So with a leaking intake valve, there's no way the mixture can ever be set
right.

That's partially why I ran the Seafoam through it, to see if burning off
some carbon would make a difference. Nada. Same with running higher-octane
gas. But that wouldn't help diagnose a leaking valve guide, either.

A couple of local mechanics told me they only do leak down tests when the
numbers are greater than 45 lbs between cylinders. Not?

On Thu, 18 Jan 2007 19:50:33 +0000, Dennis Haynes <dhaynes@OPTONLINE.NET> wrote:

>Looking at your compression numbers, A leak down test is in order. My bet
is Number 4 has a bad or guide preventing proper seating. Intake valves fail
or get carbon build up preventing closure. If you think vacuum leaks can be
bad, imagine a vacuum leak with some combination of burnt fuel mixture.
Confuses the air flow meter and further messes up the mixture for the other
cylinders.
>
>Dennis
>
>
>
>----- Original Message -----
>From: Geza Polony
>Date: Thursday, January 18, 2007 1:38 pm
>Subject: Moral qestion--Case in point
>To: vanagon@GERRY.VANAGON.COM
>
>> Ok, sorry to belabor this one, and to the person who said it
>> isn't really a
>> moral question, you're right. It's a question of strategy. Going
>> forward,here's a case in point.
>>
>> The stumbling idle on my '84 1.9 is driving me nuts. No matter
>> what I've
>> tried, with and without the help of the goodly folks here on the list,
>> nothing has helped. New O2 sensor with good ground, tested good
>> on car.
>> Compression 155-155-145-130. No oil burning, no coolant leaks,
>> no smoke,
>> plugs all textbook-beige. New dist. cap and rotor, new fuel pressure
>> regulator, new fuel filter, new idle switch tested good, rebuilt
>> AFM, AAR
>> removed/cleaned/tested good in freezer and warm stove (car
>> starts fine.) No
>> vacuum leaks--vacuum tests around 13 inches, and I've pulled the
>> vacuumlines time and again to check--all of them, even the ones
>> at the AAR.
>> Removed, cleaned throttle body, sealed at inlet, no light shines
>> throughbutterfly valve. Changed oil, used Marvel Mystery in
>> hopes that would help
>> lifters if they were air locked. Used Seafoam to get carbon out
>> of cylinder
>> heads. Changed bad thermostat. Checked all grounds and built
>> ground "web" to
>> all points in engine. Checked battery voltage at startup and
>> running (over
>> 12.5). New cat, new muffler, new rear engine mounts.
>>
>> This may not be the definitive list, and yes, I'm guilty of
>> throwing parts
>> at the problem rather than methodically testing the systems. But I'm
>> reaching the limits of my mechanical ability, never so great to
>> begin with,
>> as well as my sanity, and so am thinking of getting my mechanic
>> to deal
>> with it.
>>
>> Therein lies the rub. He's a nice guy, easy to get along with,
>> and has
>> always done good work, in the sense of replacing parts when they
>> obviouslyneeded replacing. But what about the (dreaded)
>> diagnostic question?
>>
>> It's hard to tell him, OK, you have two hours to figure it out--
>> then stop.
>> I've done all the obvious dumb stuff already. And it could be so many
>> different, unrelated things. Bad valve guides, as Dennis pointed
>> out. Bad
>> Hall Sensor. Bad resistence on spark plug wires. Failing coil.
>> Somethingwrong in the distributor advance. Something in the
>> vacuum system. Something
>> in the fuel delivery or injection system. This could take days
>> to figure
>> out. And even then, it's an educated guess, esp. with internal engine
>> components.
>>
>> So--instead of dealing with the problem in the past, as with the
>> Boston Bob
>> business, Benny, etc., how to proceed going into one of these
>> situations?
>> I'm almost thinking I'd rather leave it as is than deal with the
>> mechanicwho can't figure it out and charges a few hundred of my
>> precious dolares.
>>
>> Sure wish some of the people on the list lived around the corner...
>>
>> Sorry so long.
>>
>>
>> Geza
>>