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Old 10-14-2004, 10:54 AM
David Kippen David Kippen is offline
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Question Excess Crankcase Pressure

I have a 1952 Palmer Hercules flat-top which is, I've been told, very similar to the Atomic 4. The motor is used on a 28' wooden fishing boat built in 1924 and runs great, but according to the power curve should reach maximum torque at about 2800 RPMs. Here's the problem: when I go above 1800 RPMs I start to get blow-by from the crankcase venting out of a crankcase vent. What can I do to either redirect this vent or (better still) reduce the blowby above 1800 RPMs?
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Old 10-14-2004, 11:40 AM
Bill Bickley
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Take a look at the crankcase ventilation system offered by Indigo Electronics. Don't know if would work on your engine, but it is highly regarded by those who have installed it on an A4.

Hope this helps.

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Old 10-14-2004, 04:40 PM
Vrudik Vrudik is offline
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Smile Excellent Result with Indigo's Kit

I have now run for one season after installing Indigo's PVC filter kit on my Atomic 4 and the results have been excellent. I had excess fumes from the crankcase tube that came originally with the A4 and depended on the fumes being sucked into the carb through the spark arrestor. My A4 has the original Bendix/Zenith carb and installation was simple and uneventful. Go to for details and ordering.

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Old 10-15-2004, 02:08 AM
ericson_35 ericson_35 is offline
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Blow by

I agee (as I stated in another post) that the Indigo kit is a good after market item for 75.00. But excesive fumes from the breather sounds like some compresion blow by due to worn rings, loss of cylinder honing, glazed cylinders, etc. A compression check is an easy way to test for worn rings. Also, what type of oil are you using? Mr.Moyer recomends straight 30W I bleieve
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Old 10-15-2004, 11:03 PM
dduelin dduelin is offline
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Clean the rings

Like Don has stated in the newsletters, blowby is the sort of thing that just gets worse with time. The oil ring and compression rings get crudded up with carbon and gummy residue from the blowby and lose even more ability to seal against the cylinder walls, so there is more blowby, so there is more crud in the rings, more blowby, etc.... a vicious cycle it is.

Don, and others, have stated how the extreme Marvel Mystery Oil treatment can help clean the rings and give them back the ability to spring out and seal again. By sealing the pistons in the bores, the blowby is reduced or eliminated. A crankcase full of MMO and running the engine no load for 10 minutes on 2 or 3 successive days, then changing the oil out a couple of times before filling with 30 wt. again is what I have read Don and others do. Of course, if the rings and/or cylinder bores are truly worn the engine has to be rebuilt to regain cylinder pressures again, but this should be shown by low cylinder PSI's even after the MMO treatment.

I had this blowby problem early on in the 6 years I have owned my A4 and I had good PSI's - all over 108 and within 10% of each other and consistent each time I did the annual compression check. I installed the Indigo PCV valve kit a few years ago and got good results. The smoke and fumes that filled the cabin went away. After about 500 total hours I was getting blowby again despite the exhaust recirculation valve ( Indigo kit). My blowby had advanced past the point where the Indigo kit could stop it. Early on, my oil consumption was about 1 ounce of oil an hour. At 650 hours it was up to 2+ ounces per hour. My total engine hours start from when I first bought my Morgan 30 and installed an hour meter, I do not know the total since a rebuild in 1992.

About this time I helped my friend yank and rebuild his A4. I got to see first hand the cruddy rings on his pistons. The crud filled the machined spaces the ring fit in around the pistons. MMO soaking did little to clean and free them, but the most amazing thing happened when we squirted ordinary brake cleaner on the rings. The gummy crud just melted away and the rings became free again. I began to think about how I could get brake cleaner in my engine while still in the boat. I had nothing to lose.

I removed the spark plugs and rotated the crankshaft by hand enough to place the cylinders down somewhat in the bores. With the little tube on the brake cleaner spray can I filled each of the cylinders with cleaner. I did this over three days and tried to keep the cleaning fluid standing in the cylinder all the time. It would drain out or evaporate of course, but I kept spraying more over the days. I hoped that when draining down it would trickle past the rings and loosen the crud. I used two complete cans and part of a third. Finally I pumped out the oil, refilled with new oil, and pumped out the new oil twice and replaced a third time with new 30 wt. After warming her up, I checked the PSI's and found very little change, but I had good ones ( 110-120 PSI) to begin with. I was optimistic about the rings cleaning up because I could not really see exhaust smoke anymore, not like before. I keep an oil log, so I began to watch my oil comsumption. My recorded oil consumption dropped from over 2 oz/hour to 1/2 oz/hour!.

This was about 110 hours ago and I am still using oil at the 1/2 oz/ hour rate very consistently. If someone else told me this story I admit I would probably not entirely believe it, but it worked for me.

Dave Doolin
1969 M30 Angel's Wing
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Old 02-16-2009, 03:06 PM
RandyO RandyO is offline
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Excess Blow-by

In searching this forum, I found this post by dduelin which has the same symptom as my engine (early model):

OK compression (all ~100 psi)
Have a working Indigo Crankcase Ventilation System
Still getting exhaust smoke wafting around my engine compartment coming from the outlet where the PCV valve connects to the block.

dduelin's post indicates that he solved the problem (posted in 10/2004) by putting brake cleaner into each cylinder, allow it to soak through several times followed by several oil changes.
(I also seem to have reduced power under load. I can't get the boat over 4 knots. I'm not sure if the two are related.)
Does this forum have any opinion of the chemical treatment of the piston rings?
Randy Olson
1972 Yankee 30
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