that's normal! especially if you cruise in cooler waters or cooler evenings, a majority of engines will get what your talking about..moisture in the air will do it to..

You are correct sir. Also if you have an oil cooler or power steering cooler leak, it will leave an oily residue on the water coming out of the pipes.

These engines have oil thermostats located on the oil filter remote. Check the one in the engine you're having a problem with. The old HP450's had a major problem with condensation in the under the rocker covers, thats why they started using the thermostats for the oil cooler. I doubt it's a leak, sounds more like condensation to me.

No oil thermostats in these motors.. Look at the pic , notice the oil filter...These engines are gen IV 502 bored to 509 cu

Then maybe thats what you need.

Doesn't matter one way or the other. Condensation occurs usualy after the engine is turned off and cooling down.

He needs to run them a little this summer, Pull the dipstick and oil fill after the engines have run at temp for a while and then see if there is anything left. If oil is clean, then it is condensation and there is nothing to worry about.

Thanks for your reply.. Engine runs at 160 water temp and oil temp gets up over 200 cruising and higher on a hard run.

clogged drain Temecula

I noticed you had the short risers, what cam do you have in these engines? I use the EMI exhaust with the long risers. Before I knew better I ran a aftermarket cam with the stock exhaust and it caused reversion. I saw the same thing with the oil you are experiencing. I cannot explain why it would only be on one engine.

It has a mild crane cam, i think a 236 duration 114 lobe sep. When I bought the boat it had the stock merc exhaust with the silent choice and the same cam setup..On the emi short risers the exhaust outlet in almost 4" in front of the water outlet..Just like the stock merc which were on the boat when i got it...Wouldn't water in the cylinder from reversion show something..stains...washed spark plugs..a miss..water in oil pan ??

i cant really tell from the pic's but do you have any kind of a pcv for your engines? i see nothing going to the flame arrestor's