156 JTS spun bearing

Started by psproule, July 11, 2015, 07:14:40 PM

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psproule

So all was going well in the the new affair with the 06 156 JTS I picked up from auction. Changed the noisy variator, fresh cam belt and balancer belt, new water pump and plugs, oil change and filters. Noted a couple of worn inlet cam lobes but not too bad. Did about 3000km since and then one day it starts to rattle.It sounded like light pinging at first at part throttle openings. But then it quickly got louder and then all hell breaking loose. Thought perhaps it was valves hitting pistons from a jumped cam belt but the noise was more like a rod knock. So I made the decision to drop the motor out for a proper look. The head was fine - a bit coked up but no valves hitting pistons. But the head gasket was a bit of a mess. Bores look good with hone marks still visible at 164,000km.

Then we turned it over and took the sump off for a look, and there it was, Number 2 big end bearing completely gone and the crank journal stuffed. We found the bits lodged in the oil pump pickup and I wonder if in the end it blocked the pump enough that it started to starve the other bearings and thus the growing noise. I don't recall an oil pressure light though.The other bearings show stress but had not let go

Interestingyl, while the motor looks like it has never been apart, # 2 bearing cap has a blue letter A written on it, making me slightly suspicious.

So, where to now? Rebuild this one or source a second hand motor? For a rebuild it will at least need a crank regrind, set of over-size bearings, new head bolts and fresh gaskets. Perhaps also a #2 piston if it managed to hit the head (does not look like it). Probably should re-ring it while it is apart too. But how much shrapnel has it eaten and how much other damage is there? It's hard to tell. It might be safer and probably cheaper to source another motor. Second hand motors seem fairly common but what other issues would I inherit with one? SO a bit of a gamble both ways.

What are your thoughts folks? I don't want to part it out by the way - would prefer to keep it.

Pat

colcol

I would get a good second hand motor from a Alfa Romeo Wrecker if i was you and check the compression and pull the cam covers off to see if the camshaft lobes are worn.
Alfa 156 JTS's are not worth that much these days, your motor that died, looks like it has been run too long without an oil change and has been lubricated with dirty oil contaminated with fuel that has worn the camshafts and bearings, or it may have been just run low on oil, and has nipped up a bearing.
If it was me, then i would get a good secondhand motor from a Alfa Wrecker and have it reconditioned, with a hone and new piston rings at the minimum or a rebore with new pistons and rings and a decoke.
Alfa Romeo Service Providers know about the JTS's love of oil and when fixing these motors, modify the pistons and rings to lesson the oil use.
Your current motor may have done a cam belt and a cheap fixit job done to get rid of the car, that involved replacing the bent valves, but not replacing the bearings that received a good thump when the pistons hit the valves, they usually fail a short time later, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

psproule

Thanks Col. My variant on your suggestion is to rebuild this motor perhaps. The damage looks contained to the one bearing journal. I would have to grind the crank, new bearings, probably bore and hone the block and toss in a set of pistons and rings too in a effort to curb the standard 156 oil consumption.