How can i get wire from engine to inside car ?

[gwest]

Yes it is the same as the Haydn alarm, marketed in Australia under the Enginesaver brand. Because it just uses a single stainless steel screw as the probe for the sensor, I doubt that the Peugeot tanks fitted with coolant alarms would be suitable but I don't know how the PSA sensors actually work. The Bongo kits used in the UK use a self-tapper s/steel screw and apparently don't suffer any leakage. My kit that came from one of my previous vehicles has no screw- it used a different type of probe inserted through a rubber bung into the radiator.
However, I now find from perusing the internet that there are self-tappers designed specifically for use with plastic that differ in subtle ways to standard self-tappers and that there are thread-forming and thread cutting types, some of which strip the thread during disassembly! But these are designed to join things, not penetrate a fluid filled plastic container!
I have experimented using a ~3mm fine-thread bolt that I screwed into a hole drilled in the circular recess on a reject tank- it leaks from cracks around the midline. Fitted to the car ithe screw did not leak with the engine cold but the test will come when I take the car for a drive. Anticipating problems I will ask a plastic welder if they thought an extra blob of polypropylene where the screw emerges from the tank might help (the tank has PP as part of the part numbers). At this stage of course there is no alarm to warn me if things go badly wrong- I am still pondering where to breach the bulkhead.
Which of course brings me back to my gripe about why car engines are not fitted with coolant loss alarms as standard! I still grieve over cooking the engine on a Mitsubishi Colt in 1971!

[wheeler]

The Bongo kits used in the UK use a self-tapper s/steel screw and apparently don't suffer any leakage.

Mines hasn't leaked in over 7 years I've had it, I've removed & refitted it a few times as well to clean the threads with no problems.

[gwest]

Well I installed the 4mm metric bolt into the expansion tank and I look to have a very slight leak. I will see if it settles down and if not get some PP welded around the exit. With regard to the wiring access I had a look at the bonnet opening cable grommet but while accessible from inside the car, the exit in the engine compartment was obscured by the brake servo tank. On my 2007 Peugeot 207CC there is an alarm fitted under the bonnet, that has wires running inside the LHS front fender and into the cabin through the door wiring grommet. It looks like an afterthought because the grommet has been unseated both on the outside and inside surfaces. This provided a relatively simple way of getting the wiring into the cabin. From the expansion tank I ran the wire inside the scuttle for most of its length before exiting near the alarm on the LHS of the scuttle.

[Paul-R]

Have you looked for and discarded the idea of a blanking plug for the clutch cable? There was a post in another thread showing what was identified as a blanking plug for a clutch cable. Don't know what car that was on though.

[gwest]

Under the dash I only proceeded as far as removing the glovebox, which revealed the grommet for the bonnet release. I did not have the fortitude to contemplate removing the centre console.

[white exec]

When trying to run an extra cable through bulkhead/firewall existing grommets (bonnet release, old-type speedo, clutch cable, throttle, wiring grommets, blanking one...), once you have found a likely candidate, it's likely that
(a) the existing grommet will be a tight fit around its contents
(b) the grommet may be of extended length/double, to pass through a double-skinned firewall.

If there looks to be room for the extra cable(s), try carefully pushing a long, thin BUT BLUNT/UNSHARP END screwdriver into the rubber, to see if there could be a way through. Important to NOT use anything with a sharp end if there is already wiring (or a fluid hose) there.

You may have to use a bit of force - most of these bulkhead grommets are quite thick - a twisting action, and perhaps some oil or grease on the shaft. You may also have to try from either engine bay side or the footwell.

After succeeding in getting the screwdriver blade to go through and protrude, clean off the shaft back to dry metal, and sellotape tightly on the stripped strands of the end of a length of cable (say 1.5mm²). Strip back and tape on at least 4-5cm length, tape would tightly. Then grease the tape (or silicone spray), and withdraw the screwdriver, to pull the cable through.

This provides a temporary threader (mouse) for you to use to pull your final cable(s) through. Again, spray the cable bunch to reduce friction. Cable ends can be stripped, twisted together, doubled backwards, and sellotaped/sprayed. Sellotape is preferred as it is thin, and will not ride up and snag like insulating or gaffa tape.

[Wookey]

There are normally spare ways you can use in the bulkhead connector. It's very laborious to get to both side of this, work out if any ways have unused crimps fitted both sides, or source spares, and in the case of mine, dig out the rubbery goop they filled the spare slots with. But this is the 'right', waterproof, fireproof, extensible, reversible way to add cables. I got hold of a spare one from the scrappy which supplied lots of spare ways, then a blank can be dug out and new wires put in there.
This is not a quick and easy option. These connectors tend to be quite buried behind the dash.
I guess if you have the very top model then there may not be any spare ways...