First, I'm new to the forum and have done a search concerning water pumps and have learned some helpful stuff. I bought my 85hp new in 1978 and I doubt today I have even 100hrs on the motor. For all practical purposes this engine appears new. However it has set, off and on, for several years without much operation. I've always kept the cylinders with storage oil, turning the prop by hand to keep it lubricated and this year I decided to put my bass boat back into operation. I dunked the carbs in cleaner and along with some other engine prep I hit the switch and it starts like a showroom engine with a little 2 cycle warmup smoke and then it leveled right out to a smooth running machine. With rabbit ears the water circulation seemed fine the first half dozen times as I'm continuing fixing other things on the boat. Last time running I noticed no water coming from the overboard pump indicator and no water coming out the two exhaust relief holes at the top of the lower unit. Plenty of water coming out the water discharge and other lower unit sight holes. I ran it for 3-4 minutes and the warning horn never came on but I shut it down until I get some opinions. Thanks in advance.
You did not say whether you ever replaced the impeller. If the impeller was not replaced in the last 4-5 years, that should be your first task. Even if it has not failed, you don't want to chance it when you have the family in the boat on Sunday. It is also possible that the telltale has plugged up with some debris and may not be functioning. You can pull the telltale hose off the block and blow it out with compressed air. That nozzle in the cowling can accumulate debris over time. Normally you will get a little water out of the exhaust relief holes at idle when the stats open. If you don't could be that the stats are not functioning properly-another inexpensive routine maintenance item. With an engine of this age, it would be good to test the horn in the control box to make sure it still works. Each head has a temp switch with a nearby knife connector. When you have the ignition on, ground the temp sender wire to the block-the horn should sound. You may be able to borrow/rent a laser temp gun. When warmed up at idle, the block heat up to around 143-150 degrees.