1970 85 h.p. evinrude tell tale question

[ifitwasus]

I have a 1970 85 horse Evinrude. Put a new impeller in less than 6 months ago. This past weekend was the first time it has been on the water. I noticed at low speeds the stream from the tell tale was either not there or very week. When I picked up the throttle it would return. Is this common or should I be looking at a cooling issue?

 

[Bosunsmate]

Re: 1970 85 h.p. evinrude tell tale question

Ive had that a lot with old engines, always when there is no thermostat or poppet valve.
I dont think your engine has either of those
If it was me id renew the $40 engine temperature sensor, check the sirens working and monitor for a while

 

[emdsapmgr]

Re: 1970 85 h.p. evinrude tell tale question

Not sure about your telltale comment. The telltale did not come out till the 1978 model year. Your engine came from the factory with a single thermostat, called a vernatherm and a pressure relief valve. If you start the engine cold-hold the palm of your hand by the two exhaust relief ports at the top rear of the midsection. After a minute or so, the vernatherm will open, and water droplets should begin to form on your palm. That indicates normal functioning of the cooling system.