Jabiru engine life times

[dazza 38]

Put some abrasive paste between the valve and the seat, then rotate against each other until they seal properly. Use some blue dye stuff between them to check that they are seating correctly. ( I'm not a mechanic )Regards Bill

I posted a video on my FB page Andy.Showing how it is done.Just like Bill has mentioned here. I cant post it on here.

 

 

[planedriver]

Looks like you are on top of things Mick, keep going as you have been.

 

 

[Guest Error404]

Flashlube, yep that's the one. 20 deg reduction at least.

 

 

[foxy]

OMG!!!! Read Liz...... i voted for BOTH times i had engine problems!! Ok....so technically my Jab only lasted 49 hours when it had to go back to Bundy, get fiddled with and put back together again. Just putting in the extra note that it has had a second failure to U/S it again :(

 

 

[Gnarly Gnu]

In excess of 1000 with no breakdown at all - so no survey option available.

 

 

[foxy]

Are you talking about using unleaded motor vehicle fuel? It provides insufficient top end lub. The lead in aviation fuel is the best known lubricant followed by stuff like flash lube which is a replacement lubicant. The top grade fuel you mention is only an increase in octane rating which is useless if not required. Referring to the survey, wonder if any engines failed at zero hours./QUOTE]

when my 170 had the failure at 49 hours, it had been run religiously as how Jab specified it should be, when i picked it up. Avgas, maint done at correct times as told to me. Ive found that she ran a little smoother when running on 98 octane fuel than when she was run on unleaded. Im certainly not a Jab basher, I love my plane!!

 

Ive always stood up in their defence quoting average ratios of varying aircraft types and engines, right through Oz, but even im getting to the stage where it just comes down to the question of what else can go wrong with this jab engine!!!

 

 

[motzartmerv]

So what are you saying Liz?.. Did you vote twice? for the one engine?

 

 

[Sapphire]

foxy said: Ive found that she ran a little smoother when running on 98 octane fuel than when she was run on unleaded.

 

That's in line with expectations. Lead is the best lubricant but it also fouls engines.

 

 

[motzartmerv]

Thanx Daz;)

 

 

[Guest Error404]

Gnarly, I'll bet you $100 your engine will not make 2,000 hours without significant (and costly) issue assuming you ONLY had a top end overhaul as per the manufacturer recommendations at 1,000 hours. This is gonna cost you dearly, a newly overbauled engine plus $100.

 

 

[foxy]

Yea i did motz. Sorry.

 

Sapphire... I do realsie that. However... I have to say in the experience ive personally had.... It was running avgas that showed up a number of problems. Never had a problem with fouling with the 98 octane tho.....

 

 

[motzartmerv]

Ok Liz. And what hour bracket did you cast your second vote?

 

 

[cooperplace]

Put some abrasive paste between the valve and the seat, then rotate against each other until they seal properly. Use some blue dye stuff between them to check that they are seating correctly. ( I'm not a mechanic )Regards Bill

from my work on Ducati bikes, that's a good description. An exhaust valve gets v hot and much of its cooling is by contact with the valve seat. Dukes sometimes come from the factory (or they used to, I haven't worked on one for years) with valves poorly lapped in, and the blue dye test showed that valves would seat over a hairline or not at all, leading to hot combustion gases leaking past the valve at that point, and the valve by not seating can't cool, so it burns out. Removing the valves and heads, re-cutting the heads and valves, and lapping in with abrasive paste until there is a nice ~1mm wide seal leads to much better exhaust valve life, higher compression, smoother running and better performance, in Dukes. Also clearances had to be set properly: an improper clearance could cause an exhaust valve to hang open slightly, causing burning out of the valve. Probably asll this would apply for Jabs. No doubt someone will correct me if I'm wrong. At least Jabs don't have desmo valves!

I don't own a Jab but I'm learning to fly on one, and if I buy one, I'll approach the heads as I would those on a Duke, where accurate and correct seating and clearances are vital.

 

 

[coljones]

>>snip>>Ive found that she ran a little smoother when running on 98 octane fuel than when she was run on unleaded.

>>snip>>

was it unleaded unleaded (=91), 95 unleaded (=95) or 98 unleaded (=98)

 

 

[foxy]

motz....2nd vote was in the 800-1000 bracket. soz.

 

col..... unleaded was meant to say avgas... ran better on 98 than avgas

 

 

[cooperplace]

when my 170 had the failure at 49 hours, it had been run religiously as how Jab specified it should be, when i picked it up. Avgas, maint done at correct times as told to me. Ive found that she ran a little smoother when running on 98 octane fuel than when she was run on unleaded. Im certainly not a Jab basher, I love my plane!!Ive always stood up in their defence quoting average ratios of varying aircraft types and engines, right through Oz, but even im getting to the stage where it just comes down to the question of what else can go wrong with this jab engine!!!

just to clarify: 98 is also unleaded, is it not? do you mean it was smoother on 98 than on a lower octane rating fuel? Sorry to be splitting hairs.

 

 

[cooperplace]

motz....2nd vote was in the 800-1000 bracket. soz.col..... unleaded was meant to say avgas... ran better on 98 than avgas

just checked the Shell Australia site:

http://www.shell.com.au/products-services/solutions-for-businesses/aviation/products/fuels/avgas.html

 

there's lots of lead in Shell avgas.

 

 

[motzartmerv]

Ok. So the real 800- 1000 hours number is 3. Counting gnarleys one that went all the way.

 

 

[johnm]

.................. all the way with LBJ

 

L et's

 

B eckon

 

J abiru

 

 

[facthunter]

The poll doesn't do it. If it lost compression on one cylinder, at 500 hours and had to have the head off, what would that be classified as? A breakdown?

 

 

[Old Koreelah]

The poll doesn't do it. If it lost compression on one cylinder, at 500 hours and had to have the head off, what would that be classified as? A breakdown?

What if it hasn't broken down? (And please don't go adding "yet" you smarties!)

 

 

[jetjr]

The poll doesn't do it. If it lost compression on one cylinder, at 500 hours and had to have the head off, what would that be classified as? A breakdown?

I agree and reckon this forms part of the problem with discussions on this issue. What some see as breakdown others see as normal maintenance. Also some engine failures may have been averted by more careful monitoring, service and investigation.

 

 

[Keenaviator]

The poll doesn't do it. If it lost compression on one cylinder, at 500 hours and had to have the head off, what would that be classified as? A breakdown?

I suppose that depends on how we want to interpret the statistics. I would think not as you have averted failure.

I had a C-150 tail dragger for several years and the 0200 often had what appeared to be 'soft' compression (hiss in exhaust on pull through) when cold and having sat for a while.

 

I reckon pulling them through cold after sitting for a while is not an accurate way off assessing things as I'm sure if the exhaust valve is open for a while (parked) then exhaust byproducts/carbon etc can find it's way onto the seat showing up as poor compression on pull through. Give the engine a run briefly, stop it and try the pull through again, compression back and no hisses. No doubt it the hiss remains then it's time to look further. The LAME's often talk about doing the 'Indian rope trick' lapping in the valve to fix this issue. With the Jabi it's not necessary to to the rope trick as the heads are simple to remove and do the lap job properly.

 

 

[facthunter]

0-200's often get corrosion on the exhaust valve stem, above where it runs.. You have to remove the exhaust pipes to check this. I don't think it is that hard to remove the cylinders except I don't like releasing the through bolts as some oil may get on the wrong side of the mainbearings.

 

The jab heads are simple to remove and you have to retension them anyhow. Undoing the bolts is only one step more (plus the exhaust and inlet manifold). As I've said before I would pull the heads at 500 hours and remove the valves check the guides and seats. REPLACE exhausts. they have done enough by then and are not a lot more than refacing the seat. Valve guide play should be checked each time the heads are tensioned. It can be done without removing the heads. Nev

 

 

[motzartmerv]

Nev. Thats exactly why I set a perameter. ANY opening of the engine due to maint issue. And in my opinion yes, loss of compression and subsequent investigation is a break down, its a parameter easily set by a black and white yes no answer "is the engine servicable? ".

 

I just wanted to see what hours we are getting without any human intervention.

 

If your engine made it to 1000 hours then tick that box. Because they all have to come apart then anyway..;)