[Salzamani]

Hey guys, I had the upper radiator hose which is located on the upper right side of the engine blow a couple weeks back. It gave away at the plastic connector shown in the pic with the red arrow. The repair was done a couple weeks ago and was success. Yesterday I pulled off the bottom engine tray and discovered some fluid collecting in the tray on the driver side. The second pic shows the where exactly with the red arrow. The fluid looks to be brownish in color. It is not oil. I’ve gotten under the car from all angles with a high powered flashlight and just can’t find any evidence of where it could be coming from.

Any ideas what that fluid could be based on its location in the bottom tray?

Here is a little history; Just a year ago I did the valve cover gasket, oil filter housing gasket, oil cooler housing gasket.

[alpnwss]

Power steering resivoir is located over there and will turn brownish in color after extended use.

[Salzamani]

Originally Posted by alpnwss

Power steering resivoir is located over there and will turn brownish in color after extended use.

That was what I first suspected too based on its location and based on the fact that in the last 2 years of ownership of this car it has always had a very pronounced steering vibration that feels like it’s coming from the power steering pump or the rack. The vibration happens only at rolling speeds while turning the steering wheel like when getting in and out of a parking spot. Not a very common problem but there has been some E90 reports of this issue.

Anyways back to the leak when I open the power steering reservoir the fluid is pretty clean (CHF 11s) and light green in color. I changed the fluid when I first bought the car in an effort the see if I could get rid of that vibration. I want to point out that other than the vibration at rolling speeds you would never notice any other symptoms. Back to the reservoir, no matter how often I wipe it the top half of the reservoir always has a film of fluid which is probably seeping out from the over flow hole of the reservoir cap. That film of fluid has always existed and has never ended up in the bottom tray which leads me to believe it’s probably not coming for the reservoir. Also the bottom of the reservoir where the hoses are is always dry.

[Bimmer_Bro]

This might be a dumb question.. are you sure that fluid on the splash guard is recent? Could it be from when your rad pipe exploded, or remaining liquid from the burst that has gotten dirty and worked its way down there?
If you haven't already I would clean it best you can. Slap it back on for a while and then check to see if more fluid has collected on the splash guard. Just my 2 cents.

[Salzamani]

Originally Posted by Bimmer_Bro

This might be a dumb question.. are you sure that fluid on the splash guard is recent? Could it be from when your rad pipe exploded, or remaining liquid from the burst that has gotten dirty and worked its way down there?
If you haven't already I would clean it best you can. Slap it back on for a while and then check to see if more fluid has collected on the splash guard. Just my 2 cents.

Not dumb at all buddy. Yeah that hose bursting caused my serpentine belt and tensioners to get pretty loud after a couple days so I had to replace those as well. That process is much easier with the radiator fan out of the way which required me to remove the bottom tray and every time I pull that tray off I always clean it very well with break cleaner so that I will always know if there is a new leak.

I also suspected that the other O rings on that same hose could potentially have been what caused the new slow leak but I did check and I don’t see any evidence of that either plus I did replace the antifreeze with BMW blue stuff and this fluid is brownish rustic reddish in color. It didn’t dry up very fast either. I collected a bit of it in a small jar and it still has not dried up yet after 3 days. One of my first thoughts was transmission fluid but in that location?

[Bimmer_Bro]

Originally Posted by Salzamani

Not dumb at all buddy. Yeah that hose bursting caused my serpentine belt and tensioners to get pretty loud after a couple days so I had to replace those as well. That process is much easier with the radiator fan out of the way which required me to remove the bottom tray and every time I pull that tray off I always clean it very well with break cleaner so that I will always know if there is a new leak.

I also suspected that the other O rings on that same hose could potentially have been what caused the new slow leak but I did check and I don’t see any evidence of that either plus I did replace the antifreeze with BMW blue stuff and this fluid is brownish rustic reddish in color. It didn’t dry up very fast either. I collected a bit of it in a small jar and it still has not dried up yet after 3 days. One of my first thoughts was transmission fluid but in that location?

It does seem like an odd spot for transmission fluid to be. If you wanted to double check, find the lower filter pan of the trans and check it isnt dripping onto anything and working its way there. Does everything in that particular wheel well look ok? (Strut/brake line)

[Salzamani]

Originally Posted by Bimmer_Bro

It does seem like an odd spot for transmission fluid to be. If you wanted to double check, find the lower filter pan of the trans and check it isnt dripping onto anything and working its way there. Does everything in that particular wheel well look ok? (Strut/brake line)

Yeah transmissions is all dry too. Break lines are ok. Suspension parts are ok.

I’m starting to think more and more about that same radiator hose that I recently replaced and perhaps the other connections when removed and put back together are causing a very slow leak only under pressure. The weight of that fluid seems to be more consistent with antifreeze than anything else.

I had a different hose blow a year or so ago the one that goes to the engine block with 2 bolts as an attachment in the same side very strange engineering anyways I’m sure it’s for some good reason but still strange. Well when I replaced that hose I also replaced the BMW antifreeze which was again just a year ago. When this last hose blew 2 weeks ago the fluid was like brown I couldn’t believe it had lost it’s blue color. The inside of these radiators must be very rusted for the fluid color to change that drastically so quickly. So I’m trying to let the brownish tent to this fluid color of this recent leak not distract me from the possibility that it is antifreeze...

[alpnwss]

Additionally, if you suspect something is leaking, take a little strip of white paper towel, wrap it around the gasket and put a wrap of tape around it. Cut it after a spirited drive and you'll know if it is or is not leaking.
Make sure you tape it well and you'll have no problems.

[Salzamani]

Originally Posted by alpnwss

Additionally, if you suspect something is leaking, take a little strip of white paper towel, wrap it around the gasket and put a wrap of tape around it. Cut it after a spirited drive and you'll know if it is or is not leaking.
Make sure you tape it well and you'll have no problems.

Great technique. Thank you!