(Cracked Block) - Sudden Milky Oil - 351w

I thought I was done with this milky oil BS. The whole reason I swapped the 351w for the 302 was the 302 had milky oil. I've ran the 351 for 3+ hours since the motor swap with clean oil every time... Except last night / today.

I've been running the boat off the hose the past few days while working on the carb. Last night I noticed one drop of water on the dip stick, oil was still clean so I wiped it down, checked again and it was gone. I dismissed it as condensation. This morning I slipped the Tique into the lake, hooked up my vac gauge to the PCV intake and took it down the lake to warm it up. I opened the engine cover to adjust the idle when I noticed the unplugged PCV hose had puked about a 6 ounces of milky oil all over the engine bay. I immediately shut down the motor & checked the stick. 6" up the stick was chocolate milk. I limped it back to the ramp and brought it home.

No dirty plugs, which I was really surprised with because the motor was running extremely rich just the other day. I mean the plugs were pristine.

I checked the compression and was between 110-120 on all cyls.

There must be a huge leak to fill the pan that much with a 1 min ride down the lake & back.

Where to I go from here?

Sorry to hear the bad news Andy. Hopefully, you can get her up and running again quickly!
Have really enjoyed your thread. Great work.

Aside from just crossing fingers & replacing gaskets is there any good way to go about narrowing it down?

I pulled the valve covers and the plugs in the heads are in great shape so no luck there.

I'm currently installing new valve cover gaskets & plan on doing an oil flush & change. I'm positive it will happen again, but I want to make sure I can duplicate the milky oil I got at the lake in the driveway hooked up to the hose. Plus I found a hand tight intake manifold bolt so I'm going to torque the intake and re-test.

If that fails it'll be time to pull the heads & exhaust manifolds for a go-for-broke inspection.

That sucks Andy! Really sorry to read that. Good news, plenty of time to figure it out before your season kicks in. Good Luck!!

LeftFieldEngineering wrote: ... The only think I can think of is Friday during / after my carb test I accidentally left the hose hooked up and ON for 10-15 min after shutting the motor down. If there was a leak in the exhaust manifold perhaps it forced its way into a pistol and leaked passed the rings and into the crankcase over night. Then I fired it up in the AM to find a milky mess...

I think you might be onto something there...

I forget the details of how this happens (and it's been explained to me a couple times), but somehow if an exhaust manifold or associated gasket is weak/compromised, an engine that is being forced water on the hose is more prone to ingesting water than one that is sucking up it's own from a bucket. But, this shouldn't happen unless there is already an issue, but forcing feeding it water from the hose brings out the weakness.

Andy,
What's you set up with hooking up the hose? Is it a "Timmy Tee" which does not valve off the hull pick up or does the hook up see whatever pressure is at the hose?

Andy,
Set up your hose connection like Tim has recommended and many have followed. It's been posted several times but here's a recent thread (Disregard the picture of CQ!) The RWP will suck what is needed and the rest of the water will go out the hull pick up or all of the water if the engine isn't running.

Guess it all comes down to this afternoon: I'm going to pull the plugs one more time and crank it over by hand to see if any of the cyl's have water in them, if not it's off to the lake to see what happens.

I also picked up a 40" USB Bore-scope camera for 20 bucks on Amazon. That way if the water does returns I'll start by pulling the exhaust hoses and go looking for signs in the exhaust manifolds.

Wish me luck.

My Silver Nautique had a cracked block above the cam bearings and only leaked every now & then. Plugs were clean and ran very well but it filled the block up with water. It did that for 3/4 weeks before I found it... Good luck!   

TRBenj wrote: I'd like for someone to explain the path that the water would take if they think a garden hose can somehow force water through the RWP and into the cylinders (or oil). ...

Well, I remember it wasn't so much a matter of "forcing." It was more a matter of a leak between the exhaust port and the water jacket within the Edit: EXHAUST manifold.

Then, if the engine is running, the escaping exhaust blows out any potential water.

But, if the engine is not running, water is still going through the cooling system/exhaust manifolds etc. with the garden hose connected in a positive fashion. Water then has the potential to find it's way into a cylinder through an open exhaust valve.

Of course, this scenario requires and exhaust manifold that is already compromised.

A Ford based 351W can also leach water into the oil via the front timing cover. Consider all possibilities and systematically test it before deciding what to repair. Good luck!

The first thing I need to do is duplicate the problem. I may not be able to explain the how or why just yet, but until it comes back under normal operating conditions there may not actually be a problem.

Hell, for all I know some disgruntled mastercraft owner could have come by and poured a quart of water in my motor just to give me a heart attack.

That being said I'll take a cracked intake, cracked exhaust manifolds, or even cracked heads any day as long as the block is spared. I can assure you a full motor rebuild is not in the budget.

As for the hose hookup I can attest to the fact that with the engine off there would be some water coming out the exhaust so it must be getting past the RWP. Even then the path of least resistance should be through the exhaust manifolds & out the tail pipes so the block wouldn't see much if any pressure.

Since I ran the boat for 1.5 - 2 hours in the lake a few weeks back & the oil was clean after I'm hard pressed to believe it's lake related.

Since that trip I pulled the carb for a rebuild which required me to remove 1 intake manifold bolt (that secured the throttle return spring). I spent the next few days trying to get the boat running right in the driveway. During these on / off cycles the hose was on a majority of the time. The longest hose-on time was Friday when I came inside to update my Carb Running Rich post here on CCF.

In my opinion the only shot I have of it being a simple fix lies with the "loose" intake manifold bolt. The bolt had been removed for 24 hours before it was snugged up with a 1/4" drive ratchet. For all I know it started dripping water into the valley as soon as the bolt was removed and had emptied the intake manifold into engine before I reinstalled the carb & bolt. If not then perhaps it was the heating & cooling cycles during Thursday driveway tests that broke the seal, again allowing it to drip overnight into Friday. Now that I'm thinking of it I do recall seeing steam or smoke coming from the valve cover breather on Friday. It's an old motor so I didn't think much of it, but Saturday morning I removed the backfire arrestor to see if the boosters were dripping and noticed liquid in front of the choke horn. I smelled and consequently tasted the liquid, it was water. It must have condensed in the backfire screen overnight. Meaning the water was in there before I got to the lake and probably even before my Friday test.

Looking back having the PCV valve disconnected and it puking oil all over was a blessing in disguise. Had I not seen the milky mess on my first pass I would have continued with the plan to take my buddy footin' and would have almost certainty smoked the main bearings in the process.

I'm ashamed to say I didn't check the oil before starting the boat. I never had to worry about it with my old 2 stroke outboard. Needless to say checking my oil before each run will be at the top of my priority list.

After pulling the starboard exhaust riser I was able to use the bore camera to take a look in the exhaust runners all the way up to the valves. The resolution wasn't good enough to see hairline cracks, but it was neat to see inside without taking much apart.

The riser gasket was pretty beat up, but I didn't see any rust stains or clear evidence of leakage into the exhaust.

I have an idea to pressure test the exhaust manifolds in place so I'm machine the adapter and give that a shot this afternoon. If it passes I'll just put it back together and wait for it to come back.

does your motor have a cooler on it?