Catchtank for (x-flow) engine-breather is quickly full--why?

[Comadis]

on my kent-engined kitcar i recognized the following problem:

after a short mileage (60miles) my catchtank has already collected around 200ml oil. (block and rocker-cover are connected to catchtank)

engine: tuned 1700 x-flow, twin-weber, stage2 head, fast road cam. 100BHP on dyno at rear axle.

compression ok, power-output of engine ok, no smoke nor oilburn, "pressure-drop test" shows no failure.

any advice? or do i have to live with that?

[Jon Ison]

Is there a baffle plate behind the head and block pick up connection points, sorry I haven't described very well what I'm trying to ask.

Edited by Jon Ison on Saturday 9th February 09:16

[Comadis]

a baffle in the catchtank? or you mean a baffle on the head or block?

my "catchtank" is a plastic-bottle.

the upper hose which goes to the rocker-cover is connected to union which is welded horizontally on the end of the rocker-cover.

the hose which goes to the block uses the "original" connection on the block by a L-shaped union

[Jon Ison]

I suspect the pipe welded to the rocker cover could be your problem, if it is just an open end into the head then oil will be thrown down it into your catch tank, have a look, you need something there to stop this happening like a plate on the inside, allowing the engine to breath but not chuck oil down it ?

Make any sense or clear as mud ?

[Comadis]

sounds logic.

what i want to point out is, that this top pipe is very small (6mm outside, outlet 4mm).

could this create another problem, evtl . pressure in the system?

[Jon Ison]

I don't profess to be a x-flow expert, I'm sure one will be along but it sounds to me that this could well be the cause of you issues, the engine needs to breath but you need to stop it pushing oil out at the same time. That does sound small for a breather pipe.

[Comadis]

interesting is that the car is running like that since 17 years!! ( around 10000miles now) before it went into my ownership a few months ago. bought it from the 1st owner.

[Robertf]

Check with the last owner if you can. Maybe he's just lived with it, pouring the oil back into the engine after each drive.

[Sam_68]

For what it's worth, tuned Crossflows do tend to blow a bit of oil out of the breather, in my experience, particularly when you use a lot of revs.

Remember that you're often running an engine that was designed for max. 84bhp and (more importantly) a maximum of 5,500rpm, at 120+ bhp and 7,000+ rpm... and your probably using more revs, more of the time than Ford ever intended. The breather system tends to get a bit overwhelmed when you place those sorts of demands on it.

[Comadis]

..yeah..i rev the engine often bewtween 5500 and 7000....

anyway...i recognized yesterday, in my opinion the major fault:

the oilfiller-cap which has been used is completely closed. and as i understodd the engine needs to "such" some air somewhere and exhaust it somewhere else. with a closed cap there is no airflow and increases the oil-volume which comes out the breather. is this correct?


can you recommend an alloy-catchtank for a reasonable price and name a suplier?
found some at ebay but wondering if these have a baffle-plate inside, underneath the inlet. anybody knows?


http://cgi.ebay.co.uk/Oil-Catch-Tank-New-9mm-and-1...

http://cgi.ebay.co.uk/OIL-CATCH-TANK-SQUARE-SILVER...

Edited by Comadis on Sunday 10th February 09:17

[Sam_68]

Try speaking to Burton. They won't be the cheapest, but they have long experience of the Crossflow engine. There's a good section in their catalogue covering engine breather system fundamentals, too, so get hold of that if you don't already have a copy.

[Comadis]

i´m already a client at burton...but these catchtanks are too expensive for my valet...i mean they are perfect made, well known brand and also suitable for race aplication. but for my application-pupose a bit too "good".

[Martin Keene]

Form reading the above you seem to be saying that the crankcase and cylinder head are both going to the catch tank via seperate pipes? If so that will be a large proprotion of the problem.

Most of the oil comes from the crankcase. The accepted method for plumbing the breathers on modified Xflow is as follows:

Crankscase > Rocker Cover > Rocker Cover > Catch Tank.

Idealy the feed from the crankscase and the return to the catch tank need to be at opposite ends of the rocker cover. The theory goes that most of the oil being breathed comes from the crankcase so by feeding it into the rocker cover first most of the oil will fall out of the air and return to the sump.

Mine has been plumbed like this since day one and I can't remember the last time I emptied mine...

Another possibility is it has too much oil in it. But, I'd correct the breather system to the above before worrying about that.

[Comadis]

@martin:

this sounds interesting. but never heard of that or seen anything on other cars.

yeah you are right: i´ve 2 seperate hoses to the catchtank: one is comming from the crankcase and one from the rocker-cover.


so this means now: i need an oilfillercap to allow the engine sucking air, connecting the crankcase to the rocker-cover and using a big outlet on the rocker-cover towards the catchtank?

Edited by Comadis on Sunday 10th February 14:02

[Martin Keene]

Comadis said:

@martin:

this sounds interesting. ut nevcer heard of that or seen anything on other cars.

yeah you are right: i´ve 2 seperate hoses to the catchtank: one is comming from the crankcase and one from the rocker-cover.


so this means now: i need an oilfillercap to allow the engine sucking air, connecting the crankcase to the rocker-cover and using a big outlet on the rocker-cover towards the catchtank?

Yep, but you don't need the oil filler cap to allow it to suck air. My catch tank feed actually comes off my filler cap. It will be able to get any air it needs via the outlet hose.

[tribbles]

My XFlow locust had the crankcase and rocker cover joined with a T-piece, with the third going to a catch tank.

http://locust.tribbeck.com/niceday/DSCF0477.JPG 
http://locust.tribbeck.com/niceday/DSCF0475.JPG 

You can see the rocker cover, and the T-piece; the crankcase goes through a standard XFlow breather.

[Mr2Mike]

Comadis said:

the oilfiller-cap which has been used is completely closed. and as i understodd the engine needs to "such" some air somewhere and exhaust it somewhere else. with a closed cap there is no airflow and increases the oil-volume which comes out the breather. is this correct?

No, because you already have a breather hose connected to the rocker cover which the engine can "breathe" through. The oil filler cap is not supposed to have a breather in it on the original crossflow.

If you really feel you must have one, then the later Valencia/HCS/Endura engines used in the Ka, Fiesta and Escort etc. have a filler cap that also houses a breather and oil trap. They were available at Halfords last time I checked. However, they are rather tall, so if the original cap is close to the bonnet you may have problems.

Make sure the hose from the crankcase breather is running "uphill" as much as possible so the majority of the oil has a chance to run back into the sump before getting blown into the catch tank.

[Comadis]

thanx a lot for you help and inspirations.


i´m not sure about the t-piece solution as i think the vapour goes the easiest way and this will be towards the catchtank--> so same problem.

connecting the crankcase to rocker cover sounds as the logic one.



after another test run today (around 40miles), with a "new" 4mm breathing hole in my oil-filler cap, the catch-tank was again full (!!!)...750ml!! hmmm.....

1st thing on my "to do" list for monday:

1. fitting 1 new union on my rocker-cover to connect the crankcase breather-pipe.

2. enlarge the outlet on the rear of the rocker-cover towards the catchtank.


another thing:

isnt it necessary to use the oringal valve on the crankcase breather..somebody told me it "only" opens with a certain pressure..and if it was removed it should be logic that the engine "spits" a lot of oil through it?

Edited by Comadis on Sunday 10th February 23:28

Edited by Comadis on Tuesday 12th February 20:37

[Mr2Mike]

Are you using the original mechanical fuel pump? If not, then you can get a blanking plate that includes a splash shield on the inside to help stop oil leaving the crankcase breather.

[Comadis]

i´m using the original, mechanical fuel pump.

i remember on my pinto engine there is a small "box" fitted to the crankcase where the breather-hose comes out.

on my x-flow engine such a "box" is missing and the hose is connected directly by an L-shaped union (which comes out the crankcase)

don´t the x-flow engines have such a box fitted originally too? maybe i can use one of my pinto engine, as i would have a spare in my stock.

check out here: (the L-shaped union which i mean looks exactly like mine):

http://www.locostbuilders.co.uk/viewthread.php?tid...

Edited by Comadis on Monday 11th February 10:35