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1982 Evinrude 35hp

nytebyte

Regular Contributor
I bought a boat a while back and the guy gave me a 35 Evinrude that he had. Said he thought it had a hole in the piston and he never messed with it. I just got around to looking at it today and it does only have 65# of compression but it has that on both cylinders. I am thinking a bad head gasket being as both cylinders are the same. Do you think thats possible? Never replaced a head gasket on anything bigger than a 9.9 Johnson but willing to give it a shot if its maybe all thats wrong. I did check for spark and it will jump a 3/8 inch gap on both cylinders so that was a good sign.
 
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It could very well have overheated. I just had my 1980 rude 35 overheat and I'm left with 60 and 56 psi. I'm hoping mine will just end up being a head gasket, but I've already starting swiping parts off of it for my Johnson 35.
 
I would like to take the head off for a looksee but if the general opinion is that its probably worse I would just as soon sell it as is and let the next owner fix or use for parts. It looks like it hasnt seen much use but that doesnt tell me much about the kind of use.
 
I pulled the head this morning and found the metal rings were blown between the cylinders. There is no paint on the head that looks like it got hot so don't know what caused it. Everything looked good in the cylinders and could still see crosshatching. I would like to just replace the head gasket for now and if the compression comes up then possibly replace the thermostat and gasket and water pump and possibly carb kit. I know the thermostat and gasket would not be that much more but I would rather not put more into it till I see the compression. I have the winter months to work on it so no rush to get it done. Anyway does anyone see a problem with leaving the thermostat cover in place? I will surface the head on glass before I put it back together
 
No problem. When compression is low and IDENTICAL.....it is often the gasket blown through as you found. Very common on the old 5, 5.5, and 6's. I would give it a chance.....inspect water pump first, then order parts. See if water pump impeller is broken down, with pieces missing, Why? Could be something stuck in thermostat. Clean head bolts nicely, also holes in block....blow everything out. LITE anti seize on bolts....why? Zinc is gone now, so if you don't do a lite anti seize....bolts will rust in place. New bolts, of course, are lightly zinc coated. Whenever I repair something, I remember well what a brilliant mentor told me about bolts.....zinc coating is only temporary. Nickel anti seize will give you a satisfactory replacement. Dissimilar metals, in this case....Steel/aluminum, encourage oxidation.....a problem, especially in marine and aviation, where maintenance is critical.
 
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The cylinder head is warped.----They all are !------So resurface it with emery paper / valve lapping compound on a piece of glass or other flat surface.
 
Right, Racer....very important. I use water and wet or dry 3M paper. Start with 120 to 180, then finish with 240 to 320 grit. Got a side glass from a 49 Chevy truck that I use for backer....very strong and firm. Sierra is good.
 
It is easier to change thermostat with cylinder head off.
I probably shouldn't be so cheap on this motor as it all looks good so far but if it turns out that it still has low compression I will have very little in it. At least this thermostat and housing looks a lot more accessible than my 1980 9.9 Johnson.
 
The new head gasket looks like it might be here Saturday. Should I try and lightly crosshatch the cylinders with emerycloth before I put it back together or best to leave it? Thanks for any info!
 
The only way I would lightly buff up cylinders would be in the case of LITE rust or LITE scoring Otherwise it probably won't do much good unless you put new rings. If the cylinders look clean, I'd leave them be.
This is an example of some rust that was deep enough to cause light pitting. It's right at top of compression so buffing was important to give the rings an obstruction free surface. Think I used 400 grit wet or dry with some WD40.
 

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Update! Its back together and I have 123 and 125 compression with 5 pulls. Now I will do the waterpump and carb. Thanks for the help and advice.
 
As long as this post is still on the first page I thought I would ask another question. I have the head gasket in and will soon have the waterpump and carb done. I live in ND so wont be testing the motor anytime soon. I have seen that some will retorque the headgasket after it has ran. I torqued it to 235in pounds and should it be done again after it has ran?
 
No need....did you do anything to the headbolt threads before installing?
See post #5
 
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All I had was anti seize with copper so I coated them lightly with permatex aviation cement. I had seen somewhere that was another alternative?
 
Heres to hoping I never have to do it again then LOL! I did notice that the Sierra brand head gasket seemed to be the better gasket. The factory one had a gap between the metal rings around the cylinders and the Sierra is metal all the way between.
 
Yes, I use an awful lot of Sierra products and am happy with results over the years. Honestly, they really help me make these older motors worth fixing.
 
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