replace thermostat 1979 Evinrude 35hp *Updated 6/3

[jekuehl]

Just a quick question, I am somewhat mechanically inclined, is this something I can do? Any tips I should know about?
I looked it up and found out it's behind this plate that the spark plugs go into. Do I just remove the bolts? Will I have enough clearance to remove the bottom bolts? Model is 35902A.
Thanks.

 

[boobie]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

If you have the correct wrenches it can be done. Been there.

 

[jekuehl]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

If you have the correct wrenches it can be done. Been there.

Correct wrenches?..I don't have any specialty wrenches, just box and open ended wrenches in difference lengths and sizes. Do I need to buy a specific OMC wrench? Also, I have been looking for an Evinrude service/repair manual...I have a clymer but it doesn't have anything about replacing the thermostat.

 

[bonz_d]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

For the manual look on ebay. Search 1979 Evinrude Service manual. They are not always available there but I've had good luck with it. The Johnson manual should be the same if you can't fine the Evinrude one.

 

[jasper60103]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

Correct wrenches?..I don't have any specialty wrenches, just box and open ended wrenches in difference lengths and sizes. Do I need to buy a specific OMC wrench? Also, I have been looking for an Evinrude service/repair manual...I have a clymer but it doesn't have anything about replacing the thermostat.

Yep, just ordinary wrenches. No special tools required.
The only hard part of the job to me was scraping off the old gasket material and adhesive.
So I recommend some patience, gasket remover and a plastic spackle knife or scraper.

Also, don't forget you need a new gasket for the thermostat and the cylinder head cover.
FYI. I used Permatex Aviation gasket sealer on the new cylinder cover gasket, held-up 2 years and counting.
Note, you don't have to remove the cylinder head like I did in the pic below.
Good luck.

 

[jekuehl]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

Alright, thanks. appreciate the quick feedback. Going to start this project tomorrow.

 

[boobie]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

What I was talking about is sometimes off set box ends work good for different applications. A lot of basic tool sets don't come with them.

 

[jekuehl]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

What I was talking about is sometimes off set box ends work good for different applications. A lot of basic tool sets don't come with them.

Gotcha. I started a couple of the bolts and already found out I need a longer 11mm and posibily off-set will make easier.

Thanks.

 

[jekuehl]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

Well, I got the cover plate off. All the screws came out except one, the bottom one. Now I have a situation on my hands. I was real careful with it but it was just too corroded in there and the head of the bolt spun off. I don't know what to do...maybe there will be enough securing force with the two outside bolts that I could get away with out having a bottom bolt. If I do decide to drill it out, tap it, or whatever, the entire engine will have to be removed or I will have to drill a working hole through the bottom motor casing (not sure what you call it).
Any help is appreciated.

 

[bonz_d]

Re: replace thermostat 1979 Evinrude 35hp *Updated 6/3

Remove the head then drill. Maybe able to get it with an EZout once drilled. Start with small drill and work up. Sometimes a left twist drill bit will remove it also.

 

[jasper60103]

Re: replace thermostat 1979 Evinrude 35hp

Re: replace thermostat 1979 Evinrude 35hp

Well, I got the cover plate off. All the screws came out except one, the bottom one. Now I have a situation on my hands. I was real careful with it but it was just too corroded in there and the head of the bolt spun off. I don't know what to do...maybe there will be enough securing force with the two outside bolts that I could get away with out having a bottom bolt. If I do decide to drill it out, tap it, or whatever, the entire engine will have to be removed or I will have to drill a working hole through the bottom motor casing (not sure what you call it).
Any help is appreciated. View attachment 196611

Sorry to hear. Worst case, the cylinder head will have to come off to repair. Maybe try soaking that bolt with some lubricants? I'm sure someone will chime in with some ideas. Good luck.

 

[jekuehl]

Re: replace thermostat 1979 Evinrude 35hp *Updated 6/3

Rog, thanks. Before I remove head, gonna soak in wd40. Then try vise grips and heat to remove. Worth a shot reckon.

 

[boobie]

Re: replace thermostat 1979 Evinrude 35hp *Updated 6/3

Don't bother with wd40. Get some PB Blaster or Kroil. Stay away from EZ outs. If you break one of them off you're really screwed. No pun intended. LOL

 

[jekuehl]

Re: replace thermostat 1979 Evinrude 35hp *Updated 6/3

Well, that idea didn't work...vise grips that is. So I guess I am going to change this thread to removing the head. Doesn't look too hard. Will have to buy a new gasket. Other than removing the bolts and a few accessories attached to the side of the head, it doesn't look too tricky.
Man, I really didn't want to have to do this. I am still thinking/wanting to try and just put the plate back on there without the bottom bolt...thinking the to bottom outside bolts will give enough pressure and secure it. Do you think it's worth a shot?

 

[boobie]

Re: replace thermostat 1979 Evinrude 35hp *Updated 6/3

Put a bunch of 3M 847 sealer on the gasket and try it. It's a gamble.