Oil catch tank

[Norfolk chris]

Hi All, after a house move and work projects I have had my project shelved and now have the time to finally get finished.

I am extremely stuck on the oil catch tank situation, unfortunately beyond my knowledge of trouble shooting and trying to read up on the various posts about it I cannot get to grips with the different set ups and really looking for a lamens term feel replies if possible, 

I have a breather from my crankcase which is releasing oil Smokey fumes and when run under acceleration will spit oil out, so I need to get a catch tank fitted, please Could you send me any links to the one I need, and diagram, for where the two pipes connect to on the engine,

1)is it from the crankcase to tank and 2nd pipe re circ back to oil cap, should this then be a vented cap too, or

2)should it be from crank case up to rocker cover ( I think from looking there is a hole that’s got a plug on dash side of rocker cover)

at the minute my cap has a small wire ball mesh and two holes on the underside of the cap which I believe is a vented cap,

with a system that puts oil/fumes back into the rocker do I need a cap with a inlet for catch tank to plumb into? Then based on some reading would I need a unvented cap or block the existing cap as such

many thanks

 

chris

Edited August 15, 2024 by Norfolk chris
More info added

[Peter Bell]

The standard set up with the manifold you have is from the pcv to a connection on the inlet manifold which keeps it nice and simple, works very well. Catch tanks are usually needed when a different carb set up is used. There is a good explanation on Dave Andrews old web site, look at water and oil control. http://www.dvandrews.co.uk/
Ps forget about connecting to the cam cover.

Edited August 16, 2024 by Peter Bell
Missing info

[Sparepart]

Hi, are you sitting comfortably then I will begin.

Don't panic. Go back to basics and work from there. What is going on here ?. If the pistons and rings formed a perfect seal in the cylinders then everything that comes in through the inlet valves would exit via the exhast valves and in the crankcase below the pistons there would be a lot of oil splashing about but no increase in pressure, the air volume wont change because as two pistons travel down, two are travelling up. However, this is not a perfect world, even from new there is a leak of gasses past the pistons on compression and combustion, as the engine wears this leak increases. If the crankcase were sealed there would be a build up of pressure which eventually would blow fumes and oil spray out of all the weakest bits of the crank case, like the filler cap, dipstick, crankshaft and camshaft oil seals etc. Clearly this would not be good. For most of the history of internal combustion engines this problem has simply been solved by providing a vent somewhere on the crankcase, usually in a place where there is a minimum of oil splashing about. The vent pipe would then go into some form of oil trap to "catch" condensing oil droplets before being routed under the vehicle to a position where air flow provides a slight venturi effect to help draw out gasses. Note that with this simple setup there is not really a need for any other vents. In recent times, 1980s-90s the escape of the fumes into the atmosphere is frowned upon, and I think in some markets illegal. Today all vehicles are fitted with Positive Crankcase Ventillation (PCV). This is not complicated, what happens is that instead of the vent pipe simple being routed under the vehicle out to the environment and causing pollution it is routed into the inlet manifold where the vacuum sucks pollution back into the fuel and air mixture for comustion and exit via the exhast which now has the catalytic converter and oxidisers etc. to reduce emissions. However as with many things, it is not quite as simple as that, there are two things that come along with this solution. Firstly to avoid a build up of vacuum in the crankcase there needs to be an inlet vent, which is usually provided by a vented oil filler cap. Secondly the flow of gasses into the inlet manifold needs to be controlled to keep a steady flow regardless of engine load, otherwise the variation of vacuum in the inlet manifold will mess up the carefully metered air/fuel mixture. To do this a "PCV valve" is fitted to the vent pipe somewhere after the oil trap and before entering the inlet manifold. A clever little mechanically simple device that keeps a constant flow as the gas pressure/vacuum varies. So thats it really. If you dont care about pollution then use the old fasioned solution, which is what I think Dave andrews solution, however make sure that if your inlet manifold has a connection for the vent pipe then block it otherwise air will be sucked in. If you want to save the environment, then fit the standard vented oil filler, standard small Sierra oil trap, standard sierra PCV valve and connect the vent to your standard ford inlet manifold where there should be a place to plug it in. In your photos there appears to be a blue pipe that in two of them is connected to a filter and not connected in one photo, I assume this is the pipe that is spitting oil. I think you will find that this pipe is plugged into the block and is the vent pipe and that a previous owner has simple routed to in front of the fan so as to blow fumes and oil spray away under the bonnet. If there is a lot of oil then there probably is no oil trap or PCV valve further down. So simplest for you is to check that any connection point on the inlet manifold is blocked, which it most likely is. Then route that blue pipe to a simple catch can, there are many advertised online. Check that there is no PCV valve because without a vacuum from the manifold it won't work, although if you have fumes spitting out of the blue pipe then likely there is no PCV valve. Note Dave Andrews' warning about avoiding oil syphoning under cornering when you route the pipe to the catch can. The catch can will need to be drained occasionally, so some have a drain tap at the bottom.  Phew, still reading ?  thats enough!!

[Norfolk chris]

Thank you both for your time and directions, I will read through all of the linked blog too

 

Excuse the difference in pictures, it is currently sitting with the filter on, which is we’re the fumes and oil are escaping from under acceleration, 

so my plan will be to fit catch tank, I currently have a 400ml compact cylindrical tank with two connections, sight level and a drain tap.

this does not have a vent on it, the oil filler cap on top of engine is a vented one, but am I correct that this should be vented too? If so do you have a link for one that is correct?

[Sparepart]

Your photo appears to show a standard Ford vented oil filler cap, the one that has vents on the underside of the mushroom and a hole in the middle in which a wire gauze can be seen and an O ring seal on the outside (I think). This is adequate, wash it out with paraffin and let it drain to make sure it's not clogged up. As you are going for the catch can option the inlet manifold will not be sucking any fumes, so no vacuum possible in crankcase, so theoretically no vent in oil filler would be needed, however it can't harm.  Although if your engine gets badly worn or a piston ring leaks badly then you could get fumes and oil mist coming out of the vent in the filler cap. I'd like to think that you would fix the engine before it got that bad. It sounds like you have a good enough catch can. It doesnt need a vent because it IS the vent. That is it is the way that excess pressure is going to escape the crank case. There will be an in pipe and and out pipe. In from the crankcase out to the atmosphere. These should be marked on the catchcan, if not open it up, the IN pipe should go down into the can below a baffle or filter and the OUT should come from the top of the catchcan. As well as routing the in pipe so as to avoid a syphon of oil when cornering (read Dave Andrews) try to position the end of the out pipe where a flow of air under the car will serve to draw fumes out. Do not point the end of the pipe into the airflow under the car because this will blow air against the venting fumes and ruin everything. Something like at a 45 degree angle towards the rear seems practical, if you could also bend the very end to be in line with the airflow like the left half of a "U" then so much the better.

Edited August 20, 2024 by Sparepart
add

[Norfolk chris]

I have fitted the oil catch can, from the crankcase, up to the catch can, then to a new oil cap

 

however it is not liking it

 

pressure is building up and oil was being pushed out of the dipstick so not breathing, I take the cap off the engine and it now does. Have had a mobile tune man take a look today and his thoughts were to swap the pipes over to see if there an inlet and outlet as not marked, but that he would do away with catch can , get a pcv back in and route to oil cap?

could you take a look at set up?

 

New carb ordered as faulty and new inlet manifold gasket as was letting air in so couldn’t get idling

 

also, what do you find best, currently no choke, is it best to have manual choke kit, or connect back on the water pipe?

[phaeton]

Not au fait with oil catch tanks but surely if you are taking a feed from the crankcase to the tank, then another from the oil cap to the tank then that is no difference to putting a straight pipe between them & creating a closed system. Surely one of the pipes either needs to either vent to atmosphere or go into the induction system.

Edited May 2 by phaeton
spilling mustack

[Norfolk chris]

Yep, just don’t know why though it’s still pressured as the new cap is vented? So shouldn’t be “closed” as such, Think I’m going to put original oil cap back on, standard mushroom with vent, keep the pipe from the crankcase going to the catch can,  and use the other outlet to put a filter on and hopefully that will allow to breath as the rocker cover had no issue before, the original reason for the catch can was before it was just a filter off of the crankcase venting to atmosphere ( and all over engine bay ) so now at least oil will be caught but gases can vent and will see how that goes.

[Peter Bell]

Looks like you still have the spring loaded PCV valve going into the block, which is why it doesn't work. either get/make a straight through adaptor or get the older Cortina baffle unit or poke something through the valve to break it.

Also  as above one of the catch can outlets should be open to atmosphere noy connected back to the cam cover.

Edited May 4 by Peter Bell

[Norfolk chris]

The pipe connected to the crankcase used to just have a filter on the end and the vapour / oil mist was coming out of the end, going through different posts it says that the pcv must have been removed for this action to happen as with the pcv in then it wouldn’t let the vapours out?

based on that if there is no pcv in, then if I delete the pipe to oil cap, and put a filter on that connector from the catch tank and standard oil cap back on then it should work as required?

 

 

[Norfolk chris]

Thank you all,  as a bigger part of works today I took off the pipe from the oil cap to catch can and used that outlet to fit the filter and it vents well