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Hi newbie here,
I have a 2010 boxer diesel, had timing chains replaced due to noises etc, quietened it down at idle etc. New oils & filters done. After a few days it went back to "clacking" intermittently. Took it back to mechanic who ran 2 lots of cleaners through it replaced oils & filters each time. Start up is typical Subaru forrester diesel, few seconds of noises then quiet (for a diesel) is definitely quieter on the whole, but as soon as I do a highway run, even if only, 3-4 k's, when I pull up, the Engine is "clacking" like a bag of spanners. If I turn it off for 30 seconds, the noise is mostly gone. If I just drive around town (in Australia by the way) it seems fine (for a diesel) car runs smooth, good power even when clacking noise is there. Currently running 0W-20 penrite, have dropped from 5W -30 (clacking was worse). Car has been looked after, done easy 185k, beautiful to drive, but embarrassing when parking up when clacking, sound like Santa with a sack full of spanners. No dealer close by (nearest is 5hrs away) so mechanic made ph calls with little to no help from factory technicians. Any help would be appreciated on what it may be. Sound wasn't there when purchased.

Cheers
Steve
 

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G'day & Welcome Steve

I think your oil is too thin; even a 30 weight oil will lose viscosity at 40C. I run 15W-40 in my Triton 2.5 turbo diesel. Still sounds like a bucket of bolts but that's common for a diesel.
 

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Discussion Starter #3
Is definitely slightly better with the 0W-20 than 5W-30 the other issue is trying to find a heavier oil that suits DPF filter. Could not find any.
 

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2010 Forester Diesel 6MT
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I think your oil is too thin; even a 30 weight oil will lose viscosity at 40C. I run 10W-40 in my Triton 2.5 turbo diesel.
Steve is using the correct viscosity for this particular engine. Spec (from what I remember, can confirm when I get home) is 5W-30 and that's the Oz spec, at the thicker end. I think they do use 0W-20 O/S, mostly for fuel economy reasons I suspect. 10W-30 is too thick from memory.

Need to be careful with using thicker oil, it might quieten things down...but it can damage other things, like the variable valve timing gear if it's oil controlled (and it may perform out of spec in the meantime).

Also, sometimes these 2010's clack when idling when they seem to be doing their own injector recalibration. Mine did just that the other day when I got home- the smooth idle immediately turned 'clacky'. I've heard it do this at red lights before, should go away after a minute or two and/or if you stop/restart the engine.

Caveat is I'm not familiar with the mechanical innards of the engine, you'll need a subaru diesel specialist. You could try ringing MRT Performance (Rhodes, NSW) for some advice, they are helpful.

Steve, you may wish to check where exactly the noise is coming from- maybe you'll need one of those multiple microphone devices. Is it injectors, valve train, cam/valve timing unit, timing chain area- did they replace the tensioner(s) and or chain guides? Also is the oil pressure OK, if it's noisy when hot that could be a sign of wrong, perhaps low oil pressure.
 

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Discussion Starter #5
Hi Kevin, yes replaced chains, tensioners, cogs everything. Even water pump.. no warning lights have ever appeared in my time of owning it. I will try to contact your recommendation in near future.
 

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Fortunately my Triton does not have a DPF ;-)

5W-30 and that's the Oz spec
Same for the petrol Foz to cover -30C to +40c. Maybe they just didn't bother changing the spec for diesel; same as not changing the service interval from miles to kilometres!
 

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2012 SH Manual Diesel
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Is it more of a Clack than a Tap or a tick?

Is it super fast (sewing machine on full ball), fairly fast, or slow?

Is it rhythmic or sporadic? Rise with rpm or constant?

Is it only at idle? Or does it happen on acceleration? Gentle acceleration or heavy acceleration?

When parking, is it an enclosed carpark, or does it have walls or barriers. Would you notice the clack if driving in a tunnel, or next to the concrete roadworks barriers? If so, you might be noticing it more because the sound is reflecting off the hard structures. These then might usually be sounds from the bottom of the engine. A fairly heavy clacking/slapping sound down there, is sometimes rod ends or main bearings.

If the sound is slightly less metallic, and not as high pitched and racy as valve train noise, it might be your injectors. You could try some injector cleaner, and a lubricant (since Aust Diesel can have less sulphur). These cars do recalibrate the injectors at times. However if it hasn’t seen the Dealer for a long time, it might need the ECU updated.

I had continuing, yet intermittent injector issues. Where they would pulse extremely fast (like the sewing machine going like a bat out of hell). Couldn’t replicate it at the dealer, so they kept fobbing me off. Only happened when engine was hot, then a restart. Turn off engine (sometimes several times), and it cleared the issue, for that moment. Dealer did do an injector relearn each time it had its service (as I would say “it’s still doing it”). I believe at some stage they updated the ECU, and it hasn’t happened since (more than 2 years ago).

If it’s not valve train noise or injectors, then you might have either an obstruction in the oil lines, or a worn oil pump. So at idle or low rpm, there is much less oil pressure allowing a bit of slap in the bottom end. You could consider getting it tested, or just chuck an oil pressure gauge in and check it against spec. 12-14 psi on idle, 40 psi at around 2000 rpm, and 70’ish at 4000 rpm. Will vary depending on oil you use and the temp of the oil.

One issue with the oil, is when the car is doing a DPF burn and the engine is shut down. With the turbo being upwards of 500 Deg C it can cook the oil inside the turbo. If I have to shut down during a burn, I will switch off the engine (say at lights or intersection before destination), so the burn stops, and the turbo has time to cool down. Also another case for using good quality oil, that can take the punishment of a hot shutdown. If there are carbon deposits from the cooked oil, this may have clogged an oil line. You could try CEM’s ‘flushing oil concentrate’, to see if it can break down any further deposits.

*Cost Effective Maintenance.

The fact that you mentioned that it did get a bit better when the mechanic did a flush, and also since you put in the 0w20, does sort of hint of a potential blockage. If the oil pump checks out, then it might be worth checking the oil scavenge pump (lower, left, front of engine), to see if it’s operational, and also drain the oil Catch tank on the turbo, and inspect the strainer. Maybe stay with the lighter oil till it’s resolved, so at least oil is getting through, but just remember it’s thin, especially during summer.

I agree with Kev on the oil weight. Too light for Oz in summer. Probably good for alpine and Tassy winters though. The issue is, that it will really thin out when hot, and oil pressure will drop. Since C3 oils don’t have full wear additive packages (due to DPF), and with a thinner oil film, the engine may be more susceptible to increased wear. Keep an eye on engine temp (better with actual gauge or ODB data, as dash is not accurate), if it’s getting above say 93-94 Deg C (and there are no cooling system problems), then back off a bit, as that increased temp might be from added friction.

Red Line motor oils have a 5W30 and 5W40 Euro Series oil. Both are ACEA C3 compliant. Of all the oils I looked at (that supply the data), they have the better NOACK and HTHS figures (volatility and shear at high temps). Oils with high volatility will likely lead to high carbon build up in the inlet manifold, and excessive build up in the DPF. Of which neither, you want. PENRITE should have a 5W40 that is C3 compliant, as that was what I was using previously. I think it was called Enviro. I found that when the engine was running for a while, with the Penrite, it would drop oil a fair bit of oil pressure. I run Red Line 5w40 (with a splash of 5w50, for summer).

Maybe make a recording of the sound. When it’s not making it, and when it’s occurring, and the context of when it occurs. Will be easier for people to help narrow it down for you.
 

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Discussion Starter #8
Is a rythmic metallic sound, like a tappit rattle! Seems to be once a revolution. Very diesel sound but excessive for a forester. Is intermittent bit constant when there. At times it will just stop instantly. But i can also drive around town for 30 minutes or so, no sound at all. If i go on highway or above 90kph for example for few kilometres an pull up in driveway, the sound is there. Not sure if that makes sense?
 

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It is unoticeable on acceleration. Not that it's not there, more at idle after a highway run.
 

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If it’s a singular sound (as in not several components at the same time), and once per cycle, my guess would be injector.

Have you tried a fuel line/injector cleaner yet?
 

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2010 Forester Diesel 6sp Manual
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Hi!
I have heard of vacuum pumps rattling, but dont think this is the case.
Around 10 seconds after startup under some conditions ECU closes throttle valve to starve engine of air (to heat up CAT faster?) that quiets down engine a lot. After driving this condition reappears only after restarting engine.
I noticed EGR quiets down engine as well, sometimes it is open on idle, sometimes it closes. If it is closed, short push and release of accelerator pedal usualy opens it up and engine gets quieter.

what happens with the noise when you hit fuel cut? when you drive steady speed and hear that engine rattles more than it should, what happens when you let go accelerator pedal in gear (coasting)? does the noise stop instantly or slowly? If noise stops instantly I'd say its fuel injectors, if noise changes with falling rpms, it could be something mechanic.

Try to make some videos, maybe you are battling normal Subaru Diesel sounds :)
 

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I think pitrack_1 is on-point with his comment about injector learning, which is entirely normal. This document is somewhat outdated, but describes the process (see page 24 - Microinjection quantity learning control). It occurs at idle on a fixed interval (3000km, I read somewhere else), or every second instance that the "idle instability condition" is met. This learning process corrects the pilot injection quantity, and pilot injection is the parameter that reduces idle noise.

I often notice the changing idle noise on my 2012 diesel - it goes from a normal diesel idle clatter to a fairly resonant "knock-knock-knock" with a slight drop in idle RPM. As soon as I touch the accelerator, it's gone. It might be undertaking injection learning often because it has high mileage, and/or something else is causing idle instability, which continuously triggers the learning process.
 

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Injector learning shouldn't appear too often, I think. and if it does, it lasts 20 seconds? 30 max? and after that engine sound should return to normal.
 
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