gauge on my valve cover and plug the pcv, how much vacuum should be in the crank case? What about with the engine revving around 2500?
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