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914 turbo coking

  • pjsowe
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7 years 4 months ago #150 by pjsowe
914 turbo coking was created by pjsowe
I have been experiencing coking problems in my 914. This is a serious issue as the deposits will block the turbo oil return line causing oil to exit the turbo bearing out the exhaust draining oil and causing lots of smoke.

I am using the Rotax Oil in the crankcase, change oil and filter every 25 hours, do run 100LL as that is all thats available at airports I fly through. I also remove and clean the oil sump can and screen every 2-3 oil changes.

Since the last event I have richened the carbs one more notch to the richest setting. Hopefully this will help. I do not have a EGT or TIT gauge, the sensors just go directly into the computer.

Some have suggested using TCP fuel additive to help.

Others experience?

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7 years 4 months ago #157 by Roger Lee
Replied by Roger Lee on topic 914 turbo coking
Hi peter,

Coking may be coming from a tiny oil seep or running too cool. Are your temps up where they are supposed to be?

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
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7 years 4 months ago #161 by TroyEnriquez
Replied by TroyEnriquez on topic 914 turbo coking
make sure your using a semi-synthetic oil when running 100ll. clean the oil can every time to get that lead out it will build in your engine. also let turbo cool before shut down. what are your temps like?

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7 years 4 months ago #162 by Roger Lee
Replied by Roger Lee on topic 914 turbo coking
Troy is right. All of us should be using a semi or full synthetic oil and not straight mineral oils. Your engine will still love you at a 1000 or 2000 hrs from now. :)

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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7 years 4 months ago - 7 years 4 months ago #169 by pjsowe
Replied by pjsowe on topic 914 turbo coking
I am using the Shell oil specifically formulated for Rotax 912/914 engines www.shell.com/home/content/aviation/prod...e_oils/sports_plus4/ this is suposed to be the latest and best for the 912/914 series of engines.

All my research indicated that turbo coking comes from exxcive oil temps in the turbo bearing. I do let the engine idle a minimum of 60 seconds usually much more until temps down. Typically cylinder head temps run around 120C and oil temps on the low end especially in colder weather. Plane does not have EGT or TIT gauges from factory.
Last edit: 7 years 4 months ago by pjsowe. Reason: clarity

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7 years 4 months ago #323 by rhtrudder
Replied by rhtrudder on topic 914 turbo coking
I have a 914 in my sabre. Clocked up 900 hours. Had some problems with fuel pressures in the carbys, the turbo, although complicated enough, has worked ok,Found that the engine runs very cold on a big descent, so we fitted a in line themostat, which could help
and it made a lot of difference. Called a T-Bob ,They are avaliable on the net, made somewhere in USA.

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4 years 2 months ago #8661 by Moon
Replied by Moon on topic 914 turbo coking
I know this is an old thread (*bump*) but I haven't found a newer one on the topic. Anyway, in the past three years, has there developed any consensus on the "ideal" motor oil for the turbo engines - in terms of aiding optimum health and longevity? Is there a really oil good additive, perhaps? (or is that just asking for trouble...)

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4 years 2 months ago #8666 by pjsowe
Replied by pjsowe on topic 914 turbo coking
Keith--
I have shifted to the above mentioned Shell oil made specifically for Rotax 912/914 and still working well. BUT I've also bite the bullet and shifted to MoGas. It's a pain but doable at my home base to haul the gas in and just use 100LL when away from the base. EXCELLENT RESULTS! When using 100LL I've also used TCP oil additive (Aircraft Spruce Part #05-21300)FAA Approved. I have also heard that a small dose of Marvel Mystery Oil aids in keeping lead in solution but have not used this in the 914.
From research I've discovered the core issue. 100LL actually has much more lead than the old leaded auto gas. Normal aviation oil has detergents to keep lead in solution but these mineral oils will not properly lubricate the gearbox on a 912/914. So a specialized oil is required, typically a motorcycle type oil. But they don't have the detergents to allow lead to remain in suspension.
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3 weeks 2 days ago #20380 by Wang Shu
Replied by Wang Shu on topic 914 turbo coking
ROTAX914 run for ground level for 40 minute. as Fuel is 100LL, the oil temp was normal till 40 minute. RPM 3500-4000 .
PROBLEM TURBO Charges seize.
what could be possible reasons for seize.

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1 week 1 day ago #20491 by Wang Shu
Replied by Wang Shu on topic 914 turbo coking
Hi, Roger,

i have some question regarding 914 Turbo coking/seize and how to cool Engine by external blower.
please reply me Davidnane9@gmail.com
thanks

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1 week 1 day ago #20493 by Karl
Replied by Karl on topic 914 turbo coking
It is important, that you cool down the engine before shutdown it to oil temperature below 90 degres C or 190 degres F
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1 week 18 hours ago #20501 by Roger Lee
Replied by Roger Lee on topic 914 turbo coking
Hi Wang Shu,
I agree. Just idle down and allow the engine to cool before shut down.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
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