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My engine started making a noise on an evening drive home late last year and has been locked in the garage ever since. Now that the weather is warming up I am anxious to resolve the problem. It basically sounds like one of the four exhaust ports at the engine is open but all are bolted up tight. At idle is sounds pretty normal but when I give it some throttle it makes the sound, it also seems down on power. The sound seems to be getting external and does not seem to be internal or metallic. The engine has about 6,000 miles on a professional rebuild and is a stock '76 Beetle except for carbs, ignition and exhaust.

I'm not one to tear into an engine and nearby VW experts are hard to find plus I am afraid to drive it, so I would appreciate your experiences and suggestions. A few weeks ago someone on the list suggested checking for a loose sparkplug but all were tight. This was only the second long trip after installing a merged exhaust and stinger so I am unsure that could be the cause, all the exhaust bolts are up tight and not leaking.

One thought was perhaps a leaking head (hopefully not warped or cracked!). Someone told me VW's do not have a head gasket, is that true? I am now armed with a compression gauge so hope to check that this week. Any other thoughts?
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My engine started making a noise on an evening drive home late last year and has been locked in the garage ever since. Now that the weather is warming up I am anxious to resolve the problem. It basically sounds like one of the four exhaust ports at the engine is open but all are bolted up tight. At idle is sounds pretty normal but when I give it some throttle it makes the sound, it also seems down on power. The sound seems to be getting external and does not seem to be internal or metallic. The engine has about 6,000 miles on a professional rebuild and is a stock '76 Beetle except for carbs, ignition and exhaust.

I'm not one to tear into an engine and nearby VW experts are hard to find plus I am afraid to drive it, so I would appreciate your experiences and suggestions. A few weeks ago someone on the list suggested checking for a loose sparkplug but all were tight. This was only the second long trip after installing a merged exhaust and stinger so I am unsure that could be the cause, all the exhaust bolts are up tight and not leaking.

One thought was perhaps a leaking head (hopefully not warped or cracked!). Someone told me VW's do not have a head gasket, is that true? I am now armed with a compression gauge so hope to check that this week. Any other thoughts?
Stock VW engines do not have head gaskets, however there are copper O-ring gaskets available and some people use them during rebuilds depending on deck height and cylinder shims used. Check the basics first - valve settings, then compression and ignition timing. Then with the engine idling carefully reach up around the exhaust system at the heads and "feel" for exhaust leaks. If you can't figure out what the problem is (or fix it) take it to a competent air-cooled VW shop and let them do it.
An update on this problem: I adjusted the valves, tightened the exhaust bolts and checked the compression (okay in all 4 cylinders) and the noise persists. The engine seems to idle okay but when you "goose" the throttle when idling or on acceleration the noise is there (it sounds like an exhaust leak). Someone suggested the problem might be the head bolts need to be torqued but I am wondering if that is a good idea based on the following article: www.mvvc.net/vintage/technical/buyer_beware.htm
Questions: If the headbolts are in need of torquing wouldn't the compression be bad in one or two cylinders?
Logically it sounds as if something went wrong with the header
install, but it could be a leaking cyl/head due to a pulled/loose
stud. If it only leaks when "loaded", [don't kill yourself] but have
an assistant check it while you apply a load. be careful!
A thought might be to pull the suspected plug wire and narrow down
your search to 1 cyl. by listening for a sound change.
good luck, bruce
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