Engine Noise?!! What is it?!

[braidmeister]

Does it sound like 'pfft...pfft...pfft...pfft...' when it is running? This is a good indication that you have a blown head gasket if you are also reporting a loss of power. 1st thought was a leaky exhaust which can cause a backfire on decel as cold air rushes in...But if you are losing power then it is a good chance that you blew a head gasket. The head gasket seals the cylinder to the head/combustion chamber.

I'm not saying that it IS a blown head gasket for sure, but it sure sounds like it could be. The only way to know for sure would be to do a leak-down/compression test.

-Brady

[njgt-1]

or a blown head gasket 

hate to mention it but most air cooled vdubs don't use a head gasket, just a sealing surface between the head and cylinder. If compression is getting past that point then it might be a stud pulled loose from the case. A compression check will verify this.

[braidmeister]

True...forgot about not having head gaskets...but it definitely sounds like a combustion chamber is leaking somehow with the loss of power...

-Brady

[skymath]

okay so there's probably a leak in the compression chamber? Jack told me that my compression was always weak but we never actually checked it

if there's a way to fix it short of swapping engines I'd rather try that first.  Is there anything obvious I should be checking?

..Sky

[braidmeister]

Buy or borrow a compression gauge and screw it into one cyl at a time. It should hold pressure when both valves are closed. Record what the pressure is for each cyl. I'm sure somebody here has one...

-Brady

[Beetleboi -Greg-]

Hey the sound is back, maybe it's just somethign I've never heard before. I swear tomorrow you are going to say, "I don't hear anything" "Remove those Chitty GT Tips so I can hear what you're talking about" "It's just your fan no need to worry" It's kinda like a whine but it doesn't sound life threatening at all. Like I said I've heard VW's sound like it, maybe it's just my super sonic hearing.

[lovebus (jack)]

 s#r You must have a turbo.

[braidmeister]

LOL!

[bugs2much]

s#r You must have a turbo.

Or maybe a leaf blower. 777  Due to those damn stand offs. I1t

[Beetleboi -Greg-]

There are WAAAAAAAAAYYYYYYYYYYYYYYYYYYYYYYY to many h8ers in this club!  >:(

[Bugaru "JAY"]

 Does it sound like a slight ringing / gingleing sort of chain rattling noise? It's a sound that I thought that most VW's usually have, but oneday while sitting around the campfire and telling horor stories about what goes bump in the night, I asked master Jack  stoned# and he nailed it right away. If it's the sound I described Jack knows exactly what it is, you may have to buy him a cup of coffee for the answer but ask him.  s#r
 

[skymath]

Guys,

so is it true that an exhaust leak can cause backfiring?  because my bus was backfiring until last week when it started being super super loud and lost a lot of power..  but when the aaa guy came I started it up to move it to a better spot for the tow truck, and he said it sounded like an exhaust leak.   the reason I ask is because I have an extra muffler..  will replacing the muffler help if it's an exhaust leak?

Can someone explain to me why an exhaust leak would cause backfiring and/or a loss of power?  It doesn't make sense to me...

..sky

[braidmeister]

An exhaust leak would cause backfiring - due to the vacuum created when you let off of the gas & cold air rushes in, creating the backfire...BUT in the case of your engine, it will not cause a substantial loss in power.

Start the thing up (set parking brake and chock wheels!) and crawl underneath and LISTEN...Where is the noise coming from EXACTLY?

-Brady

[matt]

I had 2 exhaust leaks that did not cause any backfiring  ???

In putting a heat exchanger on my brother did not tighten down the bolts from the exchanger to the head,  - they eventualy came way loose, and boy that was loud,

recently replaced a heat exchanger cause it rusted out where it joins the muffler.

Maybe holes in the exhaust of a certain size or certain place  cause backfiring  - ?

Yes you have to trace the noise, that will help, if you cant isolate it, put a tube to the old ear, and stethoscope it like I mentioned in my first post

good luck


Matt