4.0 Liter sewing machine

[votan]

After pushing my Tuscan over the highway for a while and then going back into city traffic again, the car sometimes makes this super loud engine-ticking. Sounds like a giant sewing machine. Seems like it only happens when engine/oil is above 90 degrees and driving faster for a while and then going back to normal.
when I stop the car and wait for like 10 minutes, the noise is gone again. Unfortunately, due to the fixed main bonnet I could never get to the noise directly, as it was always gone again, when I reached the inside of the engine bay.
My first thought was, that the oil I use just get's to thin when hot.. and does not reach the top-end anymore after pushing the engine for a while and going back to slower driving then.... but pressure seems to be always fine (even though, I have to admit that I still use the original 1 pole pressure sensor, that, regarding to another thread, tends to send higher values anyway!?.. but even with lower values, pressure should be fine... Oil is 5W40.
Other things might be problems with the air-con clutch, as others reported loud ticking noises coming from it.... but wouldn't this sound then come constantly?

Any suggestions are welcome, where to look.... before I try to exchange oil to 10w40...
Engine got rebuilt 2 years ago and the previous owner said I should use 5w40. But maybe going up to 10w40 could solve the problem???
.... already tightened the timingchain.. so that can't produce that noise anymore.
Going to a TVR specialist is also kind of useless... as there is no one near.. .and the magic ticking tends to disappear as soon as someone is getting close to the engine bay.

[so called]

Hi Votan, where abouts in Germany are you.
I would have thought that if it was a valve / tappets problem then it wouldnt go away like you say.
Have you tried calling TVR Power in the UK ? They may be able to offer you some advise over the phone.
Sorry not more help.
Tony.

[blueg33]

This probably won't help much. But I find these engines to be inherently noisy so don't worry anymore. I have taken it to Dom a few times to be told all is well.

I use 10w40 semi synthetic oil as recommended by TVR Power. If anything mine is quieter when hot especially over 2000 rpm.

[glow worm]

The various chains can make them sound bad... two can be tightened relatively easily (so I am told) but others require engine out job..there is also a new chain guide which I'm hoping will solve my rattley engine early in the New Year.

[votan]

These engines are really magical! Tried to reproduce this nasty ticking for two days now, without any luck. I'll investigate the airco clutch again.... This ticking really sounded like the engine is going to explode.. don't think anymore, that it is a chain problem.
I really start to enjoy all these problems.... there is everyday a new "little" problem, that needs attention... and everytime you think that it is fixed for good, it reappers again! But this ensures nonstop fun with the car! But what is best... most Problems always cure themselve after some days or some bumps!
@so called: I live in north rhine westfalia near the dutch border... and just discover a dutch TVR specialist that I will consult next week (tvr.nl)... maybe someone has some more info about these guys??