1998 S90 now with 79,000 miles. About 1 yr ago I flushed out the green crud and refilled with 50-50 Texaco (orange) Dexcool. Now I've got a 1-pint-every-three-days leak coming from underneath the exhaust manifold, towards the front. (It's impossible to pin-point with the timing belt cover and the tight manifold.)

Is this the same symptom as the infamous 1993-1995 Porous Blocks?

If 'yes', I know there's the 960/90 FAQ.... bad news for me. Please tell me 'no way a '98 can have a porous block'. What else can it be?

How about Barr's Stop Leak?

Water pump, if you have not replaced the timming belt do both.
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1996 960 121,000

Haven't seen porous blocks yet but have replaced a number of heater cores on dex-cool filled newer Volvos. And these cars were under warranty, but the owner had to pay. Dex-cool is a vovo-nono.

Which model/year Volvos have lost heater cores using Dexcool?

Check the coolant return pipe under the front of the exhaust manifold, o-ring could be bad.

While you are there, look up at the block from under the #4, 5, and 6 exhaust ports. Thats where your porous block will present itself.

Oh, and yes..... 'Way' it can and has happened to 98's.

This engine has had several instances of leaking when filled with Dexcool. So use Volvo C, at 50-50. If you are concerned about the existing leaks, a little stop leak will most likely work well.

Not long ago, Tom Irwin reported Dexcool leaking out at several places in his 960 engine and in other cars he knw about. Recently, I have had Dexcool leaking out in a 760T. Steve Ringlee, the resident expert on coolant advises againt putting anything but Volvo coolant in a 960 engine. Flush with plenty of water and put Volvo coolant 50/50 with distilled water.