J400/3300 - Oil Consumption

[Guest Martin J400]

Hi - My first post on this forum...

 

I’m a bit concerned that the oil consumption is too high on my Jab and would value input from others on this forum. Total Engine time is 91 hours.

 

 

I’ve monitored the oil usage over the last 20 hours during which time it has averaged 90ml per hour. I’ve never filled it above half on the dipstick and the oil overflow bottle is only about quarter full during the same time period.

 

This consumption seems excessive to me although the engine runs fine with no evidence in the exhaust of oil being burnt.

 

Any suggestions / advice please?

 

 

[quentas]

One tip from Jabiru is to keep the oil at the bottom of the dipstick. Over filling could be a problem as it just `blows out`. I put hardly any (about 500mls) between 25 hourly changes.

 

 

[Guest Michael Coates]

Note Michael Coates has been banned from this site

 

 

[jetjr]

I agree, with my J200, anything above the bottom level is blown out and if over half way high causes hot oil temps

 

They even released a new dipstick (with the wiggle in it) with very precise measurements for installation and the marks are in the same place - still my level must be just on the bottom mark or I have trouble

 

If I kept filling up to middle of top mark, I would go through about what you are using

 

Is there oil on the belly of the fuse? Oil overflow doesnt seem to ever fill up, gets to 1/3 then blows the rest under the AC

 

JR

 

 

[Guest Martin J400]

There is a liitle oil on the underside of the fuselage directly behind the noseleg attachment point.

 

I've always been a little concerned about running with the oil level on the 'min' mark but it sounds like I should try running at this level for a while and see how it works out.

 

I had assumed that oil would only be blown out of the overflow pipe if the bottle was full but presumably that isn't the experience of others?

 

 

[Modest Pilot]

Seems high for 90 hours. Both my engines with around 100 hours burn 22ml-25ml per hour. Maybe your engine failed to break in and will need a re-hone and another break in. The other thing is that a number of engines had oversized flanges on the barrel nuts that tends to distort the barrels. If just one of the plugs is oiled this could be the problem.

 

My 2200 goes best with the oil on the bottom of the dipstick. The 3300 seems O K at the half mark. I wouldn't start a long flight on the bottom mark, you just have to accept it's going to chuck oil into the bottle.

 

 

[Guest brentc]

Hi Martin, have a look at your oil pipe set-up where it runs from the filler to the bottle. Make sure it goes UP hill before it goes down hill to the bottle. Make sure it goes over the engine mounts if that makes sense.

 

I fill my J400 oil to the bottom mark, but it can worry me a bit on a long trip so I'll go to half, however since I rebuilt my engine at 400 hours it will happily stay at the half or even full mark without blowing out.

 

You need to determine if you're burning the oil, or blowing it out so try as you said at the lower mark.

 

I get no 'fresh' oil on the bottom of my plane and nowdays don't get any oil in the bottle, in fact I haven't even thought about emptying it for over 100 hours.

 

When I drop the oil, I put in 3 bottles exactly (3 quartz - 2800mls) and would never use more than 500 mls before the next 25 hourly oil change.

 

Another option to consider is that with only 90 hours on the clock is whether it's been run in properly. Was the run-in oil used for 25 hours or possibly more? Do you 'flog' it so to speak?

 

 

[Guest Martin J400]

Reading through the replies, I'm beginning to think that maybe it didn't break in correctly. I'll try running the engine at the lowest level on the dipstick and see if it continues to use oil. I'm also going to try a compression test and will come back to the forum when I've done it.

 

Regarding the run in - yes run-in oil was used for the first 25 hours or so which I think is what was stated on the leaflet that came with the engine. Since then, I have run it on Aeroshell Multigrade.

 

Thanks. Martin

 

 

[Guest brentc]

I was told that mine probably wasn't run-in properly at the 100 hour mark so I went back to run-in oil for the next 50 hours at the request of the Jabiru engine department.

 

 

[Guest Martin J400]

Another quick update.. It was suggested to me that I turn the prop a few times by hand to give a feel for the 'stiffness/compression' of the engine whilst cold then run the engine at 1200RPM for 2 minutes and repeat the test. I did this and the result was a considerably 'stiffer' enging as I hand turned the prop.

 

I'm told there is a distinct possibility that it is barrell distortion which I presume is what 'Modest Pilot' was referring to. I'm going to take it to the 100hrs and do all the checks when I do the 100hr maintenance. Hope this doesnt mean huge expense as I'm sure it won't be covered by warranty..

 

 

[Guest brentc]

If this is a new engine on its' first 100 hours I don't think you're going to have distortion of the barrels, I've never heard of this happening on a Jab.

 

By warming the engine and turning over by hand you have found that compression has increased which is exactly what should have happened, to the extent that a hot and new engine may be very difficult to pull through. I hope nobody has told you that this is not normal behaviour?

 

As your engine ages the pull through will become easier to the point when you are near TBO you may have very little compression unless your valves are tidied up before it gets to this point.

 

If the problem is as bad as you think, I'd go straight back to run-in oil for 50 hours (change at 25 of course) and worst case it may need to be honed. Don't jump straight to the worst conclusion as this may cost unnecessarily large amounts of money when there may be nothing wrong.

 

 

[Guest Martin J400]

Thanks again Brent for your comments. As I mentioned in my last post, I'll do the 100hr checks over the Christmas period during which time I'll do the hot and cold compression checks. Depending on the outcome of all this, I'll review what to do next but agree that its not necessary to jump to expensive conclusions without the evidence.

 

Incidentally, if I go back to run-in oil, without wishing to sound dumb, isn't it too late for that?

 

 

[Ross]

A local LAME strongly suggested to me to keep my J160 2200 motor on run-in oil for at least 50 hours.

 

It is a 2200 non hydraulic motor engine number #22A 1906.

 

I will see what happens eventually.

 

 

[Guest brentc]

Martin, like I said, Jabiru told me to go back to the run-in oil, but best check with them if you can.

 

Do you have a leakdown tester? A leakdown test (simple to do) will give more accurate results than a compression tester. Make sure the engine is really HOT, as in HOT HOT HOT, before conducting the leakdown test, otherwise you'll get less than average results.

 

 

[Guest Martin J400]

Hi Brent. Sorry for the delay in replying...

 

I've now confirmed that the engine is using oil, at about the same rate, even when it is run at the low dipstick mark.

 

I'll be doing the compression check (don't have access to a leak down tester) within the next few weeks and will then run again on run-in oil for the next 50 hours as you suggest.

 

Interestingly, I found the following in the latest JabaChat which i think is what ModestPilot was referring to. I'll let you know how things progress....

 

1. Cylinder Base Nuts

 

 

 

 

 

 

 

 

¨ Low-hour engines suffering low compression and high rates of oil use may be

 

 

 

 

 



suffering from out-of-round cylinders caused by the cylinder base nuts.

 

 

 

 

 

 

¨ Advisory Bulletin AVDALSR050 gives details & describes a treatment to the

 

 

 

 

 



base nuts to address the issue. This bulletin is available on request.

 

 

 

 

 

 

¨ Later cylinders have a slight alteration to allow for varying nut radii and make

 

 

 

 

 



altering the nuts unnecessary. However, as the mod is very simple it is recommended

 

 

 

 

 



that whenever a cylinder is removed the nuts are modified.

 

 

 

 

 

 

¨ Please note that while the change to the nuts is simple, it requires that the

 

 

 

 

 



engine through-bolts be undone. This is not a trivial job and should only be

 

 

 

 

 



attempted by competent, approved, maintainers.

 

 

 

 

 

 

 

[Guest Andys@coffs]

......(don't have access to a leak down tester) ........

 

 

 

 

Not withstanding the rest of your post, if you can afford the Aircraft then you really should get a leakdown tester. A compression tester and a leakdown tester are very different beasts, a compression testor is not capable of providing the same test baselines or being used to determine the fault as I understand it.

 

 

 

 

 

 

 

If you want to check for yourself, just find a GA engine Airframe LAME and discuss it with them. My experience is that they will ALL have a leakdown tester.

 

 

 

 

 

 

 

Andy

 

 

 

 

 

 

[Guest Martin J400]

I did the first 100 hour maintenance on my J400/3300 at the weekend. Whilst doing it, I did a compression check on all cylinders when the engine was warm (250 degrees F on the CHT gauge). All cylinders showed between 130 - 150 PSI.

 

What is a bit worrying is that number 4 cylinder spark plugs had quite a lot of 'dark deposits' on the electrode and looked like a small part of ceramic had been eaten away. They weren't the worst I've seen but certainly don't look too healthy. All the other plugs looked ok.

 

When I checked the tappet clearances, all need some slight adjustment but in particular, number 4 exhaust had closed up to 5 thou - too much of a coincidence I suspect so I think it needs further investigation.

 

I've sent my spark plugs to our Jabiru engine dealer here to have a look at.

 

In the meantime, I've also bought a leakdown tester and will try this when I get the chance.

 

Any thoughts from anyone please who has perhaps had a similar experience???

 

Thanks, Martin

 

 

[Guest brentc]

When I pulled down my engine just after 400 hours, the rear cylinders were quite gummed up with crap like you have explained and the rings were stuck with carbon and the plugs were a lot darker than the others.

 

The front cylnders 1 and 2 were super clean with rings ok as they were running leaner as they are further away from the carby, however the valves were stuffed and the seats completely burnt out.

 

As for the gaps closing, mine used to do that all the time, but it was because my valves were burning out and closing the gap.

 

I'm a little confused as to why it would close more on the one with the deposits as this would imply that that cylinder would be richer than the others and there's less chance of the valves burning out?

 

Unless I am mistaken, is that making sense?

 

 

[Guest Martin J400]

Hi Brent. My front cylinder plugs were also 'super clean'. I'm guessing the number 4 cylinder is where most of the oil is being burnt.

 

The potential that valves may be on the way out is concerning....

 

 

[Guest Martin J400]

Here's the results of my compression test and leakdown test. Both done separately on a reasonably hot engine after 10 minutes of ground running. Unfortunately the leakdown test was done at approx 100PSI as my leakdown tester has a single gauge and required approx 100PSI to get it to the 'Set' position required for the tests.

 

Compression Test (PSI) : Cyl 1 - 140, Cyl 2 - 130, Cyl 3 - 150, Cyl 4 - 140, Cyl 5 - 140, Cyl 6 - 145

 

Leakdown Test (% Leak): Cyl 1 - 18%, Cyl 2 - 25%, Cyl 3 - 15%, Cyl 4 - 20%, Cyl 5 - 14%, Cyl 6 - 16%

 

When I did the leakdown test there was definitlely more air escaping from the oil breather when checking Cyl 2. This would seem to correspond with both results and may perhaps explain the 90ml per hour oil usage.

 

I'm going to have it internally inspected and probably another leakdown test done with a more 'industrial' type tester but any thoughts from this initial analysis?

 

 

[Guest brentc]

Whilst I'm not a mechanic Martin, I'm of the impression that cylinder 2 would indicate that the rings have a problem due to the oil leaking out of the breather and the low compression. Must be the rings and not the exhause valve if you're not hearing anything out of the exhaust.

 

That being said, we got differing results when the engine was HOT, as in really HOT.

 

Next time you are doing the test try it after you have been flying, when the oil is much hotter and the engine too. You may find that the rings were stuck and having the engine much hotter may free up the rings which will give better compression.

 

Make sure also that you wiggle the prop back and forth a few degrees to ensure you are exactly at top dead-centre.

 

All that aside, 25% isn't all that bad and not much worse than cylinder 3. At 90ml per hour though, you're talking 2.25 litres per 25 hours whereas would be burning at most 35-40ml per hour.

 

 

[Guest Martin J400]

Update

 

Having run the engine for another 25 hours on run in oil, I've still got 90-100ml per hour oil consumption. It's being checked and hopefully rectified this week by our Jabiru expert. Will let you know the outcome...

 

 

[Guest brentc]

Indeed that does sound a little high! Good luck with the fix Martin.

 

 

[shafto]

Hi Alan here

 

Just a few things so bare with me.

 

Your leak down tests you have done, they will give you no indication as to why your loosing oil. A leak down test will only test the compression, or the state of the top two rings, it will not test the state of the oil seal. The differing rings do completely different jobs inside the cylinder, so dont think a leak down check will show a worn oil ring. If compression leaks past the front two rings the oil ring will do nothing to stop the air heading into the crankcase.

 

I personally dont know enough about the 3300's so I cant comment on weather 90mL is excesive. But If you are using excessive oil it will show up on your spark plugs, they will be oily and look glazed. If they are not, well I would lean towards a bad run in period. If the engine was babied at all with straight 100 oil, the rings will never seat and you will have a high oil consumption and not really any other symptoms.

 

A note as well, if you are putting straight 100 back into the engine the cylinder bores HAVE to be de-glazed or all your going to do is ware away gears or other components. And that does mean pulling each pot off. Once a cylinder is glazed over, the rings have already seated and the cylinder wall is lined. All you will end up with is unnessisary ware on other components and gears.

 

In relation to only filling oil to a certain mark becuase any higher it just "blows it straight out". The type of oil used is Ashless Dispersant in regular operations. There are two things behind the oil, obviously the 'ashless' part and 'dispersant' part. Ashless meaning that as the oil cleans the engine (key point here) it cannot leave behind any ash, embers or any other crap it may pick up while its lubricating and cleaning.

 

Dispersant being that all the crap that the oil picks up while cleaning are deposited and "dispersed" throughout the oil some being picked up by the oil filter, while the rest stays suspended in the oil. If you wanted to get technical you could call it a aqueous.

 

Now my opinion and held by alot of other people is that the cheapest and most effective way of ensuring engine longevity is good clean oil. So question is why not add the oil to the full mark? Keeping the oil tank full for each flight will only dilute the crap suspended in the oil and flush all that gunk out, but you wont even need to put a oil pan under it! The oil filter will be cleaner and the insides of your engine will be to. It is only a win win situation, less ware, cleaner engine. The piece of mind that there is a full tank of oil when oil pressure starts dropping might give you those extra 5 min of flight time to make a safe landing is also worth mentioning

 

If cost is an issue just remind yourself the cheapest thing you can do to ensure good engine life is good clean oil! So why risk it?

 

Keep it clean

 

Alan

 

*ps sorry about War and Peace there but better to try and give too much info than not enough

 

 

[Guest brentc]

Unfortunately in Jabiru engines particularly the 3300 you simply can't overfill the engine more than perhaps the half way mark, it will simply blow out the breather, fill the overflow-bottle and end up all over your airframe. The Jabachat newsletters are a good source of information regarding oil usage and engine management where the overfilling problem is discussed.

 

Blow-by is a common problem and glazed cylinder walls are associated with this. Once glazed, there is no return other than honing.

 

I await your expert's opinion.