10100 miles..runs and starts great but ticking sound coming from top middle of head.thought it was a hvl so i changed them all and it still ticks at idle and when reving up till about 3000 rpm.im thinking broken spring???can i charge cyl with air and take off springs as ive done on gas cars?it performs well but i cant have the noise it drives me nuts..

 

I have read of using Filtered Compressed Air in the Cylinders (you could use one of the adapters from a compression test set) used to hold the Valves up when changing broken Valve Springs (I do not think this is your problem). Also the Piston Needs to be at Top Dead Center (all the way up).
With the Piston in this position the Valves could not go down very far anyway as there is very little space between the Valves and the Piston Head.

Go to this site and take a look at the one that has a similare Engine. I believe you will find you have Hydraulic Valve Lifters.
Hydraulic Valve Lifter Ticking is common in all cars that use them when they get older due to internal parts sticking or worn.
Ticking can also be caused by low Oil pressure.
They can be replaced or I have read using Synthetic Oils can sometimes seal/free them up.

You might do a search and see if other members using Synthetic Oil have had sccuess with the above.
Here is the site.
Look through the site until you find "Checking hydraulic valve clearance compensating elements" the Hydraulic Lifters.

http://www.ps2cho.net/downloads/MB%20CD/W124/Main.html

 

all lifters are new and tic is in same area.

 

Sorry, I missed the "so I have changed them all".

Have you listened around with a Mechanics Stethoscope and try to pinpoint exactly where the sound is commng from.

In the Old Days before a lot of Engines had Overhead Cams you could remove the Valve Cover and go down the line resting you a finger on the Rocker arms and feel which Lifter/Rocker Arm was causing the problem.
Unfortunately you could get an Oil Bath if you try that with and Over Head Cam Engine.

Again on Older Cars if the Bore the Hydraulic Lifter rode in was worn out and passed too much Oil by it or had a restricted Oil Flow the Lifter would not get enough Oil and would tick.
One of the symptoms was the were not noisy when the Engine was Cold but got noisey when the Oil got hot and thinner.

 

i remember those days im 52...so i figure its a spring.its the 4th valve back .cant hear it with window up,its real annoying when i stand outside car. and will fail sooner or later so im gonna fix it before it fails.i put 600 miles on it and it has not changed.same place with old lifters.i got the car with a bad tranny.i hope to receive ideas from more of you guys.