Crumpets
Chats A Bit
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Posts: 227 
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Post by Crumpets on Jul 30, 2021 22:17:38 GMT
did what I suggest improve anything ? :-)
I think it's safe to say that it has been solved.
I replaced the PCV with a barb, and blanked off the rearmost port on the rocker cover.
So far, around 350 miles in, and running a higher boost pressure than I was previously; the catch can level has not moved. (Whereas before it would have required emptying multiple times by now)
(EDIT 10/09/21 - +750ish miles. Still all good, haven't had to empty the can.)
Thank you for all who gave advice. I'll keep this post up in case it helps anyone else in the future.
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Post by dadbif on Jul 31, 2021 6:19:59 GMT
Excellent result, the power of the forum
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Post by grahamc on Oct 20, 2021 9:17:45 GMT
Sorry to bring this thread back from the dead, but I'm having the exact same problem on my car with the same catch can. I'm using the regular valve cover and no PCV valve. Both breather hoses are going to ports 1 & 2 of the DaveFab catch can, and the third port on the can is VTA.
The catch can is filling up alarmingly quick (full in 50 miles) and the breather 'smokes' on idle. Now, the engine was built (by me) recently and I had attributed the problem I was having to incorrectly installed piston rings or too large of a gap, but your post made me think otherwise. You appear to be having the exact problems I am but on a 'standard' engine.
I'm also seeing oil being pushed out of my dipstick under boost, which indicates the crank case pressure is too high? I don't particularly want to pull the engine out and tear it down, but will if I have to.
I saw you 'solved' the problem by blocking off one of the ports, but can anyone explain why that was necessary and if by doing that it would introduce any other issues? Seems like the design of the catch can is meant to work with both ports, and seems counter-intuitive to do this.
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Post by atlex on Oct 20, 2021 12:50:21 GMT
Sorry to bring this thread back from the dead, but I'm having the exact same problem on my car with the same catch can. I'm using the regular valve cover and no PCV valve. Both breather hoses are going to ports 1 & 2 of the DaveFab catch can, and the third port on the can is VTA. The catch can is filling up alarmingly quick (full in 50 miles) and the breather 'smokes' on idle. Now, the engine was built (by me) recently and I had attributed the problem I was having to incorrectly installed piston rings or too large of a gap, but your post made me think otherwise. You appear to be having the exact problems I am but on a 'standard' engine. I'm also seeing oil being pushed out of my dipstick under boost, which indicates the crank case pressure is too high? I don't particularly want to pull the engine out and tear it down, but will if I have to. I saw you 'solved' the problem by blocking off one of the ports, but can anyone explain why that was necessary and if by doing that it would introduce any other issues? Seems like the design of the catch can is meant to work with both ports, and seems counter-intuitive to do this. Given your dipstick is popping out it could well be your rings are still not bedded in and you have excess blowby. with VTA there should be enough 'outlet' to avoid that, which must mean there's a *lot* of blowby. I'll try to write as few words as possible to express this.... (I laugh writing this) The issue isn't so much the design of the catch tank but the instructions for it. I would really like to see the instructions, because based on Crumpet's troubles, you shouldn't have both ports venting to the same catch if you leave the PCV in. And one of the ports was never really designed to be 'flowing out' but rather 'flowing in' in the original layout. If you follow the instructions, and leave the PCV in, you'll only see flow out of ONE of the ports of your engine, the non-PCV port, which also will let a lot more oil out than if you'd used the PCV port, due to the angle involved. If you VTA, I'd block off the non-PCV port and leave the PCV port itself with a barb fitting instead of the PCV valve itself. If you don't VTA, leave the PCV in, and in the case of a turbo car, put a OWV in as well as the PCV so that you avoid sending boost pressure from the inlet tract to the head of the engine. |
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Post by atlex on Oct 20, 2021 12:53:00 GMT
How much air comes out your catch can if you put your hand over the hole where the breather filter is ? If your dip stick pops out hard, I think you know the problem  |
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Post by atlex on Oct 23, 2021 12:35:37 GMT
 Great welders, nice photo, pity about the PCV valve sitting there lol. |
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