64 Evinrude 75 hp Exhaust steamy or smokey?

[Evinrude Boater]

This past summer I used this motor for the first time. I noticed the exhaust seemed to be steamy or smokey. I thought it might be running too hot. Even now that the water is colder it still has the same exhaust appearance. I took some photos today. Is this normal?

Also, I wonder if the lower end is far enough in the water. Here's a photo while planning.

 

[OBJ]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

Have you checked the plugs for water drops or taken a compression test? They will smoke but the top pic looks more like steam than exhaust.

 

[Evinrude Boater]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

OBJ,
I don't know what to look for when checking the plugs for water spots. What would the plugs look like?
It does smoke while warming up but I attributed that to running rich. It seems to run best if rich. I've leaned it out but it stumbled out of the hole.

 

[OBJ]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

If there is water intrusion into the cylinders, pull the plugs and just look for water drops. They will stand out.

If your carbs are clean, you may just need to redo the link and sync and readjust the needle settings. Running rich can foul plugs pretty easy. Is your engine temp good?

 

[Evinrude Boater]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

I've had the plugs in and out all summer as I fine tuned the engine. They seem to be a nice tan colour. I didn't notice any spots. I did have a water leak under one of the lower cylinders dripping onto the bottom engine housing. I re-torqued the heads and the leak stopped. Some of the head bolts were quite loose, not rattling loose but low in torque.
I re-did the link & sync but there was no change in performance. The only adjustment on the carbs is the low speed needles. I followed the manual procedure for adjusting them. If it was too lean it wouldn't even start and it would be hard to rev up from a standing start. I just kept turning the needles in (counter clockwise) until it started easily and ran good. I'm thinking that an engine this old, it's as good as it gets. It blows some fuel into the water when starting but other than that as long as I run the hell out of it, it seems to perform reasonably well. I've never had a boat before, so this is a learning experience. I don't know what to expect out of it as far as performance. I just want a reliable boat that I can turn the key, put in gear and have some fun with the kids.

 

[Evinrude Boater]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

How about that lower end? Is it far enough in the water?
Here's another view out of the water.

 

[F_R]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

OK, in the first place, that motor will normally emit smoke and steam. You may be getting all worried about nothing. Smoke from burning the oil that you've put in the gas, and steam especially after running it hard and the thermostat is open. Big clouds of steam, no- that's too hot. If it does not get too hot to touch the heads and it does not sizzle a few drops of water flicked on the heads, it is OK. However, I am concerned about the loose headbolts. Is there any evidence of overheating such as burnt or discolored paint? Overheating will loosen the bolts due to burning the gaskets. They need to be replaced if that is the case.

You want reliability? Do you know the history of the water pump? They need to be inspected every few years and any worn parts replaced, especially the impeller whether it needs it or not.

It is plenty deep enough in the water.

 

[iwombat]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

If your head bolts were that loose, I'd replace that head gasket out of hand. If it's not failed by now, it probably will sooner rather than later.

 

[Evinrude Boater]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

Thanks for the reassurance and info. Come to think of it, the paint on the engine is peeling in places. When I inherited the boat I changed the water pump and I had a neighbour use his infrared thermometer on the powerhead to check the temperature. It was OK while I've been using it but you never know about its previous life. You're probably right about it overheating at some point. Maybe that's why I had the external water leak too.

 

[mikesea]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

Those older engines blow the exhust above the water,unlike the new style that blow it out the prop,so it will look more smokey. Also,they used 24-1 oil.or a qt.to the six gallons,are you doing it that way?perhaps the newer oils allow less oil but you better check.A higher oil content will give it a crop duster effect.Neat old boat,enjoy it

 

[jimmbo]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

If it is a 1964 motor it can use 50:1. Looking at the pictures it looks like the anti ventilation is a couple of inches below the bottom of the boat. Raising it up to be even with the bottom would be the normal advise, however, this engine has two water intakes, one behind the prop on the exhaust snout, the other is on the port side of the gearcase right above the antiventilation plate. Running these engines with the plate even with the boat bottom might let the water pump suck air.
As for the steam/smoke. My dads 1965 90hp had the same idle relief system as your 75 and it put out lots of water vapour( steam is actually invisible ) just like yours.
All outboard engines have an idle exhaust relief. It makes it easier for the engine to start and idle by allowing the exhaust gases to exit the motor by bypassing the under water exhaust outlet. The older motors used the increased water flow at higher RPMs to block the idle exhaust relief and redirect the exhaust gases to the under water discharge.

 

[G DANE]

Re: 64 Evinrude 75 hp Exhaust steamy or smokey?

If the plugs are all dry and nice tan colour, its running at its best. Water leak would leave one or two plugs steamcleaned, like a new one. I think you have a good running motor. Age actually only tells a little of a motors state, as noone knows how much it was used.