this is my at my set-up.. (full non-seq) and crankcase vent. check valve eliminated (93). I noticed that the line running from the bottom of the oil fill neck to the hard line was connected (@ the other end of the hard line) to the "t" that runs under the UIM to the vacuum side..WTF? The other end of the hard line is supposed to run to the nipple of the intake side of the primary while the other nipple (of the intake side of primary) is supposed to run to the "t" connector.. On a side note the top nipple of the oil fill neck is vented to atmosphere and i took off the oil neck cap and still was smoking a bit .. Now do I need to clean the oil out of those vacuum lines or will it do it itself? Eg. brake cleaner.. Please help.. Thanks Garret..

 

well i took it for a drive... still smoke on decel and when i pull outta gear. Def. oil smoke light blueish..Not losing any coolant. Have another set of turbos on the way.. i hope that cures it. Only 6k on this rebuild (all new parts). Better not be engine oil seals.. Or heads will roll..

 

If you want to clean your vacuum lines, I wouldn't recommend using brake cleaner. It's pretty corrosive.


In addition, do you understand what a PCV valve does? I can't think of any reason to remove it, at least for a piston engine. It's possible that the the rotary doesn't need to releive pressure at that point, but why did Mazda put it there?. Also, I'm pretty sure you'll want to keep the check valve in that line.

-s-

 

it will need to be vented at least. not hooked to a manifold vac source. manifold vac becomes maniflod boost. boost into the case is not good. you can run it to the inlet elbow on the turbo as that is the only place that sees constant vac. the pcv valve was a check valve to prevent boost from going into the case. a catch can to the turbo inlet is ideal as it will stop the oil blow-by from getting all inside the intake tract.

 

Eeehh

The guys above are right, you are essentially now pressurizing the filler neck....put the PCV valve in or remove the line completely and cap the filler neck and UIM nipples -- this is how 95+ FDs are setup.

 

Are you supposed to cap off the top nipple of the filler neck ? Mine is not. ( I have not been getting any venting oil mist either there. I know the bottom line is run to the hard line then the other end of the hard line is connected to the other nipple on the intake elbow of the primary turbo.Yes .. The UIM is capped..I went through the non-seq. diagram and traced every step.. Everything was perfect (nipples capped, block off plates, etc.) except for the vac. line that runs from the intake side of the primary to the vac lines by the fuel injectors. I corrected that part but still am smoking slightly at idle, one marginal puff when I let off the gas when revving it at idle, and a good puff when on decel and pull out of gear into idle. No smoke at all on acceleration. Oil is slipping by somewhere..I did not have any smoking before my tune.. Just slightly after. I probably finished my oil seals in turbos by cranking to 15 psi. Had been running only 10psi cause I needed a tune to turn it up. My tuner promises that my afrs are safe. Can some kind of compression check tell me if the oil seals are gone? I know for apex.. I would only think internal visual inspection could truly diagnose internal seal failure ( oil). Or the process of elimination.

 

well i just pulled off all the accesories to the turbos and inspected the primary and secondary intake sides. Feels real good minimal side to side and no front to back shaft play. No oil in either intake side of the turbines or piping. This is starting not to look good as I am suspecting engine oil seal problems. I will take them off and slap the new ones on to see if it cures the smoke.. Wish me luck..

 

Stock twins although not extremely likely can also go bad at the exhaust side (secondary turbine) and leak oil right into the exhaust burning it off before its able to cause any drip or leakage.

I had this happen to me with 110k miles on oem turbos. The primary had minimal shaft play, but sure enough secondary was worse off. Had me going nutts at first bec. all the IC piping and intake piping showed no sign of excess oil.

 

Hi... im curious about this. As im currently simplifying my sequentials, i was thinking alot about this. If i were to eliminate the PCV valve, i would need to plug up the inlet / outlet at the UIM and the Oil filler neck. That means i need to plug up just 2 inlet / outlets right? Would i need to replace the PCV with anything?

Thanks in advance.

 

you can't cap both nipples on the oil filler neck thoguh right? Cause then crankcase pressure has no where to go. Can you just leave one open to atmostphere or run a line to a catch can and thats it, instead of running another one from the catch can to the turbo inlet? Basically can it just be left open to vent or does it need to be pulled out by some vacuum source?

Also on a side note, how many o-rings are supposed to be where the filler neck connects to the block?

 

a vac ONLY source is ideal. thus the turbo inlet, or use of a pcv/check valve when using the manifold. the catch can does just that catches the oil droplets and seperates them from the air so you do not get oil streaking the manifold,turbos etc... iirc there is one rather large o ring that seals it to the block, 2 10 mm bolts on the sides. you could just let it vent but it will spray everywhere.

 

so a vac source pulling out the gases is better than just running one line to a vented catchcan (esentially open to atmosphere)?

 

yes through a catch can is great.

 

inlet(vac only) ---> catch can <----lower nipple on oil filler neck.

cap the top one (and the UIM).

95's only had a vacuum line from the oil filler neck to before the turbo inlet for any venting. My emission's numbers improved after installing the catch can...other mods went in at the same time too however, total decrease was 50% with new cat, AMP, catch can, lower fuel pressure and bigger timing split.

 

yes I understand peopel run it through a catchcan but my question is: is the vacuum source needed and why? If the purpose is to vent pressure this will be done on it's own without the assistance of vacuum. Using vacuum to "suck" out the pressure would just increase the likelyhood of sucking up the oil that sloshes around in the filler neck.

I want to avoid additional vacuum lines and also injesting air with an unmeasured amount of oil/gas vapor which could possible affect tuning.

BASICALLY: Someone explain to me why a vacuum is needed to vent the crankcase.

 

the way I see it is it relieves some pressure, I've known people who just vent them. If you plug those two filler neck nipples...engine most likely will smoke.

you have a pressure source; the crankcase

you have a vacuum source; the turbo

the higher the rpms the higher the crankcase pressure to a regulated point. (oil gets to about ~120psi; not sure about the crankcase)

just so happens the higher the rpms the high the vacuum (due to boost) up to another regulated point. (say 17psi pushing 52lbs/min can produce [I really have no idea, but to be simple...]~60in-hg.)

you can have a pressurized system static with a force feeding it, or you can put that system on a see-saw...while cleaning up some blow by vapors

two vacuum lines won't complicate your set-up too much



can't see a thing