Top end over haul J2200 solid lifter

ive not flowin my sp for a while and have noticed 3 cylinders during prop pull through are not as high as the other, nearly half the resistance in fact. Guessing rings are issue as valves haven’t needed adjustment for a few years, (about 96 hours) tappets still around 10thou gap. I Have noticed a bit of oil in intake but oil consumption doesn’t appear un usually high at this stage. She is the original engine 2001 with 780 hours, jabiru informed me there is no heads available and that they would be able to do top end over haul late may. My thoughts were to strip the cylinders and heads off an send to jab for service but after talking to them got the impression they want the whole engine. Any thoughts or opinions?

 

 

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ive not flowin my sp for a while and have noticed 3 cylinders during prop pull through are not as high as the other, nearly half the resistance in fact. Guessing rings are issue as valves haven’t needed adjustment for a few years, (about 96 hours) tappets still around 10thou gap. I Have noticed a bit of oil in intake but oil consumption doesn’t appear un usually high at this stage. She is the original engine 2001 with 780 hours, jabiru informed me there is no heads available and that they would be able to do top end over haul late may. My thoughts were to strip the cylinders and heads off an send to jab for service but after talking to them got the impression they want the whole engine. Any thoughts or opinions?

There are many ways to deal with your issue. Sending the engine to Jabiru involves removing and reinstalling the engine, but at least they should warranty the repairs, providing of course, that you agreed to the work they recommend, which may be substantial. If not done already, they would want to replace the through bolts, pistons, valves, rocker bushes, upgrade to dual valve springs, check and hone barrels etc. etc. without even knowing the condition of the bottom end. Sometimes the costs can get up towards a newer generation reco. engine, but without knowing the history of the engine it is difficult to say. The other option is to ask Jabiru if they could recommend someone they consider competent near you to do the work, which may not come with a warranty...... Bob

 

 

Top overhaul requires replacement of things mentioned by Biggles plus big end bearings shells and bolts, crank timing gear, distrubtor shafts, seals ! See Jabiru website ! So the motor does need to come out to access timing case, if you are experimental and don't need to do everything it is still worth buying the full top overhaul kit as it is good value. Get a local engine place to do valve seats and bore honing !

 

I stripped my 3300 and had Heads and barrels done local ( mid north coast ) I reassembled and it's running happily ! Can give name of engine place if you want !

 

 

3 cylinders are down on prop pull through.... You need to be a bit more specific and give us more details.

 

If it was when stone cold and not used for a while, then un-even compressions is not uncommon for a lot of engines. If it was after a monthly run-up (preventative maintenance) then you would know that everything is close to operating temperatures, lubricated and valve and ring contact surfaces are not contaminated with surface corrosion.

 

Give the engine a quick ground run first and check your compressions again. Do not over-do the ground run,

 

as valve seats have been known to come adrift from overheating.

 

I'm confident that your compressions will feel normal enough for a flight and be completely normal after your flight.

 

Wby.

 

 

3 cylinders are down on prop pull through.... You need to be a bit more specific and give us more details.If it was when stone cold and not used for a while, then un-even compressions is not uncommon for a lot of engines. If it was after a monthly run-up (preventative maintenance) then you would know that everything is close to operating temperatures, lubricated and valve and ring contact surfaces are not contaminated with surface corrosion.

Give the engine a quick ground run first and check your compressions again. Do not over-do the ground run,

 

as valve seats have been known to come adrift from overheating.

 

I'm confident that your compressions will feel normal enough for a flight and be completely normal after your flight.

 

Wby.

Agree, and then do a Leakdown test to "know" the state, and not rely on feel alone.

 

 

You haven't flown for a while. How long is a while? Check the bores for rust visually ( with a borescope) before running the motor unless it was inhibited in some way. A month is plenty long enough for rust to be quite evident and sufficient to make running the engine unsafe. The exhaust stems are another rust possibility as well as the valve seat(s).. Nev.

 

 

You haven't flown for a while. How long is a while? Check the bores for rust visually ( with a borescope) before running the motor unless it was inhibited in some way. A month is plenty long enough for rust to be quite evident and sufficient to make running the engine unsafe. The exhaust stems are another rust possibility as well as the valve seat(s).. Nev.

You haven't flown for a while. How long is a while? Check the bores for rust visually ( with a borescope) before running the motor unless it was inhibited in some way. A month is plenty long enough for rust to be quite evident and sufficient to make running the engine unsafe. The exhaust stems are another rust possibility as well as the valve seat(s).. Nev.

You haven't flown for a while. How long is a while? Check the bores for rust visually ( with a borescope) before running the motor unless it was inhibited in some way. A month is plenty long enough for rust to be quite evident and sufficient to make running the engine unsafe. The exhaust stems are another rust possibility as well as the valve seat(s).. Nev.

4-6 weeks she sits in hangar waiting for air work, and it’s not for very long as I don’t have time for long stints these days. Grummo advised leak down test as nev has said suspecting valve stems. Mark at jabiru says through bolts are done in full overhaul and not top end for my engine being 730 + serial number. Perhaps a good flogging may sort my issues out, or at least bring them to head..

3 cylinders are down on prop pull through.... You need to be a bit more specific and give us more details.If it was when stone cold and not used for a while, then un-even compressions is not uncommon for a lot of engines. If it was after a monthly run-up (preventative maintenance) then you would know that everything is close to operating temperatures, lubricated and valve and ring contact surfaces are not contaminated with surface corrosion.Give the engine a quick ground run first and check your compressions again. Do not over-do the ground run,

 

as valve seats have been known to come adrift from overheating.

 

I'm confident that your compressions will feel normal enough for a flight and be completely normal after your flight.

 

Wby.

Yes engine had warmed up and let cool after 1:2 hour flight. All temps good in flight, cold start with no choke as usual for this time of year, hot start good but tight as usual upon crank, ( gives a heavy clunk as starter engages) however pull through finds not the familiar even resistance.. not having access to leak down test gauge will slow my research, but I know something is wrong with my girl.

Hi Russell, I got a leak down tester from ebay, cost $28.00. It shows % drop but is great for comparing cylinders, and you can hear where the air comes out.

 

Just make sure you remove the Schrader valve.

 

Kiwi

 

 

Yes engine had warmed up and let cool after 1:2 hour flight. All temps good in flight, cold start with no choke as usual for this time of year, hot start good but tight as usual upon crank, ( gives a heavy clunk as starter engages) however pull through finds not the familiar even resistance.. not having access to leak down test gauge will slow my research, but I know something is wrong with my girl.

I think as a safety precaution you would be well advised to have someone familiar with Jab engines check it over before next flight..... Bob

 

 

4-6 weeks she sits in hangar waiting for air work, and it’s not for very long as I don’t have time for long stints these days. Grummo advised leak down test as nev has said suspecting valve stems. Mark at jabiru says through bolts are done in full overhaul and not top end for my engine being 730 + serial number. Perhaps a good flogging may sort my issues out, or at least bring them to head..

Through bolts are replaced on the top overhaul ! See Jabiru web site for manuals !

http://www.jabiru.net.au/Manuals/Engine/JEM0001-12_Overhaul_Manual.pdf#page55

 

 

I think as a safety precaution you would be well advised to have someone familiar with Jab engines check it over before next flight..... Bob

Yes engine had warmed up and let cool after 1:2 hour flight. All temps good in flight, cold start with no choke as usual for this time of year, hot start good but tight as usual upon crank, ( gives a heavy clunk as starter engages) however pull through finds not the familiar even resistance.. not having access to leak down test gauge will slow my research, but I know something is wrong with my girl.

"familiar even resistance"??? Yikes! There should only be a healthy bounce between compressions hot or cold.

Definitely do not fly it in its current state. Sounds from your description that there is tightness in the engine and it needs further investigation by someone knowledgable and experienced in these matters, specifically Jab engines. Not just another jab owner, but someone who has considerable expert maintenance experience with repairing and overhauling jab engines.

 

Well done on raising your issue for advice!

 

Wby

 

 

Wby, he has an early engine and its normal for some of them to be Stiff. I'd be more concerned about the heavy clunk when starting, though, as a reason to "do not fly".

 

There a bulletin around 2008 called AVDAL SR050 which deals with tightness, another later deals with the doubling of the cylinder - piston clearances.

 

My 2200 would frequently get 1 or 2 soft pull through cylinders which often clear after a couple of 1 hr flights. New rings and a hone to the revised clearances and fixing the base nuts issue is an improvement. I would not be sending an engine of this pedigree anywhere for major overhaul, there are so many "improvements" needed such as dowels for the crank etc. that a new engine is more cost effective.

 

 

There is much new thinking about compressions. Lycoming and Continental have changed their thoughts in the last few years. The general concensus sems to be that it is better to run the engine for up to 3 hours and then re check the leak down. Even then if the leak down rates vary quite a lot, the recommendation is to use the borescope, before committing to engine major repairs.

 

I would consider that unless the compression drop was a lot and the engine was running very roughly, and if a borescope check showed nothing amiss, that the best thing would be to fly the plane for 3 hours and re assess the situation. Of course you would have to fly from a strip that would normally allow you to climb out easily and return if there were problems.

 

A few years ago I got poor mogas which caused a detonation problem in my Jab 2200. Compressions felt OK, but i got a big mag drop and roughness when i did the mag check. Swapped the coils and still got the mag drop, replaced a coil and still a mag drop. Then I tried a mag test at full throttle and hardly any drop I decided to try to get the plane home 32 miles and climbed to the bottom of controlled airspace, 6500' I think and safely flew home.

 

When I removed the engine and pulled the cylinders, No 4 had about 25% of the top land broken off and just sitting in place, the rings were broken, the crown of the piston looked a bit hammered, but it had been giving just about full power on climb out. I say this to show that the engine is pretty good at producing full power, when it can show more symptoms at lower power.

 

 

My engine still has the original starter motor and has always gave a clunk and strain upon starting, borrowed leak down tester and found exhaust valves on 1,2,3 are leaking.

 

 

Why don't you go and do the factory course and use your engine as the instructional piece? I attended a couple of years ago and we used another student's engine (over 1500 hours solid lifter) it was updated to latest specs with cost of parts only. The owner was very happy with the result. We learnt a lot as well.

 

Ken

 

 

Removed tappet cover and checked valve clearances today and yep exhaust on suspect cylinders 2-3 thou above my set 10. Oil change and a hard run for .4 in the air ( Italian tune up ) and she has settled back down, I suspect nev was right about rust in valves which is something I never considered. My pull through now is even as it was before and I’m one very happy camper. If this reoccurs I will be removing heads and have them serviced at a machine shop such as camels.

 

Ken

 

 

ive not flowin my sp for a while and have noticed 3 cylinders during prop pull through are not as high as the other, nearly half the resistance in fact. Guessing rings are issue as valves haven’t needed adjustment for a few years, (about 96 hours) tappets still around 10thou gap. I Have noticed a bit of oil in intake but oil consumption doesn’t appear un usually high at this stage. She is the original engine 2001 with 780 hours, jabiru informed me there is no heads available and that they would be able to do top end over haul late may. My thoughts were to strip the cylinders and heads off an send to jab for service but after talking to them got the impression they want the whole engine. Any thoughts or opinions?

Take it out and give it an hour at high rpm 2950, they love it and that will clean the cobwebs and rust out , then change the oil and filter

I would like to do a factory course but the guy who did them has gone and they are no more. This was even before the virus stuff.

Are there any other good hands-on courses around?

"Something" from this is that the manually adjusted tappets tell you something, if there's a change. Also when a motor has some considerable hours say over 400 the valve guide to stem fit may be excessive and that's not easy to check in situ. and need specialist attention to rectify. There's NO reason also not to turn a Jab backwards a half turn to check an individual cylinder's feel. IF the compression is far better one way than the other , the ring gaps have become aligned on one side of the piston and you can ignore the poor feel in the other direction. . Nev

I would like to do a factory course but the guy who did them has gone and they are no more. This was even before the virus stuff.

Are there any other good hands-on courses around?

I would be in on that, i did do the MW Fly heavy maintenance course in Milan was excellent

That's real interesting Nev, I don't understand your explanation but in future I'm going to look to see if the compression is different in reverse. Thanks.

Was that Milan Italy watto? What a great place to do an engine course.

The piston goes to the other side when turned backwards and when they are cold there's quite a bit of piston clearance so where the ring gaps are makes a difference when you turn it. and "feel" it. When it's running you don't worry about it but a flowmeter on the breather would not be a bad idea of how to gauge ring condition. Nev

That's a great idea Nev. It has been suggested that inflating a rubber glove would help determine if the leakdown flow was past the rings or not.

If it is just the leakdown air, you could do this in safety as the engine is not running.

In the Jabiru we already have a hose going to the oil overflow bottle. If you put a longer hose on, you could put the end under some water and see it blow bubbles. If you caught the bubbles in an inverted measuring jug you could get a measure of the blowby. This could be compared to the leak-tester total air into the cylinder.

I reckon I will try that this winter.