1971 Evinrude Selectric impeller replacement

[fishn_n_tx]

Well the 50 hp fired right up today with fresh gas and a battery. It hadn't been started in at least 4 years. I picked up an impeller today at lunch and was wondering what I might run into. The parts counter guy told me he thought the wires had a plug where I drop the lower unit. It started and idled fine, and we had a water hose connected to the water intake. There was no water coming out of the lower unit where I thought it should, that little square vent looking deal with a slot on each side. So we didn't let it run long enough to get hot. And the Selectric shift worked fine.I'll switch the impeller this weekend, just want to make sure there are no suprises. I have already been warned about the lower unit oil with the selectric. I will pick some up as I want to change it too.

 

[ledgefinder]

Re: 1971 Evinrude Selectric impeller replacement

I'm unclear. Is this "vent" just below the powerhead, on the rear of the midsection? I'm assuming you hooked the hose up to the water intakes down by the propeller using 'flushmuffs', right? <br /><br />If I've identified your "vent" correctly, be aware there is no telltale on the 1971 50hp twin. The vent is an exhaust pressure relief. You will get a little mist coming out of there once the engine is warmed up, and a heavier 'rain' when a warmed-up engine is running at high power. However, no telltale. <br /><br />So, how do you tell if it's cooling? Tthe outer surface of the cylinders shouldn't get any more than warm/hot. You should be able to rest your fingers on there for 2-3 seconds without getting burned. (On that era V4, the thermostat fully opens at 130 degrees F, and I suspect the 50 is about the same.).<br /><br />There will be two wires going down to the lower unit. There'll be connectors within the powerhead just before the wires dive down into the midsection - they have a weird knife-edge design. Disconnect those, then tie a strong string or wire to the end. That way, when you go to re-install the lower unit, you have a way to pull the leads back up through the midsection. The leads will stay connected to the lower unit when you remove it. <br /><br />There aren't any other tricks to doing the impeller, as long as your motor hasn't seen a ton of salt water use. If it's seen salt, you may find the driveshaft is really corroded where it passes through the pump seals - bummer. Don't loose the key that holds the impeller on. Get some help and/or manual on the impeller install - the impeller is larger than the housing, so you want the vanes trailing their natural direction of rotation. The impeller will be a ways off center, also.

 

[fishn_n_tx]

Re: 1971 Evinrude Selectric impeller replacement

Thanks for the reply. Yes, used the flushmuffs, There was a very little mist coming out of the vent. I think we are talking about the same thing, does actually look more like a vent than a water outlet, just under the powerhead.<br /><br /> It does have the buzzer up by the throttle controls. Is there a place to put a sender for an actual water temp gauge on that model? <br /><br /> Are there any other gauges, ammeter or such I can use with this motor? Just rigging it up to a new duck boat and like to know something might be wrong before bells and buzzers start going off.<br /><br /> Thanks, Gary

 

[phatmanmike]

Re: 1971 Evinrude Selectric impeller replacement

gary, i have plenty of these same motors now, and as for the impellar, just make sure it doesnt go in backwards. but you may not even need it. water doesnt come out of those holes in the leg, the rectangle ones , those are relief hole, only comes out there when boat is in water, all ther times it comes out the prop with the exhaust. just touch the head while its running, you should be able to hold your hand there for 4 or 5 secs. and since your motor doesnt have a "pee" hole, or tell tale.. youll have to get a o/b temp gauge and it goes in the hole on the top of your water jack/exhaust plate, and reads the surface temp of the water jacket. its either that or start drilling and plumbing into your motor, which i vote against. i have a 50hp right now with same setup. got mine at boatersworld.com like this one out board temp gauge <br /><br />includes all hardware a boy could ever want

 

[ledgefinder]

Re: 1971 Evinrude Selectric impeller replacement

You can mount a water pressure or temp gauge, if you want some feedback on how the cooling's going. Also, as you say, there should be a 'hot' horn in the remote control box. You can test it by finding the sensor in the head, disconnecting the connnector near it, and grounding the wire - the horn should sound. (That is, the sensor works by grounding when it gets too hot.)<br /><br />That motor has a self-energized ignition, so it doesn't need the battery to run. You can rope start it in a pinch. <br /><br />For best performance, the motor wants to be as high as it can get on the transom, without loosing prop bite on corners, and without losing water pressure. Once you get it to the right height on the transom, prop it so it turns 5500-5800 rpm with it's lightest load (you alone in the boat). If you ski a lot or party with a boatload, you might prop it even higher (rpm). What you want to avoid is lugging it (running at full throttle with rpms less than 5500 or so). Those are nice motors - OMCs first looper. It is geared down (2.8? to 1) so it uses the same prop as the big V4s (they're geared at 2 to 1).

 

[fishn_n_tx]

Re: 1971 Evinrude Selectric impeller replacement

Thanks for the replies. Does this motor have a system to charge the battery? If so, how efficient is it?

 

[Paul Moir]

Re: 1971 Evinrude Selectric impeller replacement

It ought to have a 6 amp alternator, similair in style to the new outboards.<br /><br />Although that's pretty weak, it'll power the lower unit, the running lights and charge the batt a bit. Look at the bright side: it's only robbing you of .1HP.