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Rebuilding a non-cert 2200

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Rebuilding a non-cert 2200

Postby Pete Twissell » Mon Sep 30, 2019 3:59 pm

I am rebuilding my non-certified J2200, following an in flight failure on my Thruster microlight. The subsequent deadstick landing was uneventful.
The engine dropped a valve, comprehensively destroying a piston, bending a rod and damaging the barrel and head beyond recovery.
Being a non-certified engine fitted to a microlight, I have somewhat more freedom to adapt the rebuild in the light of experience.
The engine had logged a little over 1200 hours, with no history of failures. No. 1 cylinder often had low compression when cold (subjectively by hand cranking), but was OK after running. In the 1200+ hours, the engine had been regularly serviced but had not been overhauled.
On stripping the engine, the following points were noted:

Heavy wear on piston skirts (3).
Bores (3) in good condition, with a barely perceptible lip, honing still visible and measuring well within tolerance (one example was quite close to minimum).
One broken piston ring - partially stuck in groove.
Signs of corrosion (small pits) around necks of exhaust valves.
Valve / guide fits subjectively good but not measured.
Minor damage to inside of crankcase, due to contact with bent rod.
Big end shells in good condition, showing minimal wear.
Main bearing shells showing significant wear in some locations. The shells at either end of the engine and the thrust bearings showed considerably less wear than those towards the centre.
The crankcase showed evidence that the centre bearing shells had 'hammered' into their housings. A lip could be felt at the edge of the housing.
The centre bearing housings in the cases measure out of round and above the upper limit.
The rearmost camshaft bearing showed significant wear and displacement of material.
The crankshaft showed slight scuffing on the centre main bearing journal. All main bearing journals measure close to or below lower limit.
All big end bearing journals appear in good condition and measure well within limits.

A new rod, 4 sets of big end shells and 4 new pistons with rings have been purchased. These are Jabiru parts.
Good condition used head and cylinder have been sourced.
New stainless steel valves sourced locally. These have a black DLC coating on the stems.
Following an extensive search, main bearing shells have been sourced with -0.25mm ID and oversize OD.

The cases will be line bored to fit the new main shells.
The crankshaft main journals will be reground to -0.25mm
The damaged cam bearing will be bored oversize and fitted with a split bronze bush.

I will look into adding a feature to the cases to improve oil feed to the cam bearings.

If this is of interest to group members, I will update as work progresses.
Pete Twissell
Thruster T600N G-BZNP
Jabiru 2200 small head
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Re: Rebuilding a non-cert 2200

Postby Steevo » Thu Oct 03, 2019 6:31 pm

Definitely of interest to many on here.

One question, had the valves ever been replaced in the 1200hrs of use. Valves have always been a sore point and usually the exhaust valve goes. That is very good going if you managed to get 1200hrs out of them.

My previous Jab had a top end overhaul at around 550hrs. It was a voluntary decision as I was having other upgrades done. When the heads were all removed, 2 of the exhaust valves had just started to pit. All valves were replaced.
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Re: Rebuilding a non-cert 2200

Postby Red » Sat Oct 05, 2019 8:35 am

Good luck with the rebuild, looks like it's well within your abilities Peter and documenting it would be a great help to fellow jab owners.
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Re: Rebuilding a non-cert 2200

Postby Pete Twissell » Mon Oct 07, 2019 10:26 am

Hi Steevo,
according to the log book, these were the original valves. The engine was fitted to the Thruster after it had flown ~200hrs with a 582. The aircraft was used for training for several years, with regular servicing but no overhaul recorded. The inly incident in its history was a precautionary landing after the pilot had flown for 30 minutes with the choke on. Other than that, there are a few entries for re-torquing head bolts and replacement of fasteners to comply with MPDs. By the time of the 7/16" through studs mod, the aircraft was no longer used for training, so it still has 3/8" studs.
For reference, the main bearing shells I am using are King Bearings mb4523am0.25 (kit comprises 4 pairs, so 2 kits required). These are thick wall shells, requiring the cases to be bored from 52mm to 55mm. The thicker walled shells should improve load distribution into the case material. The shells come in at 18.4mm wide and must be reduced to 17mm.
Pete Twissell
Thruster T600N G-BZNP
Jabiru 2200 small head
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Re: Rebuilding a non-cert 2200

Postby Pete Twissell » Tue Oct 08, 2019 12:40 pm

Photo taken on removing #1 cylinder head after the failure:
2019-03-01 11.42.15.jpg
Pete Twissell
Thruster T600N G-BZNP
Jabiru 2200 small head
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