Tell tale anomalies?

[GJohnson]

Hi....I have a late 80's Johnson 15hp 2 stroke long shaft that I resurrected last summer. Initially, before any work, there was a very weak then no tell tale. I could not re-establish the tell tale with a piece of string trimmer line nor was there as much water as I thought appropriate coming from the exhaust. I took the head apart and cleaned out some pretty heavily clogged passages, checked that the water pump functioned (didn't replace the impeller though as it had been done then the motor not used for some time), replaced appropriate gaskgets/seals etc. The motor starts and runs great now however I'm a little mystified by the tell tale still. At idle it comes out nicely, at speed below plane it comes out strongly, and at speed on plane the tell tale is intermittent running more often than not but with a weaker stream and sometimes showing gaps in the stream? What would cause this and it is a worry? I wonder if at speed for some time a weak impeller (perhaps old even though not used much) would do this or could it be some water flow issue along the hull of the boat while planning that affects the ability of the motor to pick up water steadily?

[Solarman]

Or, possibly exhaust at higher RPMs is pushing water back. You may have deteriorated webbing between the water chamber and exhaust chamber, or there may be a grommet between exhaust and water pump pick up location that has burned/ dry rotted (?) and allowing exhaust gases to push water out of the pump pick up area. The sputtering tell tale may be a result of lower water flow and maybe getting close to overheating?

good luck. Keep us posted on what you find

[GJohnson]

Thanks for the hints...I'll have a look in the leg re. the webbing/grommet suggestions.

[Solarman]

While lower unit is off, should inspect impeller closely, it may be weak, cracking? Also the housing for any problems, grooves, holes, sleeve/ cup for any slipping.

Also, if prop has been removed, make sure it was reinstalled properly. the back edge of prop should sit just inside the lip of the prop housing, to prevent exhaust gases from interfering with water pump pick up vents. Exhaust should go all the way through prop, if the open through exhaust series.

If a spacer was installed on wrong side of prop (easy to do) there may be a gap/ space at back edge of prop that could cause exhaust to affect water pickup?

Good luck post what you find, when able.