Date: Mon, 29 Dec 2003 12:37:30 -0800
Reply-To: "Mike D." <md03@XOCHI.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Mike D." <md03@XOCHI.COM>
Subject: More Idle Problems
In-Reply-To: <20031228050256.6A8B95B8CA@gollum.dreamhost.com>
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Previous History:
85 Automatic Westy with 150k miles.
Has always had rough/loping idle
Low oil pressure lite flickers on when warm (and rpms below 1000)
Mechanic recommended AFM change, but not done.
Had lifters replaced about 6 months ago.
When cold, idles very poorly, dies frequently, but would idle
ok when warm (still rough, but not dying).
At freeway speed, runs fine : can do 70mph and gets about 15-17 mpg
Passed smog (just barely).
Compression was ok (even, around 120 in each)
Replaced O2 sensor.
Last week:
Mechanic put in new (rebuilt) AFM and changed Oil.
Mechanic said there was "a lot" of metal in the oil.
Drove van home (didn't run too well -- kept dying at stoplights).
Test drove the van the next day: wouldn't idle when cold OR warm.
I tried adjusting the timing and idle screw (both with and without
the Idle Stabilizer in circuit), but the only way to get it to idle
was to set the RPMs at about 1200.
Here are the leading theories:
(1) My mechanic thinks the engine is shot, and can't keep oil
pressure at 850 rpm idle, which causes the lifters to stop lifting,
leading to loss of compression and engine stall. This theory is ok,
but doesn't explain why the sudden worsening of symptoms after the
new AFM and oil change, and why now it won't idle when warm OR cold.
(2) Could this be a cold start issue? I've done the check of
crimping the bypass hose when warm (as per bently) and the idle
doesn't change. Also disconnected the O2 sensory wire with no change
in idle. Are there any other checks to do when warm to see if the
cold start systems are messing up the idle?
(3) The previous mechanic had done some "mods" to the old AFM when he
replaced the lifters. I also noticed (just a few weeks ago) that one
of the vacuum advance/retard hoses was off, so replaced all the old
crusty looking vacuum lines. Now I'm wondering if perhaps the AFM
mods and the disconnected vacuum line were intentional (the previous
mechanic's way of getting the car to idle without dying) and that by
fixing the AFM and reconnecting the vaccum line I "broke" his fixes?
(4) If it is an oil pressure problem, how quickly does low oil
pressure cause the lifters to start malfunctioning? Right now, if I
set the idle to 850 it will work for a few seconds but then it
sputters and dies. Would lifters lose pressure within a few seconds?
(5) I know that I need a new engine, but I'd like to squeeze a little
more life out of this one. BusDepot (or perhaps busboys, i forget)
has a "high capacity" oil pump for $30. Is it worth putting one in
on the off chance it would give me a few more months?
thanks again for all your help!
-mike