D5 buying advice - smoking engine from dipstick

wysiwyg · Post by **wysiwyg** » 02 Jul 2012, 15:49

So ive just been to look at a 2004 V70 2.4 diesel, drove ok etc but smoked a lot from both engine oil cap and the dipstick. Some people say this is normal, but looking for confirmation. Smoked a small amount on start, and quite a lot after 10 mile run.

Car done 102k allegedly new engine at 80k, the replacement having done 8k.. reason unknown

Post by **jimmy57** » 02 Jul 2012, 17:27

The rules for gasoline engines do not apply to diesels. The gasoline engines have vacuum in intake manifold to draw vapors through the system that diesel engines do not have. The diesel will have a crankcase depression regulator device to assure a stopped up air filter will not pull a vaccum on crankcase and pull oil out that could cause a runaway engine. The hose from the CDR goes to hose between turbo inlet and air filter. When the engine is under some load and turbo boost is produced there will be enough air flow to cause a faint pressure drop behind air filter and the vapors are pulled out of crankcase. Until that point the vapors free flow through that hose and any other opening you create like disptick or oil filler cap.
The DCR is washed or replaced at some interval so if you buy that will be your equivalent chore to PCV system clean or replace but it should be readily accessible and not under intake manifold as with gasoline versions.

Post by **jimmy57** » 02 Jul 2012, 17:30

http://www.volvoforums.org.uk/forumdisplay.php?f=113

This forum seems to be fairly active and has diesel discussions.

westdouglas · Post by **westdouglas** » 03 Jul 2012, 21:57

I own and operate diesel equipment and this is correct. Diesel engine should not, as a rule, build up any positive crankcase pressure. One of the ways to check for a blownhead, head gasket,bad rings etc is to block off the oil vent tube and then take the oil filler cap off turn the cap upside down and place on oil fill opening and see if the engine produces enough positive pressure to push cap off opening (take in consideration the vibration please). The diesel equipment that I work on can be left running ( not recommended ) while being fueled without throwing a million DTC's try and do this to a gasoline engine and you will be sorry you did.