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I've just completely rebuilt a C20XE head and block with ARP rod bolts, new bearings, piston rings, valves, guides and gaskets. It is running on R1 carburettors, Manta distributor, has the cam cover mod and an oil catch tank. Apart from that its standard.

Having started it today for the first time, I left it idling for a while so I could bleed the cooling system. All well, no leaks, looking good. Left it a few hours then thought I'd go for a little 2 mile drive to start running it in. Gentle and got up to a max of 2500rpm

On return i opened the bonnet to find the inlet side completely covered in oil. The 1ltr oil catch tank was completely full and was evident that the oil had come out from the unblocked outlet and spewed it everywhere. No other leaks anywhere else and engine was running absolutely fine.

Why would so much oil come out of the cam cover? I haven't done a compression test yet but I'm just trying to identify if this a common occurrence or points to something wrong.

Any help appriciated
 

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Hod did you modify the cam' cover - if the opening to the breather has been exposed to oil splashing from the valve train, it will run into the catch tank.
The other thing is, did you remove the check valve in the block and, if so, did you replace it with a restrictor or just leave it open? If the latter, there may be excessive oil to the top end and so more splashing around.

I assume there's no rags, or whatever, blocking the oil drains in the head?
 

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If you cut it too short, then this would apply - "*Now using tin-snips, or a saw or whatever you have to hand, cut the plate so you just leave the end piece by the oil filler cap. Keeping this piece fitted is important, as it stops the cams chucking oil straight out the breather pipes(a problem we are trying to reduce in the 1st place)", as it would open up a path directly into the breather outlet.
If there's a lot of leakage past the rings, then the outgoing gases may carry a lot more oil in the form of droplets or mist, to separate out in the catch tank.

In the top of the block, in the oil feed to the cylinder head, there's a one way check valve that, I believe, is intended to prevent oil drain back when turned off. It can get stuck open, which isn't an issue or be blocked or stuck closed which certainly is a problem. Some people recommend removing it and using a drilled restiction insted, to limit oil supply to the head, if it is removed and left unrestricted, I surmise it's possible to have a lot more oil finding it's way into the valve train area and being thrown around.
 

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Ehm guys, I have talked to a VERY experienced Opel mechanic about this and he knows exactly what the problem is with these symptoms.

The little hose on the cam cover is there for a reason, though the little port that makes it enter the intake manifold is often blocked. The result is there is no vacume on the crank ventilation and the larger hose starts to poo out tons of oil.

To get an allover better performing engine with proper crank breating it is best to drill this bit to 2mm and the result you'll be amazed of!! There is not only better throttle response, but smoother idling and the best part is the breathing system much more effectively removes fumes, water and acidous fumes from the crank case, and in turn makes the oil stay much cleaner.

Many mods I've seen block the little hose and put a filter on the larger hose output of the cam cover. This is a very bad choice!! This disables 90% of the effectiveness of the crank case ventilation system and the oil is very quickly contaminated and sludge formed in massive amounts!

I've done the 2mm drill and I have NO oil on the throttle valve any more, engine runs healthier than ever and the oil stays clean!!

Here's the bit I am talking about:
 

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I accidentally drilled mine to 4.2mm at first and this made it idle at 1100, still not bad, but I still had another pipe and drilled that at the advised 2mm and now it idles fine. Besides, I'd rather have a sludge free good running engine that idles a tiny bit higher...
 

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Yes that's it! According to the Opel mechanic the newer XEV engines have a larger vacume connection as well, though they would use a valve to shut the larger (above throttle valve) breather off in case of under pressure... Don't know this as I have never worked on these engines....

What I do know is that there are by now five persons that reported their XE runs much better with the drilled connection...
 

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Good luck on that mate, took me some cursing and scratched knuckles on working the hose clamps on the impossible locations!! Argh! But it was worth it, even doing it twice!! (read the above)
 

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Lucky bastard!;)
 

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An AA dude reported on the Dutch Opel forum that he managed to measure the difference of the mod in oil acidity. He said practically all Opel engines suffer from the same fairly poor crank case ventilation system and creating (more*) vacume has several positive effects, one is no oil will be forced out the upper breathing hose as long as there's vacume on the lower vacume hose. Logical if you come to think of it, with a closed throttle valve the crank breathing system would be pressurised forcing oil out the top breather. Under vacume it will be sucked in. The other advantage is a more active breathing under idling sucking away more of the combustion fumes and effectively keeping the oil cleaner and lower moisture content....

In time it will save lots and lots of wear and corrosion inside the engine!

And the engine runs a fair bit better!

* With the stock size breather pipe it won't take long for it to become fully blocked, with all the consequences....
 

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I am planning on placing a one-way valve in the larger (top) breather hose to close under vacume and open under pressure. This would allow an even larger diameter at the bottom breather hose while maintaining lowest possible RPM at idle....

I've seen this one:


Not meant for the purpose, but I suspect it will serve this goal. Will report about it if I have tried it!
 
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