Why does the twinspark spin shells? - Page 2 - Alfa Romeo Forum
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Join Date: Feb 2009
Location: Australia
County: Victoria
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The problem must be lubrication related at some level. The broken cambelt theory is also valid. In general, it is best procedure to check shells after bending valves but most engines don't have a problem.

Here's my theory. It is a combination of using oil that is too thick for the application and a crank that has not been hardened enough.

The engine is designed for a 40 weight and to meet the long oil change requirements with the technology they had at the time a 10w40 grade was spec. This is a terrible choice for a cold climate as it will be very thick on cold start. 5w30, 0w40 and 5w40 are more common these days and far better. If that wasn't bad enough, Alfa allowed 10w60 as an option to slow down consumption. 10w60 is insane for such an engine in a cold climate, it will be twice as thick as a 10w40 during cold start. This thick oil results in too much oil pressure leading the oil pump to by pass a lot of oil to the sump rather than pumping it through the bearings. This results in a lot of boundary lubrication in the bearings. Some boundary lubrication is ok and if you have really good oil it can survive. But there is only so much the anti wear additives can do before there will be some wear.

On top of that the cranks are not hardened as well as older Fiat designs, they are softer and suffer more wear. Older Fiat engines tend to wear bearings also but if you catch them in time the cranks are usually absolutely fine. I have found TS cranks are toast even before the bearings have spun.

If I owned one of these I would use a 0w30 oil that is ACEA A3 rated as this will offer the thinnest oil on cold start while maintaining the minimum viscosity required during normal operating temperature. The oil consumption over a 10w40 should be minimal. I would put up with high oil consumption and top it up.

I owned a 147 TS once and oil consumption was not that bad on 10w40 yet the dealership used 10w60 exclusively before I bought the car.

If I'm right, you can see what problems this will cause for the average driver. Cold start, thick oil, and say having to pull out into a gap in the traffic the engine gets a little 4000 or higher squirt and every morning. They are not going to last.

Last edited by Steve S; 28-06-13 at 02:58.
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shells , spin , twinspark

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