Blow-by on Fresh Rebuild

[Todd C]

Ok, I don't think it's much blow-by, and its the first or second start on a fresh rebuild, not broken in by any means. Is it normal for a trail of smoke (not really puffing) out the oil fill or dipstick tube? It is a complete rebuild with new pistons, rings, honed cylinders etc. and the rings are not worn in yet. I need someone to tell me if this means anything or not. It will be a while until I get it road legal and get to break it in.
BTW, it sounds and runs nice and smooth!

 

[gatorman21218]

I dont think you should worry. Like you said the rings have not seated and even then this is a high compression engine and some blow-by is exceptable and expected.

 

[Goose_ss4]

if you put a turbo on it, and it does not have a crankcase breather, and the blowby is coming out of the oil filler or dipstick you are pressuring the crankcase. turbo kit usally included a blowby/ breather for the crankcase. after market kit come with box to go by the filler, or if is the turbo from the factory than ford put a breather on the valve cover.

 

[towcat]

wait until you load it heavy and beat it hard can you really tell if there is a blowby problem. Don't let it idle too long in the meantime.

 

[icanfixall]

These blocks are hard cast iron. They have a high nickle content and that takes some work to break in the rings. Its even hard to bore or machine because its so hard. So warm up the motor and make it work. Running it easy or pussing around with it will varnish the cylinders with fuel and oil. You need to get the rings hot so they can burn off the oil and fuel. These motors are made to be put to work out of the crate... Look at a big rig motor... They put them to work earning their way. No babying those motors. Now I don't mean to abuse it either. The really easy way to break in these motors is to hook up a trailer that weighs around 1 ton and drive that around for around 1500 to 2000 miles..... At 2000 miles you wont have a broke in motor but the rings will be much better off than just idleing it or city driving it. Around 10,000 miles is when they are ready... If you baby it maybe never will it be broken in....

 

[gatorman21218]

You could call up our resident redline tester if you want it broken in real quick

 

[6 Nebraska IDIs]

My brown trucks motor steams vapor out the fill hole and the dipstick if they are open, and I'm even running a RDT. My RDT keeps kinking off I need to get a spring to install in the hose to keep it from kinking at the initial bend.

 

[Todd C]

Thanks for the responses!!
Hopefully I'm just being a little paranoid
I really think it sounds good... really smooth running. It was balanced during the rebuild and I gotta say it revs soooo smooth! much better than it was before!
I've got to get it inspected, then maybe I'll get a load of stone or something in the bed around a ton and drive it for a while... sounds like that would be a good way to break it in. In the meantime I'll try to resist the temptation to let it idle... It's been so long since I've had a running diesel

 

[RLDSL]

If I remember, you're in a pretty good area for hills. If you can get ahold of a nice real heavy trailer and spend a day out running the roads , you should do wonders for breaking that puppy in. Don't lug it ( meaning if you can't accelerate to full rpms at 2/3 throttle, then drop a gear and wind it up .you can lug at any speed ), and make sure to run at varrying speeds. This is a commercial grade mid range diesel, it takes a good load to break it in. If you are easy on it, the rings will never seat.

 

[franklin2]

There is a reason for all these recommendations to run it hard. The combustion gases expand the rings out to the cylinder bores. You should not run it hard and constant the first couple of runs, you don't want the cylinders and rings to get really hot. But you do want a lot of pressure to push the rings out and seat against the cylinder bore. It is generally recommended on your first run after it's warmed up, to start out slow and floor the throttle till you get to the speed limit. Slow down and do this again several times to initially try and seat the rings against the cylinder bore.

 

[icanfixall]

An old timer once told me to find a really large parking lot. Use first gear. Rev it up and let it drop back down as your driving thru the lot.... this heats the rings on acceleration and the pressures push them out to the cylinders. Then get off the go peddle and let it come back down. this seats the rings on the back sides. Do this acceleration and decelleration till you go crazy. I like to drive places so I put a load of "stuff" in the bed of my truck. Just ran the tires off it for a long time... I have 530 lbs of compression.....

 

[oldmisterbill]

Gary ShSSSS I tryin to find where you park ur truck at night-near a engine lift I hope!!!

 

[Agnem]

Time to get it timed! C'mon down.

 

[typ4]

Todd, when I did mine we fired it up on a wednesday and left for a trip to wisconsin on the next monday with the camper on and Jeep behind. I have almost no blowby.
Diesels need to be loaded to break in, that is why large shops dyno them before shipment.
And on the balancing, isnt that a nice feeling.

 

[david85]

Really wishing I balanced mine. Probably doesn't matter as much with my gearing but still wish I took the time for it.