SJVWC Forums
Archive => Archive board => Engine Shop => Topic started by: Beetleboi -Greg- on November 06, 2008, 05:20:41 pm
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So this morning I started my car, and on the drive to work I noticed a sound. *I know I should have turned around but I checked to make sure things were broken or on fire* It sounds either like the fan is working extra hard or there is an air leak in the exhaust.
The sound goes up with RPMS and is more audiable in the higher RPMS, I don't think it's the exhaust b/c it would back fire I think if there was a hole or the engine would be louder than it is.
I also thought maybe something was rubbing against the pull cause that has happened before but wasn't that.
Any ideas?
I've heard VW's that made this sound before, but never with my car.
Also thought the rain might have effected something, but I know its not possible in this situation.
Car made it there and back *30 miles both ways* no trouble
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Greg,
Had a leak in my exhaust system and never backfired, crawl around your car when it is running and see if it is the exhaust. My 55 made a pulsating vibrating sound which took me a while to figure out:the gen strap was loose and the gen wobbled on the stand at certain rpms (!).
You should be able to track the noise down, use a stethoscope or a tube to the ear, can help pinpoint.
Of course it is hard to recommend anything online not hearing what the noise is.
Hi pitched, low pitched, knocking, vibrating...?
good luck
Matt
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Of course it is hard to recommend anything online not hearing what the noise is.
Hi pitched, low pitched, knocking, vibrating...?
So true Matt.
Put your hand behind the fan house and feel inside the fan (with the engine OFF) to see if paper or something is in the fan.
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Maybe a leaf got in there, I'll check tomorrow, good points guys. I mean this noise is all of a sudden. I'll let one of you guys drive it tuesday to hear it if I cant find it. Maybe it's nothing.
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Went out to check, there was about a half of a trees worth of leaves in there, hopefully that what was making the noise. ;D We'll see in the morning! TGIF
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You have to watch that stuff if you park under trees, especially Pine trees. I've see so much crap on top of the cylinders from the fan blowing it in, it made the motors overheat and goodbye engine.
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I should get a car cover, it will take less to take the cover off than it does to pluck leaves and chit out of the engine compartment every morning.
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Great catch on that one Jack. You are the man!!! P#3
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Went out to check, there was about a half of a trees worth of leaves in there,
Ahem.....................
can you say "Deck lid standoffs??"
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can you say "Deck lid standoffs??"
LoL P#3
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sound is gone thx jack
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my car's been backfiring when dropping from high rpms to low rpms. then yesterday it suddenly started making much louder general noise than before. sounds like there's a really loud knocking from inside the engine. it's kind of like if you didn't have a muffler what the car would sound like but it's coming from inside the engine. also, it was accompanied by a dramatic loss in power. like I had to go into 2nd or 1st to get up hills on rt 1 in PA.
:(
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SkyMath - If I had to guess I would say that you either have a vacuum leak...or a blown head gasket :o
-Brady
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Where the heck have you been Sky?
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working and taking a class at the same time which means my schedule's all crazy--two days a week i'm in work at 7am (work is 75 minutes away), then straight to class in the afternoon, then home to see my kids.. the other three days I work an extra hour to make up the difference.. plus homework and personal life :)
what's a blown head gasket mean? it sounded like something blew
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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
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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.
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True...forgot about not having head gaskets...but it definitely sounds like a combustion chamber is leaking somehow with the loss of power...
-Brady
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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
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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
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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.
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s#r You must have a turbo.
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LOL!
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s#r You must have a turbo.
Or maybe a leaf blower. 777 Due to those damn stand offs. I1t
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There are WAAAAAAAAAYYYYYYYYYYYYYYYYYYYYYYY to many h8ers in this club! >:(
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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
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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
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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
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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