New battery - but why is bay full of water?

[Rory]

The inevitable happened to today – got into my car to go and buy a Christmas tree and it wouldn’t start! I don’t know – is 14yrs too soon for a battery to capitulate?

AA replaced it with a Bosch one of the same massive size and capacity.

Somewhat alarming thing discovered was the battery bay had several inches of what looked like pretty fresh water in it. Patrolman kindly took out the tray but neither of us could see how it should drain. He found a small grommet on poked that out and it seemed to do the trick. While he was fetching the battery I discovered the scuttle drain tube was out of place so assumed this has caused the water to get there in the first place – however the patrolman thought it likely he’d displaced it while heaving the battery out.

 

[Rory]

Just to follow up on this, took the car for a 30 mile trip last night and had a look at the battery bay this morning and it's bone dry in there. Perhaps it was just the very heavy rain we had a few days ago that caused it to fill up? Still wish we'd found the proper drain while he had battery and its tray out but I'll keep an eye on it.

 

[optimusprime]

Rory can i ask where on your car is rthe battery located ?

 

[John]

I am assuming it is in the engine bay as it was sat on a tray and a grommet could be punctured to let the water out.

I'd check all the drain holes etc. are clear around the windscreen etc.

Maybe the patrolman did not dislodge that drain tube and it was wrong.

A few times now over my last few cars I've had to re-fit rubbers round certain parts of engine bays etc. as they have been dislodged or taken off and not replaced correctly.

 

[optimusprime]

If the battery is under the bonnet drivers side or passengers side do check that all the grommets are in place if missing , then water will get in to the footwell on that side.

 

[Rory]

Battery is under the bonnet against the bulkhead on the passenger (UK) side. Here's a random picture I found which shows the pollen filter housing doubling up as a drip cover for the battery:

That whole area had several inches of water just stting there. The scuttle drain tube, which you can just see in the corner of the engine bay, had become dislodged. I can't think of any reason whay that would have happened so likely the patrolman was correct and he'd moved it.

Bit more research shows that tube, and the battery vent pipe, go under the battery tray and out through what looks like a combined large grommet which should have a hefty looking drain - but that wasn't apparent yesterday.

I'll keep any eye on it but really don't fancy removing the battery - it's apparently fraught with issues on this model although it appears to have gone fine this time. The only thing I had to do was reset the windows - I was bemused that the time corrected itself, it never does with the hour change. As well as that, the battery was a very tight fit - the AA man really struggled to get it in.

 

[optimusprime]

Rory do think about removing it again in the future . These batteries hide all sins if left for a long time and as you found water in there it can show up in there again . So remove the battery later on some time and treat the tray and the area in there with cavity wax ...no one will see it and the wax will be doing a good job ..

 

[Rory]

I am thinking about it...and I'm thinking if it needs to come out again I'll get the indie I use to do it! I've been "off the tools" for so long I'll hurt myself or break something - quite possibly both. He was a big (strong) bloke and it took him several attempts to get the battery in, and that was me pulling wiring and trim out the way too. I'm annoyed with myself that I didn't think to get him to leave the tray out while he went for the battery, but at that stage I didn't know there was supposed to be a drain, and the small grommet he'd poked through seemed to do the job.

I did all look remarkably clean in there which is why I originally thought the scuttle drain coming off and dumping recent rain in there made sense, but I'm doubtful about that now. However is seems odd that that compartment would see much water at all - I guess it could come in off the wing / bonnet channel if you were driving in rain? If it was always wet in there then the cabin air intake would be pulling in wet air.

 

[optimusprime]

Rory my car is older than yours . And on replacing the battery a few years ago i cleaned out,, and re painted the battery tray. And i to was amazed at the water inside just siting there in the groves .I think that mb know when the car moves that all the water gets out one way or another. I cleaned it out of old leaves and such .And gave it a good coat of waxoyl .But double check to see if the butch fitter removed a grommet to let water drain in to drivers footwell .

 

[Rory]

I think that mb know when the car moves that all the water gets out one way or another.

Thanks for your interest in this - I did wonder if the water somehow drains when the car moves, although that would be pretty poor if the car was stood for a while.

I gave it another looking at this morning - something else I missed previously is the bonnet vent just lets water fall straight through onto the battery cover, and the same on the other side where there's a similar cover. So that area (on both sides) is going to get a fair bit of water going through it. On that basis, the battery bay looked remarkable clean. Today (after pretty hefty rain over the last 24hrs) the area looks damp, nothing more. You can't even see into the base of the bay on the other side of the bonnet.

The grommet he pushed through was at the corner towards the front of the car and engine, and looking at it, would still come out under the wing.

 

[Hougrel]

I have exactly the same problem that is described here and the problem never seemed to be adequately resolved. It is obvious that water can get in there but the compartment containing the battery tray has no obviously designed drain for it to get out..

 

[W1ghty]

I have exactly the same problem that is described here and the problem never seemed to be adequately resolved. It is obvious that water can get in there but the compartment containing the battery tray has no obviously designed drain for it to get out..

There should be a hole visible when the battery is removed (if it’s not visible with the battery in situ )

 

[Hougrel]

There should be a hole visible when the battery is removed (if it’s not visible with the battery in situ )

I agree there should be a drain hole visible - but I cant see it, the original poster couldnt see it, the AA man cant see it, my petrol head friends cant see it. That is not only with the battery removed but with the battery tray removed too. We have poked in corners with a wire coat hanger probe. Thank you for posting but it needs someone very familiar with this particular model who can describe where that hole is - that is if it exists - but I cannot believe someone would design the battery to be standing in a 1" pool of rainwater.

 

[Hougrel]

I agree there should be a drain hole visible - but I cant see it, the original poster couldnt see it, the AA man cant see it, my petrol head friends cant see it. That is not only with the battery removed but with the battery tray removed too. We have poked in corners with a wire coat hanger probe. Thank you for posting but it needs someone very familiar with this particular model who can describe where that hole is - that is if it exists - but I cannot believe someone would design the battery to be standing in a 1" pool of rainwater.

MB C Class 2004 Saloon

 

[Rory]

I have exactly the same problem that is described here and the problem never seemed to be adequately resolved. It is obvious that water can get in there but the compartment containing the battery tray has no obviously designed drain for it to get out..

There's a chunky drain under the battery tray (tray comes out easily), on the nearside of the car. The battery vent tube goes through the same grommet. I had a drawing of it - let me have hunt.

 

[markjay]

Can you not drill a hole and paint it over? As long as it's not above any electrical components.

That said, I had a 2006 W203 for 9 years... and never had water ingress to into the battery tray. Can you check how the water is getting in? There's the cabin air intake and pollen filter housing on top of the battery, and behind the battery there are two hoses that drain water from the scuttle.

 

[W1ghty]

I agree there should be a drain hole visible - but I cant see it, the original poster couldnt see it, the AA man cant see it, my petrol head friends cant see it. That is not only with the battery removed but with the battery tray removed too. We have poked in corners with a wire coat hanger probe. Thank you for posting but it needs someone very familiar with this particular model who can describe where that hole is - that is if it exists - but I cannot believe someone would design the battery to be standing in a 1" pool of rainwater.

Weird , I only said what I did , because my C class platform CLK had a drain when I changed the battery and cleaned up that area with water last year

 

[Rory]

This is what I was thinking of - opposite way around for RHD. Battery Vent Tube

 

[Hougrel]

Thank you every one for your helpful advice and photos. I'll take a look again tomorrow in daylight and report back.

 

[Deleted member 126969]

Wrong section really - this is for MB EV & hybrids. You want the Electronics & Audio Section Electronics and Audio to get a bigger audience.