4FG1 black smoke and noisy clatter

[TinyRVliving]

Hello!

My wife and I finally took hold of our Isuzu Fargo camper about a month ago after it spent some time at the mechanic. 2.4L 4FG1 non-turbo engine. 5-speed. 154,000km.

We took it on 300km round trip yesterday to see how it traveled at higher speeds and for long periods of time.

A few things to consider:

1. The engine is noisy as all get out! It sounds very clattery at higher RPMs. Just super loud in general. It is a cab-over design so I realize we're right over the engine. But man, at around 60mph it's quite deafening. I was wearing ear plugs!!

2. Valve clearances were checked and effectively spot on, if a little tight (by a few 10ths of a millimeter).

3. At about half throttle and deeper, it's emitting black smoke. Full throttle makes me feel like those folk who roll coal (okay, it's not THAT much smoke). I get it...old diesel without a turbo! But I think something can be done? And maybe it suggests my fuel efficiency isn't so good. I don't see white smoke, and it doesn't appear to be burning oil.

4. I had the timing belt, pulleys, water pump, and front seals done within the last month.

5. I just changed the oil with 10-30W T5, and the air filter is new.

6. I think we got a little over 20mpg (8.5km/l) on the drive, doing about 100km/h (at a really high RPM I think...).

7. Fuel filter is probably needing a change. I haven't done it yet. Too scared of cracking old plastics haha!.d

My questions:

1. Where on the injection pump is this "smoke screw" I've heard of. Or what else can I tweak to try to reduce smoke. I know it's a bit of a black hole when dealing with fuel screws. If there's a specific screw, what direction to turn, and how much should I tweak it each time to experiment? Can I do it while the engine is running?

2. Thoughts on the clattery noise? I don't think it's like a loose accessory or something else. It sounds like valve train noise. Again, my mechanic who only does diesels re-did the timing from scratch and confirmed valve clearance at TDC to make sure nothing was impacting the valves. So...he "gets" it, you know? Is this just a loud engine? I might take it back to him to give it a once over.

3. I can barely do 100km on flat without redlining/almost full throttle. More like 80km/h. It's asking a lot. This vehicle probably weights 5-6000lb though. I guess that's something to just accept?

Here's a pic for your troubles!

IMG_20200614_120938926_HDR.jpg

[TinyRVliving]

I made a video of the engine at cold start. An Isuzu Fargo enthusiast I know suggested it was noisy tappets. How can that be addressed? Valve clearance? I know the clearances were good (if a little tight, by 0.5mm) according to my mechanic.

https://www.youtube.com/watch?v=WJkqCPaPsOU

[pig75]

That sounds normal to me

[geeves]

Diesel knock is meant to sound like that. Its normal