Where are the timing marks on renault express van?

There are no external timing marks. Timing is not adjustable. The computer controls the timing of your engine.

Every engine has a method for aligning the cam-to-crank for installing timing belts/chains.
On a dual-Camshaft Renault there will be a mark on each of the camshaft pulleys - the camshaft marks should be aligned with each other while the mark on the crank should point to a corresponding mark (arrow) on the engine block when the belt is installed.
I did a quick search for "renault timing belt marks" which produced a multitude of images and examples. One of those should be a close match for your engine. Good Luck !.

sounds like an ignition switch problem sometimes key is making contact to start and not other times

sounds like your key ignition switch is either falling apart or is worn out

The fuse should be tuked up under the dash on the drivers side fuse panel. marked cig or pw+

Has your Check Engine or Service Engine Soon light come on? If so, there is a code stored in your van's onboard computer. Have that code read and interpreted at any large auto parts store, and either arrange to have the problem repaired or repost with the code number. If no code is present, we have a whole new ball game.

renault express diesel ,not a difficult job to do but dirty and time consuming then it depends if the head is any good and not suffering from water port corrosion caused by no antifreeze head gasket set complete about 70 euros trade price plus labour plus 30 euros for a skim trade price plus the VAT and retail prices for the parts so yes around the 400 mark is a good estimate

If this is with the 3.0 V6; each cam sprocket will have a small dimple on it, these align with marks (small lines) pressed in to the dust shield.

I hope this may have assited you,
Tom

on the crank shaft

EASY ENOUGH JOB JUST MAKE NOTE OF TMING MARKS