I am beginning to look at a 960 or S90, but have often read here about the pourous engine problem of the in-line 6 cylinder engines. Did Volvo ever solve this problem, and in what model year?

Mark

In my opinion, the porous blocks had more to do with poor maintenance than anything else. The B6304s are all aluminum engines and the coolant should be changed on a regular basis (I change mine once a year). I have a VERY early '92 960 (very low chassis number) and I'm approaching 200K miles without a hint of block porosity issues. Some may disagree...

It's believed that engine block porousity plagued a small number of 92 and perhaps 93 960 for sure. There have also been other model years reported, but certainly by 95 it had been addressed. It's prevalence is not known, however, since Volvo basically denied it. and never stood behind any claims, to my knowledge, execpt to offer block replacements at a good price, as I recall. The newest model years, 97/98 V/S 90s are good cars, in my opinion.

If you suspect the problem, visually check the exterior of the block for patch attempts. If you are deciding on a specific car, have the cooling system pressure tested for about 2-3 hours on a cold engine.
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John Shatzer, '97 V90 @ 98K

The last year for the pourous block looks like 1995.
From the FAQ: [Editor's Note:  Too many reports of casting porosities in 92-95 B6304s have appeared on the Brickboard to dismiss these as related to a short run of early blocks.  If you are considering buying a 92-95 960, do some serious investigating and take a hard look at the engine block for coolant leaks, patches, attempted repairs, service records, etc. to pin down whether the car has this problem.]
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Tom F '95 945na, lien holder on a '95 944Ti, RIP '78 244