peteretep Posted September 19, 2011 Share Posted September 19, 2011 I have a feeling that my escort engine has too much blowby, but only due to the amount of oil/material dribbling out of my crappy catch can. I think a simple test will be to stick a plastic bag on the end of the breather hose at idle and measure the time it takes to fill, then very vaguely work out the volume of the bag which will give me a flow rate. Question is how much blowby should there be on a reasonable engine (apparently there is more blowby at idle than at higher rpm due to better sealing etc?) Quote Link to comment Share on other sites More sharing options...
fuel Posted September 19, 2011 Share Posted September 19, 2011 all engines have blowby to a degree. Is your blowby being recirculated back into the intake? usually the vacuum of the intake takes care of all the excess blowby pressure. Maybe the hose coming off the rocker cover isn't baffled enough therefore excess engine oil is getting into the catch can? Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 19, 2011 Author Share Posted September 19, 2011 yeah that may be an issue so if I measure the flow then I can tell if its the poor catch can setup or actual blowby because I have individual intakes and no plenum, it is not recirculated so needs to be drained every so often but at the moment it appears to be way too much Quote Link to comment Share on other sites More sharing options...
Snoozin Posted September 19, 2011 Share Posted September 19, 2011 I used to have to drain the catch can in the Honda every 1100 or so km. Hot running, cold running, whatever it just had mean blowby. Compression tests and leakdown tests proved there was nothing wrong with the car at all... it just always did it, and made near on 160kw in this state. I put it down to being "just something it did" and I didn't even expect a modern engine to do that. Same with my old Alfa - same shit, but a healthy motor by all accounts. How big is your catch can and how frequently are you having to empty it? Quote Link to comment Share on other sites More sharing options...
Spencer Posted September 19, 2011 Share Posted September 19, 2011 I am a big fan of having a working PCV system ( i know this is difficult with your carbs), I mean i dont like the thought of the engine buring all that crap, but having some vacuum on the crank case is a good thing. It circulates fresh air through the crankcase and helps suck out moisture and crap that would otherwise contaminate your oil. I would say phill could be on the money though with saying there may be insignificant baffles on the place you are venting from. With allot of old engines that had a PCV system the valve cover vent was meant to draw air into the crankcase, not vent it out so it could have no baffles at all Quote Link to comment Share on other sites More sharing options...
My name is Russell Posted September 19, 2011 Share Posted September 19, 2011 Are the PCV values sweet for going to turbo plenums also? Shouldnt mess with the tune or anything? As Raizer posted on my discussion if any help to anyone; or And yeah baffled ftw! Otherwise a lot of the vapor can get sucked from the fitting from the cam cover/block etc straight into the line going back to the intake. On my Subaru I ran a can the same as the pic you posted but without the ricer filter, but I sealed it up well and modded a fitting so it was like this sort of thing Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 19, 2011 Author Share Posted September 19, 2011 Yeah I understand the above diagrams but my system doesnt run like that, and it is alot of work to make it like that. I may be able to make it work in the future but for now it will stay without vacuum So I have removed the pcv valve due to not having any vacuum which may mean that more fluid escapes than a normal system, but there is still the baffles in the unit off the block and the hose goes to the other side of the engine bay, but I think my existing catch can is not baffled properly. I am looking at getting a new properly baffled catch can in the next week or so because my current one leaks so badly. I think the current catch can is about 1 litre but because it leaks so much its really hard to tell how much oil is getting into it. If an engine had too much blowby, would you end up with noticable amounts of fuel in the oil? Quote Link to comment Share on other sites More sharing options...
Raizer Posted September 19, 2011 Share Posted September 19, 2011 Are the PCV values sweet for going to turbo plenums also? Shouldnt mess with the tune or anything? Had no issues with it on my Subaru/Microtech, but in saying that the car was tuned with it set up so I don't know if it would make a difference. Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 19, 2011 Author Share Posted September 19, 2011 probably because a car isnt always on boost it will suck enough to work ok Quote Link to comment Share on other sites More sharing options...
mark105 Posted September 19, 2011 Share Posted September 19, 2011 hey pete i have one of those cheapy catch cans on skyline, i have nothing in mine, its always empty. i havent fanged it yet since its been on but at idle and light drives round the shed i have nothing in it. i know my rocker cover is baffled. so maybe this is the problem? Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 19, 2011 Author Share Posted September 19, 2011 Theres only a single line coming from the engine which is from the crank case, the rocker cover oil fill cap has a baffled outlet on it which doesnt leak at all. As hot oil has such low viscosity it might not be as much oil as it seems all over the floor. I guess the first thing I can do is wait till i get this new catch can and see what happens, would just be nice to be able to see how much blowby I have and what it compares to a standard engine. Maybe I should try one of these leak down tests Quote Link to comment Share on other sites More sharing options...
My name is Russell Posted September 19, 2011 Share Posted September 19, 2011 Mine had probably 300-500 mills after only 15 or so laps around manfield, aiden seemed to think it was somewhat normal when pushing a car on the track. Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 19, 2011 Author Share Posted September 19, 2011 oh really, I would have thought thats heaps but maybe not Quote Link to comment Share on other sites More sharing options...
jakesae101 Posted September 19, 2011 Share Posted September 19, 2011 some engines are more prone to this also like the big port 4ages dump more oil than what the head can drain back from what im told. hence why on the later gen small ports they added a extra external oil drain back to the sump Quote Link to comment Share on other sites More sharing options...
Rookie Posted September 19, 2011 Share Posted September 19, 2011 The Kent in my Lotus 7 filled up the 1L catch can after a few laps on the track and a bit of spirited driving on the street, and seems to be fine by all accounts, I just think they breath a bit heavy. If it still has good compression and passes a leak down test I would just try and sort out a system that traps the oil vapour better. Quote Link to comment Share on other sites More sharing options...
peteretep Posted September 19, 2011 Author Share Posted September 19, 2011 Who has a leakdown tester I wonder Quote Link to comment Share on other sites More sharing options...
DavidTheCreator Posted September 22, 2011 Share Posted September 22, 2011 theres heaps of shit on the google under "DIY leakdown tester" etc Quote Link to comment Share on other sites More sharing options...
drftnmaz Posted September 23, 2011 Share Posted September 23, 2011 or make the new catch can drain back to the sump.... Quote Link to comment Share on other sites More sharing options...
Spencer Posted September 23, 2011 Share Posted September 23, 2011 Ha, never mind having all that moisture and crap back in the oil Quote Link to comment Share on other sites More sharing options...
drftnmaz Posted September 23, 2011 Share Posted September 23, 2011 i thought it was a race car? oil changed every couple of outings anyway.... Quote Link to comment Share on other sites More sharing options...
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