Mercury 175 Optimax upper oil reservoir not filling all the way

[n8cas]

My Merc 175 Optimax (2006) was running great on its first trip of the season. I did a cross lake 10 minute run at 5000 rpm and my oil sensor alarm went off. I just filled my lower oil reservoir the day before, so I know my oil was not low. I take off the coiling and noticed that my upper reservoir was not all the way full and obviously the sensor at the top is going off. I went to relieve pressure by unscrewing the upper reservoir cap as often I needed to re-pressurize after filling my lower reservoir so it could slowly fill up the upper reservoir. It was highly pressurized, but after I did this and put even more oil in (even though I knew that was not the case) the upper res. did not refill. (maybe a very little increase, but then no increase) I took the cap off my lower reservoir and took out the plastic intake to see if it was clogged, but it seemed to be okay. I wiped the screen on the bottom of the lower res. intake plastic piece to see if there was a clog there, but it seemed ok. I took a slow run back to the ramp with the upper res. oil sensor going off every 2 minutes unsure if my engine was not getting oil. The oil level in my upper res. tank is 65 percent full still, so I'm guessing my engine is getting the oil it needs, but it is not filling properly. Is it clogged tube somewhere? All caps are on tight, and after running the engine it seems to build pressure in the reservoir tanks (but maybe not enough?). Has anyone had this problem before? This is the first time this has happened to me. Here's a pic of how it has been since this happened yesterday:





2005 Ranger 185vx – Tournament Edition – Comanche Series
Mercury 175L OPTI serial number 1b424986 Sep 2006 Model 1175D73HY

[JOE54]

check filter lower left in picture for restriction , can be no air leaks in system , try not to let bilge tank to run out of oil

[n8cas]

check filter lower left in picture for restriction , can be no air leaks in system , try not to let bilge tank to run out of oil

I will check the in-line filter - thanks! My bilge tank (or lower reservoir) was not empty, but it goes through oil quickly!!

[JOE54]

you must loosen cap on engine tank for it to fill , dont forget

[EuropeanAM]

you must loosen cap on engine tank for it to fill , dont forget

AND the engine must be RUNNING at idle the entire time you're bleeding it.

[n8cas]

Thank you for the reminders. I used to think I only needed to open the cap of the upper res. for a second to create a vacuum, but I realized it needs to be opened the whole time with the engine at idle so the crankcase can push air into the lower res. tank forcing oil into the upper res. I got her to fill after using carb cleaner on the intake screen in the bilge as suggested AND replacing the cheap inline filter.

Last question though. It took a while for it to fill. Is that a concern for my engine getting the right amount of oil it needs to the oil pump? In other words, slow to fill - slow delivery to the oil pump? I had an oil pump failure that caused my engine to seize. I had to get my head rebuilt and of course a new oil pump amongst other small fixes when that happened. I would really like to avoid that problem again.

[JOE54]

no issue with fill ,its not gonna be basted in under high pressure .... so you had a oil pump failure on an this optimax ?????

[n8cas]

Yeah. Here's how it started: https://www.bbcboards.net/showthread...ferrerid=41979

Chris Carson down in Florida fixed it up real nice a few years back.

[JOE54]