Valve Train Noise from Left Side of Engine

[vwlover77]

My '78's 2.0 engine with hydraulic lifters has a ticking/clacking noise on the driver's side (only) which appears when the engine gets hot. The high ambient temperatures (90+) we have had lately seem to make it worse.

The frequency and type of noise made me suspect a hydraulic lifter going soft or bleeding down in operation. It's not quite as harsh or loud as a fully air-bound lifter, but the sound is similar. Or like a solid lifter engine with too much valve clearance.

I got the engine good and hot, shut it down, set # 3 to TDC, pulled the valve cover, and tried mightily to push the pushrod end of both rocker arms in toward the engine with a large screwdriver, assuming that would expose a soft lifter. No movement in either case. Set #4 to TDC and tried the same thing with the same result. No movement.

Can I conclude from this test that the lifters are not the culprit?

What about the rocker arms or shafts? Would excessive wear / clearance cause the rocker arm to "clack" on the shaft as the valves open and close? (Do they ever wear out?)

Thanks!

[vdubyah73]

exhaust manifold to head leak, sometimes make you think lifter, when they first start leaking.

[vwlover77]

I forgot about that possibility. I will check it out. I have an interesting way to check.... I use a cheap mechanic's stethoscope with an open hose on the end. Go around the manifold with the hose end while the engine is idling and it's guaranteed to detect a leak. Care is needed, however!

[Amskeptic]

I forgot about that possibility. I will check it out. I have an interesting way to check.... I use a cheap mechanic's stethoscope with an open hose on the end. Go around the manifold with the hose end while the engine is idling and it's guaranteed to detect a leak. Care is needed, however!

Most usually, an exhaust leak just gathering steam will be noisy only when cold when the engine is "unclamped".
HOWEVER . . . a cracked exhaust flange gets louder as expansion opens up the stress point.

Place a rag on a piece of leather or any majorly tough enough tailpipe stopper and press for an air tight seal against the tailpipe. Listen for a hiss and see if the engine slows down. With modest contortions, you can do this under the bus and look locally.

Other clacks of note are carbon build-up in the combustion chamber banging against the piston (noisier hot), sounds very much like an obnoxious valve clack. It can be moderated a little by pulling the spark plug lead to the offending cylinder at the distributor cap.

[vwlover77]

It's very quiet when the engine is cold. I tried the tailpipe plug with the engine hot. No hiss or increase in the noise, and the engine started laboring very quickly. I also tried my stethoscope hose test around the exhaust ports - no leak apparent.

The engine was last apart around 30K miles ago. It had clean pistons, cylinders, and heads at that time, and has never been tuned excessively rich since then, so I don't think it's carbon build up.

I'm ready to focus again on the valve-train. I'll try to get some audio of the noise if I can.

[vwlover77]

I shot some video, starting on the passenger side of the Bus (the "normal" sounding side) and walking over to the driver's (noisy) side. The passenger side sounds a bit weird because the exhaust exiting the tailpipe was interfering a bit - in actuality, this side seems "normal" to me. You can definitely hear the rapping on the driver's side, though. What do you think?

http://www.youtube.com/watch?v=RI39Oh-5 ... e=youtu.be

[SlowLane]

In the video it sounds an awful lot like an exhaust leak: "ffft, ffft, ffft", like an angry cat.

I just want to mention that the last engine I had to drop a valve seat started making a worrisome "tick, tick, rattle, rattle" sound, which prompted me to pull the engine and take a look before it blocked the valve open.

Have you the tools to perform a compression check and/or leak-down test?

[Amskeptic]

I shot some video, starting on the passenger side of the Bus (the "normal" sounding side) and walking over to the driver's (noisy) side. The passenger side sounds a bit weird because the exhaust exiting the tailpipe was interfering a bit - in actuality, this side seems "normal" to me. You can definitely hear the rapping on the driver's side, though. What do you think?

http://www.youtube.com/watch?v=RI39Oh-5 ... e=youtu.be

Definitely . . . interesting. I heard too much metal, SlowLane, to attribute it to exhaust leak. If you really trust your lifter centering job at 1 1/2 or 2 turns, Don, preload, then it is time to go in a bit. Pull your rocker assemblies one at a time and go down to the lifters and pull them too. This would require pulling the pushrod tubes. Check for contact between the pushrod tubes and the pushrods. Check everything else, including rocker arm play (no big differences is more important than overall slop) and the condition of the valve stem tips and adjustment screw tips. If you have swivelfoot adjusters, check them carefully for unexpected new play.
Colin

[SlowLane]

I heard too much metal, SlowLane, to attribute it to exhaust leak.

You're the musician, Colin. Me, I'm tone-deaf.

If you have swivelfoot adjusters, check them carefully for unexpected new play.

If you are using swivel-feet with your hydraulic valve-train, read this caveat from Aircooled.net on the topic.

[vwlover77]

No swivel feet in this engine, just stock components. I verified the 1-1/2 turns preload on the valve adjustments on Saturday and reset them to 2 turns preload. I have not driven enough since then to determine if this has made any difference.

I'll disassemble and inspect as you've suggested ASAP!

Thanks!

[Amskeptic]

TWENTY SIX DOLLARS PER SCREW??
That's a screw rat thar . . .
Dumb found Colin

[SlowLane]

TWENTY SIX DOLLARS PER SCREW??

Hey, but it sez "Porsche" onnit. Dat makes it special.

[vwlover77]

I took everything apart today for inspection and everything looked shiny and nice, without excessive rocker movement on the shafts, except for this on the #3 exhaust valve:

The cam lobe and lifter face all look OK. What caused this? Should I replace the lifter?
I know I need a new adjuster screw, but can the valve stem end be salvaged?

[RSorak 71Westy]

Do they make lash caps for VW's? If not you need a valve too.

[SlowLane]

Do they make lash caps for VW's?

Yes, they do. Be sure to get quality ones. Last set I got (CB, I think) had tiny little nubs in the center from the machining process. Would have played merry havoc with my adjusters if I had installed them.