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  1. #1

    Default Break-in tips for 1978 Evinrude 35 HP new build.

    Today I started my new motor that I built for the first time and it cranked instantly and idles very nicely. I started with 1 1/4 turns on the low speed and it is smooth with that. Overall the engine is running very smooth and quiet with no internal noise or ticks and is pumping water good. I am just running in a barrel till I take it out on the river tomorrow.

    Since this is a brand new block, pistons, rings, etc. I am unsure the proper way to break it in. I am running a 50:1 mix and so far I have just idled with a few throttle blips here and there. Should I keep the RPM's low and steady or should I vary the speed somewhat? I have read various conflicting statements and I am curious if anyone knows what the factory did for break-in procedures. Thanks in advance!
    1978 Evinrude 35 HP 35853R
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  2. #2
    Join Date
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Break in is not so critical with 2 strokes as there is oil supplied with the fuel mix. There is also no camshaft with flat lifters riding on cam lobes. This is a huge concern with initial start up on flat tappet engines. I will not run WOT for the first hour or so. I hope your machinist provided adequate piston to cylinder clearance. Should be 1/3 again the clearance than a four stroke engine. For a 4 inch bore on a four stroke you want .001 per inch cylinder diameter, so about .004 clearance. On a 3 inch 2 stroke bore you want about .004, maybe even .0045 clearance. That is measured on piston skirt at room temperature 90 degrees off wrist pin line......slightly below wrist pin line with a longer skirt. You need to find the "fat part" of piston. I owned and managed a machine shop with 10 employees for over a year. We did small engines, outboards, automotive, racing engines and heavy equipment. One of our lathes, which we later sold to the Philippines, could handle a 12 foot crankshaft. Your success in overhaul is based in a huge part, on the accuracy of your machinist. Last December, with my micrometers, I discovered a problem while assembling a street rod engine. The piston were too tight. I returned the block and a piston to the machinist. He apologised. Oh yeah? Then he took out another .0025 inch. Sure it would have gone together, but that street rodder would have destroyed that $3000 block, and it would have been "my" fault.
    Note: Make sure that what caused the reason for overhaul, has been corrected. If it is bored, I like to run 1 size bigger main jet. Why? You have gained displacement and fuel should be added proportionally.
    Last edited by timguy; 08-21-2018 at 04:16 PM.

  3. #3

    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Thank you for the information.

  4. #4
    Join Date
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    I skimmed these instructions from another site (I didn't want to link to somewhere else), but it's a pretty similar procedure to what I've followed in the past. I've always used 25:1 oil for the first tank to ensure everything has more than enough lubrication as the surfaces wear together.
    Remanufactured Powerhead Break-In Procedure


    The first 10 hours of operation

    • Double your oil with a major manufacturer TCW-3 Oil.
    • Use 92-94 Octane Fuel from a major manufacturer.
    • Do not use fuel with alcohol as an additive.

    Initial Break-In & Warm Up

    • Allow 4 hours at idle speed only for break-in of new pistons or rings.
    • Avoid continuous full throttle operation for the first 10 hours of operation.
    • Liquid cooled engines require that the engine be brought gradually to normal operating temperature to avoid cold seizure resulting from pistons expanding faster than the cylinder liner.
    • DO NOT RUN ENGINE AT CONSTANT RPM FOR PROLONGED PERIODS OF TIME.
    • After gradually bringing engine to normal operating temp., operate engine in gear at approx. 1500 RPM for 20 minutes.
    • Operate in gear at no more than 3000 RPM for the next 60 minutes.
    • Cruise at 3/4 throttle or less for the next 4 hours.
    • Occasionally reduce throttle to idle speed for a cooling period.
    • During the final hours of break-in you can operate at full throttle for periods of 2 minutes or less.

    Note:

    • Use only enough throttle to plane your vessel and then throttle back to below 3000 RPM.
    • Avoid operating in the 3000-4000 RPM range at all times during the 10 hour break-in period.
    • During the 6th hour of break-in, plane boat quickly and then throttle back to maintain minimum plane speed.
    • During this 6th hour, you can throttle up to 3/4 throttle for 1-2 minutes, then return to minimum planing speed.

    Carefully following these instructions will aid in the proper break-in of your rebuilt powerhead assembly.

  5. #5

    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Thanks for that info. I 'm not sure why it says to idle for 4 hours and then in bold it says that prolonged constant speed is bad. But I get the general idea. I will double my oil also.

  6. #6
    Join Date
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Good info and new to me. I would definitely avoid that prolonged idle, however. Never, ever use ethanol blend fuel anyway.

  7. #7
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Just take it out and run it at variable speeds for the first 8 hrs. You can do short spurts at Wot just keep the first 8 hrs 3/4 throttle and below to seat the rings. It dont hurt to run a 40:1 mix for the first couple of tanks. You get the best fuel economy around 3/4 and it will extend engine life as well.

  8. #8
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Quote Originally Posted by flyingvranch View Post
    Thanks for that info. I 'm not sure why it says to idle for 4 hours and then in bold it says that prolonged constant speed is bad. But I get the general idea. I will double my oil also.
    I would follow the break in procedure described in the owner's manual for the engine when it was new!

  9. #9
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    That's a good idea. I will let you know what it says in my 1986 Johnson 30 operators manual. Its the same darn motor.

  10. #10
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Ok, right from owners manual in my hand. 50:1 for 1st 5 hours. After that 100 to 1. I followed this but with Amsoil fully synthetic 100 to 1 pre mix. I never used or trusted the AccuMix that came with motors. Especially in the huge range of temperatures that we run our motors at the NW Ontario camps. They are designed to dispense at 100 :1. Also says only minimal WOT for first hour. After 15 minutes slow to half power, then short bursts of full throttle every 5 to 10 minutes during 1st hour. Max WOT burst times are 90 seconds, then immediate return to half throttle or less. For second hour bring boat up on step and reduce to 3/4 power while keeping on step. At regular intervals go to WOT for 1 to 2 minutes at a time, then "cool down" by running at 3/4 again. For last 3 hours avoid "continuous" WOT for extended periods, or no more than 5 to 10 minutes. So break in time covers 5 hours total. After that 100:1 or if you trust AccuMix.......right, in the perfect world.
    There you go gentleman, right from my operators manual.
    I still have this motor, about 2500 hours on it.....still perfect. Its twin or mate, got stolen from the storage shed during winter.
    Last edited by timguy; 08-22-2018 at 01:17 AM.

  11. #11
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Quote Originally Posted by timguy View Post
    Ok, right from owners manual in my hand. 50:1 for 1st 5 hours. After that 100 to 1. I followed this but with Amsoil fully synthetic 100 to 1 pre mix. I never used or trusted the AccuMix that came with motors. Especially in the huge range of temperatures that we run our motors at the NW Ontario camps. They are designed to dispense at 100 :1. Also says only minimal WOT for first hour. After 15 minutes slow to half power, then short bursts of full throttle every 5 to 10 minutes during 1st hour. Max WOT burst times are 90 seconds, then immediate return to half throttle or less. For second hour bring boat up on step and reduce to 3/4 power while keeping on step. At regular intervals go to WOT for 1 to 2 minutes at a time, then "cool down" by running at 3/4 again. For last 3 hours avoid "continuous" WOT for extended periods, or no more than 5 to 10 minutes. So break in time covers 5 hours total. After that 100:1 or if you trust AccuMix.......right, in the perfect world.
    There you go gentleman, right from my operators manual.
    I still have this motor, about 2500 hours on it.....still perfect. Its twin or mate, got stolen from the storage shed during winter.
    Your '86 30 Hp was produced when OMC were in their short lived 100:1 fuel mix period. Hence the 50:1 mix for the break in.

    Flyingvranch should therefore follow the procedure but use a 25:1 fuel mix with TCW-3

  12. #12
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Right, Vic. I will agree with that. What has worked for me, might not be the best for others, depending on accuracy, observation, and perhaps operating habits.
    Would like to hear back from flyingvranch to see how the overhaul went. Be sure to check compression before and after break in to get an idea what's going on.

  13. #13

    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    I am planning on running the river this evening. I'll take a quick compression check before and then again after about 6 hours running time. I'll double my oil to 25:1. I'll get back to you all when I have some results to share. May be several days. Thanks!

  14. #14
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    Default Re: Break-in tips for 1978 Evinrude 35 HP new build.

    Thanks, we all enjoy helping as well as learning. Good job, brother.

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