Digsy Posted May 1, 2007 Share Posted May 1, 2007 Do you have those figures, Chris? You would also need to now how far the piston would need to move before it opened the oil recirc hole. Ricky: Not surprised that you didn't much with your boost guage measuring crankcase pressure - a boost guage would be much too coarse. If all is well you'll be looking for millibar of vacuum, not bar. At least you know your PCV valve hasnt stuck open and you're getting full boost inside the crankcase! Quote Link to comment Share on other sites More sharing options...
Scooter Posted May 1, 2007 Share Posted May 1, 2007 Are NA and TT oil pumps the same? I'm just curious as to my knowledge this is a TT mainly (only?) related problem. So why it doesn't happen on NA's may lead to ideas as to why it does on TT's? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 1, 2007 Author Share Posted May 1, 2007 Are NA and TT oil pumps the same? I'm just curious as to my knowledge this is a TT mainly (only?) related problem. So why it doesn't happen on NA's may lead to ideas as to why it does on TT's? A VERY VERY good point. If it only happens on TT's I'd have to say the PCV valve would be an immediate suspect. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 1, 2007 Share Posted May 1, 2007 Do you have those figures, Chris? You would also need to now how far the piston would need to move before it opened the oil recirc hole. Ricky: Not surprised that you didn't much with your boost guage measuring crankcase pressure - a boost guage would be much too coarse. If all is well you'll be looking for millibar of vacuum, not bar. At least you know your PCV valve hasnt stuck open and you're getting full boost inside the crankcase! It was only to get an idea if there where any blow by pressure related problems, mind you the vac measurement should be OK, Yes PCV valve got replaced last year when the seal went the first time;) Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 1, 2007 Share Posted May 1, 2007 Are NA and TT oil pumps the same? I'm just curious as to my knowledge this is a TT mainly (only?) related problem. So why it doesn't happen on NA's may lead to ideas as to why it does on TT's? Agree with Chris, excellent question, I wonder why we didn't think of this earlier, doh! If oil pumps were at fault, then there would be incidents on N/As, if anything people would tend to rev them harder in order to get the last drop of performance, right? ...back to crank pressurisation then.... Quote Link to comment Share on other sites More sharing options...
Lucifer Posted May 1, 2007 Share Posted May 1, 2007 Ive seen it on An na but only 1. Odd eh. Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 1, 2007 Share Posted May 1, 2007 Martin, Did it have worn piston rings? Quote Link to comment Share on other sites More sharing options...
Lucifer Posted May 1, 2007 Share Posted May 1, 2007 Martin, Did it have worn piston rings? Its an odd one as it was teh car that produces 251.5 on th dyno. 8200 redline etc... so I guess we cant really count this one. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 1, 2007 Share Posted May 1, 2007 Do you have those figures, Chris? You would also need to now how far the piston would need to move before it opened the oil recirc hole. Ricky: Not surprised that you didn't much with your boost guage measuring crankcase pressure - a boost guage would be much too coarse. If all is well you'll be looking for millibar of vacuum, not bar. At least you know your PCV valve hasnt stuck open and you're getting full boost inside the crankcase! Just another thought on this one, in order to be able to cause a FMS to fail through blow by/crankcase pressurisation,i would have thought you would need at least 20 PSI + pressure, and the rest! If its an oil pressure problem, i am sure its far more than that, so the whole scenario of crankcase pressure still won't ring true to me. Quote Link to comment Share on other sites More sharing options...
Scooter Posted May 1, 2007 Share Posted May 1, 2007 If oil pumps were at fault, then there would be incidents on N/As, if anything people would tend to rev them harder in order to get the last drop of performance, right? oi steady ...............but yes! Quote Link to comment Share on other sites More sharing options...
gregsupra4 Posted May 1, 2007 Share Posted May 1, 2007 Chris, we have had 3 brand new one's from Toyota fail within 30 seconds of starting the car. Each time we have put it down to being pinched when being pressed in however we had another one do it on Saturday on a newly built engine, instead of just accepting a bad installation we looked closely at the seal and compared it to another new one, the spring on the failed seal was not as far back as the new seal and was quite loose, we then opened and looked at 5 more seals and found another 2 that were the same as the failed one. We have sent the seals back to Toyota for inspection and will post the reply when we get one back. Quote Link to comment Share on other sites More sharing options...
SimonB Posted May 1, 2007 Share Posted May 1, 2007 Just for info, my oil pressure on hot idle (of around 850rpm) is pretty much steady at 36-37psi. That's on a new engine with new oil pump (it's done 1200 miles). The pressure sensor is in the feed to my oil cooler, so should be the same as in a sandwich plate. Quote Link to comment Share on other sites More sharing options...
Kranz Posted May 1, 2007 Share Posted May 1, 2007 Ricky: Not surprised that you didn't much with your boost guage measuring crankcase pressure - a boost guage would be much too coarse. If all is well you'll be looking for millibar of vacuum, not bar. I have a very accurate digital gauge that can read +/- pressures to a resolution of 1 millibar. Ricky, you can use it if you like? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 1, 2007 Share Posted May 1, 2007 I have a very accurate digital gauge that can read +/- pressures to a resolution of 1 millibar. Ricky, you can use it if you like? Thanks mate, may take you up on that, especially if it fails again, but i am still convinced that logically it would take a fair few PSI in order to make the seal let go whether it be air or oil. Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 2, 2007 Share Posted May 2, 2007 Guys, We can roughly estimate the crankcase psi that would push a new seal out. PSI stands for pounds per square inch, right? So if the seal surface is one square inch, then at 1psi it is like someone is pulling the seal with a fishscale set to one pound weight. We only need someone to measure the seal surface in square inches, and someone who has fitted a few to estimate how much manual pressure it takes to dislodge it. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 2, 2007 Share Posted May 2, 2007 I think it may be a bit more complicated than that John, unless your talking about what it would take to dislodge the whole seal? otherwise its only a small area around the crankshaft that is flexible enough to be deflected by pressure build up, and also the spinning crank makes it essayer for it to move outward under pressure. Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 2, 2007 Share Posted May 2, 2007 Yes, it might be a bit more complicated, but it will be a rough estimate of the ballpark pressure. At least we'll know if we're talking a handfull of psi or not. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 2, 2007 Author Share Posted May 2, 2007 The seal caanot be pushed out altogether, on it's OD. The star wheel for the crank trigger is only about 2mm away. I have never seen a whole seal move AT ALL. It seems the internal circumference spring becomes dislodged and then it leaks. To actually push out the inner lip would need a huge amount of pressure, I guess you'd balloon the sump before that happened! So unless this huge pressure was totally localised to where the seal was, IE, oil pressure, then I think you can forget crankcase fume pressure Quote Link to comment Share on other sites More sharing options...
JohnA Posted May 2, 2007 Share Posted May 2, 2007 Just to clarify something: As some here will know, I am very particular with crank ventilation, hence my firm insistence on the stock setup working as designed. However, the main reason for this is not the FMS issue (worrying as it is), but turbocharger lubrication. So even if the FMS issue turns up to be a manufacturing fault, an oil pump quirk or whatever, it won't change the need for near-zero crank pressurisation (fraction of a psi maximum). Quote Link to comment Share on other sites More sharing options...
gregsupra4 Posted May 3, 2007 Share Posted May 3, 2007 Just a quick one: Today we had a brand new crank seal let go, this was on a fully rebuilt engine with new oil pump. The engine had been run in and had around 6 hours Dyno time with no leaks. This was the same engine that on first start up had leaked from the front seal and had been replaced with a new one. So taking into account that this engine had done around 300 miles both on the Dyno and road the question to be asked is why did the seal fail again after a short journey ? At this point in time we are waiting for the car to be transported back to us in order to do a thorough inspection. It is very frustrating, you use only genuine parts and then find that they fail for no apparent reason, I never thought to inspect the oil pump as it was new in the box, this is something I will inspect as soon as the car gets here and perhaps some light will be shed. As always I will post the results and the Toyota answer ( If I ever get one) Quote Link to comment Share on other sites More sharing options...
letmeshowyou Posted May 4, 2007 Share Posted May 4, 2007 keep it up Greg Quote Link to comment Share on other sites More sharing options...
Guest McMsk Posted May 4, 2007 Share Posted May 4, 2007 The one thing i am finding inconsistent is can a worn/or a pump worn enough to produce the leakage required to overcome the seal,and still produce enough oil pressure throughout the engine without showing detrimental effects or low oil pressure? As you have probably read in my posts that i have very good oil pressure 25-35 psi hot idle and well over 90 psi from 3,000 RPM on, and only had the seal go on changing oil grade, and my engine only has in the 40K on it. It would also be very interesting to find out about the results of enlarging the drain hole, i would have done this myself but for the fact that its a case of removing the engine or sub frame to get the pump off. First of all i want to say that i don't have a technical background and i am not too familiar with the oil pump system of the 2jz. However i have a theory on the failing gaskets. As far as i have understood the oil pump builds e pressure up to a certain threshold (say 90 psi). After exceeding 90 psi, excess flow is bypassed via the drain hole to avoid the pressure exeeding the maximum pressure. If the oil is changed for a thicker grade (i.e. 10w60 instead of 5w30) the oil does not flow as liquidly through the engine (bearings, turbos, etc.) so that more oil has to be bypassed via the drain hole at limit the pressure to 90 psi. At some point the drain hole will not flow enough and.... pop Same thing for running higher than stock RPM. The oil pump flows more at 7500 than 6500, and again, the drain hole will not flow enough.. As said, just my thought, i don't know if this is technically feasible. As anyone blown these seals on stock oil grade (5w30) and stock redline? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted May 4, 2007 Share Posted May 4, 2007 Right idea, but wrong end of the stick so to speak;) the drain hole we are referring to is purely a safeguard in case of any oil leakage from the oil pump rotor and the housing, its not a drain for normal pump overpressure, your thinking of the pressure release valve which vents from the inner part of the oil pump. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 4, 2007 Author Share Posted May 4, 2007 Yes, as Tricky says, the oil pressure relief valve has a very adequately sized hole that vents excess pressure straight back into the suction side of the pump. Nothing to do with the seal issue I'm afraid. I now have 3 pumps stripped from engines that have high miles on them, and have neber suffered a seal failure. I'd like a few pumps to strip that HAVE suffered seal failure, even if they are "new". Failing that detailed pics of the rotors and inside of the casings and cover plates might help. Quote Link to comment Share on other sites More sharing options...
Kev.O Posted May 7, 2007 Share Posted May 7, 2007 Chris, we have had 3 brand new one's from Toyota fail within 30 seconds of starting the car. Each time we have put it down to being pinched when being pressed in however we had another one do it on Saturday on a newly built engine, instead of just accepting a bad installation we looked closely at the seal and compared it to another new one, the spring on the failed seal was not as far back as the new seal and was quite loose, we then opened and looked at 5 more seals and found another 2 that were the same as the failed one. We have sent the seals back to Toyota for inspection and will post the reply when we get one back. Greg have you ever thought about fitting one of these? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.