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Corsa REG05 driver side water leak drastic temp solution advice please

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  • [Corsa C 2000-2006] Corsa REG05 driver side water leak drastic temp solution advice please

    Hi, any advice or direction with this conundrum much appreciated.

    In summary: Wife's Corsa 2005 Reg used mainly for the school run drop offs has developed a water leak, if it rains heavily there is an inch of water under the drivers feet, I cut the spongy bit out.

    Been to two garages both said known problem with these corsa’s where some rubber seal breaks apart water ends up in the car but not worth fixing due to the cost of the job and age of the car.

    The biggest problem is the high humidity in the car an ice sheet forms on the windscreen in the winter it takes a while to scrape off and defrost then still looks fogy.
    Could do with getting this car through the winter save up and get something decent in the summer.
    Plan of action was to drill a small hole in the floor for the water to drain away (see pic. 1 attached) however underneath the car the floor is not flat there is a bulge in the metal floor covered with aluminum sheet (see pic. 2 attached). Is there a reason why this is aluminum covered and what’s the bulge in the floor?

    Just to pre-empt I do know I need a new car, but if that was not an option just yet, should i drill the floor to get rid of the water?

    Any advice from an experienced car mechanic is much appreciated.



  • #2
    Hi Welcome to the forum.

    As the mechanics say this is a well known problem on the corsa C . The most likely cause is the gasket gasket/sealing around the brake master cylinder servo. If you google Corsa C water leak etc there are several tutorials and You tube videos on how to carry out this repair. There is no easy cure. Simply gunning or daubing silicon sealant or the like externally around the area doesnt work. The repair normally involves removing the brake cylinder and servo , labouriously cleaning off the failed gasket and sealant, fitting a new gasket, and possibly using expensive automotive sealant, then bolting things back in place. I believe its possible to do the job by moving the master cylinder without disconnecting brake lines, which saves the need to bleed the brake fluid etc, but its still quite an involved job .Take a look. It is a job a competent diy mechanic can tackle but too big a job for many. And further bad news is that even a competent repair here does not always fully cure the leak. There are other possible sources nearby.

    This is another reason why a pro may be reluctant to do the job. Customers will be irate paying a large labour bill if it still leaks a bit .

    Ideally repair the leak , especially if you intend to keep the car a while or dont want to mention the fault to a prospective buyer. But if its near its end of life anyway, and the next stop is the crusher then IMO a drain hole is an attractive option. You will not be the first to do this, and I dont believe it usually causes any problems with the MOT. After all some cars such as off roaders have no carpets anyway and are fitted with floor drain holes in in case it gets flooded in a river. But MOT's are subjective based on what the tester considers might be dangerous. For instance if a hole might allow exhaust gases to enter the car.
    Maybe having a way of plugging the hole with a rubber bung when not in use?

    The leak starts partway up the firewall, so to minimise problems with condensation etc you might need to remove carpet etc in that area too unless you can find some form of under lay that allows water to percolate down to the drain hole without getting the carpet wet ,or itself retaining moisture . If the 'cure' still leaves the floorwell area quite wet there is an increased danger of wet feet slipping on the brake pedal, and rusting. As there is at the moment.

    I cant see what the problem is with that dip area. Is it not just part of the normal panel shaping? Floor panels are stiffened by shaping ,in the same way as corrugated iron sheets. Unless its bowed because its rusted beneath the underseal.
    The aluminium plate looks like it is a heat shield protecting the floor from the exhaust system. You must avoid damaging the exhaust system or other pipes etc when drilling, but nicking or even holing the heat shield is not important.

    A drilled hole must be protected from rusting ,. Be particularly careful of drilling in areas where two floor panels overlap each other and are spot welded together. These seams are common on car bodies but are usually sealed with mastic to prevent water ingress. If you drill a hole through both sheets water can creep ibetween the two sheets, which may be unpainted .Serious structural rusting could be rapid.

    If you find you still have to mop up wetness at times,dont leave the wet sponges and cloths in the car overnight, or the extra condensation will be just as bad.

    Another possible source of the leak, or which may make the brake servo leak worse, is blocked drain holes. The front scuttle area (The area between the engine bay and the windscreen that typically houses wiper motors etc) is open to the rain/,hosing. It has large drain holes in the bottom to let this water drain away. These can get blocked with dead leaves etc and water pools,finding new routes to leak. Gives these a poke through with some stiff wire .Also make sure the small drain holes in the bottom of the car doors are not blocked.
    I dont claim to be an 'experinced mechanic, or professional. These are just my opinions. One or two of the other guys are professionals and may be horrified at the idea of drilling a hole in the floor. If you can wait a bit to see if they comment.
    Last edited by Bugman; 01-11-2019, 11:29 AM.


    • #3
      As Bugman says, it is almost certainly the seal behind the servo that has disintegrated, But it would be as well to check behind the drain flaps each side of the bulkhead.

      It is possible to remove the master cylinder without disconnecting the brake pipes BUT there is always the risk that you could kink the pipes by so doing - there is only need to move the master cylinder forward sufficiently to be able to access the servo and fit a new seal.

      I don't like the idea of drilling the floor, as it will almost certainly induce rust to start in that area, even if you paint the newly drilled hole.

      There are a couple of 'bodges' that you can try without fear doing any further damage, these will help, but not cure the problem:
      (1) Buy a tub of 'Plumber's Mate' (B&Q) - it is a non-setting putty-like substance. You could pack that around the area between the bulkhead and the rear of the brake servo, working around the servo, but leaving the underside free of the substance.
      (2) You could also cut three sides of a square in the carpet and under-felt, leaving a flap of carpet. You then need some of those high absorbancy cloths (again B&Q or Halfords) and pack some of those between the the under-felt and the floor. They need frequent wringing out or preferably, changing, but do soak up a surprising amount of water.
      (3) With regards to condensation, those crystal containers intended for domestic use are quite effective ( Wilkinson's Hardware) - But again, need frequent emptying/changing.



      • #4
        I must bow to the professional experience of Walksall regarding rust. We can both remember the time when cars could rust into shredded wheat ,seemingly almost overnight , and Vauxhalls built in the 1950's and 60's had a particularly bad reputation for this.. Factory applied priming and paint techniques and materials have improved massively since then ,but drilling a new hole breaches this high tech defence , and risky in a place that will regularly get wet. Its not a good idea unless the remaining life of the car is counted in months not years and a great deal of care put into rust prevention.

        I like Walsalls plumbers mate idea . Non setting and relatively easy to remove or re position if necessary. By pouring water on the car to simulate rain you might be able to trace where the main flow is coming from and target the plumbers mate to divert most of it away from the problem areas It will probably be most effective on the engine side rather than inside the car, but you could do both. But as Walsksall says it important to leave it unsealed at the bottom so any water that does penetrate can drain away. Better it goes into the car than affecting braking parts.

        Using floor covering and mats that are easier to remove and more tolerant to getting wet,(maybe designed for bathroom use) and high absorbancy materials for mopping up may help. IYou can buy high absorbency sponges for car washing etc that are fairly soft. But ultimate absorbency is the PVA type sponges that you get on those special floor mops that have a small tubular PVA rubber head .You only need buy a replacment head, but they are quite expensive. . But these go hard when dry and only soften up when wet.. Possibly dangerous leaving one on the floor in case it rolls and jambs under the brake pedal.
        . Years ago I bought a square sponge in this material sold for car washing. Rock hard when dry, but absorbs an amazing amount of water. I dont know if you can still get them. Ebay sells some PVA car washing sponges from China, but I dont know if they are the same .

        Dehumidifying crystals are a good idea, especially to dry out a car after the leak has been repaired. But it might work out expensive on a regular basis . And you need to keep emptying the water out or it will spill.

        You could try these techniques first before resorting to drilling. . But some folk ,both male and female, are more tolerant to regular mopping up than others. You could always make the kids get up 15 minutes earlier to mop the car out each morning . Character building

        Incidentally , I know it probably doesnt apply in your case but in cars with air conditioning dont forget A/C is also an effective dehumidifier,and useful in winter for demisting as well as summer cooling. Must admit I tend to forget this myself. It also helps prevent the system clog up from lack of use.

        Edit. I've just had a cunning plan How about using PVA gym matting on the floor. Halfords sell an interlocking set made by rolson for £10. The top face is a hard wearing surface and water resistant but underneath may just be foam and able to absorb water, or scored so it will. . You would then have a mat that serves as a floor mat, sound absorber and water absorber in one. The £10 set may be enough to make two mats , one in use and one at home drying out. You'd need to change the mat over regularly ,. Just an idea. there may reasons it wont work

        Last edited by Bugman; 02-11-2019, 08:35 AM.


        • #5
          Just a thought, but in your second photo it show a rubber bung in the floor. Remove that and see if that let's the water out .


          • #6
            It might be a bit too high. The strengthening ridges etc are carefully calculated so any attempt to make it drain by for instance some creative re profiling of the floor with a hammer may weaken the floor - and probably damage the paint anyway.
            .. If you are literally getting an inch deep of water you could possibly install a small 12v electric self priming pump ,such as an old screen washer pump, with an on off switch,. Or use the pump and trigger from an ordinary spray bottle with a lengthened inlet pipe that is dipped into the water and a discharge pipe that could be poked through one of the rubber bungs . Your car then has a bilge pump like a boat! A few pumps now and again while at the traffic lights etc might be enough to keep things relatively dry, and cut down on mopping.


            • #7
              Gentlemen thank you all for your replies and your time on this it is much appreciated, clearly you know your cars. It confirms what the garage had said and thank you all for the solutions that could help alleviate the symptoms hopefully the time gone into this thread will help others in diagnosing similar issues. As per your advice I may use absorbent non slip PVA (scored if required) mat of some sort with a box dehumidifier to keep the car as dry as possible to get it through the winter then look at sourcing another car. (Need to put few more hours in at work). The rubber bung is too high all the water collects in the two dips, some other genius solutions suggested I like the one with the kids building character and could not agree more but trying to get 5 and 7 year old to do anything is a nightmare I wont be trying to sell this car on as a usable car as that would not be right, maybe sell it to a scrapyard for parts or just scrap it. Wife has always driven Corsa's this is the first one that has developed this type of leak, is this the case of just being unlucky? If I get another Corsa maybe 4 years old so we get value for money what are the chances of the new Corsa developing the same fault, or is this something that has been identified and fixed in later models? Thanks again. D


              • #8
                Hi. If the rubber bung is to high up along. Then I would drill two holes up from underneath, to make sure you miss the two fuel lines that run along underneath there. If your next corsa is going to be a corsa D ,then yes it's a different model and no leaks from the bulkhead into the car. But what I Advise is to purchase the 1.4 . As Vauxhall have use the same engines in the corsa C and D . But the D is a lot heavier and struggles on hills to pick up. In the 1.2 Engines.


                • #9
                  Thanks for the reply.

                  As far as I am aware, this rainwater leak only happened on the Corsa 'C' - On the drivers side it was normally down to the brake servo seal failing, and on the passenger side, water was known to leak in from the Body Control Module (BCM) - the black box to the left of the battery (right of battery if you are looking at it from under the bonnet).
                  Later models did not have this problem.



                  • #10
                    Like many so called common faults many owners wont have any problem . Problems get coverage, years of reliable service dont. And most makes and models of car have something or other that is their particular 'common fault'.

                    I tend to write at length, because as you say it may help someone, if not you. Lots of people search the site for ideas even if they dont register and post. But it does bore some

                    As for the kids they are small enough you can threaten to send them up chimneys. Dress em up in neoprene wet suits and get them to roll around on the floor. They'll love it ..