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One of the main causes of engine stalls

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One of the main causes of engine stalls

 
  #16  
Old 09-01-2015, 08:20 AM
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Originally Posted by mrgylex View Post
So I removed the AOS,PCV valve, and most of the hoses from the engines recirculation system. Lots and lots of sitting oil within the lines--this clearly shouldnt be the case since at most this should just be circulating back vapors. (crankcase->AOS->PCV->intake)

I called my local Aston Martin Dealership--they explain the AOS is always held in stock since they tend to fail and are cheap to replace ($43). As for the PCV valve the head technician said he never sees this part fail, and they don't keep them in stock, it's a special order item at $243. This leads me to believe my AOS has failed and I will be replacing today.

I wish there was a better way to test these parts but it seems to alwas be a reactive fix rather then proactive. I am hoping this addresses my stall and oil consumption issue. Will follow up in a few days after the fix.
The only thing that fails with the AOS is the O-ring, the O-ring doesn't keep the seal correctly, newer revised part now comes with the larger O-ring..O-ring can be bought separately.

The PCV fails quite often from 2006-2010 models for us..havent't seen a 2012 yet but could be just not enough mileage yet for my area(winter months 90% are stored).

The PCV is the same as Jag and LR, for example you can find the same PCV on a 2005-2009 Range Rover Sport..yours might even have the Jag/LR part number on it...and will probably be 1/4 the cost.

The PCV lines will have oil, more than usual on this system(reason for ppl installing oil catch can on V8V), but if you can pour out oil, and see burnt oil out the tails, obviously this is not normal operation.
 
  #17  
Old 09-01-2015, 09:28 AM
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PCv valve fails?

I don't know which logic to pursue--Dealer tells me they don't ever see PCV valves fail--so much so that they don't even keep them in stock since it's never ordered.

Irish, you are telling me that PCV valves have been known to fail on 2009-2010 engines which are same generation as mine (give or take some tweaks).

How does one test the PCV valve for correct function on this car?

All I know is that there is oil build-up along the lines, oil accumulated around the intake inlet for the hose, and oil accumulated inside the PCV assembly bracket (the joint that connects the PCV to the AOS). This to me is substantial for a system that should only be catching vapors.

Oil catch can is going to be ordered shortly but this probably doesn't fix the root cause.
 
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Old 09-01-2015, 10:16 AM
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Isn't the car a 2012? Was it bought in 2011 and warranty just end? Otherwise..I'd get the dealer to diagnose and repair for free.

If my mind isn't screwing up, I believe the V8 is a negative system, so PCV works backwards. The intake will suck the PCV and force it closed, when full throttle it will go open with no vacuum..So some oil residue will be found in top side of PCV for spirited drivers or over filled engines.

I don't have a V8 PCV on me but if you apply vacuum to the intake port side, it should close in theory of a negative crank pressure PCV.


Keep in mind, oil vapours are more like a mist..it's thick, it's the main reason for the AOS, otherwise there wouldn't be a requirement to drain back the oil to the sump if it was just a vapour. The Aston PCV combined with the AOS would normally be referred to as the CCV(Closed Crankcase Ventilation)..just Aston didn't have a CCV from Ford, so this design was made to do the same function.
 
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Old 09-01-2015, 10:43 AM
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  #20  
Old 09-01-2015, 10:45 AM
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That's the one..think our dealer price for a LR OEM part is 76CND
 
  #21  
Old 09-02-2015, 12:27 PM
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Question PCV valve

Same exact piece (part numbers are identical). Why the AM dealership has to do a special order of this part and quote me $236 is highway robbery when the same part at the Jaguar/LR dealership is $36.



@Irish--I installed the part and the PCV valve is making a loud buzzing noise--sounds like a remote control plane is inside the engine bay, I can feel the noise coming from the valve, when I pinch the flex hose, the noise goes away.

What's going on here?
 
  #22  
Old 09-02-2015, 12:39 PM
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If everything it connected and the new valve is buzzing..it's not closing, either a faulty new valve leaking internally or you don't have enough vacuum to pull the valve completely closed, causing the buzz. I'd fit a vacuum gauge and make sure you have correct vacuum. If vacuum is good, then a parts warranty on the new valve with jaguar.
 
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Old 09-02-2015, 12:50 PM
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Thanks! Jeez this keeps getting interesting. Well, I poured a small amount of wd-40 inside the valve and it got a bit quieter but it is still buzzing.

What do you think a correct vacuum measurement should be on the car?
 
  #24  
Old 09-02-2015, 12:58 PM
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Normal engine vacuum is 17-22in Hg with a steady needle
 
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Old 09-03-2015, 08:03 AM
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Semi-shameless plug:

http://www.velocityap.com/Aston-Martin-V8-Vantage-Oil-Seperator-Catch-Can-p/vel-amv8aos.htm

I've had to replace my AOS before, still allows oil through.
 
  #26  
Old 09-04-2015, 12:28 PM
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Well I did the vacuum test-- 19 MG steady with no fluctuations--so that's great news, mean no leaks or inherent engine issues.

I received the new PCV valve (amazon's amazing next day refund service--gotta love it)

I installed the new PCV valve, no buzzing, and engine purrs even better.

@Irish07--thanks for the help and recommendations!!
@Telum01--eager to get the catch can installed!

Only skeleton in the closet left....random engine stalls which I do not even know where to begin now.
 
  #27  
Old 09-04-2015, 01:43 PM
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So my car has stalled exactly one time. Sitting at a stop light with music volume up and looked at the dash and saw they engine wasn't running. I didn't think much of it. But really a car shouldn't just stall for no reason. I have two months left on my warranty. Should I take it in and say it stalled or just chalk it up as probably nothing?
 
  #28  
Old 09-04-2015, 07:57 PM
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Awesome photo, telum01 - it makes it very clear on what's happening. I believe that I have this same issue - I posted a thread on it here back in December, in which you posted that it's likely this issue. Now that I see what's happening, I'll give the fix a go - it doesn't sound too bad.

Two questions:
  1. How far is that hose from the access hatch? (How far in do I have to reach in and work one-handed)
  2. Do you have a part number to the new foam gasket for the access hatch?
Thanks! Very informative post.
 
  #29  
Old 09-04-2015, 09:06 PM
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@deckman--I would absolutely 100% let the dealer know of this issue before your warranty is up--be relentless about it. I only had the stall happen 3x in my 6 months of ownership but if I still had the warranty (just expired a few months ago) I would be at their door everyday.
 
  #30  
Old 09-04-2015, 09:07 PM
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@randysway--I would call the dealer to see if you have the updated gas tank--if you look at my pics that have been posted--the hoses have been updated to a different material and no clamps so they are not prone to cracking like Telum had in his.
 

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