Diesel Bell Housing

Post by **syncrodoug** » 20 Mar 2007, 21:26

Why do diesel bell housings have one or two 'snorkels' whereas petrol housings do not?

Post by **syncroandy** » 20 Mar 2007, 22:16

..discuss !

I must say the diesel arrangement baffles me.

Post by **andysimpson** » 20 Mar 2007, 22:39

My theory is the shape of the petrol engine block guarntees a good seal between engine and gearbox so there won't be air getting in so the flywheel can't pump air anywhere and suck water in.

With the shape of the diesel engine block the chances of getting a 100% seal between engine/plate/bell housing is not good, if the flywheel starts pumping air it could get a vacume and start pulling water in, by putting the breathers on they should elimianate any pressure or vacume and then the seal is not as critical.

Post by **bigbluebus** » 20 Mar 2007, 23:10

what do these look like then?

Post by **Russel** » 21 Mar 2007, 07:00

IF the diesle engine and box are fitted correctly with the correct parts then u will have a 100% seal between the 2.The bellhousing even has a drain plug not like the petrols permanent plug.
The petrol breather is incredably small compared to the diesle but then u wouldnt dump a petrol in the water like u would a diesle and diesles tend to be used for a more comercial market(especialy when they were made)

Post by **Aidan** » 21 Mar 2007, 21:13

I have read elsewhere that the idea is to allow the diesel clutch which is smaller than the petrol's to stay cool with an airflow through the housing, whilst keeping it from being drowned when wading, and the drain plug being the manual overide should you drown.
The petrol's effective one way flap at the bottom is to allow oil leaks out to prevent contamination of the clutch (like a landie's bellhousing plug) whilst preventing water ingress in wading situations. The breather hose on the petrol's bellhousing allows for expansion/contraction of air within the bellhousing and maintains a pressure neutral situation thus minimising water ingress in extreme temperature situations, eg hot engine/gearbox in cold water.

Post by **syncrodoug** » 21 Mar 2007, 21:14

Sorry, but it wont go away - why two? Unless it's an in and out for the air flow, but I've got a housing with just one with a plastic plug!
Another little idiosyncracy is that ETOS list two housing 091 301 071D at £371-97 and 094 301 071 at £219-22 - I suppose this may be due to different materials used for the casting, magnesium v aluminium??
Queue Clive......