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-   -   EIS Oil temperature ?????? (https://vansairforce.net/community/showthread.php?t=182242)

NYTOM 05-09-2020 06:11 AM

EIS Oil temperature ??????
 
For those of you who have the EIS 4000, does your oil temperature readings jump in large increments as you warm up your engine?
Just started Phase 1 and when warming up today I noticed a start temp of 59 degrees . Was waiting for at least 100 degrees and the temp stayed at 59 and then jumped to 121 degrees. I would expect to go up in a lot smaller increments of a few degrees each. Is this normal for the EIS 4000 or should I order a new sending unit? Doesn?t seem right. Contacted GRT but they may be Covid19 closed and I haven?t got a answer from them yet.
Any experience you can share is appreciated.:)

Kyle Boatright 05-09-2020 06:15 AM

Mine indexes up a degree at a time - no jumps.

Sam I Am 05-09-2020 08:11 AM

Dealt with same issue with fuel pressure
 
Tom...I had the same issue with a fuel pressure sender and EIS 4000. I don't know if the senders are the same architecture but GRT sent me a new sender and my bouncing readings were resolved. Good luck.

BobTurner 05-09-2020 11:47 AM

59 is as low as it goes, but above that should increase smoothly. If the OAT is above 59, the oil should read the oat without even starting the engine.

NYTOM 05-10-2020 09:20 AM

Makes sense
 
Thank you. Time to install a new sender. ;)

h&jeuropa 05-11-2020 09:57 AM

I'm not so sure. You state you are in Phase 1 so I assume the sensor is pretty new. The sensor is just a resistor that changes with temp. It depends on a connection of the threads for the ground.

Try a couple tests. When cold, the sensor has higher resistance (1000 ohms at 70F) dropping to 200 ohms at 140F and nearly 0 ohms at 320F. Try taking off the wire and you should see 59 on the GRT. If you have or can get resistors, try 200 ohms and see if it indicates 140. Try shorting the wire to ground and see if the indication is 300 or more.

The sensors are standard VDO units. There should be a number stamped on it, like 801/4/17. This a a VDO #323058 sensor available from a number of places on the internet.

My guess is you have a bad ground. If your sensor has tape on the threads that will cause a problem. Or if you have a remote manifold that the sensor is mounted on, there must be a connection to ground from the manifold.

Jim Butcher

NYTOM 05-11-2020 06:02 PM

Interesting Jim. Yes I do have resistors and I will try out the test procedures. I never use Teflon tape on the plane and only use Teflon paste but still will check the ground also. Thanks for the input. It?s phase one but the sensor was bought years ago in a deal at Osh and this was a slower build than I thought.

Scott Hersha 05-11-2020 06:44 PM

Is your sender a two wire, or one wire? The one wire sender grounds through the sender chasis to the engine case. The two wire has a dedicated ground wire that connects to the engine case near the sender with a ring terminal on any available bolt. Make sure your main engine case ground wire (2 awg) is secure, clean, and mounted to a good firewall/ground buss bolt.

Also, depending on your oil temp probe, you may either have straight threads, or NPT threads. If your install uses a copper/asbestos crush washer, you have straight threads. You don’t use a thread sealant of any kind on straight threads if the threads provide your ground pathway. The copper gasket/washer (most likely AN900) provides the seal, and be careful not to over tighten. I just installed one of these last week on a Grumman. That one had 5/16-18 threads and it should be finger tight +135 degrees of torque. That’s not very tight, but it’s a reason you have it safety wired. Teflon sealant on your threads might be limiting your temperature readout. Don’t reuse those copper crush gaskets.

h&jeuropa 05-12-2020 04:46 AM

Tom,

I forgot to suggest, take out the sensor and use a ohmmeter to see how the resistance changes while you heat the sensor in water on the stove.

Jim Butcher

NYTOM 05-13-2020 03:10 AM

Before I remove it I?m going to check resistance between the sensor body and the aircraft ground as Scott mentioned. Then I?ll try Jim?s suggestion of continuous resistance readings while heating the sensor. It will be interesting to see if the sensor readings jump in stages. This should isolate the problem. Now I?m mad at myself for not thinking of these tests myself.
This site makes it to darn easy to run for help. Thank you :)


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