Date: Wed, 2 Apr 2008 13:27:45 -0400
Reply-To: Mike <mbucchino@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike <mbucchino@CHARTER.NET>
Subject: Re: Exhaust valve leak on fresh top end rebuild-I need a little
advice
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
If 'staking' the valve (which is what you did) doesn't cure the leakage,
then the valve job was poorly done. The rebuilder should be checking for
leakage before he gives the head back to the customer and takes his money.
They normally use alcohol (or similar) to leak-check the valves; if they're
liquid-tight, then they're definitely air-tight. IMHO, this is definitely
not-normal, and probably won't correct itself in time.
I'd take it (them) off now and return them, so he can fix his problems (at
no additional charge to you). This is what you're paying for! Hand-lapping
should have discovered this defect also. The contact patterns on the valve
and seat faces will show any misalignments or otherwise improper seating of
the valve in the seat. Is there 'bluing' stains still on the seats and
valves? There should be, it's evidence that he checked them over for proper
seating/ alignment. My rebuilder (the incredible Tom Bowman, who
unfortunately passed away a few years ago) always did this.
BTW, a leakdown test is measured in psi, not %; I usually input 80 psi on
the 1st guage and check to see what psi the 2nd guage is reading. You
didn't say what you input psi was. It should be no more than 10% due to the
imperfect seal of the rings, with no leakage from the intake or exhaust
valves. Adding oil to the cylinder would slow the ring leakage and improve
the reading (temporarily).
HTH.
Mike B.
----- Original Message -----
From: "Jake de Villiers" <crescentbeachguitar@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, April 02, 2008 12:46 PM
Subject: Re: Exhaust valve leak on fresh top end rebuild-I need a little
advice
> Maybe tap on the valve while blowing air back up the port to dislodge a
> piece of grit.
>
> Did you hand lap the valves?
>
> On Wed, Apr 2, 2008 at 8:11 AM, Giasson, Pascal (DNR/MRN) <
> Pascal.Giasson@gnb.ca> wrote:
>
>> Thanks Bob, Unfortunately I don't have the rockers on yet so it
>> eliminates the possibility of it being an adjustment issue.
>>
>> Pascal
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
>> Of Bob Donalds
>> Sent: Wednesday, April 02, 2008 9:05 AM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: Exhaust valve leak on fresh top end rebuild-I need a little
>> advice
>>
>> Pascal
>> try backing off the adjustr and recheck the leak down
>>
>> Bob
>> ----- Original Message -----
>> From: "Giasson, Pascal (DNR/MRN)" <Pascal.Giasson@GNB.CA>
>> To: <vanagon@GERRY.VANAGON.COM>
>> Sent: Wednesday, April 02, 2008 7:25 AM
>> Subject: Exhaust valve leak on fresh top end rebuild-I need a little
>> advice
>>
>>
>> So I decided to do a leak down test on my 1.9 resealed top end last
>> night just to see if all the cylinders were the same, and to see if I
>> messed up something on reassembly. The heads have a fresh valve job,
>> new Goetz rings, and cylinders deglazed and I used Total Seal Quick Seat
>> piston ring powder on the cylinders. The results were #1: 77%, #2: 87%,
>> #3:88%, #4:89%. So something is not quite right with #1. I could hear
>> and feel air coming out the exhaust port so I tried taping on the
>> exhaust valve stem several times both with the combustion chamber
>> pressurised and depressurised. I then rotated the valve a little bit to
>> see if that mad a difference, but it did not. I assume this is not
>> "normal" and will not get better after the engine gets a few miles on it
>> (I'm kind of thinking that it might end up burning that valve). Am I
>> looking at taking it apart again and having a look at that exhaust valve
>> to see what is going on? Any suggestions? Thanks
>>
>> Pascal
>>
>
>
>
> --
> Jake
> 1984 Vanagon GL
> 1986 Westy Weekender "Dixie"
> Crescent Beach, BC
> www.crescentbeachguitar.com
> http://subyjake.googlepages.com/mydixiedarlin%27
>
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