Don't rule out your mounts unless you physically check all of them.  I would
check not only your engine mounts, but tranny mounts as well.  I once had my
tranny mounts worn out that I would get that thunk at start up only.  Really
confused me.  but if you think about it, once the engine engages on start
up, that is a lot of torque transfer, enough so that engine and tranny can
shift and hit metal to make noise like that if the mounts are bad.  Also,
check to make sure the mounts are tightened down.  they could be in good
shape but can be loose.  check those thoroughly before you start to
investigate a rod (unlikely) etc....
good luck
jason
87 syncro westy

>From: Barrett Willet <barrettw@NVENTURE.COM>
>Reply-To: Barrett Willet <barrettw@NVENTURE.COM>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Hard thunk at startup
>Date: Tue, 24 Oct 2006 21:25:13 -0700
>
>'88 2.1L
>Recently I've been hearing a hard thunk at startup.  Almost like
>somebody is kicking her in the rear.  The thunk only happens the
>second the engine catches.  No thunking while the starter is doing
>it's thing.  After that, it purrs along just fine and no thunks occur
>on acceleration.  It seems like this eliminates engine mounts.  More
>prevalent after the van is warm like during quick trips to the
>store.  I recently replaced the muffler & cat but I double checked
>all the hardware and everything is tight.  Of course it doesn't make
>a noise first thing in the morning.  Kind of stumped.  Of course my
>worst fears are rods and bearings but it seems like I would hear
>weird noise during normal driving.  Any thoughts?
>
>Barrett
>'88 Wolfsburg 2.1L

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