912 Oil Pressure Sender leaking

Hi folks 

Have been trolling around in the threads and seen plenty about 912 oil pressure senders not sending the right info to the gauge.  

However my question is, has anyone had a sensor that has begun to leak.  I think mine is leaking a bit of oil, although it is had to discern exactly where it is coming from as it get blown around a bit.

Thoughts....?

 

 

 

Thoughts....?

 

Replace 

They are expensive if the recent 4-20ma type.....325 plus bucks

I'm guessing it's the VDO type? 

There are 3 types. The vdo, honeywell and latest, Keller.

I'm guessing it's the VDO type? 

 

There are 3 types. The vdo, honeywell and latest, Keller.

 

If your using "steam gauges" why not consider Speco Thomas - most of the gauges in my aircraft are 19 years old. The oil pressure was replaced (for the first time) about 12 months ago.

The VDO type is the original bulbous style cylinder type with the resistor inside about 40 or 50 bucks. Then came the Honeywell one at about 350 and now the Keller one as the Honeywell had a lot of failures. The Honeywell and Keller are the 4-20ma type and require either a EFIS style of display or a different analogue looking gauge.

Don't know which sender you need but if interested I have an unused, still in package, purchased in error, VDO 360.003 - make me an offer!

I'm guessing it's the VDO type? 

 

There are 3 types. The vdo, honeywell and latest, Keller.

 

It is the VDO type.

Don't know which sender you need but if interested I have an unused, still in package, purchased in error, VDO 360.003 - make me an offer!

 

Is this the original sender that Rotax used for their 912 uls engines?

Replace 

 

In the words of my kids "der" 

Replacing is obvious but are they known to spring a leak?

I've not heard of them leaking from the body. Perhaps it's leaking down the thread. 

Vibration could have loosened it. Rubber engine mounts getting old? 

If you have got 250 or 300 hrs on a sender in a bed mounted engine, that's a good life.

Longer life in a radial mount.

I think they are loctited in. Use a scribe to clean out all the old loctite in the oil pump housing and spray with contact cleaner to remove the oil.

The vdo senders that came with new engines had a brass anti-vibration ring pressed on.

Replacements don't have it. I have heard of people pressing it off the old and putting on the new but most don't worry about it. The effectiveness of it was dubious.....

Oh yeah, don't buy from the Rotax dealer. It's EXACTLY the same part you will buy anywhere else at 3 times the price....

In the words of my kids "der" 

 

Replacing is obvious but are they known to spring a leak?

 

Senders are pressed together with multiple parts and an oil seal. Out of hundreds I have seen on trucks tractors and cars a few have had leaks, rare but it can happen.

I've not heard of them leaking from the body. Perhaps it's leaking down the thread. 

 

Vibration could have loosened it. Rubber engine mounts getting old? 

 

If you have got 250 or 300 hrs on a sender in a bed mounted engine, that's a good life.

 

Longer life in a radial mount.

 

I think they are loctited in. Use a scribe to clean out all the old loctite in the oil pump housing and spray with contact cleaner to remove the oil.

 

The vdo senders that came with new engines had a brass anti-vibration ring pressed on.

 

Replacements don't have it. I have heard of people pressing it off the old and putting on the new but most don't worry about it. The effectiveness of it was dubious.....

 

Oh yeah, don't buy from the Rotax dealer. It's EXACTLY the same part you will buy anywhere else at 3 times the price....

 

The can & do leak through the body of the sender (usually more of a weep than a leak).

I have used good quality (gas) thread tape on mine, to good effect. Remember you are tightening a steel thread into an alloy casing - go lightly (from memory Rotax spec is 20 Nm). For security the addition of a hose clamp and a length of safety wire will give you all the piece of mind you will ever need.

Rotax parts can be very costly - the same part can often be found through other channels eg Ducati Motorcycle dealerships, Repco Aerospace, etc etc

Oil pressure senders comprise two major parts - the thermoplastic section and the brass section. There are two rubber seals sealing the oil pressure at the face between these two major parts.

The thermoplastic section is pushed into the recess in the brass section and the lip on the brass section is merely mechanically crimped to hold the two sections together.

If the two rubber seals go hard, they can leak, and the oil will weep out between the crimped brass lip and the thermoplastic body section.

Here is a video showing how oil senders are made. The video is a bit like watching paint dry, but if you need to quickly see the crucial part involving joining the two sections, it's between 3:40 and 4:15 on the video.

Hi folks

Got a vdo 360.004 sensor from Aircraft Spruce and installed it.

Unfortunately it failed on engine start up. Oil spewed out of the sensor where the outer shell is pressed over the inners which holds the stud.

I am waiting to hear back from them to see what they can do.

My next door neighbour who is a mechanic and also flies says I should source one through a auto electrician.

Might do that next week.

Floods in Melbourne quoted me $223 for a vdo 360.081 and I thought that was a bit too expensive. 

Attached are a few pics after the engine was started and run for no more than 30 seconds.

I'm just glad it didn't fail when I was flying.

Heath

Not good, great you were not flying.  They should replace let us know what spruce and vdo say.    081's look available at reasonable prices with a bit of searching.  Hope you are back in the air soon and safe flying.  Cheers.

Click to view larger image and other views

1Pc New Vdo 360-081-030-015C Engine Oil Pressure Sensor Sender mk are 36 pound on ebay may be worth a look.

It's pretty poor that an item like this could fail  in the way it does. OIL starts a fire more easily than fuel on a hot exhaust pipe. and that's not a situation you would enjoy or should even tolerate the possibility of.  Nev

Floods in Melbourne quoted me $223 for a vdo 360.081 and I thought that was a bit too expensive. 

 

If you were going that far, you might as well upgrade to a Keller, which would mean a new gauge and wiring.....

Mine has lasted well and I've not heard of problems......

If you were going that far, you might as well upgrade to a Keller, which would mean a new gauge and wiring.....

 

Mine has lasted well and I've not heard of problems......

 

Don't rule out Speco - much better value for $$ and in my application has lasted 800+ hrs

If you were going that far, you might as well upgrade to a Keller, which would mean a new gauge and wiring.....

 

Mine has lasted well and I've not heard of problems......

 

Honeywell/Keller are 4-20mA (milliamp) current loop, which is a long standing industrial standard for all manner of transducers and instruments.

It requires 2 wires (there are 3 and even 4 wire current loop versions, but these are 2 wire).

Wire 1 takes 12V out to the sensor.

Wire 2 comes back to the gauge.

The other terminal of the gauge is then connected to 0V, completing the loop.

The sensor regulates the current in the loop between 4 and 20mA, depending on the oil pressure.

And the gauge shows the mA, but is marked off in PSI/kPa/bar oil pressure.

Works very well in noisy industrial environments, and distance is no object: the mA will measure the same anywhere in the loop, regardless of how long the wires are.

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All of which is to say that if you already have 2 wires going to the VDO gauge, you can reuse those for the Honeywell/Keller.

The only gauge I was able to find that matches the Honeywell/Keller sender is the Aviasport IM545.

There has been some confusion over this, as Aviasport also supply a gauge that looks the same for the older VDO sender.

They are available from Aircraft Spruce (or direct from Aviasport at 74eu each if you are buying in quantity, otherwise the P&P is a killer).

All of these gauges are actually just reading volts. In the case of the 4-20mA version, the meter runs the current through it's own internal resistor, and measures the volts across it.

It would be interesting to see if a VDO meter could be modified, by adjusting the resistance there, to give a correct reading from the Honeywell/Keller senders.

If anyone has a disused VDO gauge we could look into it?

The only gauge I was able to find that matches the Honeywell/Keller sender is the Aviasport IM545.

 

There has been some confusion over this, as Aviasport also supply a gauge that looks the same for the older VDO sender.

 

They are available from Aircraft Spruce (or direct from Aviasport at 74eu each if you are buying in quantity, otherwise the P&P is a killer).

 

All of these gauges are actually just reading volts. In the case of the 4-20mA version, the meter runs the current through it's own internal resistor, and measures the volts across it.

 

It would be interesting to see if a VDO meter could be modified, by adjusting the resistance there, to give a correct reading from the Honeywell/Keller senders.

 

If anyone has a disused VDO gauge we could look into it?

 

Why do you want to match the Honeywell/Keller or for that matter VDO ??

This sounds to be a dedicated instrument (steam gauge rather than part of a fancy screen display)) if is - all that matters is that sender is matched to gauge.

What it actually reads converted to psi and industry standard, is just so much interesting additional/potentially confusing info - no practical application in this context.

Why do you want to match the Honeywell/Keller or for that matter VDO ??

 

This sounds to be a dedicated instrument (steam gauge rather than part of a fancy screen display)) if is - all that matters is that sender is matched to gauge.

 

What it actually reads converted to psi and industry standard, is just so much interesting additional/potentially confusing info - no practical application in this context.

 

Some people like to understand the equipment they use, Skippy. And understanding how it works means it can be wired with confidence, also allows a degree of fault finding where necessary. Without that we are reduced to shotguning: the least efficient and most expensive form of troubleshooting where we keep swapping parts until the fault goes away, then hope that was the problem.

But, yes, this was a thread about an oil leak.

I apologise for adding to the thread drift.

No problem - I actually found your additional information interesting - just not particularly to the point.