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Nissan Navara D40 - Engine sounds different than before (lemm.ee)

submitted 1 year ago by Thorny_Insight@lemm.ee to c/mechanicadvice@lemmy.world

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I might be just hallucinating but I feel like my Navara sounds different than when I bought it. There used to be this very typical turbo diesel humming noise when accelerating and switching from first to second grear like you can hear here for example. Basically the same sound every diesel truck makes when accelerating. I feel like I can't hear it anymore, however the truck feels and runs just normally. Atleast I think it does.

I'm assuming that sound is coming from turbo because I only hear diesels sounding like that. How would I go about making sure everything is working properly when there's no other symptoms that the lack of that sound?

Here's what mine sounds like.

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[–] Everythingispenguins@lemmy.world 2 points 1 year ago (1 children)

Okay so I do not Navaras where I am from, but best I can hear it sounds normal for a turbo diesel. A few things to remember is that vehicles sound much different between the hood open and in the cab.

If there are no other symptoms like loss of power or warning lights. I would look at the exhaust and the intake piping. They can get a hole in them and change engine tone. Though usually louder.

If you have a small loss in power you might look to see if the turbo waste gate is stuck on the bypass. This would cause a loss of turbo noise along with a loss of boost.

[–] Thorny_Insight@lemm.ee 1 points 1 year ago (1 children)

The waste gate is something I've been wondering about. Might need to look into that.

I have been experiencing some intermittent RPM drops and stalling when idling with cold engine in below freezing temperatures aswell as occasional stuttering while driving but not when accelerating hard. I had the EGR valve replaced, but that didn't seem to do much. I ran some fuel system cleaner thru it which seemed to help with the stuttering while driving as well as cleaned the MAF, replaced SCV and reseted the ECU which seems to have made the engine run better but it's still too early to say. With warm engine/summer time I've had no issues with it.

The exhaust was split between the CAT and DPF which strangely enough did not make the truck louder. I've since fixed that but the muffler is pretty rotten aswell and probably has holes in it too. I doubt that this is the culprit though. In some video I watched they talked about how the turbo waste gate, EGR and throttle body are all linked together and an issue with one might mess up the whole system.

[–] Everythingispenguins@lemmy.world 1 points 1 year ago (1 children)

Okay so those are absolutely other symptoms. So that sounds a lot like a fuel delivery issue. The cold running that goes away with warmer temps is classic fuel delivery issues. So first I would put a new fuel filter on it and check your water filter if you have one. If that doesn't work you need to check injector pressure and spray pattern. Because it could be low fuel volume, low fuel pressure or a bad injector. This is something that you should address soon because if it is a leaky injector that could cause premature failure of your engine.

That all assumes that it is not bad compression and you need a new engine but that is pretty unlikely.

[–] Thorny_Insight@lemm.ee 1 points 1 year ago* (last edited 1 year ago)

I have replaced the fuel filter recently aswell. It seems to be running fine since I replaced the SCV but I can't say for sure yet because I haven't driven much lately. I feel like what helped the most was the new SCV aswell as the fuel system cleaner. There likely is a leaky injector because there's oil/diesel on top of the engine cover which seems to be coming from the injector closest to the firewall but I'm not sure. It's not leaking enough that you could see it while it's running. I've been meaning to clean it and see where it's coming from but I haven't gotten around to it and it has been looking like that ever since I bought it.

Another thing I noticed was oil/diesel on the clamp of the pipe that's coming from turbo and going to the intercooler as well as some inside the throttle body but not much and it looks pretty clean otherwise. I think I might try the turbo cleaning stuff from the same brand (forte) of which fuel system cleaner I used aswell. That's what the guy at the parts store recomended aswell when I got the new SCV.