Jab engines

[facthunter]

What a lot of complexity in that sender. You would think there must be an easier way. Warning light's are much simpler but I've found them not so reliable either.. Nev

[440032]

Or you could enjoy 16 trouble free years and over 500 hours by doing nothing, like I have.

If it aint broke, don't fix it.

[Bruce Tuncks]

The Jabiru gauge is just screwed onto the engine block, and it suffers from vibration as a result. But it is not going to cause the engine to die from a burst or leaking hose. And if the engine is running well and the other gauges ( especially oil temp ) are normal, then the gauge is faulty and you continue flying. 

I understand why Jabiru decided to do it this way, just as I understand why the pressure gauge manufacturer wanting a bit of rubber hose between the block and the sender.

[Bruce Tuncks]

Not off topic, but a change...  I really liked the Jabiru engine article in the latest online Kitplanes.The article did not seek to hide issues but dealt with them well I thought

[Old Koreelah]

1 hour ago, Bruce Tuncks said:

Not off topic, but a change...  I really liked the Jabiru engine article in the latest online Kitplanes...

Bruce could you post a link?

[Bruce Tuncks]

Making Peace with the Jabiru Engine

 

[Bruce Tuncks]

Sorry old k, I tried but don't think it will work properly. I am a subscriber and that is why I get the stuff. So here's a brief summary... 

the topics were: oil cooling; CHT's and their tweaking for lowering and evening, taildraggers and dipstick adjustment;bing carby's , cylinder heads; better exhaust systems.

Most of the stuff has been discussed here, although not the use of the sonerai exhaust setup.

The only problem with the article was that it was specific to the older engines, those with the machined heads like mine and not like the gen 4.

[facthunter]

Easy read not much detail. No harm in it. Nev

[Yenn]

The manifold as I said above is mounted away from the engine vibration.

If you think that a drop in oil pressure is no problem if the engine is running well and oil temps are OK, you could be in for a shock in a coupe of minutes. A leaking hose to the oil cooler will take some time to drain the oil, but it will drain it and the first indication is most likely a drop in oil pressure, unless you get a visible spray of oil.

[onetrack]

Bruce, the article you linked to above is dated 2013, and I think a lot of water has flowed under the bridge, as regards Jabiru engines in the last 8 years.

[Yenn]

I am grounded at the moment due to letting my BFR expire, now I wait for an instructor to call by. Today I decided to run the engine to get a bit of oil circulated. Compressions were really good when I pulled it through.

I have had a bit of trouble with the tiny tach, which reads of an ignition lead. Just a few coils of wire around the lead and it induces a current which the tach reads and counts. Problem is the tach keeps re setting to one pulse per revolution instead of two. Not really a problem as I can tell if it is idling at 1000 rpm or 2000.

Today when I started up the tach was dead, no rpm at all, just a blank screen. Not a problem as I was not going flying, then suddenly it came alive, reading at twice the real revs.

I thought I would pose what happened as a problem for you. My first thought was that the tiny tach had failed completely, but as it came good, I thought an intermittent fault was probable.

I did a mag check and running on the left mag there was very little mag drop, running on the right mag there was some roughness and the tach went blank, but that is normal as the pickup is on the left mag HT wire.

[tillmanr]

Maybe check the device battery. Limited life in them.

[spacesailor]

Arn,t those ' tinitach ' sealed units ?.

BUT cheap enough to replace.

spacesailor

[Bruce Tuncks]

Onetrack, do you mean to say that the article in the latest  online kitplanes email mag was actually from years ago?

And they let me think it was just written?

[onetrack]

Bruce, unfortunately, this style of journalism happens all too regularly today. I'm often infuriated to find "news" articles that are undated!

[Bruce Tuncks]

Yenn,I reckon it is impossible to fault-find an intermittent while things are working. You are trying to find a fault where none exists.

Jbiru had problems I  know with the tacho sender. Mine triggers off a low-tension pulse, and it works but when I tried it on another plane, it would not go to 3000 rpm,

Can you borrow another meter to try out?

[Yenn]

I know the problem with the info I posted here. The fix is under way, I just wondered if others could spot what the problem is?

[facthunter]

You've left your self open there. Nev

[planesmaker]

Yenn a broken sensor wire?

[Yenn]

Not a broken sensor wire. If that was the case I would not have got a reading after running for a while/

[RFguy]

hmm leakage due to moisture that moisture evaporates off ?

[Yenn]

RF you are just about correct. I have a replacement coil ready to fit nd that should fix the problem.

[Markdun]

Yenn, you can cut/grind the back off the TinyTach to expose the battery.  Replace with a cr2032, and recover with a small section of old canopy lexan/acrylic and a few screws, or just goop. Like new from the front.   Don showed me this.  Cutting off the back will also allow the water therein, to drain out....much quicker than Glenn’s suggestion of evaporating the ingested water off, particularly if you take the plane up and do several cycles of spins 🙂

 

On the rpm reading, my TinyTach also had a two stroke default, ie. on pulse per revolution, not a four-stroke that has 1 pulse per two revolutions. To avoid the resetting to two stroke giving half the rpm, I had the sensor wire wrapped around two HT wires from the same magneto, to produce 1 pulse per revolution.  I’m thinking your problem is your maths, not the TinyTach, unless you wrapped the sensor around the HT lead from a coil to a distributor.....do change the battery —- it’s not hard.

[planesmaker]

23 hours ago, Yenn said:

Not a broken sensor wire. If that was the case I would not have got a reading after running for a while/

Broken wires can be intermittent 

[spacesailor]

Thanks Markdun.

I probably need that idea, instead of throwing OUT ANOTHER Tinytach.

spacesailor