Tricky-Ricky Posted May 4, 2006 Share Posted May 4, 2006 Going to open up a can of worms, but i have just found some interesting/worrying results whilst testing the breather system, took off the main breather hose that normally feeds into the turbo inlet, and also the plenum side breather and connected a pipe to each, tested the one way valve and it seems OK, but when blowing through the other pipe i can defiantly hear it escaping through the seal that's popped, but the worrying bit is that there is a definite resistance/pressurisation of the crankcase/camcovers! and that's just with me blowing through, now i can't shift much CFM but i'm dam sure that the engine can at medium/high RPM! now is there something wrong or is the engine just not breathing well? I am not going to get into the rights or wrongs of running catch tanks/venting to atmosphere again! but i will say that i'm not convinced that even with the std breather system in place that the vacuum generated by the induction system is by no means high/large enough to counter this, as by shear size/percentage its not going to overcome ring/bore blow by if there is a little wear! does anyone know what size the transfer/oil galleries are? Going to do a cold compression test later, to give me some idea if there is a lot of wear in the rings/bore. I'm not completely convinced that my crank oil seal failure was down to this yet, but it would seem to be the most likely cause, unless its an oil pressure problem. Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 4, 2006 Author Share Posted May 4, 2006 Anyone care to comment? just interested to see what peoples thoughts on this are! Link to comment Share on other sites More sharing options...
Alex Posted May 4, 2006 Share Posted May 4, 2006 Digsy's your man for breather systems!! Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 4, 2006 Author Share Posted May 4, 2006 Well just done a cold compression test and the results are very good! 1/ 13.1 bar = 190 psi 2/ 13.3 bar = 193 psi 3/ 13.5 bar = 195 psi 4/ 13.2 bar = 191 psi 5/ 13.2 bar = 191 psi 6/ 13.2 bar = 191 psi so as the test was done stone cold i would expect the reading to go up when hot as all the tolerances will have closed up a bit, so no real reason to suspect there is lots of blow by pressurising the crankcase. Link to comment Share on other sites More sharing options...
Terminator Posted May 4, 2006 Share Posted May 4, 2006 Toyota do not give any cold figures, the manual only gives hot figures and as hot as possible ie very quickly. Hot range 185psi or higher lowest allowed 156psi 14 psi max difference between cylinders. Link to comment Share on other sites More sharing options...
JohnA Posted May 4, 2006 Share Posted May 4, 2006 191 - 195psi all six cylinders, that's very good:d Link to comment Share on other sites More sharing options...
Whitesupraboy2 Posted May 4, 2006 Share Posted May 4, 2006 i only got 185psi on my NA...should i be worried? Link to comment Share on other sites More sharing options...
Digsy Posted May 4, 2006 Share Posted May 4, 2006 Can you clarify what you did with the blow tests on the two hoses, and where you thought there was a leak when you blew down the WOT breather pipe (the one that connects to the turbo inlet)? It sounds like you are saying you blew down the WOT pipe, which woud pressurise the camcovers unless there was flow through the PCV. If it is a true PCV valve (rather than just a one-way valve) then it will need a decent pressure difference across it to make it open - probably more than you can generate by blowing down the tube. Usually this pressure difference comes from it being sucked open from the plenum side, not blown open from the crankcase side. If the plenum sucks too hard then the PCV will actually close off again. If your breather system was fooked then you would probably be getting oil in your exhaust or oil seeping from around the breather connections. If its working properly the stock breather system will be adequate for the car at stock levels of performance and blow-by, and probably adequate for a fairly worn engine, too. *EDIT* Ah, I should have read more closely. Your front crank seal has gone, which does sound like crankcase pressurisation. Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 4, 2006 Author Share Posted May 4, 2006 The leak was from the crank oil seal the one that went, so that was expected, i know the system should be adequate, i'm just trying to find a reason for the seal going, but the worrying thing about my little test was the fact that it felt like it was pressurising, now i know that the WOT breather will be subject to a small vacume most of the time as a result of the turbo intake drawing on it, and the other plenum side will only have a vacume when there is no boost or the throttle is closed, so at high boost rpm there is only going to be one breather open, just trying to get my head around why my seal popped, other than that i will have to look at whether it was down to too high oil pressure, perhaps i should use 5-30 instead of 10-40? Link to comment Share on other sites More sharing options...
Digsy Posted May 4, 2006 Share Posted May 4, 2006 Well, it is also possible to pop a front crank seal by leaking a lot of oil from thr pump rotors into the space behind the seal, but there is a drilling to allow that to vent off. Just to clarify, you pulled both hoses off and blew down the WOT breather pipe and it felt like you were creaing pressure in the camcover? There was no flow at all through the part throttle breather? Did you try sucking on the part throttle breather? Link to comment Share on other sites More sharing options...
Terminator Posted May 4, 2006 Share Posted May 4, 2006 Sorry guys the compression figure I gave were for N/A engines. TT are as follows High 156psi or higher, low 128psi and 14 psi difference. Which would make the cold 190 seem high? Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 4, 2006 Author Share Posted May 4, 2006 Well, it is also possible to pop a front crank seal by leaking a lot of oil from thr pump rotors into the space behind the seal, but there is a drilling to allow that to vent off. Just to clarify, you pulled both hoses off and blew down the WOT breather pipe and it felt like you were creaing pressure in the camcover? There was no flow at all through the part throttle breather? Did you try sucking on the part throttle breather? Yes thats correct, and the part throttle breather behaved as it should when sucked:blink: Link to comment Share on other sites More sharing options...
Whitesupraboy2 Posted May 4, 2006 Share Posted May 4, 2006 Sorry guys the compression figure I gave were for N/A engines. TT are as follows High 156psi or higher, low 128psi and 14 psi difference. Which would make the cold 190 seem high? phew....you got me a bit worried for moment there phil Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 5, 2006 Share Posted May 5, 2006 The ONLY ONLY times I have seen front crank seals pop out have been when there is detonation damage or the bores / pistons are so *uggered that the crankcase suffers a lot of blow by and pressurisation. I frankly don't believe that oil from the rotors of the pump has anything whatsoever to do with it. The Yanks suffer this problem a lot, `cos they insist on running crazy boost on stock engines, with no mapping or with silly add on gizmos that fail to address the real needs of making a lot of BHP, like a lot of octane, proper cams, proper pistons, proper ecu with proper mapping, et cetera. Link to comment Share on other sites More sharing options...
Digsy Posted May 5, 2006 Share Posted May 5, 2006 I agree with you, Chris, although I must say that iin OEM-world we do add a drilling behind the front crank seal specifically to vent off any excess oil that might be getting in there. I too have never actually heard of one popping out because of that, though. Ricky: If you take the PCV valve out and blow through it in the dirction of the airflow, does it work then? Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 5, 2006 Author Share Posted May 5, 2006 I agree with you, Chris, although I must say that iin OEM-world we do add a drilling behind the front crank seal specifically to vent off any excess oil that might be getting in there. I too have never actually heard of one popping out because of that, though. Ricky: If you take the PCV valve out and blow through it in the dirction of the airflow, does it work then? Yes as i said with the pressure i can supply it works as a one way valve as it should, If i am getting those sort of compression figures when cold, i can't see the being a lot of crankcase pressurisation, as for oil pressure could it be down to running 10W 40 oil my oil pressure at idle is never less than 32psi and thats at 110c oil temp at 2,500-3,000 rpm its about 70 psi and over that i have not noticed to be honest as i have been monitoring other things, so would that be high enough to cause pressure relief problems? Link to comment Share on other sites More sharing options...
Digsy Posted May 5, 2006 Share Posted May 5, 2006 Yes as i said with the pressure i can supply it works as a one way valve as it should, If i am getting those sort of compression figures when cold, i can't see the being a lot of crankcase pressurisation, as for oil pressure could it be down to running 10W 40 oil my oil pressure at idle is never less than 32psi and thats at 110c oil temp at 2,500-3,000 rpm its about 70 psi and over that i have not noticed to be honest as i have been monitoring other things, so would that be high enough to cause pressure relief problems? Hang on a moment I'm not finished with our breathers yet! So, to recap (correct me if I'm wrong on any of this): 1) If you blow through the PCV from the camcover side, air passes through. 2) If you suck through the PCV from the plenum side, air passes through (if you suck REALLY hard, it should not). 3) If you blow through the PCV from the plenum side, air does not pass through. As an additional test, run the engine and while it is running pull the hose off the plenum side of the PCV. Your idle speed should rise by about 100RPM. If all of the above is OK then the PCV appears to be working fine. 4) If you take the WOT breather off at the turbo end and blow down it then you can hear air escaping from your popped front seal, but there is no air passing through the PCV. This all sounds logical. By blowing down the WOT breather you are pressurising the camcovers, head and block. If the front seal has popped then the easiest way out for the air is through the seal and not through the PCV, which requires a decent vacuum on the other side to help it open. 5) When you do the test in (4) you can feel some "pressurisation" which amesk you think the breather system isn't working. I don't really get this last bit. If you can hear the air escaping fromt he front seal then you can't be building up that much pressure. if you were building up a lot of pressure then the PCV would open, because we already know that is working. Have you checked that the pipes that link the exhaust and intake sieds of the camcover are clear? Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 5, 2006 Share Posted May 5, 2006 Yes as i said with the pressure i can supply it works as a one way valve as it should, If i am getting those sort of compression figures when cold, i can't see the being a lot of crankcase pressurisation, as for oil pressure could it be down to running 10W 40 oil my oil pressure at idle is never less than 32psi and thats at 110c oil temp at 2,500-3,000 rpm its about 70 psi and over that i have not noticed to be honest as i have been monitoring other things, so would that be high enough to cause pressure relief problems? A compression test can be OK if you have broken ring lands, under load the blow by can be tremendous. If it pops seals it has a piston / ring problem, period. Has it been modded? Link to comment Share on other sites More sharing options...
Bob Posted May 5, 2006 Share Posted May 5, 2006 A compression test can be OK if you have broken ring lands, under load the blow by can be tremendous. If it pops seals it has a piston / ring problem, period. Has it been modded? Would a leak-down test show this kind of thing up? Link to comment Share on other sites More sharing options...
Digsy Posted May 5, 2006 Share Posted May 5, 2006 How about taking the dipstick tube out and sticking your thumb over the end while getting a mate to rev the engine? Any crankcase pressure should be noticable at the tube end (if it isn't already just venting out of the front seal). Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 5, 2006 Author Share Posted May 5, 2006 A compression test can be OK if you have broken ring lands, under load the blow by can be tremendous. If it pops seals it has a piston / ring problem, period. Has it been modded? No not been modded other than a decat+ exhaust, Wallbro, colder plugs and as i said, and its only making .8 bar so the second tubo is not coming in, also if rings/bore have a problem, would i not get some indication like burning oil, smoke etc? every other engine that i have tested for compression with a ring/bore problem has shown a marked difference, suppose i should do a wet test as well just to be sure, but as the readings where good, i didn't bother, i will also check the for pressure with the engine when i have replaced the oil seal, as i don't really want to run it as is. Link to comment Share on other sites More sharing options...
JohnA Posted May 6, 2006 Share Posted May 6, 2006 A method I've used in the past is fitting temporarily a pressure gauge onto the dipsitick and see what happens when the engine is under load. Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 7, 2006 Author Share Posted May 7, 2006 As i decided to polish my cam covers,while to cars in bits, i removed the PCV, managed to crack the rubber in the process:( so i think i may have to replace both now as i have found that if you blow through the PCV from the plenum side fairly softly it will pass air and it doesn't stop until you reach say 2psi (guessing) which can't be good as on light throttle/slight boost it must be passing a small amount pressure, and causing the crankcase to become pressurised! is the PCV assembly available of the shelf from Toyota? or is it a wait for it to come from Japan anyone have a spare that works? Link to comment Share on other sites More sharing options...
Digsy Posted May 7, 2006 Share Posted May 7, 2006 12204-46020 - Valve 90480-18001 - Grommet Should be avaiable from Toyota. Link to comment Share on other sites More sharing options...
Suprash Posted May 7, 2006 Share Posted May 7, 2006 This seems an interesting subject.........so could anyone say why when you vent the cam case breather to atmosphere, why you might get oil seeping back down the air filter ? Is there any other place to safely vent the cam breather instead of it going back into your inlet ? Link to comment Share on other sites More sharing options...
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