Air Cooled Engine Noise - Confirm diagnosis please

[Macwesty]

Hello all,

I'm looking for some confirmation on this engine noise.
My van sat for at least several years before I acquired it
Total mileage 95k
Engine has "VW of Canada Remanufactured Engine" sticker on it. Could be pretty low miles.
When I first got it running it had a really bad tapping noise. Over the last 1500 miles I've changed the oil 3 times using synthetic oil and Marvel Mystery Oil and on this last change a full quart of Rislone.
The noise got much better initially but has not gone away and seems to have stabilized and is no longer improving or getting worse.
The noise is not present while coasting in gear
The noise is not able to be heard at all while driving above 40 mph (not sure if it goes away or just isn't loud enough to hear with general noise level)
After fully warm the noise is present while idling and at low speeds in first and second gear but under light load disappears almost entirely
The engine makes great power for an air-cooled 2.0. Cruises easily at 65-70 on the highway and maintains 60-65 with some attention on rolling hills.

I think it is an air-bound or otherwise defective lifter. So, am I right? If so, is it likely to fail suddenly? Keep in mind I've got approaching 2000 miles on it in this condition. I've got about 7 hours of driving I'd like to use it for this weekend. Starting to wonder if I'm pressing my luck.

Here is a link to an audio file: https://www.wuala.com/macanswer2001/Westfalia/?key=0TK9OySy1qWu

Thanks![/url]
_________________
'82 Vanagon Westfalia
Subaru SVX power!

[jismay]

Have you adjusted the valves on the engine yet?

I know they are "hydraulic, never need adjusting" but thats not really true.

Before you do anything else I would go through and check that the valve lash is correct on all 8 valves. That might solve the problem right there.

If that doesn't make a change then I wouldn't sweat it too much. It certainly is unlikely to cause a catastrophic failure anytime soon.

But my money would be on a loose valve adjustment fixing the issue.

--
1980 Vanagon Westfalia
1978 Super Beetle Convertible
1970 Squareback

[jismay]

Also, a good reference site if you haven't seen it is http://www.ratwell.com

Specifically:
http://ratwell.com/technical/HydraulicLifters.html

--
1980 Vanagon Westfalia
1978 Super Beetle Convertible
1970 Squareback

[Macwesty]

Thanks for the replies! I have adjusted the valves with each oil change so I've done it three times. I've set them at 2, 1.5 and .5 turns after contact with the valve stem to give the lifters different points to move around to in the hopes it would help loosen up the noisy one if that was, indeed, the problem. Adjusting the valves and changing the lash never impacted the noise that I could tell, however.

The good news is that I went ahead and did the trip this weekend and the van ran fine and the noise did not worsen. When I got home today after three hours of 65mph on highway the noise seemed like it was definitely lessened. I let the van sit for about 30 minutes while unloading and then moved it into the garage and the tap was back, though, when I started it back up. I think I'll adjust the valves again and put them at 1.5 turns and let them be. I've tried pushing on rocker arms to find a weak lifter but I've never found one that pushed down. They all seem solid. As I was driving this weekend I came up with the theory that may one lifter has a spring broken and so at lower speed when oil pressure is low the lifter is noisy and at higher rpms with higher oil pressure it does its job better and quiets down. I've found ratwell's site before and I will review the information there again.

Thanks again for replies!
_________________
'82 Vanagon Westfalia
Subaru SVX power!