Engine Help

John&Robin · Posted: Sun Jul 17, 2022 1:34 pm Post subject: Engine Help

Hi-
We have Honda 40's on our 22, about 300 hours. I've just started doing the maintenance myself. Last oil change the starboard engine was milky and over-full. I put it down to condensation from lots of idling during crabbing, refilled and hoped for the best. I'm now having a small oil sheen on the water surface, both idling and with the engine off at the dock. I'm planning to pull the boat out to investigate. Any thoughts on what to look for?
Thanks,
John

SnowTexan · Posted: Sun Jul 17, 2022 2:02 pm Post subject:

Sounds like water in the oil. Thermostat, head gasket. I’d cross my fingers and check to make sure theres not some thermostat hanging half out or something goofy. Is there oil on the surface of the motor anywhere? Some gasket or part designed to keep water OUT has likely failed.

ssobol · Posted: Sun Jul 17, 2022 2:36 pm Post subject:

I had a problem with my oil. I would see a sheen when the boat was still in the water.

Turned out that I didn't tighten one of the rocker cover bolts last time I checked the valve clearance. Had oil all down the inside of the engine covers. However, this did not allow any water to get into the oil.

SnowTexan · Posted: Sun Jul 17, 2022 2:54 pm Post subject:

I want to clarify the thermostat comments i made pre-coffee. Your thermostat is unlikely to be allowing water in through leakage, but it is possible it is failed in the open position. This would be an easy and relatively inexpensive fix. If you have trouble locating thermostats I have twin bf40’s and I believe a couple of spares and will be on the west side next week for an airport run.

Nigel

T.R. Bauer · Posted: Sun Jul 17, 2022 3:44 pm Post subject:

Water in the oil from the thermostat sticking open is from condensation and generally minimal. There should not be lots of it if the oil change interval has been followed. A small oil sheen on the water often happens after a fresh oil change - lots of reasons for it, mostly because you just can't get it off everything all the way. And the oil from the filter generally drains downward into places you can't always get to. It would not surprise me at all this is where the sheen is coming from.

Since it doesn't sound like you've really torn into anything, check the basics. Is the drain plug tight? Did you use a new plug washer? If not....they are a one time usage item because they can leak. Is your new filter tight? Did you accidently double gasket the filter? Is your oil still looking good after a few hours usage? If it is, and it's not filling up on you and getting milky, I suspect the sheen will disappear in short order on its own.

If you are getting water in your oil and it is not from the drain plug or condensation from a stuck T-stat, which you should check and change, then it must be a crack in your engine block/head or the head gasket. I hope it's not that. Head gaskets do fail and blocks and heads crack - mostly with engines that have been overheated.

John&Robin · Posted: Sun Jul 17, 2022 5:22 pm Post subject:

You guys are great and I really appreciate the expertise available here. I replaced the stats during this last service but suppose one could be bad... I like the waste oil idea best and will keep fingers crossed on that. Nigel, your offer of thermostats is extremely kind, thanks! I ordered Boats.net parts to stock everything that went into the servicing and have replacements, but some parts had long delays.

SnowTexan · Posted: Sun Jul 17, 2022 9:15 pm Post subject:

Almas Only · Posted: Sun Jul 17, 2022 11:00 pm Post subject:

A failed thermostat will cause water to condense in the oil, and depending on circumstances, the amount of condensation can be far from minimal. The good news is if that's the source, there won't be any salt.

T.R. Bauer · Posted: Sun Jul 17, 2022 11:27 pm Post subject:

John&Robin · Posted: Tue Jul 19, 2022 11:20 am Post subject:

Pulled the boat leaving some crabs for the rest of you and I found oil leaking from the joint above the extension case, through a gap where the under cover rubber is missing. About half of it is gone. It's a slow but steady ooze. Is replacing the seal enough or should I be looking for something additional? And what might cause the seal to be missing? Here are some photos:
http://www.c-brats.com/modules.php?set_albumName=album3444&op=modload&name=gallery&file=index&include=view_album.php

Many thanks for your thoughts!
John

ssobol · Posted: Tue Jul 19, 2022 2:53 pm Post subject:

Not sure on the 40s, but on my Honda 90, the exterior covers are for decoration. If oil is getting on the outside of the cover, it means that oil is spraying on the inside of the cover from someplace on the engine and it is running down the inside 'til it finds a way out.

John&Robin · Posted: Thu Jul 21, 2022 10:40 am Post subject:

Well it turned out to be another self-inflicted wound- the oil filter was leaking. I couldn't see it without a flashlight and careful watching while running. I couldn't tighten it enough to stop the drip so changed the oil and replaced it with a new one. This was the first NAPA Gold filter I've used on the boat and now I'm back to Hondas. I've read here that the NAPA Gold filters are solid but I think I'm going to stick with Hondas now. Ready for more summer fun.
Thanks again to the brain trust!
John

T.R. Bauer · Posted: Thu Jul 21, 2022 2:06 pm Post subject:

That is great news and I'm glad you got it figured out Smile