WTB 156 2.0 JTS Catalytic Converter

[bteoh]

Hi,
Looking for a catalytic converter for a 2004 156 2.0 JTS. It has developed a fault code which points to the catalytic converter. Was hoping someone has a good condition used unit that hasn't faulted before? An OEM catalytic converter is unfortunately hideously expensive. Was also told some aftermarket new ones still have the problem with fault codes coming back.

[colcol]

There was one on the 156 Ebay site for about $500?, second hand, i have been told that if your thermostat goes bad and opens too early, then the car runs too rich and clogs up the catalytic convertor, also the Lambda sensors being faulty can also cause the cat to become clogged, due to an over rich mixture, Colin.

[bteoh]

Hi Colin,
Thanks for the info. When I bought the car, the thermostat was faulty and the tail pipe was very sooty. I have since changed the thermostat and it runs perfectly now. I have also changed the oil to Penrite 10 tenths 10W-70 (Listed as recommended oil for the 156 JTS in the Penrite Oil chart). After changing the oil, on the first country run, it blew a lot of smoke whilst overtaking and checking the oil the next day showed almost no oil left in the sump. However, it has used very little oil since with regular / normal commuting. Not sure what was happening there?
On the Penrite container, it says it has full zinc protection. Would the zinc content cause any damage to the cat? When the first fault code came up, it had cat 1&2 faults and lambda 1&2. However ,  2 weeks after resetting the ecu, the fault code reappeared this morning but this time it registered as cat 1&2 faults with NO lambda faults. So I presume just changing the cat converter should fix the problem??
Any ideas ?

[wankski]

1) that oil is waay too thick, you will guarantee excessive cold start wear with that oil. see this thread for all you need to know and more:
http://www.ausalfa.com/viewtopic.php?f=4&t=4278&start=375

2) if you were blowing smoke that bad, it could indeed foul the primary cats. u might get lucky and clear it out with some hot runs, or you may be successful in cleaning it after removal. they are expensive. make sure the code reappears after clearing to confirm long term. the code is actually 'catalyst (in)efficiency'.

HTHs

[colcol]

Zinc will cause damage to your Catalytic Convertor, its hard to get an oil with Zinc in it now, due to emmision rules, but zinc in oil is ok for pre 86 cars that are leaded without cats.
Sometimes when you go for an enthusiastic drive and blow the cobwebs out, all the diluted oil and acid and petroleum and water get burnt out, and the oil level drops alarmingly, and you think your car is starting to use oil, just change the oil a bit more often or take it for a good drive.
I use Castrol 10-60 edge in my JTS in the summer, and in the winter i use Mobil 1 5-50, can't really tell the difference between them.
When the JTS came out in 2002, the listed oil to use was 10-40, but because the JTS uses a bit more oil due to the ring design, they used more oil and had a few engine failures related to them running out of oil, Alfa Romeo then changed the engine oil specs to 10-60, unless your engine is using a lot of oil, i would stick to 10-60, Colin.

[Steve S]

The majority of oils available have zinc in them. You'll struggle to find a 10w60 that doesn't. Lower zinc oil "low or mid SAPS", still has zinc in it, only roughly half as much. Low SAPS oil can extend the life of your exhuast after treatment devices,  but it is not essential to use one in this case as the engine was designed around using a "high zinc" oil. Technically the zinc will poisen the cat over time but cats and high zinc oil have been around a long time together.

For your next oil change I would switch back to a 10w60. From a mechanical point of view, 10w60 is really too thick too, but Alfa specify it due to the nature of the JTS engine. 

[colcol]

You could use 10-40 in a JTS, but you would have to keep a very close eye on the oil level, from my point of view, the 10-60 Castrol Edge i put in mine is quite runny when i pour it in and when i drain it out, its like water and i get it everywhere except in the oil drain pan, mind you, thats comparing it to the 20-50 mineral oil in the 33 i use,  the lack of zinc in the modern oils was put down as the reason for severe camshaft wear in the JTS, but it is most likely running it out of oil, too long a period between oil changes and contaminated oil with petroleum, acid and sludge.
We had the discussion at a workshop night for 156's a few years ago, something which i didn't know was that the zinc content in oils had been coming down due to problems with Catalytic Convertors, Colin.

[Steve S]

It is true ZDDP levels are dropping but it's only the Ilsac grades that have low limits. That's Xw20 and Xw30. Once you get to anything Xw40 they are not bound by the same limits and are usually full of ZDDP. I did a UOA of Selena Racing and it showed 1300ppm Zinc, that's more than enough. I've seen 1970s-1990s Fiat twin cams (and SOHCs) with worn lobes, the problem is not new.