water in the oil

[mvaughn]

I have a new 88' 4.3L OMC, (new due to a previous freezing) new manifolds ect. Continues to get water in the oil, apprx. 2 quarts after 7-8 hours of use, at trolling speed. Engine now in many pieces, with all casting having been pressure tested, and all checked good. All gaskets appeared to have a good seal upon disassembly. Any ideas, before I reassemble and hope for the best?

 

[fdnytoneny]

Re: water in the oil

sounds like you may have a crack or worn cylinder wall.. are the heads off if so have them magnafuxed this detects cracks you cant see i say heads or cylinders .. Im not a mach.. but Ive been there.. good luck..

 

[mvaughn]

Re: water in the oil

everything has been magnifluxed, and checks good, no cracks. It's back together now, going to run it this weekend, I'll let you know how it goes!

 

[Greyhound24]

Re: water in the oil

Did u use sealant on the Head bolt threads ? I recently had a valve job done on my OMC 3.0L and the "mechanic" neglected to do this. Water leeched into the oil after one boating trip and had to have it all cleaned out. I'm suing him in small claims court.

 

[mvaughn]

Re: water in the oil

Must have been a bad head or intake gasket that I didn't find when I took it apart. After rebuild, I took it out for a short break in( about 2 hours) and no signs of any leakage! Thanks for the help!

 

[4 Reel Pleasure]

Re: water in the oil

Had same problem with my 165 merc Found that wall between manifold and riser had deteriorated and had to replace both. No problem since. might want to look to see that walls inside haven't deteriorated from the inside.

 

[mvaughn]

Re: water in the oil

ok, back at it again. After a 7 hour fishing trip ( at idle 99% of the time). About half a quart of water in the oil! Keep in mind, every thing has been pressure tested and magnifluxed, complete rebuild, with new omc 1 piece manifolds. Engine temp is a consistant 110 degrees, I've been told this could be the problem, exhaust manifolds not getting hot enough to evaporate any water that get's into them? Seems like a long shot to me. Any ideas of where I should direct my efforts?

 

[Coolerman]

Re: water in the oil

Isn't 110 degrees a little cold? What degree thermostat are you running? I always thought marine engines needed to run at least 130-180...

 

[mvaughn]

Re: water in the oil

It is the original thermostat, your right, most i've seen run warmer 140 or so? I figured it was worth a try. I have ordered a replacement to try out, it is a 160 degree. Should be in this weekend.

 

[akriverrat]

Re: water in the oil

sounds like it could be reversion from to much cam overlap. stock marine cam? how high above waterline is top of riser when you're trolling with everyone in back?

 

[mvaughn]

Re: water in the oil

Stock marine cam. The manifold and riser are one piece, the top is about a foot and a half above the water line with all the gear and people, at idle.

 

[akriverrat]

Re: water in the oil

what is sea state on yor fishing trips? how new is this engine? i have seen some discussion that the roller cam engines are on the edge with the cam overlap and the lower the engine speed the more likely you are to get reversion. friends zz4 would get that much water on the hose in 5 minutes till he figured out mods to stop it.

 

[flashback]

Re: water in the oil

good luck

 

[mvaughn]

Re: water in the oil

Akriverrat,<br />Typically waves are calm to 3 feet. The engine was purchased new in 2000' it however did not get much use till this sping, 40 hours or so. Last month, was a complete rebuild, rings, bearings, valve job, milled heads ect. Now the engine has about 10 hours after rebuild. Yes, it is a roller cam engine. To make sure I understand, are you saying the exhaust valves are staying open at the start of the intake stroke, thus causing water to be pulled in from the exhaust manifolds? If so wouldn't I be able to see white smoke while running on the muffs, or at least some poor performance under load?

 

[akriverrat]

Re: water in the oil

amazingly-no. what i have been reading about the roller cam engines is they pushed the overlap to the limit.above idle operation gives the exhaust enough velocity that the water keeps going out. it is prolonged slow speed that is the problem. any water that gets in the cylinder that flashes to steam is recondensed in the exhaust cooling water befor it comes out the back. if it goes by the rings it condenses in the engine, usually inside the valve covers. that is my understanding of it all anyway.

 

[mvaughn]

Re: water in the oil

Then it seems in order to correct the problem I shoud get or alter the current cam sproket so it can be degreeable. Seems as if it would need to be "retarded" stightly? In your readings have they mentioned what degree will correct the problem? Thanks

 

[akriverrat]

Re: water in the oil

i have told you everything i know about it except how we got the zz4 fast burn to quit doing it. that involved welding to the exhaust manifolds. brand new aluminum center rise. don't think it would apply to old saltwater aluminum or cast iron. cheaper fix may be to just get trolling rpms up a bit by using happy troller or hydrotroll or trol-a-matic type device. you may be able to get rpm up just by trimming up your outdrive or using ventalated prop. changes to your cam timing are going to affect top end too. i am not to great on the theory, but isn't overlap determined by the spacing of the lobes when the cam is ground? BTW, are your exhaust flappers in good shape? if i can remeber where i saw this discussion on reversion i will post it.

 

[mvaughn]

Re: water in the oil

Does make sense, it should come from the grinding. Degreeing would only change the relationship to piston stroke. The flappers are in good shape. I thank you for your time and efforts! If I ever get it figured out, I'll let you know what the fix was! Thanks again!

 

[akriverrat]

Re: water in the oil

"All the major marine engine makers -- Mercruiser, Volvo, Crusader, et al -- build their engines on GM big blocks which have considerable valve overlap. <br />While this allows the engines to run more efficiently and produce more power at high rpm levels, it also allows them to aspirate water because the intake and exhaust valves stay open during the start of the intake stroke. <br /><br />This is a big problem for all makes of engines built on the GM blocks. You might want to search the forums for earlier discussions of this topic. Also, I wrote about water ingestion in the December 2002 issue of *BoatU.S. Magazine.* Please e-mail me (CAjootian@BoatUS.com) if you'd like to get a copy." from boatus forum.

 

[mvaughn]

Re: water in the oil

After you mentioned that I did a lot more research on the overlap as well. And looking back on other Marine engines I have worked on. It is clear that this is a problem for many boaters, weather they are aware or not?? <br /><br />The new thermostat runs about 180 degrees. This has "bandaged" the problem, I am certain the water is still being introduced through the valves, however it no longer appears in the oil, as it is now being evaporated. This being said, I have little faith that top end will have a long life span.<br /><br />As you have mentioned, this occurs in most engines currently manufactured. The question is, Why would you continue to produce engines, knowing that the valve overlap will ingest water into the engine, thus shortening the life span? Is it calmly written off as "the nature of the beast"?