Blow by

[mrb2001]

I have a stock 7.3L that has a lot of blow by. it has enough that it is pushing oil out the dipstick tube. the ccv is not plugged. If you plug the tube for awhile then open it, it blows white smoke for a minute then the oil starts bubbling out. did a compression test and a leak down test and everything seemed fine. there is no diesel in oil or diesel in coolant. Is there anything else that could cause the pressure to build in the crank case? Any input would be great. thanks

[purplehorn1977]

also check the seals in the turbo this could be part of your problem that its forcing high pressure exhaust or fresh air into the oil thru a seal in the turbo center section. have seen that a few times on the 7.3's

[away]

Originally Posted by purplehorn1977

also check the seals in the turbo this could be part of your problem that its forcing high pressure exhaust or fresh air into the oil thru a seal in the turbo center section. have seen that a few times on the 7.3's

How in the world do you check that?

[purplehorn1977]

the easiest way is to remove the turbo and put the oil feed supply hose into the turbo oil drain. then start it up and let it idle and see if the blow by is lower if it is then that is the problem. then either rebuild the turbo or get you a better one. also look for oil to leak out of the center sections into the fresh air or exhaust sides can indicate this also.

[mrb2001]

Are you saying there is a supply and return line for the oil going to the turbo and to check it remove the turbo and connect those two lines?

[purplehorn1977]

no there is an oil supply line in the top of the turbo and then there is ther turbo pedastal that has a drain in it to the block. pull the line off and then remove the turbo. install the line into the drain in the block and then start the truck this way ir will still flow oil but wont go every where it just returns back to the block. then run it and check your blow by the best way is to have it warm as thats when the rings seal the best. yes the exhaust is going to go into the engine bay but not a big deal. if the blow by is less then the turbo is the problem. if its not then you must start looking into other causes.

[mrb2001]

On a 7.3L i thought the only way oil got to the turbo was from the pedistal it sits on.

[purplehorn1977]

yes you have to put a piece of line to make a loop in the system. sorry if i cornfused ya

[mbahr22250]

Originally Posted by mrb2001

On a 7.3L i thought the only way oil got to the turbo was from the pedistal it sits on.

The oil returns through the pedistal.

[mrb2001]

I got ya, pull turbo put a line from one hole on the pedistal to the other for oil flow and see what happens.