Pcv valves will keep the oil in the motor and the crankcase vapor will get pulled out. Should have a breather in one valve cover to let fresh air into the crankcase also

Good idea red, I will put PCV valves in the valve covers to help keep oil coming up them. There is no vent right now, I will have to pick up one of the vents that go in the filler opening. I wonder if the hose on one side was clean as air was being pulled in through there and sucked out the other side.

At least the big issue of water just ended up being condensation, that was a huge help.

Brian

The thermostat that belongs in that motor is a 140 degree. I would not use PCV's to remove moisture, even though they do work. All you have to do is get your oil temps above 212 degree and all the white stuff will disappear. Going out for short quick rides or running on land with a garden hose does not let the oil heat up enough and with the weather cooling down it causes condensation. I was told by a performance shop never put a PCV valve in a boat engine unless you want to blow it up. Oil and contaminants recirculating back into the carb via PCV could be setting up a detonation situation. Just my 2 cents.

just fyi,the merc hp500 comes with a pcv setup.

Oil on the top side of the intake? On one side?

Remove and reinstall the intake to head bolts one at a time. Spray a little non-chlorinated brake clean in the hole....then fill it with permatex black gasket maker.....and a bit on the lower threads of the bolt.

do not put PCV valve in unless you are plumbing it to engine vacuum. if leaving it as a breather that blows out at flame arrestor, it is just a breather vent. the check ball will shut that side off if not to vacuum and it'll vent anywhere it can causing oily exhaust smell throughout the boat. also, PCV doesn't work that well at high throttle. no vacuum, no sucky sucky blowby. (and you have more blowby at high throttle.) so the breather side STILL has to be plumbed to the flame arrestor.

I know..I was told this by Nickerson performance in Bristol Pa..They setup my carbs and when I asked about PCV's they said NO unless I wanted to blow them up..Apparently PCV's are like a vacuum leak and can cause a leaning of A/F ratio. recirculating oil and contaminants to be re burned also can cause detonation.
My friends HP500 was sucking his oil out thru the PCV. On the Hp500's it is mounted on the lower part of the intake behind the carb. NOT in the valve covers. Above 3000 rpms the PCV valve stops working (no vacuum) and now blocks that breather hole from venting building up more crankcase pressure.
Puke tanks are better

What thermostats do you have in now?

I put 160's in both motors, they had the 140's. When I run it now, it warms up to 165 to 170 and stays there. That one vent line will still drip some oil onto the intake manifold if the tube is pressed tight up against the flame arrestor. Leave about 3/8" gap and the oil drip stops. With the 160's in it, the oil on the manifold is now back to looking like oil, no moisture in it.

The motors are roller cam, vortec heads. Basically a L31 truck motor with a mercruiser cam, 4 barrel, aluminum intake and HEI.

I have one PCV valve that I was going to install in just the one side that was dripping oil, but it was for a different diameter hose so I never installed it. After several hours of running, there is much less than an ounce of oil on the intake manifold. Not sure if I will solve it this year or try something over the winter, not much warm weather left.

I will also only install only one PCV valve, the other valve cover will be direct vented like stock so the engine can not vacuum seal itself.

Brian

I had a similar issue at first and corrected it the same way you did...exactly...but I did put a PCV valve on one valve cover and ran a rubber hose up to the Flame Arrestor while I have a breather on the other Valve Cover. I had to go with 160* T-Stats because I'm running oil coolers. Even running in 85* water my temps never went over 140* water and 180* oil...even spinning up 5000 RPM !! Now I have a good mix of 155*-165* water and 190*-oil (measured at T-stat housing & Oill Filter w/laser thermometer)...regardless of how I run it.

I did my first oil/filter change today and corrected an oil leak that developed on the starboard engine at the hose/brass nipple threaded connection to the oil filter adapter plate. I had to get a friend to get in there to do it...my big ass just want go in places it used to!! LOL

Glad to hear you are getting some time on yours as well.