LouC wrote:
Yes no flappers on newer Volvos. First drain the manifolds on both sides. Pull the plugs disable the ignition and spin it over get any water out. Then spray fogging in the cyls replace the plugs and spin it over with the ignition still disabled. Then pull the exhaust elbows and check in the exhaust gas passages for rust. If no sign of rust then pull the manifolds and check for leaks in the manifolds by filling them with acetone and look for leaks at the exhaust ports. If any sign then replace both the manifolds and elbows. Water can get in other ways including a rusted out intake manifold right under the thermostat housing. That can easily put enough water in a cyl to hydrolock it. Until you find the source of water intrusion change the oil and leave the engine and exhaust drained of water.
Could water get past the risor on say a sudden stop? And just spill in there ahead of where the exhaust gas and water are supposed to mix?