[fgpalmer71]

I picked up my 2009 E93 335i a little less the 2 months ago now. About a week after getting it home from the 900 mile drive from Orlando to Indiana I had the coolant light come on. Checked the level and it was LOW. We had checked the fluids before leaving Florida and rechecked them upon arrival, it was full. I topped it off, light went out, all was well and I've been monitoring it. Temp levels have been rock solid and level seems steady.

Driving last night on the interstate I thought I smelled a faint burning of some sort. Top was down and I was moving pretty briskly. I was a couple minutes from the house, no smoke, and the smell left my nostrils almost immediately. Temp still rock solid, I figured it was a vehicle around me. Pulled into the garage, let it cool down, checked the coolant level and it was full. It was about 830 pm. I went out to the garage this morning and checked the level again. Still looks full.....but my float was off kilter....I grabbed it and tried to straighten it up and the float popped off its base. I looked at the float and it had what is surely oil at the base of it. The coolant in the reservoir is not off color at all. Then I looked at the cap and the O-ring had a missing chunk that had surely fallen inside of the reservoir. Then I glanced down and saw it.......a puddle of coolant on the ground and a slow drip coming from the passenger side door sill!!! Where is this coming from? I see no leaks in the engine compartment, none from the expansion tank, it's 730 am and the car hasn't been driven since 830 last night and it's actively dripping coolant from the passenger side door sill area.

I'm going to order a new expansion tank today as the cap and float definitely must be replaced anyhow. Thinking about doing the relocation tank as expansion tank leaks seem to be an issue anyhow and the aluminum relocation kits I see sound like they may stop that for life. But, with the location of this drip I'm thinking this is NOT the expansion tank leaking coolant. I can't see where it's leaking from, everything I can see looks dry.

In researching I stumbled across a thread about a black cap close to the firewall that leaks coolant....but that thread made it seem as if the leak would be coming from the drivers side of the car if that was the culprit.

Any ideas on what could be leaking and dripping from the passenger side door sill area?

Water pump and thermostat were replaced @ 76k miles and I bought the car with just under 79k on it....it's @ 82k now.
















Below is a sample of the coolant from the reservoir. I stuck a large straw inside to the bottom and it looks perfect to me.

[Steve Sas]

Isn't that where the window washer tank is?

You sure that's coolant dripping down?

You may have more than one issue.

[fgpalmer71]

I'm standing here next to the car waiting for the coolant bleed procedure to finish, hood up, and I was JUST thinking that same thing.....maybe that's windshield washer fluid! Is the tank for the washer fluid behind this passenger side wheel well? I can't see where the fill tube connects to a tank from the top side.

[fgpalmer71]

Also....from researching this morning, am I correct in assuming that this oil on the now disconnected coolant float is from an internal OFHG leak? That's obviously concerning the hell out of me right now. The OFH housing has zero visual evidence of any external leaking at all. Its clean and dry.

[Emilime75]

Yes, the washer tank is directly behind the passenger front wheel. You remove the fender to get to it.

And, yes, oil in coolant is a major concern. Open your oil fill cap, anything look milky or milkshake like?

[fgpalmer71]

I didn't hook the car up to my battery tender when doing the bleed procedure just now. The battery was replaced a few days before I picked up the car, thought it would be fine. Now the car won't crank over and the ABS light is on. I JUST sold my 2016 Genesis sedan last week and haven't bought a 2nd car yet. Good lord....great start to my day!!!!!

[fgpalmer71]

Just checked the oil. Everything I can see inside looks beautiful....including the underside of the cap.

[Steve Sas]

Yes in the wheel well.

OFH gasket is easy to do. Just change it and use a small amount of permatex gasket sealant as well. Do both gaskets if you have the oil cooler.

[Emilime75]

Do not use gasket sealer on the OFHG.

[fgpalmer71]

Yes, I have the oil cooler. So I need to change this expansion tank....and do the OFHG, both of them....and replace the washer reservoir.

I shouldn't drive this thing should I?

[Emilime75]

If you say your coolant looks spotless, and the OFHG does not have any external leakage...it could be that the sludge you're seeing on the dipstick only is residual from a past OFHG leak and it's been replaced before you bought the car.

That's not to say that the OFHG leak couldn't be internal only.

[ro881e]

I had a pretty bad OFHG leak and drive it for ages, no problem. Made a mess though! Prob no good for the aux belt as these can self destruct with long term oil contamination


hilst the drained coolant was a bit discoloured it wasn't obviously oily, nor was there reverse leakage of coolant into the oil. However on removing the deceased water pump, there was visible oil on the impeller blades. So the oil on the stick thingy may well be the same isolated deposits indicating oil contamination even if coolant looks ok.

Agree with other replies, gasket is fairly easy if follow guides on here, use original actual gaskets too as said. Or maybe as prev post, it was fixed before and it's old deposits.

[fgpalmer71]

Thanks guys.

I'm thinking the sludge is from a previous leak. Makes sense. The windshield washer warning light came on just now when I tried to start it just now, so I'm fairly certain the puddle of fluid is washer fluid.

Even though I'm fairly certain that this sludge is from a previous incident, based solely off of the current condition of the coolant, I'm going to replace the OFHG anyway.....along with this expansion tank. Should I be worried about the radiator having similar sludge inside of it?

[fgpalmer71]

Also.....my battery tender will not charge this battery and I have no jump box. During my pre-purchase research it seems like jumping this car in the traditional way is no bueno because of risk of voltage spikes murdering sensors.....is this true? Do I need to go buy a jump box to start this car safely? Why would a 15 min coolant bleed procedure drain enough juice to cause it NOT to start on a battery that's literally 2 months old? My concerns are growing....

[Emilime75]

These cars are electrical heavy. Lots of modules and the WP has a decent current draw. It's always recommended that any time you need to do something that requires the ignition to be on for more than a few minutes you put a charger on it...and if you're servicing anything electrical that you disconnect the battery.

Your trickle charger "should" be able to charge your battery back up, but it'll probably take a long time. If you're messing with the car while it's trying, it'll just take longer.

Might want to drain coolant and replace OFHG before doing the expansion tank. Clean it as much as you can, refill with distilled water only and run that for a while to try and flush as much out as you can, maybe even add a coolant flush liquid of some kind. Then drain again, replace rank, refill with the right coolant mix.

[fgpalmer71]

Thank you. I'll take that advice. I knew I was going to have to get elbows deep in this thing eventually!!!

[fgpalmer71]

And there's 2 opinions.....to use a sealant on both sides of these 2 OFHG's I'm going to replace, or not!?

Is there a chance of damage of some sort by using the sealant?

[Emilime75]

There is zero evidence it does anything to prolong the life of the seal, and some of potential issues. Just get both surfaces super clean, use an OEM gasket and torque to spec.

[fgpalmer71]

Thanks again!

[fgpalmer71]

just to be safe I extracted some fluid from the reservoir and updated the OP with the photo. If it were an active OFHG leak at the factory oil cooler this fluid would look differently.....right?

[Steve Sas]

Maybe ask the previous owner if the gaskets were replaced? And look for paper work with the log books.

[fgpalmer71]

The mechanic who worked on the car for the roughly 3 years the previous owners had the car tells me that he never changed the OFGH gaskets. I've already ordered a gasket set, I'm replacing them.