Another 1HD-T engine noise thread - '91 (1 Viewer)

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My apologies for this post in advance, I know there is lots of threads about similar things already but I'm kind of losing my mind a little here and need some direct feedback. I started hearing a tapping/knocking sound at idle in my 1HD-T. I cannot tell if it's normal or if it has always been there. I'm hoping that if I share these recordings someone might be able to say if it's worth investigating and what are some good first steps for me. This is not the random ticking that most report (I actually don't have that sound), it is in sync with the rpm and is a high pitched clicking that's sort of subtle. Sounds to be most present on the exhaust side and perhaps coming from the somewhere near the back of the head. It is actually less present if I record from underneath so I'm not thinking it's bottom end related... I have listened to earlier recordings I made of the idle and I can kind of tell it's there but maybe not as present. As well, other recordings I have found online of healthy motors kind of have a hint of this noise but it's difficult to tell. I have found recordings of piston slap, spun bearings, failed cranks shafts etc. and there is a similarity but this is obviously far more subtle, wondering if I'm hearing early signs of something failing. It has almost 200k kms at this point and this year there are replaced bebs, installed brand new injectors, new timing belt/tensioner, and adjusted the valves. There are no symptoms of anything wrong, oil pressure is normal/consistent (~30psi idle, ~70psi @2500rpm), no rough idle, no smoke, no performance issues.

Edit: engine temp does not cause any change in the sound.


 
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IanB

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Does your injection pump still have the ACSD intact, or has it been deleted already? I found my pump quieted down once that was removed.

From your video's, it sounds pretty normal for these engines IMO. These engines use mechanical injectors, and they are a bit noisy as they open and close.
 
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I have chased down so many noises in my 1HD-T and based on your videos, I've got to say that I don't believe you've got anything to worry about. As IanB said, ACSD removal might quiet your pump down, though it hardly made any change for me.

When you rebuilt your injectors, did you replace the copper washers? If not, then its possible your injectors are making a little extra noise - it happened to me. Of course, this isn't critical and isn't going to blow your engine up imminently.
 
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Thanks for the responses. The ACSD has been deleted, it actually arrived to me that way so it was done sometime in the past. As for the injectors, I didn't have them rebuilt but opted to spend the dough on new ones from toyota to get a baseline. I replaced the copper washers in the head and on the return fuel rail. I'm not ruling out the fuel system though since the sound is coming from quite high up on the head. I'm not sure if a slight pump timing issue could cause a sound like this without some other symptoms as well. I also noticed that the sound is louder if I remove the oil cap, so possibly it's coming from a valve?

I can rest a little easier hearing that it doesn't sound particularly odd, but I'm just going with a plan of attack of simple things before driving it regularly again.

1. change oil and see if the sound changes
2. get an oil analysis
3. check torque on injector clamps
4. check torque on exhaust manifold (possibly a leak is causing valves on one cylinder to be extra loud)
5. check valve clearances and look for cam damage

Of course checking the timing of the pump would be good to do as well but want to do the free stuff first - I don't have the tools for checking the timing properly.

I'll report back, thanks again.
 
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Little update here, my steps above revealed nothing so I went out and got a stethoscope to thoroughly go over the engine while it was running. The same tapping sound is very audible when held to the injectors, no noticable variance between them. The only thing that has changed is I ran out of liquimoly diesel additive and haven't put any in the tank for the last 3-4 fill-ups. I have put this in every tank since I've been running the engine in early 2020. My theory at this point is that the injectors gradually got louder while doing miles on untreated fuel. I would not expect such a change so quickly but I'm not afraid to drive it at this point. I'm going to try treating the fuel again to see if it quites down to the sound I had been used to... I think maybe I'm just being a little ocd. Thanks for the help regardless.
 

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