j0nathan

I've had a GS450h for about 6 years and it has developed a tapping from the engine when pulling on a incline at around 10 to 35mph.
The problem is growing worse over the last 6 months.
It seems to disappear above 40mph, perhaps because of extraneous noise levels.
It is almost metronomic in its frequency and its definitely audible to my ears.
It happens mostly on short runs but also sometimes when the engine is fully warmed up after a longish run.
I have taken up the problem with Lexus/Snows of Plymouth.
They have had the car in for diagnostics twice, once overnight so that they can experience it with a cold engine.
They claim there is nothing wrong and that they can hear nothing.
So, either I have very acute hearing -- or they are hard of hearing…
The car is still under Lexus warranty until July 2017 but I feel I should get rid of it quickly.
Any suggestions?