Date: Tue, 19 Oct 2004 11:21:58 -0400
Reply-To: vw4x4@FYI.NET
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Eric Zeno <vw4x4@FYI.NET>
Subject: Re: '88 engine knock diagnosis
In-Reply-To: <6.0.1.1.2.20041019102911.02d6a9f0@pop.starpower.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
LIfter tap.... Change the oil, with 20w-50. That for long drive.
Eric
Eric wrote:
> Greetings.
> I'm a new owner of a 1988 Westy that was picked up cheap because of a
> loud
> engine knock. I would appreciate the list's help in a possible diagnosis
> before I pay to have it towed since its destination depends on the
> malady.
> (If the engine is toast I'm diving right into a Subaru transplant. If
> there
> is hope for a few more miles it goes to the local VW shop.)
>
> The symptom:
> It is a LOUD knock or rap that sounds like a hammer hitting the block. It
> is quite loud, maybe louder than a bad rod bearing but less of a deep
> "thonk" and more of a sharp rap. Seems to be louder from beneath the
> engine. If my calculations are correct, its frequency is about 1/2 the
> crank speed at 5-6 times a second at normal idle (valve/cam related?).
>
> What I've investigated:
> Don't really know the history of this engine. Odometer has 142,000
> miles on
> it. Looks like heads have been replaced sometime. Oil level ok but don't
> know when the last change was. Small oil seep (main crank seals?). Small
> coolant leak from hose connection, nothing serious. Cold compression
> seems
> ok (first stroke 90-100 tops at 140-150 for all 4). Starts and idles fine
> with slight roughness. The oil pressure light goes out shortly after
> start
> and stays out at idle, though the engine hasn't had the chance to
> completely warm up during my investigations so don't know about hot oil
> pressure. I've been afraid to rev it above 1500rpm or run it for long
> if it
> is a rod ready to liberate itself.
>
> I've grounded the plug wires for each cylinder individually with it
> idling
> and there is no change in the knocking. I've popped off the valve covers
> and cranked it. All the valves seem to move more or less. I've cranked it
> with all plugs out and there is no obvious knock.
>
> Early diagnosis:
> I'm much more familiar with OHC in-line 4 engines. This WBX throws
> some new
> geometries into the mental picture not to mention the complexities of the
> hydraulic lifter push-rod valve train. My first intuition was a rod
> bearing
> due to the loudness, but it didn't seem to change as expected when the
> plug
> wires were grounded and its frequency seems half of what it should be.
> Suggestions please?
>
> I am grateful for your insights,
> Eric
>
>
| 
