My mechanic proposes that we remove the windscreen to take a good look down under. Prior to that we would try to simulate the leak by pouring water and see how water finds ways into the cabin. If it were the rubber tubes inside the side panels then it will be a lot more work, and I might wait till the car goes for body or paint work.

 

Have a quick look as I've looked at dozens. Remove the windscreen wiper panel that goes from side to side. The dirt and mud collects here, but as the flat panel disappears under the wing corners is where the rot starts and perforates that seam where it meets the firewall. I've looked at many where that corner has almost vanished and can be pushed through by fingers.

 

More updates. Water leak is still causing repeated ECU damage. It has been a pain trying to clean and fix the ECU connectors physically. The copper pins and receptacles are very fragile after corrosion-fix-and corrosion, detachment and and re-attachment of the connector buckles. My mechanic managed to fix the ill-fated ECUs, but they seem to have the same permanent damage now - cylinder #6 is not firing any more, and idling can sometimes rise and stay at 1300-1400 rpm.

I am on my third ECU now, including two remapped by Andy. So a permanent fix is to find and stop leak and seek permanent protection and water-proofing of the ECU, possibly through relocation and a permanent wrap. It is difficult to find a spare ECU harness to make an extension cable. There are far too many different versions out there from SC and NA models, and it would be a very tedious job to match 64 wires.

The mechanic has now found the cause of the leak. It turned out that Rose's windscreen was replaced many years ago and the people reinstalling the windscreen unwisely or accidentally sealed the drainage holes on the bottom of the windscreen that meets the leveling metal sheet. As water cannot escape through the designed drainage passage, water stays or flows sideways, and causes corrosion and then holes unseen from the top. Hence only removing the windscreen first can one see what and where needs fixing. I would also try to remove the side panels to check on the rubber tubes as shown in post #17 above.

 

There may be a way of extending the length of the 2 wire bundles and instead of making what is called a service loop as a full circle you make a U shape before going into the top connectors .

To turn the ECU upside down so the leak on the wires would have to climb does not seam possible but then maybe it can .

This would eliminate the need to resolve the source of the leak .

PM me on a tool I made up to make soldering the extensions easier in the cramped space I used it as i cut out and eliminated a broken RS3 connector down in that corner .. The repair worked for that connector .

Had a picture somewhere

 

More update here. Rose survived Typhoon Mangkurt which has delayed the stop-leak operation. The mechanic has, after many rounds of trial and error, managed to get Cylinder 6 back to working order. A moment before that, with the engine running, all lights on the dashboard stayed lit up. After replacing many copper pins in the engine ECU connectors, only the seat belt warning and Airbag lights remain, and engine fires up easily, idles at 800 rpm but when stepping on the gas pedal, idling would go up to 1400 - 1600 rpm and stays there. Clearly the ECU is acting up but at least car starts fine. My primary concern is that this and past two ECUs were custom-made by Andy to bypass the immobilizer. How many ECUs would Rose chew up to stay alive?

 

Hello and greetings from the XJ40 forum!

The 40 and the 300 have (basically) the same body shell so both have similar "leaking issues" - My own '94 XJ40 had a similarly annoying leak in the footwell area which took quite a while to sort out, I too went through the usual advice route of checking blocked drains etc etc, and of course nothing cured it.

The leak that runs along the wiring harness is due to a design flaw in the manufacture of the body shell drainage channels.

Eventually I did cure the leak and the cure was fiendishly simple! Check out this thread from post 16 on

https://www.jaguarforums.com/forum/x...5/#post1600179

 

Excellent stuff! I shall ask the body shop technician to have a good read of the thread and the pictures to trace the source of the leak and tackle the problem spots.

 

Updates: Before embarking on a more intrusive method of removing the windscreen and fenders to check on water ingress locations, a buddy suggested investigating drainage blockage first. We tried to simulate heavy rain by pouring water around the windscreen including the water collection louvers under the wiper motor. Water was found escaping quickly down under the firewall in the form of waterfall which seemed normal. No sign of water ingress in the cabin. We then found a water drainage pipe outlet on each side of the front wheel above the mud flap (see picture).



We believed that spraying air-conditioner cleaner foam (cheap stuff available from most home repair shops) into these two drainage pipes using a flexible plastic tube that comes with the cleaner foam bottle might free up any blockage along the way, as the cleaner foam would dissolve the dirt that might exist inside c.f. endoscopy from below. The cleaner foam would travel up through the drainage pipe and would present itself in white bubbling liquid in visible areas. The solution also has some special odour so you can smell it where it leaks.

During the process, the left side of the drainage pipe was obviously free of blockage, as the flexible tube entered and travelled freely upwards. The right side, i.e. my driver side, where the engine ECU sits, was the problem spot. The flexible tube could only travel a few inches from below the drainage pipe and was stuck. After using some force the flexible tube appeared to have freed up the drainage pipe and spraying the cleaner foam quickly saw dirt flowing down. We sprayed the cleaner foam generously through the drainage pipes and saw white foam appearing in the louver below the windscreen (see picture).



We also saw a couple of cracks and little holes in the firewall, clearly indicating that these are the areas of possible water ingress. We then used a water jet to simulate heavy rain from above. Water escaped from the left side of the drainage pipe freely. Much less so in the form of a little stream from the right side. We then used water jet to send water inside the drainage pipe and the result was the same, water escaped freely from the drainage pipe on the left side; far less so from the right side, indicating that there was blockage mid-way. It was at this time that we found water dripping inside the foot well right above the foot pedals. Jetting more water from below would aggravate the leak and drip.

We tried to identify the ball-shape object where water flew downwards and it is the air-conditioner heater blower motor duct and assembly (see short video clip at the end of this message showing water dripping from the heater blower). Also see that a metal clip under the blower near the ECU is rusty, clearly showing prolonged contact with water.



Our initial conclusion is that the drainage passage on the right side is heavily blocked, and water table inside rises during heavy rain and find ways into the cabin through the fresh air air duct that supplies fresh air to the driver's foot well. Prolonged water exposure and moisture have been causing rust under the dashboard. I now see why I have a history of rusty Body Processing Module on the left, the radio unit at the centre, and corroded engine ECUs and connectors on the right. A solution is to remove the dirt made up of leaves, sand, etc. from the catch water area of the drainage pipe, but the steering column and the very cramped position down under the driver foot well are not easy to work round. So a suggestion is to cut open from above the engine bay and remove the right fender to gain a good view and easy access to the problem spots. The search continues....

 

Unless I'm mistaken, those two drainage tubes are the sunroof drains - not sure why they would drain if you poured water on the windshield?

Anyway, keep at it!

Larry

 

My XJR does not have a sunroof, but I imagine that there must be a passage way for any water coming from the car top to pass, and hence an X300 with or without the sunroof would have the same drainage valley, so to speak. I presume the rubber seal around the windscreen is not 100% waterproof, and the louvers under the windscreen near the wiper motor collects some of the rain water running down the windscreen, but when the car is in motion most water runs to the sides and would need a fast pass to the ground - imagine a downpour and how water flows from the car surface. It would help if there is a drainage diagram so we know how the drainage system works on the X300. However, one easy precaution is to regularly free the drainage pipes of obstacles by poking from below the pipe outlet. Nevertheless, I guess mine would not be a problem in most parts of the world. Here in Hong Kong we have downpours and storms during summer and if you happen to park outdoor with trees nearby you can imagine the car collecting all sorts of dirt, which would accumulate and build up in invisible and not easily accessible areas. Rose had a dark history of sitting outdoor for almost three years outside a workshop while waiting for solution to a no-start problem. Fortunately, I pulled her out and found another mechanic to identify the problems. The problems are: a badly corroded ECU, fuel tank and fuel rails filled with water, engine jammed with surface rust, and failed electrical connection as a harness crossing the trunk and the cabin had a broken buckle due to an earlier attempt to remove the fuel tank.

 

Just saw this thread entitled X300 ventilator, water drain?, and believe that rain water finds way into the cabin through the fresh air system. Am wondering how to gain access to locate and clear up the blockage.

 

My car does have a sunroof, and I have two drainage tubes exiting into the front wheel well each side, one of which I assume relates to the sunroof, and the other the scuttle drain?

 

Dear All,

Although Rose has been largely fine in the past six months despite the rainy days in Hong Kong, my mechanic and I have yet to find out what caused the water leak into the cabin that destroyed the ECU, twice in the last two years. Two days ago, my mechanic finally found someone with the tools to cut open the horizontal panel in front of the windscreen (RHD driver side). I shall let the pictures explain themselves.






The car has no surface rust anywhere.......except in the hidden places and above the ECU. It is so bad that we are now scratching our heads what to do. Any ideas? Unless we ingeniously restore the water basin to channel water to the proper drains, it is going to get worse.