Herm Posted October 23, 2012 Posted October 23, 2012 I have a 2200 Jab engine in my SK that has only done 6 hours. At three hours I noticed oil on the underside of my aircraft. Looking into the problem it was found to be the rear end seal that was leaking and was replaced (simple job). I have now done another 3 hours to find I have the same problem starting again. I have a warranty on the motor so all is good in that area, however I just wanted to see if others had had the problem? And please can the Jab Bashers Bu--er off as I am looking for assistance. In recent times as soon as a question is asked about a Jabiru, out they come... I am not sure if this problem is relative to another problem or if I have just been unlucky and perhaps put in a second faulty seal. I don't have vibration and all my temps are normal and oil pressure is correct. The aircraft seems to run fine apart from this oil problem.. Thank you Mardy 1
brilin_air Posted October 23, 2012 Posted October 23, 2012 Mardy, The only problem with oil leaks that I have had has been the oil cooler adaptor oring under the oil filter, when this leaks the oil can travel to the back of the motor very quick, the replacement oring is slightly thicker than the original, if you are having trouble with the rubber seals for the crank and distributor shafts, make sure there is plenty of lube on the sealing/wearing surface when it is installed as it can wear the new seal very quickly. Brian
frank marriott Posted October 23, 2012 Posted October 23, 2012 Herm I have 440 hrs on a 3300 engine without experiencing your problem - so I cannot help you there. I find in relation to other matters (I have just been through a suspected problem with carb ice). I find overall that the info available on this site is valuable and after a couple of years of looking and recently posting less but still reading - the relevant info still comes out - and ignore the static I will be interested in what you find in due course and I will ignore the other rubbish posts that will no doubt appear. FrankM
Sapphire Posted October 23, 2012 Posted October 23, 2012 Had that problem on another piece of machinery. Is the seal moving. The easy ones to get out are a press fit and should have some sealant glue to hold it in place.
Guest Andys@coffs Posted October 23, 2012 Posted October 23, 2012 Mardy How full are you filling the crankcase? Jabs dont like too much oil in the crankcase and just dump any extra in the overflow bottle...which then overflows onto the bottom of the plane in flight. If you are constantly toping up to the 1/2 way mark on the dipstick that might explain it...... If you search this site you'll find that most J owners say only bother filling to around 1/4 on the dipstick anything extra just gets chucked overboard...... Andy
rick-p Posted October 23, 2012 Posted October 23, 2012 I have a 2200 Jab engine in my SK that has only done 6 hours. At three hours I noticed oil on the underside of my aircraft. Looking into the problem it was found to be the rear end seal that was leaking and was replaced (simple job). I have now done another 3 hours to find I have the same problem starting again. I have a warranty on the motor so all is good in that area, however I just wanted to see if others had had the problem?And please can the Jab Bashers Bu--er off as I am looking for assistance. In recent times as soon as a question is asked about a Jabiru, out they come... I am not sure if this problem is relative to another problem or if I have just been unlucky and perhaps put in a second faulty seal. I don't have vibration and all my temps are normal and oil pressure is correct. The aircraft seems to run fine apart from this oil problem.. Thank you Mardy Mardy can you post a picture of the area where it is leaking because it is unusual for the rear mount plate as such to leak. Sometimes the ditributors will weep past the seals and up the shaft. The oil feed tube installed in the back plate when refitted must be orientated with the slot pointed upwards. But once again without a picture it's a little difficult to know exactly where you are saying the engine is leaking. I assume that Jabiru replaced the seal for you? Regards, Rick-p
Herm Posted October 23, 2012 Author Posted October 23, 2012 MardyHow full are you filling the crankcase? Jabs dont like too much oil in the crankcase and just dump any extra in the overflow bottle...which then overflows onto the bottom of the plane in flight. If you are constantly toping up to the 1/2 way mark on the dipstick that might explain it...... If you search this site you'll find that most J owners say only bother filling to around 1/4 on the dipstick anything extra just gets chucked overboard...... Thanks Andy and Rick. I am not getting any overflow into the bottle it is the rear end seal. We have had the rear mount plate off and replaced one seal. Without doubt that is where it is from this time as well. I can look at the oil running down from behind the flywheel. When it first happened I used my bore scope to look up behind the flywheel as at first I though it was leaking at the distributor. Sadly this is not the case. I have found no information on the net to suggest this is a common problem, so I am puzzled. Second seal in 6 hours is a little odd. Mardy
biggles Posted October 23, 2012 Posted October 23, 2012 Mardy , Leaking of the rear seal is certainly rare , and most of the causes of seal failure have already been listed here . I also know little about the engine , but assume that it was reconditioned at Jabiru. If not , I wonder about the seal/shaft running surface , or if the seal is in fact the correct one for the application ( shaft dia. Etc. ) Main bearing wear as well as shaft distortion as mentioned by KA are other possible causes . I also assume that the cylinder compressions are all similar. Not really related to the seal problem, but mentioned on this thread , most 2200 engines take 2.3 litres of oil , however Jabiru had a number of different dipsticks for the 2200 . Establish the correct oil volume for your particular engine and mark the stick accordingly. As others have said , keep us informed of progress . Bob
JabSP6 Posted October 24, 2012 Posted October 24, 2012 Herm One thing that comes to mind that may have some relevance to this issue is the fact that the Crank Shaft Gear that this rear main seal runs on has been upgraded in the last year or 2. The New Gear has a slightly thicker walled section making the OD of the gear bigger. This in turn also led to the seal being superseeded to a slightly bigger ID. The reason behind the gear being upgraded to a slightly thicker walled section was to overcome a few issues of these gears failing/cracking. Now if you are still running the original smaller OD gear and you have been supplied the new bigger ID seal there could be a possibility that you now don't have enough tension on the sealling surface to be effective which could explain the oli leak at such low time. The change in dimensions of the parts were not huge and i'm not saying that this is the case in your situation but it may be worth looking into. Hope this helps. JabSP6
jetjr Posted October 24, 2012 Posted October 24, 2012 From experience finding the true source of oil leak is VERY hard, crank seals front and rear rarely give problems but often look like it. Check all the obvious like hoses etc but around the mechanical fuel pump is a more common place. Youll see theres not much flat there to seal on and pump extends over sump/block juction Overfilling can help oil leaks too
Sapphire Posted October 24, 2012 Posted October 24, 2012 Just wash the engine down with degreaser and water and dry out. Run for a couple of minutes only and oil leaks will glisten in your torch light at their source.
Herm Posted October 25, 2012 Author Posted October 25, 2012 HermOne thing that comes to mind that may have some relevance to this issue is the fact that the Crank Shaft Gear that this rear main seal runs on has been upgraded in the last year or 2. The New Gear has a slightly thicker walled section making the OD of the gear bigger. This in turn also led to the seal being superseeded to a slightly bigger ID. The reason behind the gear being upgraded to a slightly thicker walled section was to overcome a few issues of these gears failing/cracking. Now if you are still running the original smaller OD gear and you have been supplied the new bigger ID seal there could be a possibility that you now don't have enough tension on the sealling surface to be effective which could explain the oli leak at such low time. The change in dimensions of the parts were not huge and i'm not saying that this is the case in your situation but it may be worth looking into. Hope this helps. JabSP6 Thanks for this info as it was something I had not been aware of. I did make some phone calls and found that this is not the case on my motor. Next week the plane is going to be taken away for the guys to have a real good look as to why this has happened again. I have been made aware that on rare cases the Crank Shaft Gear cracks near the shaft allowing oil to pass rear of the seal. We are not sure if this is the case at this stage, but will post back the results of what is found. It seems my problem is not a common one so the results will be good to post for others when I get them. Thanks to all those that also posted suggestions of other things it may be. It is to be noted that the oil IS leaking at the rear end seal behind the flywheel... Mardy
JabSP6 Posted October 25, 2012 Posted October 25, 2012 Herm The Crank Shaft Gear has on the odd occasion been know to fail/crack as you have described. This is why they have changed to a slightly thicker section gear and in turn a different inside diameter seal. One of the main causes of this failure was found to be the clearance between the shaft and the gear was insufficient. In other words the gear was a tight firm fit on the crank and when tensioned up with the flywheel it could lead to the gear being under stress. I believe the new thicker sectioned gear is not only stronger but also runs a slightly bigger clearance so that it is easier to slide it onto the crank. If you do pull this gear off to have a closer inspection and find it is the earlier gear i would definately recomend upgrading to the new gear and seal even if you don't find any problem with the gear. Also when fitting the gear back to the crankshaft make sure the gear fits on easily and goes all the way and bottoms out on the crankshaft. If it doesn't bottom out the internal radius of the gear may not be correct. Keep us informed of your findings. JabSP6 1
Yenn Posted October 26, 2012 Posted October 26, 2012 I seem to remember that way back Jab had a problem with a few engines leaking at the rear end. What happened was that one of the drilled oilways was incorrectly drilled. I doubt that the problem would pop up again, but anything is possible.
Herm Posted November 3, 2012 Author Posted November 3, 2012 Well here is the update on my oil problem... It turns out that the hole for the seal in the rear plate was not concentric. Not only that, but it was not central to the rear shaft. Turns out that I had a defective rear plate. It has now been replaced and I hope the problem is fixed. The rear gear and shaft are brand new and don't even have any seal rub marks as the engine has only done 5 hours.. Happy that they found a problem, as this allows for a rectification.... Now it's time to go flying. I hope this helps anyone else that may have a problem of a rear end leak (on the plane that is) Mardy 3
Yenn Posted November 4, 2012 Posted November 4, 2012 So it did pop up again. Why would this happen? Poor quality control?
brilin_air Posted November 4, 2012 Posted November 4, 2012 So it did pop up again. Why would this happen? Poor quality control? Yenn, see earlier posts about this plane, it was an older kit recently finished so it would probably be an earlier problem not rectified due to the time that it took to finish the aircraft, problem didn't just pop up again. Brian
Yenn Posted November 4, 2012 Posted November 4, 2012 Didn't see the earlier posts, in fact going back to the start I still cant see them. But that would explain it. It must be about ten years since I first heard of the problem.
ruffasguts Posted November 4, 2012 Posted November 4, 2012 Didn't see the earlier posts, in fact going back to the start I still cant see them. But that would explain it.It must be about ten years since I first heard of the problem. again we jump to conclusions this engine was built by someone other than jabiru (known fact) Mick
frank marriott Posted November 4, 2012 Posted November 4, 2012 Just another informative and helpful thread turning to crap - no wonder less informative information is posted when so often the info posted which is of great interest to many is treated in this way. This is just one more thread that I will ignor from now and let the people with a axe to grind carry on. 3
dazza 38 Posted November 4, 2012 Posted November 4, 2012 again we jump to conclusions this engine was built by someone other than jabiru (known fact)Mick Jabiru doesnt make engines Camit P/L makes the engines for Jabiru.Under contract.
Herm Posted November 4, 2012 Author Posted November 4, 2012 As Mick mentioned this engine was not built by Jabiru directly. In fact the content of my post really has no relevance to this fact. I just wanted to help others that may have or have been chasing this same oil problem. I am sure we have all done or been involved in a project that has had problems due to human error or some very odd fault in a manufacturing process. Near all advancement is derived from failure. I am sure the builder ( who I know well) had no intention of fitting a part that had a fault measurable in the few hundreds of of a mill. I wish I could get the same level of assistance with my car and other problems as I have in relation to this problem. Could not have asked for better assistance and support as I have had with this problem... Just a simple but annoying problem with what turns out to be a very simple fix thanks to a well designed engine that allows easy replacement of a rear plate. Some other engines don't have this well thought out system and would have resulted in a very major problem. Mardy 3
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