Date: Wed, 19 Mar 2008 15:27:28 -0700
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: Still running like crap, the saga continues - Compression Test
In-Reply-To: <140901c88a0a$40f36c60$0a00a8c0@OWNERMIKE>
Content-Type: text/plain; charset="us-ascii"
And that's s not to say that the ragged and lowish compression is THE REASON
it won't run right.
True, those compression #'s are out of spec, but 95 on the lowerst worst
one isn't all THAT bad.
It probably says in a german book that 121.5 is the min acceptable.
Traditionally for gasoline engines 100 psi is considered the minimum OK.
So sure, it's not correct and it's not that great, but ...I forget right
now exactly how it wasn't running right, but.........with those compression
numbers......it's capable of starting well, idling good enough, and running
quite decently.
You can of course start working on the heads if you want - and someone
should for sure. . On all the waterboxer engines that I take the heads off
of, the exhaust valves........at least 2 or the 4 usually are leaking some.
You know there are sort of two different worlds. One world is the very
exact and german world..........where a shop will tell you there is no way
to make it run right if it's not exactly within limits on compression
readings. And 'that's sort of true' .......but it's not totally true.
And.........to really get anywhere, ultimately........mostly head work is
indicated. Really.......you should just pull all waterboxer heads at 60 to
80K miles and re-do things - valve job and head gaskets.
So in that sense it really needs it. That's long term. It can only get
worse generally speaking.
In the short term it probably can be made to run better.....but if you're
going to keep it, or want it right .......then head work is indicated most
likely.
If someone asked, " can I drive it 1,000 miles to some city without doing
more damage?" I'd say 'probably."
If they said 'can I drive it like this another year?" ......I'd say that
wouldn't' be a smart thing to do at all. It wears out the rest of the
engine too, not running right or having ragged compression.
You're sort of at the end of the road you've been driving down all this
time with this engine - as far as head work being due, and for some reason,
it's also not running correctly either, is what I gather.
Oh btw, if your cat is hollowed out, gutted, not recommended at all. Needs
to be a good cat, or a straight pipe as a replacement. Hollowed out cat is
verboten. ( not for smog or legal reasons - speaking in terms of flow and
correct running - definitely has some affect. )
You could have a leak down test done - mostly though waterboxer pistons
and barrels last extremely, extremely well. It's almost always the heads,
the valves and gasket sealing - and I haven't found too many cracked
waterboxer heads myself. It does happen of course, but I wouldn't have huge
worry that they heads are not re-useable yet.
How's your car repair and maintenance budget lookin' these days ?
Scott
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mike
Sent: Wednesday, March 19, 2008 2:43 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Still running like crap, the saga continues - Compression Test
Not good. Max differential between the highest and lowest readings should
be 10%;
so 135psi X 10% = 13.5psi as the max allowable difference between the
highest and lowest cylinder readings, your MIN should be 121.5psi. Your
lowest reading is 95psi = not good.
Now to determine where the pressure's escaping; valve(s) or rings (or
even a cracked head).
A differential compression (leakdown) tester will show your mechanic
where it's leaking, and then you can determine a course of action from
there. Teardown is the other alternative.....
I'm afraid to say, but it's a probably a valve job at least, a top-end or
complete overhaul at worst.
Mike B.
----- Original Message -----
From: "BJ Feddish" <bfeddish@NETREACH.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, March 19, 2008 5:04 PM
Subject: Still running like crap, the saga continues - Compression Test
> OK, my mechanic has had my van since last Friday and he called to tell me
> it's done. Anyway he did a allot tests and some other work. Details on
> that
> later. He said the compression varied from 95 to 135. How bad is that?
> What
> have I got a month, year, decade left on this engine?
>
> Thanks,
> Bryan
>
--
No virus found in this incoming message.
Checked by AVG.
Version: 7.5.519 / Virus Database: 269.21.7/1335 - Release Date: 3/19/2008
9:54 AM
|