Hello all. Started hearing a buzzing noise a couple days ago but it’s only for about 1 second on cold start. Only happens on cold start, If I turn the engine off and on again after about 5 seconds it doesn’t make the noise but coming back out to my car after work it’ll make the noise again. Sounds like you’re holding a piece of metal to a spinning plastic fan or a weed whacker or a heat shield . Sounds like it’s external and coming from somewhere around the bottom of the engine bay. Occasionally has the wobbly rattle sound as well on startup for the first 1-2 seconds but more concerned about the buzzing sound. Just wondering if anyone here knew what it could be? Cheers
Buzzing noise on startup S3
- Thread starter HarrisonT
- Start date
Write the specific type of engine, volume, code designation, number of km, used engine oil, last major work on the engine. If possible, try to record the sound and send it here. Maybe I can advise you
It’s a 2.0 tfsi CDLC with 130,000kms (80,000 miles) just changed the oil last weekend and always use Castrol 5w-30 LL. I change the oil every 10,000kms and a couple weeks ago replaced the thermostat and coolant temp sensors to sort out overheating and fans not turning on. I have a video recorded but I can’t find out how to show it on here kinda new to these forums.
Noise started happening a week after I replaced the thermostat. I added about 2.5L between the last change. It’s been worse since I found a leak down the front of the block which I’m suspecting is the oil filter housing or oil cooler which I’ve bought gaskets for both just need to get round to replacing them. Usually it’s about a 1-1.5L between changes. I’ll record a vid tomorrow morning and send the YouTube link here cheers 
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Ok. So when it started doing this after the replacement, it would be good to check if you have connected something wrong. Sometimes it is not visible at first glance. For example, a quick coupling on a hose that has not been engaged will result in a bad seal and thus a leak. Check everything you have unpluged. Oil onsumption, In many cases on these aggregates is caused by the oil separator. Have you replaced it? If you decide to replace the separator, I recommend exclusively the original part, not aftermarket. We'll see how it sounds based on the videoNoise started happening a week after I replaced the thermostat. I added about 2.5L between the last change. It’s been worse since I found a leak down the front of the block which I’m suspecting is the oil filter housing or oil cooler which I’ve bought gaskets for both just need to get round to replacing them. Usually it’s about a 1-1.5L between changes. I’ll record a vid tomorrow morning and send the YouTube link here cheers
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Here’s the video link: https://youtube.com/shorts/KAiBbj4Jx1o?feature=share
I’ve done a check through of the pipes and connectors I removed and they all seem fine. I think I’ll be replacing the whole plastic oil filter housing assembly as they can warp over time causing even a new gasket to leak. Only changing the oil cooler gasket just in case.
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I’ve done a check through of the pipes and connectors I removed and they all seem fine. I think I’ll be replacing the whole plastic oil filter housing assembly as they can warp over time causing even a new gasket to leak. Only changing the oil cooler gasket just in case.
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Sounds like the timing chain rubbing against the tensioner for a split second whilst oil pressure builds up
Are you running out of water? By the sound of it, it could be a lot of things. I don't know your engine exactly, but I assume that it has a timing belt and cams connected by a chain. Also a chain for the balancing shafts. dave_beastttt may be right. I don't know exactly how the oil pump is driven, whether it's via a pulley or a chain. But it can also be a water pump, starter, oil pump, grooved belt. At home, you can try the following: drop the grooved belt and try a cold start without it. This excludes auxiliary aggregates. Then try the smoke test. You can still hear where the sound is coming from through headphones. If you can't figure anything out, only the service can help you.
Alternatively, there will be someone here with the same problem and find a solution for you.
The water is at the recommended level since i did the thermostat. it has a belt going to the exhaust cam and a small chain and tensioner on the opposite side of the engine connecting the intake cam to the exhaust cam. This is a common thing to fail and I’m going to replace mine this weekend to see if this is the issue like [mention]dave_beastttt [/mention]suggested. In person it really doesn’t sound like it’s coming from that area it sounds external and on the other side of the engine and very confusing because if I turn the engine off right after starting it the noise won’t happen again even after a couple hours but after a whole day sitting it’ll come back. could be oil draining out of the tensioner but i’ve never seen anyone’s tensioner sound like this. I was thinking it could be the starter motor pinion sticking out after cranking and making a racket but who knows. Maybe my oil leak has gone down to my starter and gunked it up over time I’ll have a look when I can next.
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Does your vehicle start/stop? It's the 188kW? I would still try to let them run idle without adding gas if the sound does not appear. And try to drop the belt and exclude helping aggregates. It will look difficult because it takes about a second and only cold.
*Update*
The problem has been fixed! I narrowed it down to a lack of oil pressure due to the noise it was making and had the oil pickup pipe replaced. Night and day difference. Cold starts are smooth and engine runs quieter overall now. Car has roughly 135,000kms and the shop said the pickup pipe was thoroughly blocked with sediment and carbon and some plastic parts from the broken dipstick I had to replace earlier this year I’m guessing. If you guys are having a rattle on startup look at the pickup pipe! It probably isn’t the chain tensioner making all that noise.
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The problem has been fixed! I narrowed it down to a lack of oil pressure due to the noise it was making and had the oil pickup pipe replaced. Night and day difference. Cold starts are smooth and engine runs quieter overall now. Car has roughly 135,000kms and the shop said the pickup pipe was thoroughly blocked with sediment and carbon and some plastic parts from the broken dipstick I had to replace earlier this year I’m guessing. If you guys are having a rattle on startup look at the pickup pipe! It probably isn’t the chain tensioner making all that noise.
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