Hijet e85 2003 noise with increasing interval (but only with gas pedal pressed) puzzles me

This early spring i got my hijet e85 out of 2003 running again, i bought this one last year. Previous owner did major work on the engine judging on the new bolts in the engine. Last week I've been cleaning it a bit, stripped the inside because of molt, remove all kind of accessories (led, boxes) and wires running everywhere from previous owners. Stripped the entire back area of things bolted or glued on.

One thing that worries me a bit is the ticking / slipping noise i get while driving this great van.

Let me describe the noise:
* the noise only lasts one or two minutes, and happens frequently, about 3, 4 times on a 15 minute drive.
* it starts with a slow slipping / ticking noise, next the interval increases until it is one continues noise, then (sometimes) a tiny tick sound can be heard and it stops and sometimes i play with the gas and it stops.
* the noise can only be hear when gas pedal is pressed
* when i release gas pedal noise immediately stops (pressing gas again the noise is back with the same interval as before)
* when i engage the clutch pedal the noise immediately stops (releasing clutch and the noise is back with the same interval as before)
* when having the continues noise i can down/up shift and the noise stops being continues and start slow again.
* the noise is unrelated how fast/slow the engine is running.
* although the interval of the noise tend to increase when the gas pedal is pressed (most noticeable on lower gears), but there is not direct relation.
* driving on a very bumpy road sometimes stops the noise (although this might be a coincidence, not many bumpy roads here)
* it happens in all gears at all speeds
* it doesn't seem to do any harm (been driving every day for 2 weeks)

This one really puzzles me, can anybody offer a helping hand / brain ?

Cheers for any insights you might have!

That souns to me like it could be the propshaft

Cheers buttondup for the reply.

Is there a way i can confirm (by looking or wiggling it or doing something else) that it is the propshaft?

Thanks for the help, i'm going to do a bit research on propshafts.

The universal joint on mine has failed three times, the original, a replacement I got from a breaker and a new one that failed after a year. I think that was because the balance weight had come off.
See if there is any play in the joint by trying to move the propshaft from it's axis of rotation.

my vehicle is 2003 too. And if looking for a replacement bear in mind the van and pickup propshafts are different lengths. Woodie would probably know how they differ exactly.

Thanks buttondup!
I will take a dive and good look and wiggle below the van if the weather clears up a bit.

I think I could perceive the sound you are referring to in the period leading up to the propshaft's failure. Don't be too worried about the noise yet as the truck would vibrate like crazy around 20-30mph as the joint failed more and I drove it around like this for a fair while!

Good to know there is another stage between the noise and parts flying against the windshield of the driver behind me

In the meantime i will do more research and start looking out for replacement parts or other solutions.

Cheers for the help!

Contact Daihatsu - re recalls. After I had changed my prop shaft I discovered that for some models prop-shaft is on a recall.
BTW mine started clanking on the way to Scotland - we went over 2000 miles over mountains etc before fixing it!
Jon