1935 7.5 hp evinrude

[loupis]

I've obtained another old evinrude motor 7.5 hp 1935 motor and ...<br /><br />I replaced the coils, plugs, wires, condensers and points. She then fired up in 1 pull - but...<br /><br />I noticed she was real smokey so I figured I'd take a look at the lower unit and sure enough, the pump needed replaced, but also the drive shaft was stuck in the head and coated with a serious exause/carbon residue. Any ideas what could cause this?<br /><br />loupis

 

[Laddies]

Re: 1935 7.5 hp evinrude

Hundreds of hours of running at 20 or 24 to 1 oil mix on not to good of oil. Did you get it out ok? Bob

 

[Chinewalker]

Re: 1935 7.5 hp evinrude

Hi Loupis,<br /> Please post your model number for us. Evinrude didn't make a 7.5hp in 1935...<br /> If you're running the correct oil ratio for any pre 1964 Evinrude, it'll be smokey compared to a modern 50:1 mixture. My general rule of thumb is anything from WWII up to 1964, run at 24:1, and anything prior to WWII, run at 16:1...<br /> Many of those older motors didn't have the oils we have nowadays to lubricate them and they ran straight 30wt. oil in them. Regular 30wt doesn't burn cleanly at all and leaves lots of deposits. It was standard practice back in the day to tear down a motor on a regular basis and clean the carbon out of the rings, exhaust passages, etc..<br /> Most pre WWII motors didn't have a waterpump as we know them now and use prop vacuum, forward motion, or a metal mechanical pump to keep things cool. Some worked and lasted better than others. Again, we'd need your model number to nail down what style pump you've got...<br />- Scott

 

[loupis]

Re: 1935 7.5 hp evinrude

Model Number is 7512 1953 7.5 hp<br /><br />i'm still working on getting it out - it's not real pretty - lots of scraping with a long screwdriver while holding a mini-mag in mouth and blowing solvent into it to help break down.<br /><br />The pump is interesting - no tube going up to powerhead. It also has a clutch in the system.

 

[Chinewalker]

Re: 1935 7.5 hp evinrude

Hi Loupis,<br /> Much better - Your post said '35 not '53 - BIG difference! <br /><br /> You can get a new impeller for your motor - ask for one for a 1976 6hp at a dealership. Iboats has it, too - #18-3001, which is also a valid number at NAPA, West Marine, or any outlet that handles Sierra aftermarket parts.<br /><br /> BUT, you cannot use the impeller as is. You'll need a belt sander to "thin" the horizontal profile of the impeller. When you compare the 18-3001 impeller to your old one you'll see what I mean. I did this to mine and it worked perfectly (I've got a '52). Lay the impeller on the belt sander and shave off equal amounts from each side until its profile matches that of the old one.<br /><br /> Good luck!<br />- Scott

 

[loupis]

Re: 1935 7.5 hp evinrude

would there be any reason to tear the powerhead apart to clean out any residual residue?

 

[Chinewalker]

Re: 1935 7.5 hp evinrude

Hi Loupis,<br /> Unless you have some indication that there is a severe internal carbon issue, (low compression being the chief indicator), then I'd leave the powerhead as is and run a can (or two) of decarboning agent (Sea Foam, BRP Engine Tuner, etc.) through it to flush out the goo. Follow the instructions on the can, and let it do the work for you...<br /><br />- Scott

 

[loupis]

Re: 1935 7.5 hp evinrude

it's pumpin 60psi per cyl so i guess it's probably ok eh?

 

[Chinewalker]

Re: 1935 7.5 hp evinrude

Hi Loupis,<br /> That's fair, but could be better. I'd still do the decarboning just because of all the carbon you found elsewhere... Certainly won't hurt...<br />- Scott

 

[loupis]

Re: 1935 7.5 hp evinrude

we'll do. any idea how this old timer gets cool water into the heads? Is it a vacume aparatus?

 

[loupis]

Re: 1935 7.5 hp evinrude

ok - new question on same motor. I'm working on the lower unit - sometime in it's life it lost seal and filled with water. it was re-put together rather poorly so it wouldn't hold any lube. <br />I'm trying to get it apart and first the cover comes off with 3 bolts) then there is a lock spring seated outside of a plate (with the 3 bolt holes) that has a counter clockwise arrow and says remove. The spring comes out ok, but it seems that this piece has to be removed to get in and clean or replace the gears. How do you get this thingy off. Is there a special tool or do you need a grip of steel while holding your tongue just right?<br /><br />loupis

 

[Chinewalker]

Re: 1935 7.5 hp evinrude

Hi Loupis,<br /> It's been awhile since I had mine apart, but I seem to recall a slight amount of twisting involved, as you need to thread the shift mechanism around the swing arm that activates it. That swing arm/plate thing is mounted to the back of the "disc" with the three holes that you're seeing. Ther'es also a sprung wire that puts tension on the swing arm to keep it from flopping around in there. I don't recall much brute force needed extricate it... I seem to recall using a bolt or two in the threaded holes to give better grip...<br /> Hope that helps more than it confuses...<br />- Scott

 

[loupis]

Re: 1935 7.5 hp evinrude

hmm - haven't tried bolts. I was afraid to break them off - it's really stuck - the spring is inside is pretty grimmy (quite a mess this one).<br /><br />I'm going to try soaking it in some 'break it loose juice' for a couple days and if that doesn't work i'll take it down the the john-rude mech across the valley. (One hates to resort to that tho....)<br /><br />loupis

 

[loupis]

Re: 1935 7.5 hp evinrude

ok - i'm back on it. It's not coming apart without destroying it. <br /><br />Would anyone know where to get a prop shaft seal for this badboy. I could really use a new one.<br /><br />loupis

 

[Chinewalker]

Re: 1935 7.5 hp evinrude

Hi Loupis,<br /> Pry the seal out with a screwdriver, perhaps driving it out from the other side. I have a cheapie screwdriver that I modified with a propane torch to allow me to put a slight hook in the tip to better grab seals for removal.<br /> Take the housing, propshaft and what's left of the old seal with you to a bearing supply house (something like Kaman Bearing, etc.) and have them mic it up for you. If you're lucky, the seal will have a CR-number on it which will make matching it up even easier.<br /><br />- Scott

 

[loupis]

Re: 1935 7.5 hp evinrude

i tried that yesterday in fact. I went to Kaman Bearing and he measured and scratched and measured and scratched and looke in many books and finally he looked at me with a dismal look and said - "Damn, i'm not finding nuthin that's gonna work" <br /><br />Unfortunately, the local mechanic said the same thing and sent me there. <br /><br />any other ideas?<br /><br />loupis