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Plumbing an oil catch tank
David Jenkins - 6/6/21 at 05:02 PM

I've been thinking that I need to re-visit my oil catch tank setup on my X-flow.

When I used bike carbs I had a pipe from the crankcase to a pot with a air breather filter on top. This is fine, but I made a silly mistake - I used an empty insulated metal bottle as a catch tank. The whole point of a catch tank is to take the oil vapour, condense it, and collect the gunge in the pot, but it was never going to condense in an insulated bottle! The end result was that the vapour went straight through, fouled the vent filter and the chassis nearby. That catch tank has been retired...

At the moment I have a single Weber 32/36 DGV carb with a PCV feeding the oil vapour into the inlet manifold. This works OK, but I'm missing the bike carbs as they're more... interesting. If I swap over (again!) I need to install a catch tank once more - and this time I want to do it properly.

There are loads of catch tanks on ebay (and other places) that have a sight glass on the outside, steel mesh inside, a drain on the bottom, 2 hose connectors, but no sort of vent on top. How am I supposed to plumb these in?

I have an outlet that comes from the crankcase, and a rocker cover filler cap that also has an outlet. If I connect the crankcase to one inlet, and the rocker cover to the other, how will this vent any over-pressure to the atmosphere?

I've had a look at the Burtons website, but I'm still confused... am I over-thinking this? Is it really that complicated? What is the meaning of life? (apart from 42?)

cliftyhanger - 6/6/21 at 05:28 PM

I Teed the crankcase and cam cover breathers (st170) and fed those into a catch tank. The other connection I fed to my air filter. Keeps sucking any smelly fumes. All seems well after a couple of years (though only a couple of thousand miles in the past year, including 2 trackdays and 2 autosolos)

rusty nuts - 6/6/21 at 05:29 PM

I don’t have a breather on my rocker cover , just use a breather elbow connected to one of the pipes on the catch tank , the other pipe is connected to a filter. Obviously I use a breather type oil filler cap and also a fuel pump blanking plate with a deflector which helps to limit any oil being thrown up into the breather elbow

rusty nuts - 6/6/21 at 05:31 PM

2ltr-large-oil-catch-tank

Similar to the one I used

snapper - 7/6/21 at 06:26 AM

You can get baffled catch tank with either a breather cap or desperate filter.
There is an option to connect the crank case breather pipe to the rocker cover then a second pipe from a different location on the rocker cover to the catch tank

David Jenkins - 7/6/21 at 07:54 AM

quote:
Originally posted by snapper
You can get baffled catch tank with either a breather cap or desperate filter.


How desperate does the filter need to be?

(looks like auto-correct strikes again!)

JimSpencer - 7/6/21 at 12:20 PM

quote:
Originally posted by snapper
There is an option to connect the crank case breather pipe to the rocker cover then a second pipe from a different location on the rocker cover to the catch tank


^ This ^

Block > Rocker Cover > Rocker Cover to catch tank > Catch Tank vented to atmosphere (you can get really dinky Breather Filters if you want a bit of bling)

Rationale is that you can get some remarkably think 'mist' out of the block breather when really 'on it'.. get that back into the top of the engine where you want it.. then a separate pipe from the rocker cover to the catch tank deals with just the pukka 'mist'.

Oddly came up on another thread on here the other day too, amazing how many Xflows are still out there!

GaryM - 7/6/21 at 04:08 PM

I'm also running a 1600GT xflow with bike carbs.

I've got an ali catch tank (mounted on the fire wall). It has two hose connectors, a vented cap, sight glass and drain plug.

I've connected the crankcase breather (no pcv) to one catch tank connector and the other to into the rocker cover. My fuel pump is deleted with a blanking plate that has the oil deflector attached.

I'm currently running the engine in, but after 100 miles i've collected nothing but a little bit of tar in the catch tank.

[Edited on 7/6/21 by GaryM]

[Edited on 7/6/21 by GaryM]

Stuart Walker - 9/6/21 at 10:56 AM

I have a T piece on the top of the rocker cover, one side to the breather and one side to the catch tank. Catch tank is an old (single wall) ali bottle with a cheap vent filter thingy on top and a drain tap on the bottom.
Only just getting the engine running nicely so I don't know how well it works at the moment, but this seemed to be the concensus when I looked into it 6 months or so ago. 1300 xflow with DHLAs if it makes any difference.