Comment

Comment by Phillip Owens on April 4, 2011 at 12:27pm

Robert, When we originally installed the oil cooler we changed the hoses to high quality aircraft type and used AN type fittings. The poor quality K&J cooler expanded and failed under normal operating conditions. Having changed to the Positech cooler reveals the difference in the quality of the coolers. We chould be able to complete the change of coolers on friday, I will try to remember to take some additional photos and post them for all to see. We are allso making a change in the fitting coming out of the engine block to allow more room to change the filter, the original design is real tight in that area. We have added foam padding to the cowl opening to make up for the difference in sizes of the coolers, where the K&J was 11" wide the Positech is only 8" and we want all of the air to go through the cooler and not around the sides at all. 

 

Comment by Robert Caskey on April 4, 2011 at 11:33am

Phillip

We had oil temp problems that started after 4 hour of flight. We installea a lycoming 0360 and purchased the firewall package from Zenith. We eventually foun that we had two problems. Firsta we made the oil hoses with hte materials supplied and in the process created flappers on the inside of the hoses. My reccomendation is have a company that makes certified hoses make up your hoses as most don't have the alignment tools necessary to attache fittings safely. Second the oil cooler was not working properly. We replaced it with an american made certified cooled. The company would not take the core that Zenith provided because it is Made in China and not up to snuff. We also removed the scoop for the oil cooler that zenith provided and the new cooler works great.

We are still trying to get our chts to remain below 400

Bob Caskey

Comment by Phillip Owens on April 2, 2011 at 3:44pm

Worked on the oil cooler today, mostly went well but had to order a special fitting to complete the jobm part scheduled to arrive this coming wed, so should be able to finish the job on friday and maybe get in an hour of flying. Major difference in the quality of coolers between the K&J and the Positech, Positech much higher in quality.

Comment by Phillip Owens on March 22, 2011 at 11:57am

Had a good day on Monday,weather co-operated so I  managed to torque the Heads,re-set the valves and install a new manifold pressure guage.  Will install the new oil cooler when it arrives and add the oil, filter was replaced after draining the oil. A sample was sent for analysis to make sure we don;t have any internal engine problems.

Looking forward to getting back into the air again.

Comment by Phillip Owens on March 20, 2011 at 11:15am

Did not notice any drop in oil pressure just an increase in temps. New oil cooler on order from Aircraft Spruce, will re adjust the valves and torque the heads on Monday.

Comment by Ben Haas on March 19, 2011 at 5:56pm

Yuck !!!!!!!!!!!!!!!!!!!!   Did you notice a drop in oil pressure during the flight  or on the taxi back in ?

Comment by Phillip Owens on March 18, 2011 at 7:24pm

Today we started our investigation and discovered a hole in the oil cooler....it was made by KJ thermal Products and was supplied along with the engine when purchased. This cooler is 8"x5.64"x1 1/8" single pass aluminum. The oil cooler we have ordered to replace it is a Positech cooler with similar dimensions except it is 3.62" thick instead of the 1 1/8" old cooler. The oil filter was removed and cut open and inspected and did not show any metal particles, an oil sample was pulled from the remaining oil in the sump and sent to a lab for analysis, an original sample had been sent after the first 5 hrs as a baseline. We will be installing a new manifold pressure guage as well and will look carefully at the engine to determine if the additional location for an oil sender is available as suggested by Steve in his comments, thanks Steve. Will still need to re-torque the heads and re-set the rockers as we are just past the 10 hr engine mark. Weather permitting and speedy mail delivery will determine the nextflight, will keep you posted.  Thanks for all the info and suggestions.

Comment by Stephen R. Smith on March 18, 2011 at 10:06am

Phillip,

 

A few more thoughts... 

 

I don’t know if you follow the discussions on the Yahoo Jabiru engine group or not.  There have been discussions of oil pressure drop (restriction) in the oil cooler plumbing and the sandwich plate.  You will not see this on you panel because Jabiru put the sensor before these restrictions; lame design.

 

Keep in mind first of all, I am not familiar with your 8 cylinder engine but since Jabiru generally recycles design ideas from one engine to the next I suspect your engine is not much different then the other Jabiru motors.

 

Oil coolers are tested to withstand far more pressure then they will generally encounter.  Yours could be defective or there may be something else going on.

 

In the past Jabiru engines have had oil cooler failures.  This was tracked down to impulses from the pump that were especially bad when the oil was cold and when 50 weight oil was used.  Obviously oil does not compress.  The pump produces pulses; this is largely unavoidable.  Cold oil does not flow well.  Something has to give.  This is one reason why Jabiru wants the oil up to 114 degrees before high RPM and takeoff.  Personally I think straight 50 weight oil is an abomination and inappropriate for Jabiru motors, especially when temps are low.  Perhaps you are using the recommended multi-grade – that is important in my opinion.

 

The oil lines running to the cooler and the associated fittings on the sandwich plate are, some say, too small, especially for cold oil.  My engine was supplied with AN6 fittings and lines.  I have increased these to AN10.  I also replaced the stock sandwich plate with one that is far less restrictive.  Other folks I know have retained the stock sandwich plate and just increased the fitting size.

 

Steve

 

 

Comment by Stephen R. Smith on March 17, 2011 at 10:22pm

Phillip,

 

I moved the physical pressure sender off of the engine so it is not damaged by engine vibration, which has happened on several higher hour motors, including mine. When damaged the pressure sender reports incorrect pressure - not so good.  In my case it was reporting less pressure then I had by about 15 PSI.

 

On the front of the engine, immediately below where the pressure sender is normally mounted is a plug.  The threads are the same as the hole the pressure sender is normally mounted in.  Behind this plug is the main oil galley.  You can run a high-quality line from this hole to the remotely mounted presser sensor.  You can move the plug to the hole where the presser sensor is normally located.

 

With the pressure sensor reading galley pressure, you will notice that the pressure drops some with increasing RPM.  What you are seeing is the pressure dropping as the oil passes through the cooler and the filter.

 

You want to see a minimum of 10 PSI per 1,000 RPM. More is OK but not necessarily helpful. If your motor is red-lined at 3,300 like the 6 cylinder motor then you want a minimum of 33 PSI at red line.

 

Steve

Comment by Phillip Owens on March 17, 2011 at 9:26pm

I am also glad I made it back on the ground, it would have been much worse if the engine had siezed while I was flying!

I have not yet had a chance to asses the total situation yet, the oil cooler came with the engine and we have had some previous problems with it not wanting to seal properly at the connection points. However we did fix that issue and will have to see exactly where the failure occured. I believe you may be correct regarding the position of the pressure guage, we wll pay attention to this during our investigation, thanks for the tip. I did not have a low oil pressure warning on the engine instruament panel but noted the temps getting a little warm. where did you relocate your pressure guage to or did you just add an additional guage? I will try to see if there is a manufacturers name on the failed cooler and let you know. I have some photos but have not yet loaded them to the computer.

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