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Powerhead rebuild or not

ggmurray191

Regular Contributor
Hello Everyone,

I’ve been working on a 89 70hp Evinrude E70tlcem. My problem is the smoking and oil droplets floating in the test tank. The smoking is excessive not the regular 2 stroke that you would normally see. Never ending smoking. Not white smoke, kinda of grayish maybe.
 

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Here is more info, I’ve done several things carb rebuild, plugs, new head gasket, etc. this passed weekend I ran for 30 mins to warm the engine up then I checked the compression plugs out and WOT. 80/81/81 I know it’s important for the cylinders to run about the same and they are but the 80s are pretty low. Is it yes that’s low and it’s time for a rebuild or no you still need to check this or that. I’ve read on the web 100/120 is normal so I’m thinking it’s time. Can anyone point me in the right direction.
 
Have you tested it in the water under power?
I’d like too but I was concerned about the oil getting in the water. Im guessing the oil droplets are unburned oil in the fuel. I rebuild all the carbs with OEM Evinrude kits and made sure they were super clean. All jets removed and checked and clean. I need to add that I found #1 cylinder not firing with the spark tester and discovered a connection on coil was loose. I sure thought I’d found the problem! It started and ran much smoother but still the smoke and oil in the water.
 
Here is a good pic of the oil droplets in the water. When you tilt to pull the tote out all the oil sticks to gearcase.
 

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There is not nearly enuff water in your test bucket.-----Test compression with a better gauge.

R1, yeah I was finished and the hose was off that’s why it’s low. Already been thru the gauge detail. Brand new Winters gauge oil filled brand new one.
 

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R1 you’re absolutely right! Let me explain the use of the tote. I started using it sometime back to verify the water flow out of the side grills in the gear case. Tell tale always has good flow!
 
More to explain on the tote use but it’s time to get back to work! More to come! Bottom line though low compression and fuel/oil just blowing thru to the exhaust must mean it’s pretty worn.
 
On a new 2 stroke motor there is a certain amount of oil and gas blown right through the motor.------At the bottom of the stroke the new charge comes in under pressure.-----Exhaust ports are wide open.---- Compression does not start until exhaust ports are closed off !
 
R1, wanted to add these pics for you to checkout these are back when I checked the thermostat and for scaling in the block. Notice in the head on #3 the damage (what I thought was old damage from days gone by). Maybe it’s not old damage at all.
 

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That damage resulted from broken piston rings.-----Likely his motor was apart before.----Any other numbers on those pistons ?------And I do not like the looks of the #2 piston.-----Looks like it is running hot.
 
R1, Just hit the clock and heading home so more to come when I get home. Wanted to let you know I appreciate all your help and advice! The 70 is on my father-in-laws old Malibu that we fished on together until he passed with Covid. It’s a special rig to me and I want to do whatever I can to keep her in the family.
 
R1, let me skip back to why I used the tote. It was after I replaced the impeller and changed the oil in the gear case. When I put the gear case back on and put the muffs on it. I started it up and water was shooting everywhere so I took it back down to check my work and couldn’t find anything wrong with what I did so back together again only to get the same results water shooting out the seam between the midsection and gear case not out the side grills like the manual shows. So I pulled the gear case off again and decided to check the water flow to see what was going on. I went as deep as to pull the head so I could see if the block was scaled up also checked the thermostat. All that was fine with no scale in the block and a new thermostat. So bottom line after some rigged up some tubing to simulate the water flow I discovered the flow was fine but the seam between the midsection and gearcase wasn’t sealing very well so I used some gasket sealer around edges to take care of that. Once back together and in the tote I fired up it was fine flow was like the manual shows. I needed to see the discharge out the side grills to make sure it was right and the tote was the perfect level. Anyways thats why the tote. But you absolutely right water needs to be a over the impeller.
 
Water leaks at mounting seam is not a problem and is common after impeller change. I myself would just surface the head ,replace gasket and add some decarbon additive to fuel and run it on the water to see what it will do.
 
FB, thanks for the reply! Those were pics from couple weeks back. It’s all back together now new head gasket and such. FB what about the compression being in the 80s do you think that could be an issue?
 
Morning R1, thanks for the info! Well I’m going to pull it, and hope you guys will stick with me and point me in the right direction. It’s a working weekend for so I’ll see what I can get done and post some pics.
 
Here is a good pic of the oil droplets in the water. When you tilt to pull the tote out all the oil sticks to gearcase.
Those droplets just seem like par for the course as far as I'm concerned. It's a small container so it probably also looks worse than what it is. There's no way around it, these bad boys do pollute but heck, it also pollutes to waste resources in the fabrication, shipping, handling of a brand new motor/vehicle or other when the old unit works just fine! So for me: extend the life of your old cars and motors as much as you can and you are doing more than your fair share for the environment! Now, will your neighbor with the brand new tesla, two homes, solar panel roof, regular water cooler jug deliveries (when city water is 2nd best in north america) think same...probably not.
 
R1 and BigT, Tear down underway! I hope to have the block all the way down tomorrow and some pics to post on what I find! So far knock on wood no broke bolts...
 

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We'll here is an update, couple things holding me up! Rear main seal plate and taper pin. I was able to get the rear main off used a pc of plastic so I wouldn't damage anything. But the taper pin wouldn't budge. I warmed things up with a heat gun but no luck. Soaking down again maybe tomorrow it will decide to cooperate!
 
The pin is removed by driving it towards where the carburetors were.------Should not require heat or any potions !!-----On more than one occasion have I seen u-tubers blundering on this.---Lower crank seal housing falls off when crankcase is separated.
 
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The pin is removed by driving it towards where the carburetors were.------Should not require heat or any potions !!-----On more than one occasion have I seen u-tubers blundering on this.---Lower crank seal housing falls off when crankcase is separated.

RC1 no special tool just a brass punch
 

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