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codesx codesx is offline
Senior Member
Posts: 889
Join Date: Feb 2018
Car: 2008 335i Vert (E93, N54)
Default 04-22-2019, 09:50 AM

Well, I pulled my OFH off again.
The seals are in perfect condition with no signs of leaking/cross contaminating.
Further, the coolant in the upper rad hose is pure and clean green, as is the coolant seen in the block with the OFH removed.
When I removed the Coolant reservoir cap, the coolant that came out the described areas remained clean and clear green.
I drained my oil and there is zero detectable coolant in it.

However, my coolant reservoir tank appears to be straight-up oil.

I'm not yet sure of the coolant circulation flow, though I'm guessing the oil is coming from the block up into the coolant reservoir tank from the lower (larger) hose, and not from the little hose at the top, that feeds into the upper rad hose.

I can't see any way that this is happening in the OFH, or OFHG related. I checked every mm of the gaskets for cracks. They are simply a nice, flexible rubber.

When I first started the car after doing the work, there was a light coolant leak, which since turned to a coolant & oil leak. I still haven't isolated the leak, but it's certainly from the lower half of the engine, passenger side, front. (not rad or rad hose)

Is the Head Gasket the ONLY other place where oil can get into the coolant?

The car runs great, holds boost and has no codes. WGDC, fuel, AFR, everything looks clean in the logs. No smoke, just drips and coolant expansion tank full of oil. Oil level never measured the loss to the coolant tank, so it is likely 200~ml.



2008 335i Convertible, E93, N54, A/T (200,000+ km)
Wheels: 322 | Tires: R.275/35r18, F.245/40r18
TUNE: JB4/Trebila | 24 PSI | 100% Meth via dual BM5 | 94 Octane
BMS: JB4, Map 6 | WMI | 5" FMIC | OCC | DCI | Cowel Filters
TMAP: 3.5 barr
xHP Stage 3 (v2.0)
RB PCV Valve
NGK 5992 Plugs @ .020

2018 - A/T Replaced | Plugs | Ign Coils | Walnut Blasting
2019 - Index 12 Injectors | VCG | OFHG & O-rings | Alternator w/ Clutch Pulley | Water Pump & TStat
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