engines sucked a lot of mud...

I went out yesterday for a boat ride in Clear Lake/Clear Creek (on galveston bay) with the the inlaws. The tide was down a couple of feet, so keeping to the channels was recommended. One time I missed a channel and started churning mud. I tilted the engines up some and made my way back to the main channel. A couple of minutes later, one engine alarm sounded and I shut that one off, then looked to see if water was coming out of the telltale hose on the other engine. About that time (no water) that one alarmed and I pointed her to shore. I got a quick tow to a ramp (luckily just a couple hundred yards away) and had a friend bring the truck the 'rescue us'.

While on the trailer, (the engines had cooled; no alarms) I could run both engines up to about 2500rpm and this black sludge looking gunk would come out of the telltale hose, then nothing. I went through that routine a few times until water was coming out somewhat regularly. I took her home an ran the engines (at idle) with the muffs for about half an hour (each) and all -seems- to be OK.

Does anyone have a suggestion on what to do next, if anything? Should all the mud and silt be out by now?

Could I have damaged my new impellers?

The engines are Johnson V4 140's made in 1989 if that matters.

Thanks for the help!

Havis