Evinrude big twin 40

Open Water

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I have a 1967 Evinrude 40 hp big twin electric shift. My issue is with milky lower unit lube. Had it air pressure tested and held for a full day. Fella told me it looked like the seal had been changed. I’ve changed lube a few times this summer, it’s worse after I run it in higher rpm’s. To me two things are different from pressure testing or in the lake. Drain and vent plugs and RPM
 

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jimmbo

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Welcome to iboats

Likely the Seal under the Water Pump.

Have you tried pulling a Vacuum on the Case?

Looking at the Pic, the Boat looks like it is nice Condition

FYI, Your motor was called 'LARK'. 'Big Twin' would have been used for the Mechanical Shift models

013.jpg
 
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racerone

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Are you checking gear oil 1 hr after your trip or 3 days after your trip ?
 

Open Water

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I have a 1967 Evinrude 40 hp big twin electric shift. My issue is with milky lower unit lube. Had it air pressure tested and held for a full day. Fella told me it looked like the seal had been changed. I’ve changed lube a few times this summer, it’s worse after I run it in higher rpm’s. To me two things are different from pressure testing or in the lake. Drain and vent plugs and RPM
Thanks I’ve done a lot. No vacuum yet, I think I’ll just replace the seals. Would you think the screw washers are bad. I’ll change those 1st.
 

Open Water

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Thanks I’ve done a lot. No vacuum yet, I think I’ll just replace the seals. Would you think the screw washers are bad. I’ll change those 1st.
Well all be go to…. It says Lark on the back.
 

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jimmbo

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The Washers on the Screws should be replaced every time the Screws are removed/loosened.
 

racerone

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Best to look after that electric shift gearcase.-----New seals are cheaper than the springs , clutches and gears.
 

tphoyt

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Yea unless your a serious time crunch May as well do the seals and be done with it. Then you know everything looks as good as the rest of the boat.
 

kbait

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Use omc premium blend or older type c in your electric shift gearcase..
 

airshot

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Very cool looking boat and motor, brings back memories from my youth. Hopefully we will see the boat in action when you get the bugs ironed out !
 

jimmbo

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As Mentioned about the Gear Lube, but beware that some 3rd Party Oils claim to be Type C, but then go on to say they are NOT Compatible with Electric Shifts
 

Open Water

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Well folks I’ll have to go ahead and change the seals in this lower unit. Found new washers for vent and drain. I use Sierra brand type c lube. Ran it at the lake this morning, still came out looking like chocolate milk. I have had the parts on order for a few days. I’ve changed the water impeller, so I can get that far. Any decent blown up views on how this electric shift is put together. Model 40778E. SN E02326. 40 hp Lark
 

tphoyt

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I may have a manual but I’ll have to look for it.
That could be a challenge. If all else fails take lots of pictures.
 

Open Water

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Welcome to iboats

Likely the Seal under the Water Pump.

Have you tried pulling a Vacuum on the Case?

Looking at the Pic, the Boat looks like it is nice Condition

FYI, Your motor was called 'LARK'. 'Big Twin' would have been used for the Mechanical Shift models

View attachment 409662
Have the lower unit off. Bingo!
 

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