[Luft]

I purchased a 2016 AWD 435i from an indy shop around 8 months ago and ive had several minor issues with it. I have sorted out most of these, but the problem of a coolant/oil mixture in my coolant reservoir hasn't gone away. After flushing the coolant system and letting a few weeks go by, i'll get a coolant notification again. After checking the reservoir I'll see a oil/coolant mixture that is sort of light brown, that seems to be floating on top of the coolant.


Here's some background.

Here are the mods I know I have, much more could be modified but I don't have a good way to check (this was all told to me by the euro import shop and some friends of mine)


-Dinan air intake
-VRSF down pipe and charge pipe
-Custom oversized turbos
-Ground control camber plates and coilovers (camber is set to stock)
-Custom engine mounts
-Custom catless exhaust



I bought the car thinking it was stock, and as it turned out its super modified. I know that I should've known but the dealership stated it was stock. I had an issue of getting a bad turbo leak whenever I would accelerate hard to the right. I found a super reliable and cheap euro import shop and they've been helping me through all of this. They fixed the initial leak, and then when it happened again they fixed it for free and installed something to make sure whatever hose was getting clamped down on didn't happen anymore. The second issue was a slow coolant leak, I would have to top up my coolant every week or so, but that was fixed easily by a local BMW dealership before I found the euro import shop I mentioned. The local BMW dealer told me to find a place that would work on modified cars, so much was modified that they couldn't replace much without using custom parts, which they weren't allowed to do. I took it back into the euro shop and told them about the oil/coolant mixture, and they spent about 3 days looking for the problem. They told me it wasnt the OFHG, or a head gasket. They said it was most likely due to my car being so modified and running a stock tune. I also get drivetrain errors everyday, unless I clear the codes, then it'll stay light free for weeks. They told me this was due to catless exhaust and lack of a tune. A buddy of mine and the euro shop were able to determine some of the mods I had, but not all of them. I tried to set up an appointment with a local tuner, but I had some worries. The euro shop told me I had a wastegateless turbo, which was why fixing the turbo leak was a bit difficult for them. I assume that would mean im running an external wastegate? I have custom turbos, not sure what brand because they are bottom mounted. I can see where my air intake connects to, and the pipe has a speechtech logo engraved on it, but thats all I know. My fear is that I'll take it to a tuner, and they will tune it without knowing everything that it has installed. Should I just bite the bullet and pay the $1000 they asked for to tune it? Would I be able to solve this problem with a BM3 tune or something similar, or does it need to be taken to an actual tuning shop?


Other than all of that, my exhaust smoke looks normal, it drives great at all speeds, with no strange or odd noises, fuel consumption is normal and I've had multiple people more knowledgeable than me say it feels completely fine when they drive it. with the only apparent issue being the mixture in the reservoir. Sorry for a long post, but there was a ton of prior context with the issue so I wanted to get it all in. Thanks.

[lens]

100% OFHG

Dealer must be retarded.

There's a gasket in the Oil filter housing that seperates coolant and oil, and if that fails, you get coolant in oil and vice versa.

That's how I found mine was slowly leaking, I sent a oil sample to Blackstone and they found quite a bit of coolant.

[visionaut]

#4 is the Oil Filter Housing Gasket, #3 is the Oil Thermostat Gasket. Both have an oil/coolant separation function. If it’s not #4 then it could be #3.

With a leak from #3, you’ll typically find white residue from the coolant spray which happens once it’s pressurized. Check around the air box and on your alternator. You may also find oil seepage down on your belt tensioner. If you see wetness on your belt, be very wary driving it, the belt can slip off and possibly get ingested down by the crank seal.

BMW runs these motors hot for efficiency, with added mods (without added cooling) it’s even hotter. The high heat specifically kills the rubber in these two gaskets. Try getting Viton gaskets they’ll hold up better to the heat.

I doubt the leak/mixture is from your modded hardware…

[F32Fleet]

Originally Posted by Luft

I purchased a 2016 AWD 435i from an indy shop around 8 months ago and ive had several minor issues with it. I have sorted out most of these, but the problem of a coolant/oil mixture in my coolant reservoir hasn't gone away. After flushing the coolant system and letting a few weeks go by, i'll get a coolant notification again. After checking the reservoir I'll see a oil/coolant mixture that is sort of light brown, that seems to be floating on top of the coolant.


Here's some background.

Here are the mods I know I have, much more could be modified but I don't have a good way to check (this was all told to me by the euro import shop and some friends of mine)


-Dinan air intake
-VRSF down pipe and charge pipe
-Custom oversized turbos
-Ground control camber plates and coilovers (camber is set to stock)
-Custom engine mounts
-Custom catless exhaust



I bought the car thinking it was stock, and as it turned out its super modified. I know that I should've known but the dealership stated it was stock. I had an issue of getting a bad turbo leak whenever I would accelerate hard to the right. I found a super reliable and cheap euro import shop and they've been helping me through all of this. They fixed the initial leak, and then when it happened again they fixed it for free and installed something to make sure whatever hose was getting clamped down on didn't happen anymore. The second issue was a slow coolant leak, I would have to top up my coolant every week or so, but that was fixed easily by a local BMW dealership before I found the euro import shop I [...]

Oil filter housing gasket.

[Orion4]

Ditto on #4. That is the mostly likely candidate!

[Luft]

Got the OFHG replaced back in December by a BMW dealer in another state while on vacation. Since then, I haven't seen a significant amount of oil in the reservoir.

I asked the dealer to flush the coolant and they did, but they told me they had to flush it 5 times before they could get it back to normal. I haven't seen much oil in the reservoir since then, just some residual stuff built up near the cap and on the very top of the reservoir, the coolant is normal color and doesn't appear to have any oil in it.

Thanks for the replies.