Excessive Blow-by on Kama 554

[Bob Rooks]

Well, here's my 2¢ worth, jumping into the foray.
I would connect a manometer (or magnahelic gauge) to the dipstick tube and measure the amount of blow-by pressure; also, if there is a large fluctuation in the manometer reading (at idle) it will be an indication of a particular cylinder problem.
I have witnessed the same symptoms on larger diesel engines that had been run lightly loaded for quite some time, and with relatively low operating hours. The cylinder liners will become "glazed" and un-porous so the piston rings will not have a good sealing surface to be pushed against by combustion pressure. If you have a borescope, you can remove an injector to inspect the liner to see if any cross-hatching remains, and if the liner has an unusually high gloss. The only remedy for this situation (unfortunately) is to hone or replace the liners, since they are intentionally made harder than the piston rings.
Back in the day when I worked for Caterpillar, we would break in newly rebuilt engines on a dynomometer, and when at full load and speed would toss a "pinch" of Bon-Ami into the turbo; blow-by and blue smoke dissapeared almost immediately. I'm sure this practice is no longer used, but nothing I know of can seat rings faster and more efficiently (there were subsequent oil and filter changes also).

I would also seriously consider installing a 3/8" NPT PCV valve between the upper portion of the filler neck (or valve cover) and the intake manifold. It won't hurt a thing.

And FWIW, the brand, weight, and type of lubricating oil used has little to do with short term blow-by solutions.

 

[SPYDERLK]

Well, here's my 2ï½¢ worth, jumping into the foray.

I have witnessed the same symptoms on larger diesel engines that had been run lightly loaded for quite some time, and with relatively low operating hours. The cylinder liners will become "glazed" and un-porous so the piston rings will not have a good sealing surface to be pushed against by combustion pressure. If you have a borescope, you can remove an injector to inspect the liner to see if any cross-hatching remains, and if the liner has an unusually high gloss. The only remedy for this situation (unfortunately) is to hone or replace the liners, since they are intentionally made harder than the piston rings.
Back in the day when I worked for Caterpillar, we would break in newly rebuilt engines on a dynomometer, and when at full load and speed would toss a "pinch" of Bon-Ami into the turbo; blow-by and blue smoke dissapeared almost immediately. I'm sure this practice is no longer used, but nothing I know of can seat rings faster and more efficiently (there were subsequent oil and filter changes also).
And FWIW, the brand, weight, and type of lubricating oil used has little to do with short term blow-by solutions.

Rob, how soon did you change over to the high visc synthetic? If early, your engine may not have broken in properly. I have heard of the Bon-Ami trick - never witnessed it tho. First thing Id try is giving it a hard day on regular petroleum oil of recommended viscosity - with a few stops and starts to thermal cycle it well. It may not be too late to break it in!
larry

 

[3RRL]

Bill, right.
I'd stick with what works for you if you have no problems.

Good info Bob, thanks.
So you think the oil change might not have any effect? I plan to do it anyway since it's at the 100 hour mark. One thing I noticed before, when I did use Rotella 15w40 synthetic, is that the oil pressure got real low when it heated up. The Mobil1 15w50 has always had good oil pressure, hot and cold. But I will try it again since Greg and Jerry seem to think the 50w might be a contributing factor.

It also sounds like you agree to having a hose from the breather run to the intake manifold, except use a check valve, like a PCV valve (Positive Crankcase Ventilation) valve. Is that correct? Scott suggested that very thing on his board too. Although Dave suggested not doing it for reasons he stated, I am leaning towards it. Another thing is that I was advised I didn't need the check valve for the diesel like on a gas engine.

If I can reduce the blow by somewhat with an oil change and a PCV valve connection, I might just keep an eye on things and maybe hone the cylinders and change the rings, valve guides etc. at 1000 hours? I'll do a few things suggested here first to see if any of them make a significant difference. IF the huge Kama starts to run really crappy, then I'll do an overhaul right away.
Thanks.

 

[Bob Rooks]

The reason for the PCV valve is twofold:
1) In a carburetted engine there are times when there is no vacuum, and in rare circumstances, a negative pressure that would be higher than actual crankcase blow-by pressure.
2) To reduce the possibility of a crankcase explosion (hot crankcase vapors are extremely flammable) caused by a backfire in a gasoline engine application. The diesel engine, while less prone to backfiring, nonetheless can happen.

I personally think the oil change will have little effect, if any, on the blow-by issue.

 

[Flyhiflylo]

I'm with you Bob... The oil ain't going to mean crap.

 

[SPYDERLK]

One thing I noticed before, when I did use Rotella 15w40 synthetic, is that the oil pressure got real low when it heated up. The Mobil1 15w50 has always had good oil pressure, hot and cold. But I will try it again since Greg and Jerry seem to think the 50w might be a contributing factor.

I thot Rotella syn was 5W40. That would explain the lower oil pressure. How low was your pressure? How did it vary from low to full rpm? Same ? for the Mobile1. It could be youre running at relief pressure with the thicker oil. Thick oils are bad for engines with tight clearances because the relief pops and not enuf oil flows to the hot spots. Plane bearings have a real problem when there isnt enuf oil getting to them. Hi pressure with thick oil usually means less oil in the tight spots. The thick oil may be preventing your rings from seating well at high rpm too. Give it some hard time on non syn 15W40. If the Hot pressure is more than 10 at idle and 20 at hi rpm that is non threatening. 7-15 would probably still be healthy, but I wouldnt expect that in a young engine.
larry

 

[greg_g]

The diesel engine, while less prone to backfiring, nonetheless can happen.

Please clarify. I don't understand the relationship of this group of words to the preceding sentences.

//greg//

 

[3RRL]

I thot Rotella syn was 5W40. That would explain the lower oil pressure. How low was your pressure? How did it vary from low to full rpm? Same ? for the Mobile1. It could be youre running at relief pressure with the thicker oil. Thick oils are bad for engines with tight clearances because the relief pops and not enuf oil flows to the hot spots. Plane bearings have a real problem when there isnt enuf oil getting to them. Hi pressure with thick oil usually means less oil in the tight spots. The thick oil may be preventing your rings from seating well at high rpm too. Give it some hard time on non syn 15W40. If the Hot pressure is more than 10 at idle and 20 at hi rpm that is non threatening. 7-15 would probably still be healthy, but I wouldnt expect that in a young engine.
larry

Larry, my bad.
I meant to type 5w40 Rotella synthetic, not 15w40.
I'll try 15w40 Delo in it.

 

[Flyhiflylo]

Please clarify. I don't understand the relationship of this group of words to the preceding sentences.

//greg//

Maybe you should read preceding sentences better.

 

[greg_g]

Maybe you should read preceding sentences better.

Is there any particular reason you choose to be so disruptive Fly?

To use your very own words, "That would be a very cleaver (sic) response if I was talking to you".

//greg//