WBX engine tapping. Lifter or?

[SCM]

My van has been running great but I started hearing a tapping noise when the engine is under load. Typically, when my lifters are bled-down, the tapping is loud, occurs immediately under idle, and goes away after a few minutes at highway speeds.

This is different in that it ONLY occurs when I'm in gear and accelerating. Not at idle, and not in neutral while revving the engine. It hasn't gone away with fast in town driving but I haven't had a chance to get on the highway yet.

I do have a small exhaust leak but that's been their a while and hasn't become worse.

Any ideas on how to troubleshoot or fix?

Thanks
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[Syncronoid]

CV's?
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'90 Syncro Westy w/GW2.5L

[Wildthings]

Maybe an exhaust leak?

[SCM]

It was a tough day to diagnose/listen due to heavy rain but I think the noise went away, leading me to believe it was just a lifter acting differently than I'm used to.

Way less likely is that there was a grape sized stone wedged tightly between my cylinder head and exhaust flange. Maybe that was transmitting some noise. I've been impressed with the ability of my engine to pick up gravel while driving dirt roads - I even had a piece wedged into my crankshaft pulley that was destroying my alternator belt at one time.

And my exhaust leaks (particularly in the muffler and 2-to-1 elbow) are bad enough that I can kinda justify shopping for a new exhaust.

Oh, and not CVs. I drove some tight circles and heard nothing. When the tapping was noticeable, lifting my foot off the gas pedal immediately made the sound go away even though my direction and speed were no different.
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[SCM]

Argh. I replaced my J-pipe with a Vintage Speed unit (which I love) and replaced the muffler that had worn away at the muffler bracket bad enough that I think I could probably shove my entire hand into the gap - if I didn't mind a bunch of blood and scabs on my hand.

Oddly enough, my exhaust sounds exactly the same as before! And that's great, my wife and I love the "thump thump thump" of the WBX.

But the tapping hasn't gone away. I'm going to try some Marvels's Mystery Oil since I'm due for an oil change soon and hopefully that fixes things. If not I guess I need to learn about valve adjustments.
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[MarkWard]

Piston slap? With the engine idling, kill one cylinder at a time and see if the noise changes. I have a 12 volt test light that I can short one plug wire at a time. If the noise goes away when you short a particular cylinder, it’s likely not the valve train. MMO works wonders. Buy a qt and top off the oil level. Drive it 100 miles and change the oil and filter. Add the remaining MMO and drive. Best of luck.
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☮️

[SCM]

[VdubVanner]

Piston tap or slap?

If you'd like to see what a TAPPing/SLAPPing piston looks like in the flesh run halfway down this page of my thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=715716&start=340 .

I just had a piston set on my new GoWesty 2.3L engine replaced under warranty. The skirt coating is the culprit. Initially, it was thought to be a lifter problem but got worse noise-wise.
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"Fritz", a temperamental and unforgiving 1989 Westy that proudly bears his German flags and status as a member of the exclusive GoWesty Belly Flop Club.
1989 Westy Makeover: GoWesty 2.3L Engine plus plus plus https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

[4Gears4Tires]

When was the last time the valves were adjusted? My van sounded terrible for about 6 months (I thought they were just really clacky) and then I adjusted the valves. It really quieted it down, not scary sounding anymore. It was wildly out of spec.

My issue was the worst at idle though.
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[VdubVanner]

The best way to rule out piston slap is to run a borescope in for a look see. Check out the page before the one that I linked for what trouble looks like.
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"Fritz", a temperamental and unforgiving 1989 Westy that proudly bears his German flags and status as a member of the exclusive GoWesty Belly Flop Club.
1989 Westy Makeover: GoWesty 2.3L Engine plus plus plus https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

[Wildthings]

[kamzcab86]

[SCM]

One could also read the post where I thanked Mark and said the problem is fixed.
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[VdubVanner]

I recognize that your problem might be fixed, SCM, but others doing a title search on engine tapping + lifter might find it of some use (and actually you still might down the road, too, since mine happened on a GW 2.3L engine which, I believe, is what you're running):

https://www.thesamba.com/vw/forum/viewtopic.php?p=9453561#9453561

Just to square things away, the date of that post was Monday, Sept 7 2020 at 2:54pm on the thread page BEFORE the one I linked to above as stated. Apologies for not directly linking it as I'm not as technically savvy or smart as kamz (just call me feeble-minded). [UPDATE: After a quick education lesson from kamz below, I now provide the direct link above with the bore scope photos included. I owe teacher kamz a shiny fresh apple for her desk. ]

Some folks might initially think what they're hearing is associated with lifters or valves when in fact it may be piston related which is far more serious. Think COVID-19 vs a normal flu. A bore scope exam might put the doubt to rest and lead one to the proper conclusion.

The direct link that kamz provided illustrates what that scored piston looked like after being ousted from the engine. Not a pretty picture. I haven't seen good pics on the subject so thought a few nervous owners might be interested to see both the bore scope exam and the follow-up images.

Cheers!
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"Fritz", a temperamental and unforgiving 1989 Westy that proudly bears his German flags and status as a member of the exclusive GoWesty Belly Flop Club.
1989 Westy Makeover: GoWesty 2.3L Engine plus plus plus https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

[kamzcab86]

[Jake de Villiers]