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My 97 528i I6 auto with 255k miles has had an oil leak for years. It never left a puddle on the driveway. The oil pan gasket was always wet and the tranny pans were slick. Years ago I casually asked the mechanic and he immediately said the RMS. I don't know how he knew. He didn't drop the tranny or add dye to the oil.
Fast forward to today and the oil leak is worse. It leaves a small puddle on the driveway. I added 1 bottle of dye from O'Reilley and could never spot the leak. Bought a better UV light, did an oil change, then dumped in 2 bottle of dye. Still can't find the dang leak. Based on this forum and friends, here are my options. I even sprayed gunk where I could and shoved my hand w/ a rag everywhere else to wipe off what I could.
Oil filter housing gasket. Probably original. Lots of gunked up oil on the engine block in that area, but nothing is showing from the dye. Seen lots of posts here about this leaking. Pretty sure mine isn't. Not a bad DIY if I keep the bolt sizes straight, per cn90.
RMS. Probably original. Can't see it. I do see drops of oil thru the bell housing holes on the bottom to access the pan bolts. When I pulled the tranny last year I also took off the flywheel and saw oil, but nothing excessive. Assumed it had just migrated/blow back there over the years from the pan gasket leak. I could do the RMS DIY, almost did it last year. (Note to self, just do the RMS when the tranny is off).
Oil pan gasket. My mechanic says these never leak. Look at the RMS instead. The pan gasket is wet all the way around. Dropping the subframe doesn't sound like fun. Would copy mudbones approach and cut the gasket. Does a fully saturated pan gasket point to that gasket, or could it be the RMS leaking down, then wicking around the entire pan gasket?
Could it be the oil sending unit or some other "port" on the engine block that oil could be seeping from? Drive's side has more dirty oil than pass side. Again, I can't see any dye trails.
To maximize the dye, I've worn the yellow glasses, removed the front tires to see in from the sides, and did it at night so my flashlight was the only light source. Making matters worse is I have a small coolant leak near the exhaust manifold off cyl 6. So when coolant runs down the bell housing past the torque converter bolt access hole, then mingles w/ the oil, everything under the UV light looks like coolant. I think the coolant glows on it's own. I wonder if the coolant is contaminating my dyed oil. Can I stick an absorbant pad up there to catch the coolant? How and would it stay while driving and hot? Can I put the car on jacks and just run it in the driveway and repeatedly wipe away coolant?
In summary, if I rule out the areas of the engine that I can see, then I'm left w/ the oil pan gasket or RMS as the source of the leak. But I want proof before I start one of those jobs. Any advice? Am I doing something wrong w/ the UV dye? I'm not pulling the head to fix the coolant leak. Car isn't worth that much. It's small, I'm living with it.
Fast forward to today and the oil leak is worse. It leaves a small puddle on the driveway. I added 1 bottle of dye from O'Reilley and could never spot the leak. Bought a better UV light, did an oil change, then dumped in 2 bottle of dye. Still can't find the dang leak. Based on this forum and friends, here are my options. I even sprayed gunk where I could and shoved my hand w/ a rag everywhere else to wipe off what I could.
Oil filter housing gasket. Probably original. Lots of gunked up oil on the engine block in that area, but nothing is showing from the dye. Seen lots of posts here about this leaking. Pretty sure mine isn't. Not a bad DIY if I keep the bolt sizes straight, per cn90.
RMS. Probably original. Can't see it. I do see drops of oil thru the bell housing holes on the bottom to access the pan bolts. When I pulled the tranny last year I also took off the flywheel and saw oil, but nothing excessive. Assumed it had just migrated/blow back there over the years from the pan gasket leak. I could do the RMS DIY, almost did it last year. (Note to self, just do the RMS when the tranny is off).
Oil pan gasket. My mechanic says these never leak. Look at the RMS instead. The pan gasket is wet all the way around. Dropping the subframe doesn't sound like fun. Would copy mudbones approach and cut the gasket. Does a fully saturated pan gasket point to that gasket, or could it be the RMS leaking down, then wicking around the entire pan gasket?
Could it be the oil sending unit or some other "port" on the engine block that oil could be seeping from? Drive's side has more dirty oil than pass side. Again, I can't see any dye trails.
To maximize the dye, I've worn the yellow glasses, removed the front tires to see in from the sides, and did it at night so my flashlight was the only light source. Making matters worse is I have a small coolant leak near the exhaust manifold off cyl 6. So when coolant runs down the bell housing past the torque converter bolt access hole, then mingles w/ the oil, everything under the UV light looks like coolant. I think the coolant glows on it's own. I wonder if the coolant is contaminating my dyed oil. Can I stick an absorbant pad up there to catch the coolant? How and would it stay while driving and hot? Can I put the car on jacks and just run it in the driveway and repeatedly wipe away coolant?
In summary, if I rule out the areas of the engine that I can see, then I'm left w/ the oil pan gasket or RMS as the source of the leak. But I want proof before I start one of those jobs. Any advice? Am I doing something wrong w/ the UV dye? I'm not pulling the head to fix the coolant leak. Car isn't worth that much. It's small, I'm living with it.