Hi

All of our diesels have blowby - some more - some less - even engines with good compression have some blowby.

Blowby only becomes a problem when it causes excessive oil loss and/or starts to quickly gunk up the air filter with oil. Very bad blowby in worn out engines can only be corrected by rebuilding the engine.

That said, if your filler cap will stay over the hole at idle - your blowby isn't bad enough to be a cause for alarm. Just keep the breather hose open to avoid pressure buildup.

If you have an oil separator, it is located inside your air filter housing and you can remove the top and see it. The breather hose will actually plug into the oil separator through the air filter top. If you have a separator, you can remove the air filter housing (take out the filter inself) and wash everything with diesel fuel or a solvent.

Of course you should also check your air filter from time to time to make sure it's not dirty - to insure that the engine is getting enough air for proper combustion.

The thing about trying to check the oil with the engine running - is that it has no meaning. The only purpose of the dipstick is to measure how many quarts of oil are in the engine - and this can only be done with the engine off and all the oil resting in the crankcase.

Good Luck,

Joseph