EFR6758 shaft play woes - I need your brains to help diagnose please - Miata Turbo Forum -Boost cars, acquire cats.

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Old 10-11-2016, 09:05 PM   #1
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Default EFR6758 shaft play woes - I need your brains to help diagnose please

Hey all,
My car has been running like a champ for the longest it's been. Though today, I noticed something weird. It sounded like there was compressor surge when shutting down from high load/full tilt, but be totally fine at lower boost.

I removed the filter and it rotates freely, doesn't snag however....I notived more shaft play than I'd like. A little more radially than axially. It's to the point where I really want to replace the thing with another supercore but this turbo has less than 8,000 miles on it. It's the newer aluminum core one.

The oil feed is -6AN being pulled from the driver side of the engine block. Coolant is -6AN in and out, diagonal as per the tech document. Drain is a 5/8" barb down to a bung under the A/C bracket.


What causes shaft play and surge on these turboes? Excessive bearing wear for short mileage? Not enoug cooling? Running too much oil pressure with a BE pump and +14 psi over stock (Full-Race once told me not to worry about slightly higher oil pressure, that their hondas and EVO runs 80+)?

What am I doing wrong. I really don't want to repeat a turbo/engine failure

Edit: just ordered a supercore but I am concerned that this will repeat itself. I'll contact Full-Race in the morning, but they've been kind of slow to respond to my last couple inquiries.

Last edited by psyber_0ptix; 10-11-2016 at 09:18 PM.
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Old 10-11-2016, 09:43 PM   #2
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How much is it moving? Making housing contact? I have a brand new 6258 with cast iron bearing housing and it has a little bit of axial play even with 0 miles. But not enough to come in contact with the housing of course. I dont have a dial caliper to actually measure the amount though.
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Old 10-11-2016, 09:48 PM   #3
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The play is more radial than axial. It seems to tighten up when it cools down though. I'm not sure if this is because of the thermal expansion of the bearing housing or what. I don't have a way to measure but it's way more than I've ever felt. Luckily no contact on the compressor side. Haven't inspected the turbine. I want to replace and assess anyways and worst case have a spare or send it in to see if it's all in my head.

But again, I really don't think it's normal for how robust these turboes are supposed to be.
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Old 10-11-2016, 10:39 PM   #4
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Sorry, I meant radial but typed axial. Either way, no way to measure. Any chance BW publishes tolerance specifications for things like this? Would be nice to have.
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Old 10-11-2016, 10:43 PM   #5
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I have no idea where to find that info. I'm just miffed because there seem to be tons of folks who run EFR's without issue. I seriously wonder if I'm doing something wrong. I may try to replace both the coolant and feed lines just because.
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Old 10-11-2016, 11:02 PM   #6
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Have you measured the CHRA temperature after driving and during shutdown? I have never ran a water cooled turbo until a couple weeks ago, I always just ran them with oil-only even if they had water ports. I hooked it up to improve reliability.

My ebay turbo, with water ports hooked up, showed 215*F CHRA temp after a 1hr drive beating on it in 80*F weather, after 1-2 minutes of idling it was 205*F and dropping. Exhaust was 580-650 for the turbine and manifold at the time. I shut it down and it heatsoaked to 230*F max. All of this seems great. Garrett says without water cooling they can heatsoak to over 500*F on shutdown.

I would check how your temps look on your CHRA. If they are reasonable I really doubt your water lines are to blame. What oil viscosity do you run? What kind of oil temps do you see?

My guess is either it was an oil issue (not enough or way too hot) or you just got a bad turbo.
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Old 10-11-2016, 11:28 PM   #7
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I have yet to measure temps, don't really have a reliable means of doing so. I might have a type K thermocouple that came with my multimeter but I'd have to find it; it just be contact measurement.

I'm not sure if I should believe my STRI gauges, but lately oil temps at the pan have been around 220F and oil pressure hasn't been below anything normal that i've noticed (again, running a BE street/strip extreme with 1 shim).

will see if anything as made it's way though to block up the internal restrictor, but -6AN should have plenty of flow.

Rotella T6 5w-40
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Old 10-12-2016, 05:47 AM   #8
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why are you using such a massive oil feed line most use -3 or -4
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Old 10-12-2016, 07:34 AM   #9
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Quote:
Originally Posted by ctdrftna View Post
why are you using such a massive oil feed line most use -3 or -4
Because it was recommended on page 37 of the tech brief. The turbo is internally restricted so it shouldn't matter that badly.
I am thinking about scaling back down to - 4 even though the line is 30" in length


edit: for those who haven't familiarized themselves yet www.full-race.com/articles/efrturbotechbrief.pdf

Quote:
A -4AN male fitting has been provided on the EFR turbo and a -4AN (1/4”)
line is sufficient as long as the engine supply pressure is healthy and the
line(s) are kept short. If the line is longer than about 18” then it’s
advised to step up to a -6 supply line. This is most critical for people
living in cold climates.

---------------------(Page 73)----------------------
Oil Inlet Fitting
An oil inlet fitting has been provided that allows easy connection to a -4AN line. This fitting has been pre-installed into the bearing housing oil inlet port (M12x1.5) and is sealed with both a washer and an o-ring. Additional oil restrictions should not be used. The required restriction to throttle the oil flow to the ball bearings is already integrated into the bearing housing. The oil supply line should be kept as short as possible. If a line of unusual length is required, we recommend a -6AN line especially for very cold climates. -3AN line is not recommended due to excessive oil supply delay times during cold start. We recommend that oil reaches the turbo in less that 4 seconds during a cold start cranking, and in under 1 second during hot-start conditions.

We often get questions about oil selection. The simplest answer is that turbos prefer warm (but not overly hot), high viscosity (e.g. 10W40), synthetic oil. Non-synthetic oils may of course be used but the user can expect a higher degree of laquering and coking. Users of thin oil (e.g. 5W20) can expect lesser bearing system robustness against harsh conditions or abuse, especially if the oil is very hot. Inlet oil pressure (gage) is recommended to be at least 1bar (15psi) and not more than 4bar (60psi) under all “fully warmed-up” conditions.
Maybe my oil temp is cooking the turbo? I'm without an oil cooler yet.

Last edited by psyber_0ptix; 10-12-2016 at 08:55 AM.
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Old 10-12-2016, 10:54 AM   #10
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If you don't have an oil cooler then your oil is probably super hot and pretty thinned out. Could lead to bearing cartridge damage.

Do you have access to a new or known good unit that you could compare yours to? It might be normal. Without oil pressure there will be some radial play in even brand new units.
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Old 10-12-2016, 11:25 AM   #11
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I could probably bring up one or 2 6758 to compare with you OP.
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Old 10-12-2016, 02:32 PM   #12
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Temp on exhaust housing after a 45 minute highway cruise.

66F ambient


CHRA temp after 45 min drive.

Ambient 66F


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Old 10-12-2016, 04:45 PM   #13
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Video of shaft play by any chance?? If not contacting the housing, you are probably in the clear....for now anyways. My brand new 6258 and 7163 loosened up some after the first 10-20 miles. Less than a mm of play axially and none radially. Ran them with no issues, so I suspect you may be in good shape to keep running this.

My only concern (and you have addressed this) is if you had an older core as BW had initial problems with the initial batch. But you said it's aluminum, so that shouldn't be an issue. You can confirm build date by removing the compressor housing and taking a look at the back plate for build date. That should take you less than 2 mins to confirm. It will be in black ink and not very hard to miss.

Unfortunately, these bad boys are not rebuildable :(
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Old 10-12-2016, 05:42 PM   #14
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If you send it to Southeast Power Systems, they will evaluate it and if it has failed they will determine a cause of failure. They sent RyanG a multiple page summary of tests they performed, measurements and findings. It included multiple pics and a friggin' video of one of the tests being performed. He posted a snippet of the report in his build thread.

Ryan's build thread - Clean and Mean
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