New Motor...Blow By?

turboman1

turboman1

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Aug 20, 2008
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Just finished up my motor and have put 70miles (hard miles) on it to seat the rings but it still has what I would call blow by (i.e. whitish smoke coming out the stock breather vent with the motor running). However when the truck is off and the oil fill in the front is open there is some whitish smoke coming out of there, but the motor is not running which would leave me to believe it is not necessarily blow by.

If it is blow by the question is how much blow by should it have after 70 hard miles...none...some? I would have thought by now the rings would have been pretty much seated...judging from what I have read.

Thanks
Adam
 
This is why I always break in with no water. Just keep beating on it. It may take a few hundred miles.
 
Fresh engines will always have blow-by. Like the others said, just keep driving it and as the rings seal, it will ease up on the blow-by. Unless broken in without water, then it shouldn't have much, if any blow-by..
 
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When its running take off the oil fill cap and see if there's actually any blowby(pressure) if it were blowby you'd feel it.....
 
Well when I start it up cold there is no whitish smoke coming out of stock breather (probably because it isn't hot) vent and there is a little bit of air (i.e. not much at all) pushing out of it. The only way to check the oil fill tube for whitish smoke is when the truck is shut off, otherwise the fan just disperses it all to quickly to tell.

By hard miles I mean I hooked it to a trailer after I broke the cam in and then just hammered on it. Unhooked and drove around hammering on it too.

Sorry blackdieselhp I guess I was just to chicken to try it without water (First motor I have ever rebuilt). I know hypocrite for beating on it but being chicken about the whole no water thing.

Can anyone give me a gauging point as to how much air flow would be coming out of the stock breather vent with the truck idling if the rings are seated?

Thanks
 
turboman1 said:
Well when I start it up cold there is no whitish smoke coming out of stock breather (probably because it isn't hot) vent and there is a little bit of air (i.e. not much at all) pushing out of it. The only way to check the oil fill tube for whitish smoke is when the truck is shut off, otherwise the fan just disperses it all to quickly to tell.

By hard miles I mean I hooked it to a trailer after I broke the cam in and then just hammered on it. Unhooked and drove around hammering on it too.

Sorry blackdieselhp I guess I was just to chicken to try it without water (First motor I have ever rebuilt). I know hypocrite for beating on it but being chicken about the whole no water thing.

Can anyone give me a gauging point as to how much air flow would be coming out of the stock breather vent with the truck idling if the rings are seated?

Thanks
Click to expand...

Whats the ambient temp? that determines if I can see smoke at all. I'm starting to think I don't have bad blowby and it was just super cold out.
 
turboman1 said:
Well when I start it up cold there is no whitish smoke coming out of stock breather (probably because it isn't hot) vent and there is a little bit of air (i.e. not much at all) pushing out of it. The only way to check the oil fill tube for whitish smoke is when the truck is shut off, otherwise the fan just disperses it all to quickly to tell.

By hard miles I mean I hooked it to a trailer after I broke the cam in and then just hammered on it. Unhooked and drove around hammering on it too.

Sorry blackdieselhp I guess I was just to chicken to try it without water (First motor I have ever rebuilt). I know hypocrite for beating on it but being chicken about the whole no water thing.

Can anyone give me a gauging point as to how much air flow would be coming out of the stock breather vent with the truck idling if the rings are seated?

Thanks
Click to expand...

Its normal. I know a lot of guys that are afraid to use that breakin procedure. But they always have cam or rings seating issues. It is a tried and true procedure that almost all big engine builders use. When i started building diesels, I didnt hear of any diesel guys doing it this way, so the first two i built, I didnt do it. I had blowby on both for almost 1000 miles. So after that, I have used it ever since just like on a gas engine. No problems since.
 
Jim Fulmer said:
Enlighten me on the now water deal!

Jim
Click to expand...

When you get your fresh engine installed, do not fill with water or coolant. Start engine and bring rpms up immediately to 1800-2200. Hold it there for about 5 minutes(i have went as long as 20 minutes). This will seat the rings and "wear the cam in" faster. after doing this, let cool and fill with coolant. Should be ready to go with no blowby.

A lot of people are afraid to do this for fear of damaging a new engine. If something in the engine fails during this breakin, there were problems somewhere anyway. Just make sure you use a good assembly lube on the cam/lifters and bearings. I have seen numerous people start a fresh engine and let it set at idle. Thats the worst thing you could do.
 
Think there would be any good in draining the coolant and doing like you say?

Adam
 
If you unscrew the oil fill cap, and leave it in place, does it dance around with the engine running? Does it completely blow off?
 
Blacksdieselhp said:
When you get your fresh engine installed, do not fill with water or coolant. Start engine and bring rpms up immediately to 1800-2200. Hold it there for about 5 minutes(i have went as long as 20 minutes). This will seat the rings and "wear the cam in" faster. after doing this, let cool and fill with coolant. Should be ready to go with no blowby.

A lot of people are afraid to do this for fear of damaging a new engine. If something in the engine fails during this breakin, there were problems somewhere anyway. Just make sure you use a good assembly lube on the cam/lifters and bearings. I have seen numerous people start a fresh engine and let it set at idle. Thats the worst thing you could do.
Click to expand...

This is exactly what I do. After it cools I fill with coolant and double check everything. Then I hook a trailer up and go vary speeds on the road for a few hours. I also use a good break in oil and add extra zinc via Lucas break in additive. I then tell the customer at 1000 miles to change the oil out to conventional oil and watch the oil level close for 1000 miles. Ive never had one call saying its using alot of oil yet by this practice.
 
Sorry for the lack of a quick reply but things have gotten really busy and I just got back to driving the truck.

Big Blue, I checked the oil filler cap and it wouldn't even bobble it around. Even putting my hand over the stock breather tube there is not much air blowing out just a whitish smoke. Engine seems like it has really good seal because it gets pretty hard to turn it over by hand (at least more difficult than it was than before I rebuilt the motor). I am beginning to think it is not a blow by issue. Is it possible the oil could just be getting too hot and burning off? Could it be coolant leaking into the oil? I will probably send it off for an oil analysis when I change the oil around 500 miles or so.

Any ideas?

Thanks
Adam
 
Not to hijack your thread too much but what about if you have oil coming out of the blow by tube and breathers at high rpms (3k-5k) but no pressure out of the breathers at idle?

Are the rings gone?

This is a competition motor.
 
I was thinking today and was wondering if the engine assembly grease could be what it is burning off? Truck has about 250 hard miles on it now.

Adam
 
could be, or could just be the moisture in the oil burning off.... If its getting cold then hot then cold moisture will build up and when the oil heats up it will burn it off. It doesnt sound like its causing an issue. esspecially if there is not any actuall pressure being built up in the crankcase. id say a good couple oil flushes/changes and a few hundred more miles with actually running it and working it and your steam or whatever is comin out the pipe will go away.
 
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