QuestionQUESTION: I have a customer , I rebuilt his engine about 6000 miles ago . He called me with the complaint of blow by . Only under a load . I went to the local Detroit dealer and watched this engine on the wheel dyno . As the truck accelerates there is no problem but when it is loaded all of a sudden the blow by gage is blown out of the oil fill tube and oil is sprayed 10 feet . When you back off the throttle the smoke and blow by goes away in about 20 seconds . The smoke coming out of the blow by tube is not huffing it is a steady stream . I'm sure you know on the EGR engine the fresh air for the compressor comes from the breather it isn't on the pressure side of the turbo .
Looking for some guidance here . I specialize in building heavy diesel engines , this is a first for me . I have built hundreds of engines over the last 30 years . This the first 14 liter I have built , I do understand that often times it takes them a while to seat the rings .
Also before the blow by gage blows out it is a steady 3 to 3 1/2 bars . Then all of a sudden it goes off the scale .
Thanks , Cliff
ANSWER: Does the motor run rough when the blow by starts. The things that come to my mind is check the blow by tube make sure its not pinched or anything. A lot of freightliners I deal with if the tube gets pinched it will start huffing oil out of it. Another thought I had is what about a head gasket leaking between a oil galley and the cylinder causing too much pressure. I'm with you the only way I see the pistons causing it would be one of three ways a ring has broke, which I don't think or it would do it all the time not just under load. two a ring has been put on upside down or they were not staggered gaps on installation and sounds to me you have enough experience that I would doubt that's happened.
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QUESTION: We are pulling the head tomorrow . This engine is in a Western Star tri axle dump . The blow by tube is unobstructed for sure . Also the valve cover has been replaced due to a small crack leaking oil . We replaced the compressor and it made no difference . Detroit's help line suggested it might be the compressor . The next step is the head gasket , it was suggested to check the compression but I don't have a way to check it on the 60 series engines . I thank you for your help , if you will respond back I will let you know what we end up finding on this engine .
ANSWER: By all means let me know what you find out maybe we all can learn something. A quick way i'v used to check for compression or a bent valve is to take a blow gun with a hose and rubber tip and blow air in through your injector cup hole. Wont tell you if its in specs but if the rings are seated good it will spin the motor around to the bottom of its stroke.
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QUESTION: After removing the cylinder head today , I found a blown head gasket . It was to late to stop at my machine shop to check the head . It was blown a little between all cylinders but between 4 and 5 there was a chunk gone . The liners were intact , no visible damage . After I check and resurface the head I am also going to check the liner protrusion . I don't think it should be a problem . The block we rebuilt only had about 90,000 miles on it and the counterbore was absolutely perfect on it . The Original engine had lost oil pressure and wiped out 5 mains and 3 rods . We felt it was better to replace the shortblock . I am still unsure why this engines head gasket failed . One thing that is crazy is that it has never lost a drop of coolant , all the compression went to the crank case . The owner says his driver never ran the engine hot . Tomorrow the straight edge will tell that story .
I will keep you informed on what happens .
Thanks , Cliff .
Advantage Engines
AnswerWe had a similar thing happen to us to except we never lost coolant but it sent all the pressure to the cooling system. We had Detroit tell us that it's common for these 60 series with egr to blow a head gasket. Their number one problem with the newer engine is getting it hot they don't like it. Not saying this driver did our driver said the same thing he never got it hot.
