blowby F100

[Searider]

Hi ,
I noticed today accidently that I have - I would say quite a lot - blowby on my F100 from 1999 .
The motor was serviced regularly , runs very smooth , has the power as always and reaches 6000rpm @ WOT , does not smoke or consume oil or others - it is just blowing out of the crankcase ..
Have this motor since 7 years and never had trouble . Use it between 50 - 80 hours per year .
I am very much aware about leakdown tests / compression tests etc but have all my tooling in Germany .. ((
We perform such works on medium and large CAT engines .
In the manual I cannot find any indication of how much blowby is within specs ..
Blowby gas hose from the head to the airbox is free .
Has anybody an idea ?
Cheers

[99yam40]

Only way to tell if you have stuff coming out of combustion chambers and into crank case and which piston would be with leak down test.

Hole in piston, broke ring, ring grooves lined up, stuck rings are all things that can cause it.

How are you detecting the blow by?

[Searider]

didŽnt put the dipstick properly in after oil change and noticed when the motor was idling an air stream coming out there .
Pushed the dipstick in and opened the oil filler cap .
With motor @ low idle it was blowing "quite" strongly against my hand .

[99yam40]

with pistons going up and down there will be displacement occurring in the crank case causing some pressure and vacuum.
You may just be worrying for nothing. I have heard of motors blowing oil out of dipstick if not seated properly before
leak down test will show if you have a problem or not

[Searider]

Thanks mate - IŽll run the boat tomorrow on the water - first time after winter break and will see how it works ..
just wondering why I have not seen this ever before cause I an usually very attentive to such things .