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Roadrace Roadrace is offline
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Question N54 bad oil burning - 06-10-2021, 01:45 PM

We have two N54 135i cars. One has RB turbos, intercooler, etc running JB4 but engine is original and 80,00km. The problem car is running currently RB turbos, wagner intercooler, twin catch tank now, PCV mods, blanked head galleries, intercooler pipe kit but is running Motec full ECU and wiring, running standard injector system, this engine has been rebuilt with J & E pistons, head studs, and brand new parts ( cam boxes etc ) plus brand new BMW oil pump. It won't stop smoking, at idle with dump ***** off it fills workshop with smoke when warm to hot. Turbos have been checked and show oil flooding but we have large drain tubes fitted. Engine builder currently changing make of pistons....engine has been apart several times. We are changing turbos to Pure 2 to eliminate turbo possible issue.
BUT.....this engine has very high oil pressure compared to our stock engine ( we'd expect a little difference as comparing new to worn ) . We now know that later engines have electronic oil control, our one does not . Are the two oil pumps different ie could our problem be that the ( electronic controlled ) pump has been fitted inadvertently , causing high oil pressure and thus high oil feed to the turbos. The exhaust ports are showing no sign of the cylinders causing the oil burning. We have experimented with open breather tanks etc.
Or are we missing some restrictors from the oil supply lines. Excessive oil to the turbos seems the most likely cause.
We need to explore all avenues as engine has been out now four or five times
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Rob@RBTurbo Rob@RBTurbo is offline
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Default 06-11-2021, 10:01 AM

Quote:
Originally Posted by Roadrace
We have two N54 135i cars. One has RB turbos, intercooler, etc running JB4 but engine is original and 80,00km. The problem car is running currently RB turbos, wagner intercooler, twin catch tank now, PCV mods, blanked head galleries, intercooler pipe kit but is running Motec full ECU and wiring, running standard injector system, this engine has been rebuilt with J & E pistons, head studs, and brand new parts ( cam boxes etc ) plus brand new BMW oil pump. It won't stop smoking, at idle with dump ***** off it fills workshop with smoke when warm to hot. Turbos have been checked and show oil flooding but we have large drain tubes fitted. Engine builder currently changing make of pistons....engine has been apart several times. We are changing turbos to Pure 2 to eliminate turbo possible issue.
BUT.....this engine has very high oil pressure compared to our stock engine ( we'd expect a little difference as comparing new to worn ) . We now know that later engines have electronic oil control, our one does not . Are the two oil pumps different ie could our problem be that the ( electronic controlled ) pump has been fitted inadvertently , causing high oil pressure and thus high oil feed to the turbos. The exhaust ports are showing no sign of the cylinders causing the oil burning. We have experimented with open breather tanks etc.
Or are we missing some restrictors from the oil supply lines. Excessive oil to the turbos seems the most likely cause.
We need to explore all avenues as engine has been out now four or five times
I know this case, front and back/side to side, hopefully some different turbos cure these woes.

Last convo we had several months back, was that these turbos were "gone through" by some local shop during one of the engine (re)builds over the past years. But we were never given clarity to what extent (ie. disassembled, rebuilt, or visually inspected), and were waiting on the pics.

These units, at least as how built by us back in 2017, should 100% be non-smokers, unless one of the engine builds thrashed their bearings. The only thing that we have seen over the past nearly 6 years (on our actual builds anyway) to cause smoke was total turbo obliteration cases, not units that are in otherwise good physical condition/not been known to eat engine bearings/etc.

Rob


See www.rbturbo.com for N54 Twin Turbo Bolt-On upgrades, or contact directly 314-630-8950 rob.rbturbo@gmail.com for a price quote.
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Roadrace Roadrace is offline
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Default 06-13-2021, 12:45 PM

Hi Rob, nowhere have I said its turbos. As said to you many times turbos were vacuum tested, stripped, reassembled VSR etc with no apparent explanation for any fault. BUT there was evidence of flooding. Both us and the engine builder checked out oil return etc. Incidentally, it turns out yet another engine built next to ours has same pistons etc and a later version of RB's but burns no oil. Since then everyone has had theories and as said, the engine builder fully standing behind his workmanship is fitting a different make of pistons but because of his copping all the expense wanted a turbo change as well. OK for us as we'll have a spare pair of RBs for our other car. Two crucial things though to consider....this car is on Motec and this car has higher than normal oil pressure. So forum readers know, you and I have discussed this. As we did not build the engine and together with evidence of flooding in the exhaust housings we are at wits end and have even considered in the build whether some stock oil feed restrictors have been overlooked. The engine has been in excellent condition on each teardown. The boost levels have been kept low ( under 1 bar ) until this problem is fixed.
The oil pressure indicated issue is what I'm trying to get feedback on by this forum, not to point any fingers at the RB product .
I wish I could get adequate information on this oil pressure / oil feed. Of course we can fit oil feed regulators but why ? Why this one engine ?
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Default 06-13-2021, 03:15 PM

Been doing this for a long time. You have a few things to consider:
1) Engine condition. Need to confirm leak down is good, per cylinder. Normal healthy OE N54 builds are usually between 2-5% leak down. Get specific results, even if from 3rd party, to confirm "checks out" is really checking out.
2) Turbo condition. We can only assume the shop that rebuilt/serviced the turbos did a good job on them. If there is any in/out (axial) shaft play then the thrust bearings are fried.
3) PCV/Ventilation. You have the RB External PCV with plugged head ports to further bullet proof potential issues within the valve cover/gasket sealing, a sure fire way to rule out this being a consideration in itself.

If the above 3 all 100% check out, you'd be the only case I've ever heard where smoking persists.

I get you have the oil pressure wildcard as it is very high, and while I am sure that doesn't help I can't imagine that alone causing massive turbo smoking issues. If the turbos bearings are wore out it would make sense, however, but that goes back to #2 above. It does make me question why the Oil Pressure is so high as well, perhaps from too tight of rod/main bearing clearances or the like (as part of the engine build), which brings me back to potential of something awry with #1 above.

Rob


See www.rbturbo.com for N54 Twin Turbo Bolt-On upgrades, or contact directly 314-630-8950 rob.rbturbo@gmail.com for a price quote.

Last edited by Rob@RBTurbo; 06-13-2021 at 03:21 PM..
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