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  1. #1

    Default New guy here, first boat, many questions.

    Hey everyone. This will probably end up being a long post so please bear with me as I'm new to outboards and want to make sure I'm doing things right and in correct order.

    Anyway i picked up a 1994 Lund boat with a 1994 Johnson 40hp engine (j40tlere). Boat ran fine when i picked it up but it does however have low compression on both cylinders. Has approx 75 on top cylinder and approx 50 on bottom. My assumption is the head gasket is failed and compression is leaking between the cylinders. I don't believe it has any internal engine damage as scored cylinders or holes in pistons as i feel that would create a poor idle scenario. However as i said I'm new to outboards so I'm not holding myself to anything.

    First thing i will do before anything else once it warms up here in Iowa is buy a can of OMC engine tuner and decarb the engine then re-test the compression and see if there's any change - i also feel the engine needs it anyway as i peeked in plug hole last fall and all i saw was black. If compression still reads low i will remove head and inspect gasket for any failed areas. Check head for flatness and have planed at machine shop if needed. Replace head gasket and retest. If still low what's next. Cylinders/pistons?

    Once i get the engine sorted out (hopefully) i will go through the carbs and rebuild them whether i believe they need it or not as the boat has been sitting with presumably old gas in engine. How easy or difficult is it to rebuild carbs on an outboard? Should i do carbs before addressing the low compression?

    Next I'd like to test the fuel pump/VRO pump to make sure its in working order. How does one test that to ensure its good? Does anyone offer a rebuild kit for the fuel/VRO pump as the only thing i can find on marineengine.com is the non VRO fuel pump rebuild kit.

    After those three items are sorted out i plan to pull lower unit off and replace water pump. Seems like that's a fairly common piece to replace and beings i don't know current condition or length of time its been in there i feel its just cheap insurance to do.

    I also feel the gear housing needs resealed as i did have SOME water contamination in there - however i don't know how many seasons the gear lube had been untouched. May run it this season and see how contaminated lube is this fall then address at that time. Replaced gear lube with AMSOIL 75w-90 marine gear lube which allows up to 10% water contamination.

    I'd also like try and figure out if the VRO system is hooked up and still in tact or not. If it is id like to run through the VRO system to make sure its working as it should so I'm not burning anything up. I'm ASSUMING the system is working as the primer bulb and lines are hooked from tank to engine. I plan to run AMSOIL sabre oil in it regardless of pre-mixing or running through VRO system.

    Will also perform a full tune up on boat, new plugs, wires etc. What else should be replaced on a general engine tune up? Fuel filter etc?

    I'm positive there's some stuff in here i need to check that I'm missing. Please let me know what else i need to do or check/replace/rebuild etc before i put this boat on the water as i want to make sure its as close to if not 100% ready to go on water without issue/trouble expected.

    I've included pictures of my boat motor, ID/serial number and lower end gear lube. Please let me know your thoughts, concerns, tips/trucks, advice, order of repair, etc so i can do all this correctly and in correct order.

    Lastly if your still reading this than thank you. As i warned this would become long and i really am needing/looking for all above mentioned to do this right. I'm fairly mechanically inclined and refuse to pay someone else to do something I can do myself AND learn from doing it myself.
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  2. #2
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    Default Re: New guy here, first boat, many questions.

    Yuck, water means a pretty good leak. Motor has been abused looking at the lower unit. Skeg is half gone. Low compression could be in part the gauge you have, or a slow cranking too. Do you have the spark plugs out and a fully charged battery providing a nice fast spin. A close up picture of the powerhead would be worth a thousand words. Using Amsoil Saber is a great idea but introduced to the VRO system it would be giving you more lubrication than you need. These vintage VROs are calibrated for basically a 50 to 1 oil. If you want to run Saber then I would recommend disconnecting the VRO and pre mixing to 100 to 1. I run 64 to 1 in my older outboards and all air cooled equipment like weed eaters and chainsaws. My guess is that you will find some cylinder damage and you should probably remove the cylinder head and give a visual inspection. Of course an inspection can also be accomplished by removing the exhaust cover however the head gasket may be getting bad anyway. Check for discoloration of the white paint on and around the head and exhaust cover. Certainly a "red flag".
    Last edited by timguy; 02-23-2020 at 06:39 PM. Reason: Typo

  3. #3
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    Default Re: New guy here, first boat, many questions.

    Here is a before and after of a lower unit I did last season. This is a used skeg welded in place on the original lower unit.Click image for larger version. 

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ID:	22747 The prop shaft was not bent but you might want to check yours. It has had plenty contact with rocks.
    Last edited by timguy; 02-23-2020 at 06:49 PM.

  4. #4
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    Default Re: New guy here, first boat, many questions.

    Here is a 2007 Stihl 660MS which has been run its entire life on Amsoil mixed at 64:1. This was only dismantled because of a faulty jug base gasket. The repair included changing from a paper type material to a steel gasket. This saw has diced hundreds of cords of red oak.Click image for larger version. 

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  5. #5
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    Default Re: New guy here, first boat, many questions.

    Not sure why you would want to remove an exhaust cover on this motor.---There is no exhaust cover.

  6. #6

    Default Re: New guy here, first boat, many questions.

    Timguy - being my first boat i guess i really didn't know what exactly to look for. The gauge i have could be low as its a harbor freight guage. Battery was full and it had a nice fast powerful spin when checking compression. I will go out and get pictures shortly. Hoping to not find any cylinder/piston damage, hoping its just a gasket failure causing a compression leak down between cylinders. I will look for discoloration as well. Pictures will be posted shortly.

  7. #7
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    Default Re: New guy here, first boat, many questions.

    Right, sorry Racer, thanks for correction....I'm thinking too generally.

  8. #8

    Default Re: New guy here, first boat, many questions.

    Heres the pictures. 3 groups of 3 as their to big to attach individually. I am curious what the reddish brown oil is on the top of the "fin". Did i overfill the gearcase somehow? Powerhead to me looks good but im not exactly sure what i need to be looking for. If needed i can get more pictures tomorrow.
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  9. #9
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    Default Re: New guy here, first boat, many questions.

    Quote Originally Posted by ProStreet83C10 View Post
    1994 Johnson 40hp engine (j40tlere)....low compression on both cylinders. Has approx 75 on top cylinder and approx 50 on bottom. My assumption is the head gasket is failed....First thing... decarb the engine then re-test the compression .... If compression still reads low i will remove head and inspect gasket for any failed areas. Check head for flatness and have planed at machine shop if needed. Replace head gasket and retest.

    I will go through the carbs and rebuild them... How easy or difficult is it to rebuild carbs on an outboard? Should i do carbs before addressing the low compression?
    If your pistons are black and your compression is that low it's doubtful the issue is a just a head gasket. A de-carb doesn't hurt but those would be horribly stuck rings to give compression that low. Carb rebuilds are very easy. But, I would wait until you solve the low compression before spending any more money.

    Quote Originally Posted by ProStreet83C10 View Post
    Next I'd like to test the fuel pump/VRO pump to make sure its in working order. How does one test that to ensure its good? Does anyone offer a rebuild kit for the fuel/VRO pump as the only thing i can find on marineengine.com is the non VRO fuel pump rebuild kit.
    I believe you can rebuild the FUEL side only. Testing is pretty straight forward. You have to run on a tank of pre-mix, remove the oil OUT line from the VRO and run it into a container. I forget the exact volume over a given run time but you should see about 1 part of oil in your catch can for every 50 parts of fuel used.

    Quote Originally Posted by ProStreet83C10 View Post
    I plan to pull lower unit off and replace water pump. I also feel the gear housing needs resealed as i did have SOME water contamination in there - however i don't know how many seasons the gear lube had been untouched.
    Water pump is easy and highly advisable to replace if you don't know the age. DO NOT wait on the gear lube. From your picture that is badly contaminated. While you have the LU off you should run a leak down and vacuum test to see which seal is leaking. Evinrude HPF gear oil works great.

    Quote Originally Posted by ProStreet83C10 View Post
    I'd also like try and figure out if the VRO system is hooked up and still in tact or not. I plan to run AMSOIL sabre oil in it regardless of pre-mixing or running through VRO system.
    You'll have a 1/4" ID line running from the oil tank to the VRO if it's operational. If not, that line into the VRO will be plugged. AMSOIL is fine but not really necessary. I run Evinrude Premium Semi-synthetic in my 1996 150 and it works just fine.

    Quote Originally Posted by ProStreet83C10 View Post
    Will also perform a full tune up on boat, new plugs, wires etc. What else should be replaced on a general engine tune up? Fuel filter etc? I'm positive there's some stuff in here i need to check that I'm missing.
    Check your spark. If both lead jump a 7/16" gap there's no need to replace plug wires. You'll only need to replace the plugs. Check battery condition, all your switches, navigation lights, anchor and rope, dock lines, fire extinguisher (no more than 10 years old), and paddle. Next move on to trailer lights, trailer bearings, and tire age. I like to replace trailer tires every 5 years to avoid internal rot issues.

    KJ

  10. #10

    Default Re: New guy here, first boat, many questions.

    Awesome. Thanks KJ. Really hoping the compression issue isnt going to be an expensive fix. Fingers crossed.

  11. #11
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    Default Re: New guy here, first boat, many questions.

    If there was water in the gearcase I would take it apart now.------These gearcases are NOT robust.-----Some will argue but I have seen a few sudden failures with teeth ripped of the pinion gear.-----If gears and bearings are good then install new seals and pressure test..

  12. #12
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    Default Re: New guy here, first boat, many questions.

    Looks like head gasket has already been replaced. If that's the same oil that you put in the gearcase it shouldn't have gotten out unless you have a large leak above.

  13. #13

    Default Re: New guy here, first boat, many questions.

    Not sure. It wasnt there earlier this winter but weve had some very cold days lately. Just not sure where it might be coming from

  14. #14

    Default Re: New guy here, first boat, many questions.

    So if i get it running right what can i do about the skeg. Is it something i need to have welded and fixed or can i use it as is with no ill effects?

  15. #15
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    Default Re: New guy here, first boat, many questions.

    You can use as is but your prop now has very little protection. As it is more exposed a rock strike could more likely bend the prop shaft. A GOOD EXPERIENCED mig welder can repair it without even removing the gears if everything else checks out.....do a quick pressure test and then evaluate. You can get a skeg section cut off and sent to you from Tim's Outboard in Hackensack Minnesota phone 218-682-2331 ask for Mike or Dan. Probably 20 or 30 bucks.

  16. #16

    Default Re: New guy here, first boat, many questions.

    Ok. I live in iowa so that wouldnt be a bad deal. Being my first boat i never would have even known that wasnt right.

  17. #17
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    Default Re: New guy here, first boat, many questions.

    It's best to use cast aluminum for this repair as the properties are exact to make the perfect weld. That's why I recommend bringing the part right to the welder....bring him a used skeg to weld on. Many repair shops use "wrought" aluminum which is a different alloy and gives a second rate repair. I have done "wrought" repairs with little motors but the bigger motors have a taper and is hard to get the shape correct. Strength is also a factor. If you have him rough it out like in my lower photo, then you could save money by grinding, sanding, and painting it yourself. Probably will charge you an hours labor which could run $100. The repair you see above with new shaft seals, not including the prop repair, cost the customer $250 with an epoxy base/clear finish and new water pump impeller and grease. The lower unit in my photo also had a bad hub in it's damaged prop, so I scrapped the prop and repaired another I had in stock which was better suited for his pontoon boat....same diameter, but a little less pitch. Pitch is determined by calculating how many inches the prop should travel with one complete revolution.
    Last edited by timguy; 02-27-2020 at 12:12 AM.

  18. #18

    Default Re: New guy here, first boat, many questions.

    Geez. You really know your stuff. Wow.

  19. #19
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    Default Re: New guy here, first boat, many questions.

    If there was water in your gearcase it needs to come apart for inspection and new seals.------Pay now or pay a lot later is the concept here.

  20. #20
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    Default Re: New guy here, first boat, many questions.

    Racer is correct. If water was mixed in long enough it can cause the gears and even bearings to get rust so it should be dismantled/inspected. A certain amount of pitting from rust can be tolerated, but an experienced tech should be consulted....

  21. #21

    Default Re: New guy here, first boat, many questions.

    Would i be safe to run the engine on the boat in this tank as long as its raised up enough to suuply water to inlets on engine? Also am i able to put the boat in gear and run it under a load to do engine decarb and testing etc.

    https://www.fleetfarm.com/detail/fre...0000065541?bc=

  22. #22
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    Default Re: New guy here, first boat, many questions.

    Water level should be 4 inches min. above the water pump level. With fresh grease in lower unit........why not? Then later recheck the grease.....see how it looks.

  23. #23
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    Default Re: New guy here, first boat, many questions.

    Quote Originally Posted by ProStreet83C10 View Post
    Would i be safe to run the engine on the boat in this tank as long as its raised up enough to suuply water to inlets on engine? Also am i able to put the boat in gear and run it under a load to do engine decarb and testing etc.

    https://www.fleetfarm.com/detail/fre...0000065541?bc=
    An old 55 gallon drum or a large plastic trash can works fine too. The main thing is to get the water level correct as Tim mentioned and also leave the hose running at a low flow so you're constantly getting the water refreshed.

    KJ

  24. #24

    Default Re: New guy here, first boat, many questions.

    Ok. Would i be safe to throttle boat up in gear with a big tub like that?

  25. #25
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    Default Re: New guy here, first boat, many questions.

    It will immediately shoot out your water. Gotta go to the landing, but most landing discourage powering up your boat while on the trailer or at the dock. Gotta just go for a ride to really "power-up".

  26. #26

    Default Re: New guy here, first boat, many questions.

    Oh ok

  27. #27

    Default Re: New guy here, first boat, many questions.

    So would i be money ahead to just skip the tank and use dual feed muffs? Or is there a place for both at diff times.

  28. #28
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    Default Re: New guy here, first boat, many questions.

    Muffs don't effectively challenge the water pump like a real barrel of water......which also gives some noise abatement if you have lovely neighbors. Also some motors will demonstrate different operation with a little backpressure supplied by the water barrel......plus it's fun to shoot out all the water when your done.....at least for me.....
    Last edited by timguy; 03-03-2020 at 11:50 PM. Reason: Add info.

  29. #29

    Default Re: New guy here, first boat, many questions.

    Ok so skip the muffs and buy a tank?

  30. #30
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    Default Re: New guy here, first boat, many questions.

    Well muffs have their place especially to flush the motor from salt water. Will you be using it in salt water? Also if you want a basic start up before you go out, muffs make a simple starting test to give you confidence for your outing, especially if your boat has been stored awhile. A brief test will only use a small amount of water compared to using 35 to 50 gallons for the barrel test.

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