Uneven wear on valve adjustment screws, what might cause this? Options

[75914-L20C]

'75 1.8 liter, 170XXX miles on completely stock engine, heads never been off, case never opened.

I was adjusting the valves last night and took out all the adjusters to check for pitting, and noticed the off-center wear pattern and some pitting at the outer edges of the adjusters.

The adjuster at the top of the pic looks like I would expect with criss-crossing wear patterns all centered on the adjuster face. The adjusters in the bottom row are the worst ones with a much wider wear pattern offset to one edge. I didn't think to keep track of which cylinder or intake/exhaust they came from until they were already in a pile on the floor.

I checked the clearances before removing the adjusters and all were in the 0.006 to 0.008 range. I think the 0.008s were as a result of setting those a little too loose last time.

Is this a sign of mis-adjustment or some type valvetrain wear?



Thanks,
Pete Klager

[rhcb914]

For 170K on those I would say they look pretty damn good!

The ones with the more circular wear pattern probably needed more adjustment over the life of the engine. They normally wear in a linear pattern.

Oh, and (IMG:style_emoticons/default/welcome.png)

[jk76.914]

Offset axially like that is from gross misadjustment or push rods too short (if it's offset towards the ground) or too long (if it's offset towards the sky).

I agree with rhcb914 on both points- every time you adjust them there're a tiny bit different, so you'll see a asterisk pattern form *. Over time, they'll merge like yours have.

rhcb914's other point- they look great for 170000 miles! I don't think I'd reuse them though. The tips are no long spherical- they've flattenned along the path where they wipe the valve stem tip. Plus, you can never be sure of how deep the hardening was originally, and if you've worn through it, they'll really wear fast from this point on. At 170000, they don't owe you a thing.

VW still stocks them, and my opinion is that that's the safest route, albeit pricey. I just replaced mine own at $12 each! I think Jake sells used but serviceable ones. I may have heard wrong, but I think he does....

On a related note, while you're in there, you may want to pop a pushrod tube and lifter and check out lifter wear and do a visual on the cam lobe with a flashlight. You may not be willing or able to do a teardown just now, but it'd be a good data point for future planning. Also check out the valve stem tips for concave wear.

At 90000 miles my stock cam had typical but unacceptable wear patterns, and my lifters were polished but concave.... Worn lobes plus worn lifters would have the same effect as too short pushrods....

Jim

[rhcb914]

I agree that you shouldn't reuse them or they could end up looking like this! This one was actually a brand new one that probably didn't get the proper hardening. It wore to this in about 300 miles.

[jk76.914]

I agree that you shouldn't reuse them or they could end up looking like this! This one was actually a brand new one that probably didn't get the proper hardening. It wore to this in about 300 miles.

That's exactly why I went with the VW $12 adjusters... No guarantees, even from VW, but I'd bet there's a higher likelihood they were hardened properly vs. the $3 aftermarket ones.

Jim

[75914-L20C]

Thanks for the replies and the welcome! I've been lurking since the "#4" days, so I don't feel like I'm new here, but, yeah, I don't post often...

Offset axially like that is from gross misadjustment or push rods too short (if it's offset towards the ground) or too long (if it's offset towards the sky).

I wish I had paid attention to the orientation at the time. I'll do a better inspection next time I'm in there. I did replace those adjusters with some spares that I had and buttoned it back up already.

On a related note, while you're in there, you may want to pop a pushrod tube and lifter and check out lifter wear and do a visual on the cam lobe with a flashlight. You may not be willing or able to do a teardown just now, but it'd be a good data point for future planning. Also check out the valve stem tips for concave wear.

Thanks for the tip! I will definately do this next time.

Pete

[HAM Inc]

How do the ends of the valves look? While you're in there you should look for any valves that are sticking out more than the others. If you can see a difference without using a straight edge then it's time for a valve job. After 170,000 miles it probably is anyway!