GCSS

Hi,my 1997 has new pistons and rings..after 2750 miles,it still uses oil and has blowby.how much longer will this go on for???

infidel

The more you load the truck up and work it hard the faster it will break in.
Driving around empty it might take 15k miles.

GCSS

thats the trouble with these cummins engines....it is amost impossible to make them work hard... they take whatever you give it and ask for more more more!
Im thinking about loading up my Mercedes onto the car trailer and hauling it around....

infidel

You've got some hills in Kentucky right?
A loaded car trailer and a nice long 6% grade will do the job.
Only problem is you have to go downhill (no work) in order to go uphill again.

Diesel Dave2

Got to put a load on her..I don't know if this affects a Cummins..But when dad was farming,he bought a new Massey tractor with a Perkins engine...He didn't worked the tractor hard enough and landed up glazing the cylinder walls..Had to overhaul the engine..

Tate

http://www.mototuneusa.com/break_in_secrets.htm

Some food for thought.

GCSS

well I am concerned about the blowby. Is it normal to have blowby until it's broken in??

patdaly

All diesels have blowby, the key is how much? How much oil is it using?

GCSS

I can feel the blowby coming out of the oil fill tube,
one qt. oil in 200 miles
there is 2800 miles on the motor since the overhaul

Robert Rausch

I've got 291,000 on mine and I think I'm still breaking it in!

totalloser

Mototune moron: Do not follow this advice this guy is a IDIOT with a capital I.

Manufacturer break in procedures vary little, but if you "run it hard" to break in the rings, likely what will happen is the excessive heat friction from break in will overheat the rings and anneal them. This will take the spring tension out of the rings and they will BE RUINED IMMEDIATELY.

If the hone on the cylinders was inadequate to wear in the rings to match the bore, it may be hundreds of thousands of miles before the engine breaks in, since under most operating conditions with modern metallurgy (dissimilar materials-iron vs chrome moly rings) and modern petrochem engineering particularly zn oxide, the cylinders and rings simply do not wear appreciably.

Having said that, blowby is perfectly normal. It is impossible to create a reciprocating piston engine that is free of blowby, though full circle rings (overlapping step ends) cut it down a bit. Also the vacuum pump vents into the crank case, so it can be mistaken easily for blow by.

Oil use can also come from other places though. Bad valve seals for instance. Usually you don't use THAT much oil from valve seals though.

If you are using that much oil from the rings not being broken in, the problem is that the hone on the cylinders was not agressive enough, and it will take quite a good long time to fully break in.

bnold

One quart of oil in 200 miles means something isn't right. Not a break in issue.

Head work done at the same time?

patdaly

Yep, that's what I am thinking.......... I have never had one use nearly that much that was the least bit healthy.

Time to get it back to whoever did the work for a compression test.

On edit, this isn't the one that went down on you in Az. is it?

GCSS

Yes it is the same one that went bad in AZ.
I need to drive the truck more.
I have a buddy who's Dodge uses a qt and then stops... every time.
I need to drive it more to see if this one is doing the same thing.

patdaly

Yep, run it 600 miles and check her. I would think if it isn't puking the oil all over that you would see a blue haze if it were burning that much oil.

You did change out the Injectors, right?