Oil Separator

[AC Cobra]

I fitted an oil separator to the breather on the cam.
I was getting blue smoke, dirty plugs and using quite a bit of oil after I replaced a leaky gasket on the cam.

Did 30 miles with the separator fitted and got 200ml of oil in it.
I know that oil can come back up from the engine so I clamped off the hose from the separator to the cam. Cleaned the plugs(again) Did 20 miles NO OIL in separator.
Also no blue smoke and no dirty plugs. So it would seem that the oil is coming from the cam?

I know this works as a vacuum but I am at the limit of my knowledge.
Has this happened because I have a really good seal on the cam's after replacing the gaskets?
Any suggestions on what to look for?

I did see a post from a guy called Mike who put a baffle on the cam to stop too much oil going into the breather, the mess filter in the cam is OK and in place.
Any ideas???

[Lingen]

AC.
Assuming your cam cover has still got the factory fitted gauze separator and cover plate fitted at the outlet to the carb breather hose, perhaps the gauze is blocked so it can't "Condense" the oil.droplets in the crankcase fumes.
To clean it thoroughly it may be necessary to drill out the spot welds on the plate to get at the gauze. However, if you have access to one of those detergent cleaning tanks with a pump, that garage workshops often have, it could perhaps be flushed clean if it was left in there for a while.
Mike.

[jbuckl]

Having taken a few gauzes out when refurbishing cam covers, I found them to be severely corroded & or gummed up.
Its possible to carry on with a catch tank instead.
But best to cut out & replace the gauze with stainless mesh imho.
However, if the engine is worn, the piston blow-by can be too much to expect the gauze to collect.
This condition invariably leads to an idle that is impossible to set as the engine is seeing too much oil to cope with or burn.
then the only solution is rebuild or use a catch tank to keep the oil away from the intake.

[MandM]

I copied Edd's idea, the factory welds break with a gentle tweak from a screwdriver, but it's no good doing this job after the cam covers have been refurbished for obvious reasons
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[AC Cobra]

Thanks to all for your replies. This is a great forum.
I am going to have to take the cam covers back off. The catcher fills up after 10 miles. So 10 miles = 150ml of oil in the catcher.
Sounds like you all feel the breather mesh is done and needs replace.
Anyone got a link to the stainless steel mess to buy?

I am assuming that the oil is coming from the cam, but could I be wrong and it is coming from the engine? There is good suction on the breather pipe.
Would you expect to see that much oil coming from the engine. At one point I clamped off the hose to the cam and no oil ended up in the catcher but not sure if that is a valid test since it does not take into account the suction.
Could I have messed up somehow when I replaced the cam gaskets?

Seems a lot of oil.....

[Wheelz]

I am assuming that the oil is coming from the cam,................

I would say that's likely the case. Most engines have covered a high mileage, but as cam bearings are not replaceable, the clearance must increase and allow more oil to be sprayed around. Unfortunately as the engine leans back, most oil collects at the back where the breather is. Not the best place to have a breather.

[AC Cobra]

Thanks Wheelz, useful info and does help me to understand and problem solve.
Do you think Mike's idea of a baffle over that area will not help? It should help with the splashing oil. Could it be the oil is not draining away out of the cam case correctly. I don't think there is a valve that opens to drain the oil from the cam.
I do have a spare set of cam's but the best ones were used when the engine was rebuilt. I just wonder if there is something stupid I am not considering or done when I replaced the cam gaskets..
Many thanks

[KOY 23]

I would say that's likely the case. Most engines have covered a high mileage, but as cam bearings are not replaceable, the clearance must increase and allow more oil to be sprayed around. Unfortunately as the engine leans back, most oil collects at the back where the breather is. Not the best place to have a breather.

Really? If cam bearing wear was an issue, the heads would have to be line bored and shells fitted when rebuilding engines, I’ve never heard of this unless the bearing was damaged. My engine was rebuilt by a Stag expert in Surrey and there was no wear in the cam bearings at over 100k miles.
The only time I had excess oil in the cam covers was after fitting an aftermarket carb, an expensive mistake.

[wilf]

Would be interested to know how a carb, any carb, could affect oil drainage from the heads back to the sump? I should be interested to learn the physics of that?

[AC Cobra]

You are correct Wilf physics is the key

Back on Point. Help me understand

The system works in a vacuum?
The cam breather pipe SUCKS gases from the engine?
If that suction is too low it will allow oil to run into the pipe?
In repairing the leak in the cam covers I should have improved the suction?
Does that mean I have a leak somewhere else on the system?

OR is it the other way around, the engine SUCKS air from the cam and my suction is now too good and it is sucking oil as well?

[Wheelz]

Thanks Wheelz, useful info and does help me to understand and problem solve.
Do you think Mike's idea of a baffle over that area will not help? It should help with the splashing oil. Could it be the oil is not draining away out of the cam case correctly. I don't think there is a valve that opens to drain the oil from the cam.
I do have a spare set of cam's but the best ones were used when the engine was rebuilt. I just wonder if there is something stupid I am not considering or done when I replaced the cam gaskets..
Many thanks

When I rebuilt my engine recently I removed the cover plate inside, then removed and cleaned the gauze. I modified the cover plate so it could be easily remove refitted in future.

One member here who changed to fuel injection moved the breather outlet to the other end of the cam cover and fitted an external gauze/flame trap. I think that worked well for him. Maybe he will post and answer?

[AC Cobra]

OK I think I have got this. There are some other good posts on the site dealing with it.
My oil catcher does not have steel mesh inside so it cannot condense the oil. Even if it could would the oil be able to run back into the cam if the gauze in the cam is blocked?
The oil catcher sits higher than the cam so gravity should run the oil back to it . So if I put some stainless steel mesh in the oil catcher as a temporary fix will that work.

I have organized for a garage to clean the gauze by spraying gunk into the breather then dry with air. See if that helps and might save me taking the cam covers back off.

I think this gauze is actually a "fire trap" I did find a thread where an external Rover one was fitter, but again would that work?
Also when I went to Rimmers and searched for Fire Trap it just came up with a pipe. see link.

https://rimmerbros.com/Item--i-ERC9116A

well this is certainly a learning curve!

[richardthestag]

When faced with any peculiar issues I always try to "get it back to factory" if possible. It does sound from your words like your engine in breathing heavily. With a standard setup and a healthy engine running I could remove the oil fill cap and witness a slight drop in rev but no excess "blow" out of the cam cover oil cap.

If your engine does breath heavily and does have standard setup then chances are that it is not long from needing some attention.

Good luck

Richard

[richardthestag]

You are correct Wilf physics is the key

Wilf was right though, there is a drain hole direct to the sump at the back end of each head. It is normal for oil to pool just upwind of each of the cam bearings.

[MikeParker]

AC,
I had a very similar issue. Very high oil consumption but not sure about where the oil was going (past rings and being burnt or out of the breather). I fitted an oil separator and found that all the oil was coming out of the breather. So pouring the oil from the separator back into the sump and no net oil consumption. I was talking through this with Chris Spain (Stag Weber man) and he said he had often wondered if the oil was spinning off the cam shaft and being blown out of the breather. So I made up a plate to go over the cam bearings directly under the breather ... and .. lo and behold...no oil consumption. Since I have fitted that plate I have gone from 1 litre per 200 miles to about 3mm on the dipstick after 1000 odd mile's. See plate below:
20191107_115045.jpg