Primary inlet elbow (PCV?) questions
11-03-12, 09:09 AM
#1
Primary inlet elbow (PCV?) questions
So I was in the middle of installing an idler pulley to finally replace my deleted air pump when I cracked the nipple off of the primary turbo inlet elbow. To be specific, the second one (the smaller one, the one cut off in every hose diagram right at the nipple).
I've searched and all but confirmed that it is part of the PCV system. In searching I also found a post saying that the other PCV routing to the intake manifold can be deleted (this one, post #2) but can the one to the intake nipple just be vented to atmo? I think so but does it serve a second function such as lubricating the turbine for the primary (unlikely) or does the PCV system need that intake suction to relieve pressure properly (less unlikely)?
I know some ppl may ask why I don't just replace it but iirc the last time I priced it (the other nipple broke before but I was able to save that one) the part ran over $100 which I'm trying to avoid.
I've searched and all but confirmed that it is part of the PCV system. In searching I also found a post saying that the other PCV routing to the intake manifold can be deleted (this one, post #2) but can the one to the intake nipple just be vented to atmo? I think so but does it serve a second function such as lubricating the turbine for the primary (unlikely) or does the PCV system need that intake suction to relieve pressure properly (less unlikely)?
I know some ppl may ask why I don't just replace it but iirc the last time I priced it (the other nipple broke before but I was able to save that one) the part ran over $100 which I'm trying to avoid.
11-03-12, 11:13 AM
#2
Eye In The Sky
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Two nipples on the plastic curved inlet to the #1 turbo.
One supples vacuum to the top of the two OMP oil jets.
The other goes to the oil filler tube.
This later one does function as a suction breather to the engine, or positive crankcase vent. In 1995 Mazda actualy removed the PCV valve which also attaches to the
oil filler tube as it was redundant and fatal if the valve stuck open when boosting.
It has nothing to do with lubication of the turbo. You could vent it to atmosphere.
When going single turbo, many of us take the two vents and route them to a catch can which is requirted for racing. Then the catch can is vented to atmosphere.
You can use some common supplies and fix the broken nipple. I have done it before.
One supples vacuum to the top of the two OMP oil jets.
The other goes to the oil filler tube.
This later one does function as a suction breather to the engine, or positive crankcase vent. In 1995 Mazda actualy removed the PCV valve which also attaches to the
oil filler tube as it was redundant and fatal if the valve stuck open when boosting.
It has nothing to do with lubication of the turbo. You could vent it to atmosphere.
When going single turbo, many of us take the two vents and route them to a catch can which is requirted for racing. Then the catch can is vented to atmosphere.
You can use some common supplies and fix the broken nipple. I have done it before.
11-03-12, 02:21 PM
#4
Correction: one of the lines supplies clean, filtered air to the OMP jets. When the motor intakes air, it breathes in oil through the nozzles at a metered rate. Under boost the check valves in the nozzles close and continue to allow oil to be metered in. If the nozzles fail, oil will be blown back into the primary turbo inlet. This is one of the causes of oil in your inter cooler piping. Adding a filter to the nozzles is an adequate replacement if the nipple on the inlet pipe breaks. Just make sure you cover the hole where the broken nipple is.
11-04-12, 02:08 PM
#5
Eye In The Sky
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Correction: one of the lines supplies clean, filtered air to the OMP jets. When the motor intakes air, it breathes in oil through the nozzles at a metered rate. Under boost the check valves in the nozzles close and continue to allow oil to be metered in. If the nozzles fail, oil will be blown back into the primary turbo inlet. This is one of the causes of oil in your inter cooler piping. Adding a filter to the nozzles is an adequate replacement if the nipple on the inlet pipe breaks. Just make sure you cover the hole where the broken nipple is.
It does not need a filter as there is only a pressure differential, no flow.
11-04-12, 02:21 PM
#6
Just fix the nipple if it keeps you up at night.
Find a large diameter piece of pre-flared brake line at the auto parts store about the diameter of the missing nipple.
Cut brake tube an inch or so long and keep the flare. Drill the hole in the inlet so the small end of the brake tube just passes through.
Insert the brake tube from the inside of the plastic inlet until it stops at the flare.
Liberally JB Stick Weld the brake tube in place from the outside of the inlet.
Find a large diameter piece of pre-flared brake line at the auto parts store about the diameter of the missing nipple.
Cut brake tube an inch or so long and keep the flare. Drill the hole in the inlet so the small end of the brake tube just passes through.
Insert the brake tube from the inside of the plastic inlet until it stops at the flare.
Liberally JB Stick Weld the brake tube in place from the outside of the inlet.
11-04-12, 03:14 PM
#7
A significant component in the health of the oil injection system is the oil delivery lines, check valves, orifices, and air source. One area I have seen that would be of concern is loose bayonet fluid fittings. The total volume of oil flow is very small and a leak at a fitting would starve the critical oil to the engine; if there is an oil film or visible oil at the bayonet fittings get it fixed; maybe simply tightening the fitting. The second and probably highest failure rate component are the little check valves that thread in above the orifices in the rotor housings. If these check valves fail and they do quite often the oil will be blown into the primary turbocharger compressor inlet (if you have the stock configuration) rather than injected into the engine. I believe this may contribute to more engine failures than many other things. I would consider the check valves a standard replacement item whenever the engine is apart. Lastly, the air supply to the check valves must be filtered clean air. The check valves are sensitive to dirt and contamination and will not close properly if there is dirt on the seat. Also, the metering orifice that is pressed into the rotor housings is very small and with oil on it dirt can easily accumulate and plug the orifice again closing off or restricting the oil flow into the combustion chamber.
OP, the fix mentioned is an easy one. I broke a nipple on my primary inlet pipe when I was doing my silicone vac lines. A new one from ray @ Malloy was about $90 if I remember.
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