My friend has a 1980 115hp Chrysler outboard, model #158HOD. He wasn't getting any water out of Pee hole, so he replaced the impeller. The old impeller looked ok. Now he gets a little water, but not a stream. Do ya think its plugged up, thermostat needing replacing or what. The housing where the impeller was in, looked a little pitted. He just bought this boat and is kind down about it not working, any help would be appreciated.