M52b28 - what to do about elephant trunk?

[Ess]

Hello,

My car's elephant trunk rubber drain pipe was removed to make space for the m52b28. We tried to fit a spare one yesterday but there isn't enough clearance, and even if we managed to get it on, it would be touching the cylinder head and would probably melt. I'm keen to get a fix for this as it must be there for a reason!

I'm troubleshooting a water leak into the cabin and while I'm sure the lack of elephant trunk isn't directly responsible, I believe it might be contributing? The water coming out of the hole in the firewall is pouring down the back of the rubbery/foamy insulation material on the firewall and I'm worried this will cause rust in the long term too, so I'm keen to get a fix.

Presumably this is a problem which anyone with an m52b28 engine conversion must encounter - any advice on what to do would be greatly appreciated. Many thanks!

[bosers]

I didn't have to remove it in my conversion, I know it's very tight to the bulkhead but it all should fit, just. Are you're mounts correctly positioned? Cheers Joe

[DanThe]

Your gearbox mounts are probably old/soft and need replacing/upgrading, this will let the engine tilt back, it usually touches the drain anyway but its not a problem, cutting it won't hurt unless you have an exhaust leak in the engine bay in which case it will poison you as you drive along

Don't do this though, which I found on a car recently”¦.

[Ess]

I didn't have to remove it in my conversion, I know it's very tight to the bulkhead but it all should fit, just. Are you're mounts correctly positioned? Cheers Joe

Interesting. I assumed this would always be the case. As far as I know the mounts are okay. Thanks for the info.

You could cut the front face off the trunk leaving the rear bit hanging over the lip and the sound proofing. That will ensure that the rainwater flows over the front of the sound proofing.

I also didn't have issues with any of my conversions being so hard up against the firewall? What engine mountings are you using? Do they perhaps have offset studs which is forcing the engine further back?

It sounds like I might have to do this, thanks for the advice - hopefully it should work. I'm using E28 M5 engine mounts which I believe are the ones recommended by the 'zone?

Your gearbox mounts are probably old/soft and need replacing/upgrading, this will let the engine tilt back, it usually touches the drain anyway but its not a problem, cutting it won't hurt unless you have an exhaust leak in the engine bay in which case it will poison you as you drive along

Don't do this though, which I found on a car recently”¦.

Thanks Dan, good to know that old gearbox mounts could be causing this when others don't seem to have this problem. So you reckon the engine touching the drain pipe isn't a problem, it's not going to melt? Do you know what the ultimate purpose of the elephant trunk is - is it a drainage thing or is it to prevent exhaust coming in if there was an exhaust leak?

Also - that photo is excellent. Unbelievable!!

Thanks all for your help.

[Brianmoooore]

Elephant's trunk is a one way valve to allow water to drain from the centre of the scuttle box, and to prevent air from the engine compartment being drawn into the heater inlet, which is in the scuttle box, so yes, to a degree it prevents an exhaust leak in the engine bay reaching the interior of the car.

[HairyScreech]

Your gearbox mounts are probably old/soft and need replacing/upgrading, this will let the engine tilt back, it usually touches the drain anyway but its not a problem, cutting it won't hurt unless you have an exhaust leak in the engine bay in which case it will poison you as you drive along

Don't do this though, which I found on a car recently”¦.

Took me a second to work out just WTF I was looking at.

[Ess]

Elephant's trunk is a one way valve to allow water to drain from the centre of the scuttle box, and to prevent air from the engine compartment being drawn into the heater inlet, which is in the scuttle box, so yes, to a degree it prevents an exhaust leak in the engine bay reaching the interior of the car.

Thanks for clarifying!

[mattxr2]

I pulled mine off, maybe I should get a new one ?

[Ess]

I pulled mine off, maybe I should get a new one ?

Personally I'm going to try and fabricate a replacement as suggested above. The way I see it, if BMW thought it was worth adding cost to the car to have the part there, they must have thought there was a damn good reason to have it!

[ACJJ619]

I don't have an elephant trunk on my M52 swap and I've recently found the passenger floor to be wet. Would a lack of elephant trunk cause this?

[DanThe]

No, that will be the bulkhead/floor rotting away!

[ACJJ619]

Excellent.