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Bug Valvetrain Problem

I recently posted this on a popular tech forum and got no responses so maybe someone here can help me out.

My 72 Bug has a fairly new 1600 DP. I rebuilt it 2 years and 15K miles ago using NEW parts. New case, crank,cam,heads,carb etc. All stock.

The day I started it I set the valves at .006 and it was pretty noisy. It is my first VW and my first engine rebuild. I bought it with a trashed engine so I had nothing with which to judge the sound of the valves on.

I recently had to pull the engine because of an oil cooler leak.

I changed the spark plugs and stripped the spark plug hole so I had to remove the head.

Here's where my question comes in. All of the valve stems are beat to pieces. I checked the other side and they look the same way. They are concave instead of flat. I installed lash caps and put the engine back together and back in the car. I set the valves to .006 and started it. The valves sound worse than ever. So I check the clearances when the engine was warmed up. At operating temp they are .006 to .008. What's the deal??

Any ideas would be greatly appreciated. I don't want to drive it until I figure out what is going on, but I know not to tighten them up for risk of burning a valve.

Thanks,

Dave

Reply to
John
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Do you have steel (black) pushrods in there, in place of the stock aluminum (silver) ones?

Jan

Reply to
Jan Andersson

I am going to read everyone's replies with much interest because I hope to be going through the same nerve wrecking thing of starting my newly rebuilt engine soon.

Do remember reading somewhere that the very first time you run a rebuilt engine your set the valves a little sloppy (like 0.008) until things get settled. You goose the engine for 15 minutes, change the oil and then adjust them to 0.006. Another thing I read said that you have to drive the car really hard when you first rebuild it, which seems counterintuitive but made sense when I read it. (I'll find the article and post a link to it here when I find it).

Remco

Reply to
Remco

Nope, No Steel pushrods. Aluminum.

I've been researching this problem on the net and ran across an article about aftermarket cylinder head studs. It seems that some of the aftermarket (not German) cylinder head studs allow for too much expansion within the stud itself and let the clearances increase? Any thoughts on that one?

Remco,

If you can I would highly recommend Tom Wilson's book "How to Rebuild Your Aircooled Volkswagen". Man, did I learn a lot from that book.

B.Dalton and Books-a-Million both usually have it if you are somewhere close to one.

Thanks,

Dave

Reply to
John

Sounds like your valves have got too hot and stretched, they go mushroom shaped shortly before they snap! I think 0.15mm is plenty of lash. I would run it on higher octane fuel and check your ignition timing. You have to rev the engine to about 3000 RPM for about 15 mins only if you fit a brand new camshaft to burn it in. If you don't then the lobes will wear prematurely. According to VW ownners manuals beetle engines can be run at maximum speed from new and it's maximum speed is it's cruising speed. I some time wonder if anything was lost in translation!

--Steve

Reply to
Tunafish

Thanks -- I just got that book from Amazon but haven't seriously sat down with it yet. It will rain over the weekend, so that will be a prime opportunity.

I found that information regarding break-in of an engine:

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Reply to
Remco

Reply to
P.J. Berg

sounds like you have stainless steel valves(softer than "stock" valves) and possibly steel pushrods...but steel usually end up with a larger gap than that when hot...BTW...how are you judging "warmed up"? do you have guages or just figuring on warmed up time-wise?...do you have a fully functional cooling system including the aircontrol veins and working thermostat? if not then the expansion of the dissimilar metals in your engine can be less accurate..

Reply to
Joey Tribiani

The cooling system is completely intact and even the thermostat is connected and working properly. The engine has never overheated that I know of.

So is there anything at all I can do other than tear the engine back down?

Dave

Reply to
Crash

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