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  #1   IP: 174.62.214.116
Old 05-21-2016, 08:46 AM
Vermonstah Vermonstah is offline
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Seeing Oil Smoke at oil fill cap / tube for first time

Hope all are enjoying a good start to the new season.

For the most part, my season is off to a good start. Lots of projects over the winter, most were "mostly successful" which is pretty good for me. I rarely get it right the first time...

Engine started on the 4th crank, which is typical for my engine after coating the cylinders with MMO per the MMI winter layup. Initially, lots of blue / white exhaust which dissipated after 10 minutes.

But as the engine began to warm, within 5 minutes of starting, I saw oil smoke at the fill cap and removed it to find a steady flow of smoke. Definitely not typical exhaust (CO), it smells like something hot / burning as described elsewhere on the forum.

This level of oil smoke and vapor in the cabin is new for my engine. So I am trying to understand what might cause this sudden increase in oil smoke.

If it was caused by blow-by, I guess I would have expected that to increase more gradually.

I do NOT have a PCV kit. And I can / will install one, but would first like to understand the root cause of this increased oil smoke before I attempt to mitigate it. I don't want to eliminate a symptom that could be masking a more serious problem.

I have attempted to follow the threads on the PCV kits, both from Indigo and MMI. I will admit that I struggled to follow the discourse on the Indigo kit, changing from horizontal orientation to vertical or vice versa. Unless there is a compelling case for the Indigo kit, I always prefer to source my parts from MMI. I must be looking in the wrong place though as I could not find the PCV kit in the MMI catalog and I could not find a pointer to it in any of the associated links.

I have a late model engine which is RWC. I have a sparkling new MMI carb which I did NOT remove, re-build, or touch in any other way over the winter.

I did however remove the distributor to gain access so I could replace the 6" drain nipple that broke off in the block when I drained the water jacket. Timing is close, but likely needs refinement at cruising speed.

For now, I can tolerate the smell in the cabin until I install the PCV kit, but just wondering if there could be a bigger issue here in need of attention.

Thanks for any advice or insights,
Brian
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  #2   IP: 107.0.6.242
Old 05-21-2016, 09:17 AM
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hanleyclifford hanleyclifford is offline
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It will take a few hours of cruising to completely eliminate the "winter oil". Oil gets into the combustion chamber primarily by getting past the piston rings or the valve guides; both are normal wear items. The PCV system is a workaround for the gradual wearing of both. The PCV is good idea and can give you some more time before a rebuild is required. The idea of setting the PCV up vertically is to prevent flow of condensed oil into the manifold or carb. Better that it should flow back to the valve chamber.
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  #3   IP: 97.93.89.70
Old 05-21-2016, 09:27 AM
Dave Neptune Dave Neptune is offline
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Brian, yes it's blowby. I would not worry to much until the engine has a couple of hours on it. Even with the MMO and engine that has sat for a while can have an increase in blowby~~this is really not that big of a deal as long as the gasses get vented outside or better back to the cylinders via a PCV for a better burn and a run out the exhaust.

I have run a PCV for over 20 years now and would not go back under any circumstance. Clean air in the cabin is a must and anything that helps is going to be used to keep crew and dog safe and happy.

My engine was resurrected 35 years ago from being seized when I bought the boat. It does have a low compression cylinder (#4) and the others are close. Rather than rebuild I fashioned a hood for the flame arrestor until I found a PCV that would do the job efficiently and keep the motor happy.

Dave Neptune
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  #4   IP: 99.30.185.198
Old 05-21-2016, 10:16 AM
thatch thatch is offline
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The other side of the story

Brian, Before going the PCV route, I would like to suggest that you re-set the timing to where the factory says it should be (TDC at idle) and see what happens to your blow-by situation. Also, make sure that your slash tube is properly positioned. There are many of us with well warn A4's who are have not seen the need to go to a PCV valve, along with it's almost mandatory adjustable main jet. I am convinced that the root of most of the A4's with blow-by problems comes from adding too much ignition advance. It's a well known fact that as you increase the ignition advance in an engine, you also increase it's blow-by. One of the worst design aspects of our A4's is the lack of easily read, accessible timing marks. In some installations, such as in Catalina 30's, the flywheel pin is completely covered. The only way around this dilemma is to cut a viewing port in the kick panel by the flywheel or to read TDC from the #1 cylinder and transfer the TDC mark to the accessory drive pulley.
Respectfully, Tom
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  #5   IP: 174.62.214.116
Old 05-21-2016, 12:10 PM
Vermonstah Vermonstah is offline
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HC, Dave and Tom,

Thanks for your timely replies. As always, your expertise and willingness to share it are greatly appreciated.

Mostly, I wanted to ensure that I was not seeing symptoms of a more significant issue than blow-by. And I am accustomed to seeing blow-by in the spring from the MMO at winter layup, but this year I am seeing more oil smoke than I recall from previous years. Maybe I got more aggressive with the MMO last year trying to apply a thorough coat to the valves.

Tom - thanks for the heads up on any possible relationship to the timing. Since I removed the distributor over the winter, my default assumption is that I threw it out of timing which needs to be re-visited. I just had not gotten to it yet, since it started so easily so I knew the timing was "close enough" for now. But I did not realize that increased advance can lead to increases in blow-by.

And on my C&C, I thankfully have easy access to the flywheel pin under the companionway steps so I will get on this soonest.

Thanks again.
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  #6   IP: 107.0.6.242
Old 05-21-2016, 07:07 PM
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hanleyclifford hanleyclifford is offline
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Excessive timing advance can cause a lot of problems. That is why I treat it as a specification and set timing with a strobe light.
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