912S Reduced Oil Pressure.
in 912iS Technical Questions
14 years ago
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Re: 912S Reduced Oil Pressure.
by Anders Eriksson » 13 years ago
I guess you are correct, but can you explain this to me?
Look at the document you refer to, 1.2.1
"1.Remove the oil pressure sensor part no 956 413" and then they write that you can screw in the 456180. These two then must have the same thread. Or can 956 413 have different threads?
Rob said:
Quote:
"The new oil pressure sensor with metric threads is only on engines produced since the summer of 2012.
see SI-912-020 R6 section 79-00-00.
Rob"
This is true because I put a new 912 engine on a plane and it was a March 2012 and it is 1/8" NPT. So how old is the engine? If it was prior to June 2012 it is a 1/8" NPT and if it is later in the summer then a M10X1.
If you are real close to the line where the split in time then check the serial number on the SI. Here are the two pages that you need out of the SI.
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Re: 912S Reduced Oil Pressure.
by bill martin » 13 years ago
Anders,
If you have the VDO imprinted with 29/12, that is the one with 1/8NPT threads.
If you have the pump housing #810-809, that housing is for the 1/8NPT thread.
VDO makes the 0-10 bar gauge with both 1/8NPT and MM10-1. Both types are available from many sources other than Rotax.
Bill.
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Re: 912S Reduced Oil Pressure.
by James Ott » 13 years ago
There is a real mess here!
I have a new 912ULS received in June this year S/N 6779693. I removed the factory installed oil pressure sender (Honeywell) Rotax PN 956413 in order to mount it remotely. When I did so, I noticed the threads in the pump housing looked damaged and I had to clean out metal shavings. The sender I removed (956413) has 1/8 NPT tapered threads. There is no doubt about this, I am a hydraulics engineer and I know an NPT thread when I see one. The pump housing number is 911810 which has an M10 thread according to SI-912-020R6. That explains the damaged thread-the factory installed an NPT sender into the M10 thread! But according to the SI the old 956413 was supposed to have M10 threads and be interchangeable with the new sender 456180. At least in my case THIS IS NOT TRUE!
What do I do now? I have a damaged, by the factory, oil pump housing and their SI is not accurate.
Jim
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Re: 912S Reduced Oil Pressure.
by Mike Brown » 13 years ago
The bad news is that M10-1.0 and 1/8"-NPT threads are virtually identical so that with very little effort a male 1/8"-NPT thread can be screwed into a female M10-1.0 thread.
The major diameter of a 1/8"-NPT pipe thread at the widest point is .405", which is 10.3 mm. So a little further down the taper the 1/8"-NPT thread easily engages the M10-1.0 thread. The thread pitch is a little off, but not much - 27 TPI for the 1/8"-NPT thread versus 25.4 TPI for the M10-1.0 thread. So be careful out there in oil pressure sender-land.
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Re: 912S Reduced Oil Pressure.
by bill martin » 13 years ago
James,
Don't know what Rotax would recommend, but I would go ahead and tap the housing a little deeper with a 1/8 npt tap. You are going to install some sort of hose barb anyway and a 1/8 npt barb will be the easiest to find. Mike's measurements are correct and tapping should give you a proper clean cut for a 1/8 npt fitting. I have no doubt that Rotax will resolve the mistake for you, but you will grow old waiting for the new parts.
Bill.
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