J230 High OIL Temp.

[emaroo]

Has anyone had problems with J230 having high oil temps during summer.We purchased a new factory built J230 at the end of Jan 07 and flew it in hot OT air temps 30c plus without problems. We have now done over 300 hrs and are having major problems with high oil temps. With a OT of 31c we are struggling to climb to a 1000ft without the temp moving into the red, we have to level off and back the revs to 2600 rpms. This makes it very difficult to climb.

 

We have tried everything suggested by Jabiru without success inc. leak down test, compression test. new sender and oil gauge, check and cleaned oil cooler, changed filter oil, tried different levels of oil in sump. Oil pressure and CHT are OK.

 

Our real concern is that we had no problems in possibility higher OT temps when the motor was new but now without changing anything except the engine is older we are having problems. Our last fix is to try and change the ducting on the cowl but if this was to work, does not answer why the change. My feeling, with very limited experience is it could be an engine problem.

 

PS Have just heard on grape vine that Jabiru are working on a mod for cowl to adress oil temp problems.

 

 

[Guest J430]

We have 550 hours or so on ours and no high oil temp issues. Rarely gets above 90 in a climb and is often in the cruise 80-85 max.

 

I have 20% of the cooler front taped up, just to get warmer sump temps.

 

Take your gauge and sender out and do a test with another known device. Heat oil in a can or something and measure with a thermometer.

 

Also check or replace the wire from the sender to the gauge.

 

 

[Guest DonC]

High oil temps

 

I have just left Bundy after having them try everything they could think of to reduce oil temp in my J230 - no change, 90+ deg at 9500 ft!

 

 

[Yenn]

Given that your CHT's are not changed, and the only place heat can come from is the combustion chamber or its surrounds, it would point to the oil being heated by the piston or cylinder walls

 

I can't think of anything that would change with the cylinder walls except blow by and you have done a leak down test. If the piston is overheating it will raise oil temp, but I would expect to see CHT go up.

 

What is the oil pressure doing? If the oil temp gets too high the pressure is bound to drop, so that would be another reason to worry, but if it stays in the normal range there is a lesser problem.

 

It is an intriguing problem and my guess is that it is a faulty sender or gauge, but you have changed both of them. Have you done any checks on the resistance in the temp gauge wiring. I cannot remember offhand what an increased resistance would do to the reading.

 

Good luck.

 

 

[Guest Andys@coffs]

... I cannot remember offhand what an increased resistance would do to the reading.

The guage is a voltmeter, no mater what its supposed to be displaying. A change to wiring such that a resistance is inserted in series (example being a poor connection etc) will always result in the guage showing less than what it previously would have (ie the pointer will be closer to the resting position) if your oil temp guage is like mine that would be a decresae in indicated temp, not an increase. An increase in indicated temp could practically only occur as a result of a faulty sensor, or, if the sensor requires a source of voltage to work (ie it acts as a variable resistance) if the supply voltage is rising. Such a thing could occur if the voltage regulator is not doing its thing properly and could be tested by flying the aircraft, landing, noting the temp and then turning off both mags. If the oil temp drops back as soon as the prop stops then that may be the issue, or not, as a failing battery will also make the temp drop as the voltage drops below the 12V when it stops. Either way a voltmeter across the battery when the engine is running will tell you if the reg is Ok, and when the motor is stopped if the battery is Ok.

 

If the voltage reg or battery isnt working then any other guage which relies on a supply voltage will also show incorrect readings. Anything that uses a thermocouple like EGT, CHT etc will be unaffected as the thermocouple is a voltage source, whose voltage is dependent on the temp of the device. They dont need the main battery supply to operate.

 

Andy

 

P.S when I worked on Aircraft avionics for a living in the RAAF experience taught us to never ignore the earth return in a circuit as time and time again a wierd outcome could invariably be traced back to some earth point not being as close to earth as the manufacturer intended. A quick check of resistance via a multimeter from the cct of interests earth to the Aircraft earth reference point (which in our aircraft is invariably the battery Neg terminal) is worth it. Of course that check is made with power off, and depending on load, load removed. Alternately a voltage check with the cct powered, load installed, from cct earth to aircraft earth reference is also useful. In a good situation resistance should be as close to zero ohms as practical and voltage drop should be negligable (no more than 0.2v in our 12V world is a rough go/no go indication. ) Vibration is the key architect of poor earth returns, followed by disimilar metal electrolysis as the close second cause, electrolysis of cause generates oxides and in general oxides are poor conductors when compared to their pure initial form.

 

 

[emaroo]

Changes to cowl

 

Squadron Leader

 

Just wondering what year your jab was built and whether you have have done any mods to the cowls or venting too oil cooler that would help the oil temp.

 

 

[TechMan]

Don,

 

What speed are you climbing out at? There are some who climb out at 80knots just to get the cooling happening better. Admittedly, that is not the best practice for circuit work, though can help for navs etc.

 

I would also recommend testing the sender unit. Also get in behind the panel and make sure the spade connectors are supplying a proper connection to the avionics, as I have had some reports of the wiring/connectors causing issues.

 

Chris

 

 

[TechMan]

Forgot to ask Don, what power settings are you using in a cruise?

 

Do you have the new carby jets installed?

 

Chris

 

 

[Guest DonC]

High oil temps

 

Flying around Mildura today @ 2000ft 2850rpm 95-100 degrees at ambient around 33C

 

Don

 

 

[Guest DonC]

High oil temps

 

Sorry, forgot had 290 needle jet fitted, heads wont go over 260F now, just oil temp high. Usually climb at 90-100 knts

 

Don

 

 

[Ross]

I heard a couple of things that might help.

 

All below assumes the instrument is working correctly.

 

The pressure sensor might not be well earthed because of the thread sealer used mounting the sensor - the cure was to use a copper washer from an injector off another engine that fitted the base of the sensor nicely and gave a good earth connection to the engine.

 

Another earth potential problem is the earth bus mounted behind the instrument panel if it is made of aluminium - although aluminium is a reasonably good conductor (low resistance) it quickly forms a high resistance oxidised surface when exposed to air that can affect instruments that are essentially voltmeters as has been mentioned in other posts.

 

Of course all the other connections that make up the earth current pathway from the sensor to engine and back to the instrument via the earth bus need checking as well.

 

To test this theory of a good or a bad earth you could make up a test lead with alligator clips on each end. The lead needs to be long enough to connect the body of the sensor back to the earth connector on the back of the instrument.

 

If you connect this up soon after the engine has been running with the oil hot - if there is a problem with the earth connection the connected lead should immediately change the temperature reading without doing anything else and change again when it is removed.

 

Regards

 

 

[Guest brentc]

Don, do you have the newly updated cowls with the lip at the bottom? Refer back to previous posts in the Jabiru forum here where I posted pictures of cowl modifications we made to some Jabs down here experiencing the same problems as yours. I was at the factory 2 days ago and took a picture of the latest cowls - I shall post here tomorrow. There is an approximate 5-6cm lip at the bottom of the cowl that didn't use to be there. Can you post a pic or email pic of your cowl base, down where the exhaust passes it?

 

PS - I aim for 90+ knots climbout minimum. 100 is better, but not always achievable easily if you're tight on room or have noise complainants nearby.

 

 

[Guest DonC]

I have fitted lips to existing cowl

 

Don

 

 

[Geoff]

Don are you still in the Mildura area? I was in Derby in May this year in my J160 with other aircraft, did we see you there?

 

 

[Guest brentc]

Here's pic of latest cowl.

 

Do you have a duct around the oil cooler yet? A mod is about to come out to block the holes around the oil cooler where it attaches to the cowl. The mould was being finalised only a couple of days ago.

 

 

 

[Guest DonC]

High oil temps

 

Geoff, back in WA now, was in Derby then but must have missed you.

 

Brent, my aircraft was the first one (after BNP) to get the duct between the cowl and oil cooler - made no difference. Changed to the slippery oil at Forrest - made no difference either - got into the red on climb out from Kalgoorlie, so not looking good for flying in the Kimberley. Have heard that hydraulic lifters could be to blame, but don't know how.

 

 

[Guest brentc]

If I were you and the aircraft new, I would head back to the factory and leave it there until it's sorted. Sounds like a pain in the butt, but it might be the only way. Seems extreme, but you'll be better off in the end.

 

 

[Guest DonC]

High oil temps

 

Yeah Brent, but I have flown there six times in the last five years and it's a fair hike from Derby!

 

 

[facthunter]

High Oil Temp.

 

There is a lot of good advice so far, but still no conclusion.

 

Q.. has there ever been any evidence of metal in the filter? The filter should be cut open and checked every time. Any evidence of other than slight contamination (in the early stages) is enough to require a strip-down, regardless.

 

Any scuffing of bearings will increase the likelihood of complete failure later. Any change to the clearances will change the oil flow within the engine. (More clearance, more flow) More flow will remove more heat from the hotter parts of the engine, and that heat has to be dissipated.

 

Suggestions: 1.Check oil pressure when HOT (as in VERY), and engine idling slowly, and compare with other similar engines.2. Listen carefully to the engine on first start-up after an oil & filter change for noises that disappear when the oil pressure starts to rise.3.Try running engine on ONE magneto. (Engine HOT) and carefully short out the remaining plug on each cyl. in turn ( so that cyl does not fire momentarily) and check for any sharp metallic noise as the spark is restored. Be VERY careful of the propeller proximity.There could be a possibility of an exhaust backfire of the small amount of unburned fuel present, but that should not present any problem if you are aware of it. Good luck ..Nev..

 

 

[brilin_air]

Don, Have you checked the earth lead from the motor to the battery, it sounds like a bad electrical connection if it has only happened recently and the other guages read ok.

 

Brian

 

 

[emaroo]

Update Some improvement oil TEMP J230

 

****!!!!!!!

 

This the second time I have have tried to write this and each time I have lost it - so third time lucky.

 

I now have my wife typing this as it takes me all day with one finger typing.

 

First, thank you for all the responses to our problem. We have checked all the wiring and the earths and all appears to be okay and no change to the oil temperature.

 

We purchased our factory built Jabiru in Feb this year 07 and it was one of the first planes to have a lip attached to the bottom cowl. It was screwed to the bottom cowl unlike the later models such as Brent C which are part of the fibreglass mouldings.

 

We have a new J230 in the hangar which has the larger moulded lip and bigger hole in the bottom cowl. We have now tried increasing the size of the hole of the bottom cowl to improve the airflow.

 

The good news is this has slightly improved the oil temperature but is still too high for our liking in moderate to hot outside temperatures. Our real concern remains why weren't we having problems back in Feb when temperatures were hotter and the motor brand new.

 

We checked the service records and earlier in the year we were having trouble with oil pressure as it was always running just in the yellow. After consulting Jabiru we tried several different things and finally by changing the sender this fixed the problem. However one of the fix's suggested by Jabiru was to increase the oil pressure by adding a washer to the relief valve. At our first attempt adding one washer this increased the pressure too high to the point where the motor would not start. I assume the high oil pressure meant that the hydraulic tappets would not totally close causing the motor not to run. We tried a thinner washer which slightly increased the pressure and we were able to start the motor but it wasn't until we replaced the sender the problem was totally solved.

 

So now we are thinking like Don C that this higher oil pressure could be affecting the hydraulic tappets and causing the motor not to run at its optimum and maybe contributing to our problem of high oil temperatures. So we plan to try and remove the washer and reduce the oil pressure to see if this could help solve the high oil temp.

 

 

[facthunter]

connection/effect

 

emaroo, high oil pressure= more oil flow and more heat removed by the oil. This could be your problem. Overfilling the oil gives a similar effect, as more of it gets flung about the insides of the engine, picking up more heat from the hotter parts. Nev

 

 

[Guest disperse]

The higher pressure will increase temps on it's own. But it may increase the flow rate through the cooler as well. if it flows through the cooler too quick. It dosen't get the chance to cool properly.

 

Much the same as removing the whole thermostat from your car. Instead of just cutting out the center. The water CAN flow too quickly through the radiator

 

 

[Guest disperse]

Just to clarify. if you apply pressure to a liquid or gas, it generally increases the temp.

 

 

[emaroo]

"Service Letter" from jabiru high oil Temps

 

After contacting Jabiru about my concern with high oil temps. Yesterday I received a email and an attachment from Jabiru advising a service Letter JSL 004-1 to to address probems with engine and high oil temps. They have addressed cowl modifications to improve air flow, removal of gull wing baffles, changes to oil cool ducts, cowl inlet modification and oil levels and dipstick range.

 

I assume this will be avaiabkle on Jabiru web site shortly.