What colour is yours?

[tomtrout]

I have just drained some engine oil out of the catch tank in my crossflow powered Vixen. I read somewhere that some folks just pour this captured oil back into the engine but having looked at the colour of my oil there is no way that I would recycle it. My sump oil is clean and clear and I'm not losing coolant and the car runs beautifully but the oil in my catchtank definitely has some moisture in it, being opaque and dark grey in colour. There is no emulsified oil on the inside of my valve cover so the source of the "grey" oil I presume is via my crank case during combustion? The question is do I have anything to worry about?

[Dollyman1850]

tomtrout said:

I have just drained some engine oil out of the catch tank in my crossflow powered Vixen. I read somewhere that some folks just pour this captured oil back into the engine but having looked at the colour of my oil there is no way that I would recycle it. My sump oil is clean and clear and I'm not losing coolant and the car runs beautifully but the oil in my catchtank definitely has some moisture in it, being opaque and dark grey in colour. There is no emulsified oil on the inside of my valve cover so the source of the "grey" oil I presume is via my crank case during combustion? The question is do I have anything to worry about?

Are you running 2 returns? if so you have 2 sources..1 is from breather PCV return and other is from your rocker..Older x-flows tend to start to breath a bit heavier as the guides wear in this case you would be more likely to get slightly emulsified oil vapours settling out in the catch tank, especially this time of year, short journeys lack of use etc…No big deal though if it isn't breathing too heavily..I would never re-cycle ejected oil. Also if you have an ally tank chances are it gets condensation internally as well just because they do.

N.

[Hansoplast]

As the bricklayer noted fresh oil is the best for the engine.
And what are the costs anyway.
Engine revision costs 100 times oil. Or do I miss one 0 (nill)

I always change the oil and brake fluid every year (19 years ).
Never missed a beat.

Hans

[magpies]

grey oil in the catch tank is ok (just empty it and clean the tank)....only worry if emulsified oil is found in the engine

[tomtrout]

I don't think I have any wear in my valve guides as they have been replaced and the car has only covered a few hundred miles. I'm pretty sure the source of the graphite coloured oil is via the PCV breather which is designed to vent combustion gases. Presumably part of that process can involve condensing out water vapour as part of the breathing process? I would be surprised if it is condensation associated with the ally catch tank because my garage is warm and very dry but a possibility when running out on cold days.

Hans don't worry, I won't be reusing this oil but I have heard of some systems (not necessarily on the heavy breathing crossflow)where the catch tank is permanently plumbed back into engine, with the catch tank simply acting as an external breather. In light of my observations I don't think I would recommend this approach on a crossflow. I know there are not too many folk on this site running modified crossflows with oil catch tanks but for those that are I was just wondering if you were having the same experiences.

[Dollyman1850]

tomtrout said:

I don't think I have any wear in my valve guides as they have been replaced and the car has only covered a few hundred miles. I'm pretty sure the source of the graphite coloured oil is via the PCV breather which is designed to vent combustion gases. Presumably part of that process can involve condensing out water vapour as part of the breathing process? I would be surprised if it is condensation associated with the ally catch tank because my garage is warm and very dry but a possibility when running out on cold days.

Hans don't worry, I won't be reusing this oil but I have heard of some systems (not necessarily on the heavy breathing crossflow)where the catch tank is permanently plumbed back into engine, with the catch tank simply acting as an external breather. In light of my observations I don't think I would recommend this approach on a crossflow. I know there are not too many folk on this site running modified crossflows with oil catch tanks but for those that are I was just wondering if you were having the same experiences.

The original system just allows a return path from PCV valve back into inlet manifold / rocker cover. As you say the catch tank merely removes this and vents to external atmosphere. All engines breathe and crossflows tend to breath via the top end as well, hence the need to vent the rocker cover. and generally add an additional vent pipe in aftermarket alloy rocker covers. The catch tank will merely be catching emulsified oil / water vapour which is better out than in If it is catching a large amount of oil then it can be a sign of an overfilled engine or too much crank case pressure which is a result of ring wear or badly designed vent system. as you say though if your engine is fresh then it is likely just a result of condensation which is always present in engines. I have seen problems with new engines and new shiny alloy rocker covers not allowing the top end to vent properly

A well designed vent system will seldom need emptying?

N.

Edited by Dollyman1850 on Sunday 28th December 12:38

Edited by Dollyman1850 on Sunday 28th December 12:40

[tomtrout]

I agree Neil but if a tuned crossflow isn't predisposed to spitting out some oil with the crank case fumes then we wouldn't need oil catch tanks would we? I have emptied my catch tank once in about 1000 miles and then it only had about 250 ml of oil in the tank so no big deal for me.

I guess you only have to see the water vapour coming out the end of most exhaust systems, especially on warm-up on a cold morning to realize there is plenty of H20 generated in our precious engines.

[Dollyman1850]

tomtrout said:

I agree Neil but if a tuned crossflow isn't predisposed to spitting out some oil with the crank case fumes then we wouldn't need oil catch tanks would we? I have emptied my catch tank once in about 1000 miles and then it only had about 250 ml of oil in the tank so no big deal for me.

I guess you only have to see the water vapour coming out the end of most exhaust systems, especially on warm-up on a cold morning to realize there is plenty of H20 generated in our precious engines.

Hi Andrew The bit I am trying to get across is that you need to also vent from rocker cover to catch tank. If you don't it can result in excess pressure in crank case and hence more oil expelled. This is because you have removed the PCV valve which controls vacuum to the crank case. Many high performance race x-flow engines run the crankcase vent to the rocker cover and then take a larger vent from rocker to catch tank..In this way oil from crank case gets pushed around engine and instead of being pushed out goes to top of valve gear but still allows vapours to escape…This also means less actual oil gets into the catch tank and less draining required.

1/4 ltr in 1000 miles is more than I would want to be draining.

Have you got a picture of your catch tank.

N.

Edited by Dollyman1850 on Sunday 28th December 16:02

[tomtrout]

The top end of my engine is also vented to my catch tank via a pipe connected to a Burton oil filler cap breather. In the scheme of things a half pint of oil per 1000 miles is probably less than many crossflows burn or leak in half that distance so I'm surprised you think it's an issue.

My catch tank has two inlets plus a filtered breather. I think I can afford an extra pint of oil a year so don't be too concerned for me. I can even oil my wheel barrow with it!

[tomtrout]

Of course I could also raise the height of my catch tank by a few centimeters which might save me 50 pence a year!

[Dollyman1850]

Interesting thread showing the correct way to do it.
N.

http://www.oldskoolford.co.uk/ipb/index.php?/topic...

[tomtrout]

Interesting thread and thanks for sharing.

The bit that I don't understand is where the guy who has fitted the breather in - breather out system to his rocker cover states that his old catch tank used to fill up in no time and since converting to the above his new catch tank hardly catches any oil at all! Presumably in this case the contaminated oil blown out of the crank case is just poured all over the top of the engine, with a tiny amount then blown out via the rocker breather with the majority left to recirculate within the engine. Although very neat looking, I'm not sure that solution offers a better way of making sure the engine breaths for optimum performance or for the long term protection of the engine itself.

As my current set-up doesn't spew out lots of oil (in my opinion at least) then I think I will leave it as it is.

[Dollyman1850]

tomtrout said:

Interesting thread and thanks for sharing.

The bit that I don't understand is where the guy who has fitted the breather in - breather out system to his rocker cover states that his old catch tank used to fill up in no time and since converting to the above his new catch tank hardly catches any oil at all! Presumably in this case the contaminated oil blown out of the crank case is just poured all over the top of the engine, with a tiny amount then blown out via the rocker breather with the majority left to recirculate within the engine. Although very neat looking, I'm not sure that solution offers a better way of making sure the engine breaths for optimum performance or for the long term protection of the engine itself.

As my current set-up doesn't spew out lots of oil (in my opinion at least) then I think I will leave it as it is.

The oil which is getting "blown" out isn't contaminated. The oil vapour is contaminated and mixes with blown out oil in the catch tank so shouldn't be used.
Ejecting the crank case oil into the rocker re-circulates oil so keeps it all where it should be and still allows water / oil vapour to escape via the catch tank in the usual way via a larger diameter breather.

Your set up is mixing blown oil with vapour from another source which means that you can't really re-use it (apart from wheelbarrow lubrication)

Race engines like lots of oil circulating and would fill a 2 ltr catch tank quickly when racing hence the need to do it in a more efficient way.

The guy who has built the engine is part of the south london mob and between them legendary crossflow engine builders.

Ron Harris builds the best crossflows and pinto's around, in retirement now but a true ford legend. His sons are carrying on the tradition.

N.

[tomtrout]

I bow to the superior knowledge of the London mob - I wouldn't want to get my ears nailed to my garage floor!

[Dollyman1850]

https://www.youtube.com/watch?v=IxfAqbwfOsU

N.