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Results 1 to 14 of 14
  1. #1

    Default 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Hi, I have felt that my engine has been a bit low on power. It runs to good to be running on one cyl, but I'm not getting the speeds I should. Took it up and measured compression today. 110 PSI on the lower cylinder and 70 on the top. Tried putting some oil in the top cylinder and remeasured at 95 PSI. According to the tester-manual the rise in compression after adding oil is an indication on worn piston rings.

    1. Do you agree?
    2. How hard are they to replace?
    3. Do I need to fix both cylinders or only the faulty one?
    4. Can I keep running for the summer and fix it in the winter?

    I've had trouble with the VRO lately, getting water instead of oil, and having a leak in the vacuum membrane. Could this have been causing the problem? (As far as I have figured out, this should have destroyed the lower cylinder, not the upper).

  2. #2
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    ontario
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Pull the cylinderhead off for an inspection.------It may be repairable now, but if you keep running it it may turn into scrap !!!

  3. #3
    Join Date
    Oct 2011
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    maplevalley WA
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    It could be just the head gasket also. When you did the compression test did you remove both plugs and test the engine cold three times 1-2 1-2 1-2. If there is no scoring on the cylinder walls put a new head gasket on it and then get a can of seafoam spray. Run the engine until it is up to engine temp and then spray seafoam into the carb/s at a high idle until it starts smoking real good and quickly shut it down for 1/2 an hour or so then start it and run it around 2500 rpm until the smoke stops. You do want to get the VRO working properly first off that could very well have created the problem with compression water dont burn very well and is a terrible lubricant. If there is no scoring on the cylinder walls you should be able to re ring it and cross hatch both cyls the same. I ran a 59 40hp with the upper cyl at 90psi and the lower cyl at 115 for for six years I just had to change the upper plug more often from fouling out when trolling alot. It is not recommended running any engine with compression numbers more than 10% between the high and low numbers. In general the lower cyl gets the most oil it falls down through the center crank bearing there is a oil tube that goes from the bottom of the crankcase up to the upper part of the crankcase to keep it from puddleing in the lower part and a check valve so the oil only flows up. Running with those numbers will only cost you more money down the road.

  4. #4
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    You can also scrap the VRO and premix the fuel at 50:1 just plug the oil supply to the pump and disconnect the wires to the VRO warning system. I looked at your crankcase and couldnt see any tube to transfer the oil from the bottom to the top crankcase anyway. GL

  5. #5
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    ontario
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    The " tube " is not a seperate part in the pictures.----------Oil does go from the bottom of the engine to the top bearing using a " secret passage way "

  6. #6

    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Quote Originally Posted by racerone View Post
    Pull the cylinderhead off for an inspection.------It may be repairable now, but if you keep running it it may turn into scrap !!!
    I guess I need to replace head gasket after removing head for inspection?

  7. #7

    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Quote Originally Posted by kimcrwbr1 View Post
    It could be just the head gasket also. When you did the compression test did you remove both plugs and test the engine cold three times 1-2 1-2 1-2. If there is no scoring on the cylinder walls put a new head gasket on it and then get a can of seafoam spray. Run the engine until it is up to engine temp and then spray seafoam into the carb/s at a high idle until it starts smoking real good and quickly shut it down for 1/2 an hour or so then start it and run it around 2500 rpm until the smoke stops. You do want to get the VRO working properly first off that could very well have created the problem with compression water dont burn very well and is a terrible lubricant. If there is no scoring on the cylinder walls you should be able to re ring it and cross hatch both cyls the same. I ran a 59 40hp with the upper cyl at 90psi and the lower cyl at 115 for for six years I just had to change the upper plug more often from fouling out when trolling alot. It is not recommended running any engine with compression numbers more than 10% between the high and low numbers. In general the lower cyl gets the most oil it falls down through the center crank bearing there is a oil tube that goes from the bottom of the crankcase up to the upper part of the crankcase to keep it from puddleing in the lower part and a check valve so the oil only flows up. Running with those numbers will only cost you more money down the road.
    I have converted to regular fuel-pump and pre-mix so water problem is solved. I'm in europe and I don't think we have seafoam here. What is it made of? And can it fix the problem without opening the engine? I only measured compression once. But if I change piston rings I'll replace the head gasket at the same time.

  8. #8
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    ontario
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    New motors are expensive over there.-----------The whole motor will have to be torn apart to replace rings.---------If you do it now you likely will be able to re-use crankshaft and connecting rods.---You may have to bore one cylinder to fit an O/S piston and rings.---If you run it till it dies you may be starving those expensive parts of oil. Then it gets expensive.

  9. #9
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    http://www.ebay.com/itm/Sea-Foam-Spr...09b220&vxp=mtr They never tell you all the ingriedients they make this and seafoam deep creep it makes a good fogging oil also. When you spray it into a hot motor it soaks into any carbon and dissolves it then when you run the motor at mid throttle it blows it out the exhaust. If you have to pull the engine apart you may as well get a complete gasket kit and replace the main seals also while your there. It is worth a try before you tear into the engine.

  10. #10
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    http://www.ebay.com/itm/Sea-Foam-Spr...ea9f97&vxp=mtr This stuff works great on any engine just bring it up to temp first so the rings are good and hot then spray it in until alot of smoke comes out the exhaust and quickly shut it down for 1/2 hour to soak then run at mid throttle until the smoke stops.

  11. #11

    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Quote Originally Posted by kimcrwbr1 View Post
    http://www.ebay.com/itm/Sea-Foam-Spr...ea9f97&vxp=mtr This stuff works great on any engine just bring it up to temp first so the rings are good and hot then spray it in until alot of smoke comes out the exhaust and quickly shut it down for 1/2 hour to soak then run at mid throttle until the smoke stops.

    Hi, will this do the same thing? http://www.justboating.com.au/Engine...18-9570-0.html
    I can't wait 3-4 weeks for shipping as the season is soon over I found this in a local webshop.

  12. #12
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Give it a shot be sure and bring the engine up to temp first and get the motor smoking good before you shut it down.

  13. #13

    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    Quote Originally Posted by kimcrwbr1 View Post
    Give it a shot be sure and bring the engine up to temp first and get the motor smoking good before you shut it down.
    Thanks, I'll come back with results and propably a bunch of questions if I have to open her up. Couldn't find details on piston rings in the service-manual. Only complete removal of powerhead. Can I get to the pistons by removing the cylinder head only, or is more disassembly required?

  14. #14
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    ontario
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    Default Re: 1993 Evinrude 50 HP, 2 cyl. Low compression on one cyl.

    There are no " short cuts " to the job.------------Removing the cylinder head allows you to have a look / inpect.------------------Motor must be removed from exhaust housing . Flywheel must come off and motor must be totally taken apart to do this repair work!!!!!

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