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2016 Forester XT
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30 Posts
Discussion Starter · #1 ·
Light throttle, slightly in boost, if I take my foot off the gas, there is a slight whiney whistle that comes from the turbo. Normal for the TD04? I can’t remember if my Saabaru did that. I'll admit, I did swap the TD04 out pretty quickly for a 16G :biggrin:
 

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2011 turbotek tuned fxt 4eat paddle shift
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3,539 Posts
Just a litlle surge or flutter most likely nothing to worry about. If it starts making noises when you floor it then you have a issue.
 

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2016 Forester XT
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30 Posts
Discussion Starter · #3 ·
Just a litlle surge or flutter most likely nothing to worry about. If it starts making noises when you floor it then you have a issue.
Kind of figured it might be something like that, but wanted to make sure. It sounds great otherwise. That was the only thing that had me a little worried.

Anyone else have this same noise?
 

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1999 Forester S Turbo 5MT
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Generally the TD04 is fairly quiet but have you checked all your hoses for leaks? If there is hole or loose pipe somewhere then the noise should be in both directions increasing in level as the boost is built but not necessarily so if the leak is off the main path. On one of my earlier experiments the turbine shaft nut came off allowing the compressor wheel free reign in it's space and even though it trashed itself, I heard nothing and still got good boost for over a hundred miles before I realised something was wrong. A boost gauge is a useful and economical (depending on how much you spend of course) tell tale tool to have on a turbo charged car although some folks who dislike extra gauges mount them for diagnostic purposes and then remove it once satisfied all is well.

Some ball bearing turbos whine/whistle a little "off boost" but generally plain bearing units are pretty quiet. My turbo with the bigger compressor always shrieked at me under boost with the standard 6+6 compressor wheel but try as I might, I was only able to tame it by insulating the y pipe from the outlet to the IC. The current billet 11 blade wheel is very quiet though.

Are you mechanically capable? Would you be up to pulling the IC and checking all the pipes and tubes from the BCS, MAP sensor and anything else in the pressure pathway? How is your BPV behaving? None of these things should be defective on a 2010 car. On the older Foresters you have to pull the turbo to inspect it, I don't know about the later models though. Taking off the IC also gives you a chance to ascertain other things by the condition of the inside of the Y pipe and cooler relative to oil or other deposits, a little oil coating on the Boxer engine is ok, I think, but I stand to be corrected.

Do you know anyone who has a flexible scope they might lend you, or somewhere that hires them so you could run it down the inlet pipe for a quick look? (a lot less time and work than pulling the turbo, just remove the pipe from the air box to the turbo inlet pipe, if you just want peace of mind). Even if the bearings were wearing out they will still function and the only problem is a bit of oil leakage and when the wear becomes bad enough, the vanes on the compressor wheel will touch the wall of the housing, hence using a flexible to scope to confirm or put you mind at ease.

One other minor possibility is that something got into the intake and nicked a vane on the compressor wheel leaving a rough protrusion that might make a noise at 100k rpm. If the nick was bad enough it would throw the wheel out of balance and 'singing/harmonics' might occur but again, the scope will allow you to check that too.

Generally speaking, the TD04 is a well built and strong unit which rarely go wrong, probably why they are so widely used, so if you are changing your oil and filters for good quality synthetic then the blower should be ok.

A quick note on synthetic oils though, and even if it has been put up before, due to the nature of this post perhaps it's appropriate to note it again. There was a legal case taken some years ago by one of the bigger oil retailers, in the US I think, against another because the defendant was selling oil marked fully synthetic while the contents were not. Bizarrely, the case was over turned and the result of that ruling is that just because it says "Fully Synthetic" doesn't mean it legally has to be, so buyer beware. One poster I came across suggested a simple and nice way to decide whether you have fully synthetic in your engine or not - "if it makes your engine sound like a sewing machine, it's rubbish." I have found this to be true after purchasing the less expensive FS oils for many years, in my ignorance. Also, the cheaper lubes get burned by the engine requiring constant top ups on the Boxer. Since using the correct type of FS (as in VW, Porsche etc if you can't remember the designation) my motor is quieter and I haven't had to add any extra in the roughly 3k it's been in there, and the lube is still golden brown if a little darker than when it went in. The FS I was using before would be black by this time and requiring around 1 liter per 1200 miles top up. As far as modern engines go, and particularly turbochargers, the stresses the oil has to deal with cause non synthetic molecules to shear thereby rendering them ineffective at preventing surface contact once the additives break down. FS requires no additives because it's grown under 'lab' conditions so each molecule is the same as the next and it has better cohesion under duress.

A bit long winded but I hope this is of some help.
 
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