"Are you sure it is a sheared bolt?" said wise old Dad, the retired engineer and civil servant.
"What do you mean?" says suddenly intrigued son 😲
"Well, could it be something else that isn't a sheared bolt?" says a thoughtful Dad. In his eighties and a mind still as sharp as a pin when it comes to anything engineering wise.
Well that set me off thinking. After all, as I normally do, I just assumed it was a sheared bolt.
"But why would such a bolt shear in the first place and wouldn't it be the wrong bolt in there anyway?"
After all the depth of the hole from the surface to that metal bit is 8mm and the actual Tohatsu part - the proper screw plug is actually 8mm in depth, so its end must be just touching that metal bit when it is screwed in tight.
I found the parts catalogue for my four stroke Tohatsu 3.5hp B outboard online last night. It doesn't give the actual dimensions of the proper screw plug but it did give a very useful exploded parts diagram.
"What if it wasn't a sheared off bolt?" 😮
I'd owe an apology to my outboard servicing people for a start.
Oh no I wouldn't.
After all they must have discovered the same problem and didn't tell me about it. 😬
Unless!
"Unless, between the service and now - something in the outboard gear area has slipped and is blocking the oil hole and so preventing air or oil from escaping through it?"
Or, maybe it could be something extraordinary but possible! It could be that when the outboard was made - the hole boring and threading process wasn't fully completed for some absurd reason and so this is flash or part of the casing wall that hasn't been holed.
"But then , surely someone, somewhere would have quality controlled this outboard and spotted the issue?"
"You know what I'd do son" says wise old Dad, "I'd ring up the people you bought the engine from and ask their engineer if he has ever come across this before or has any ideas on how to resolve the problem?" 😀
The screw plug that goes into the offending hole
Totally inaccessible from this position, so I would have to remove the pump housing and then start removing other layers. And, frankly, I'd rather not do that!
So this morning I emailed them and they said they would get back to me in a couple of days with some thoughts, bless them. In the meantime, regular readers of the blog posted some fantastic comments and morale boosting thinking on my previous post and I am really grateful to Steve, Stu, Max, Tanzer and Alden.
While I am waiting for some divine inspiration, I have also, along with the guys above, been giving some thought as to how to get enough oil into the gear casing.
One possibility is to take off the prop and shaft - that is lie the shaft horizontally, undo the two bolts, break the seal and lift the prop shaft assembly out. Then pour in 6 fl ozs of gear oil, replace the seal and put the prop assembly back in. 😰
As tempting as it is to take off those two nuts and remove the prop assembly.......I really don't like the exploded diagram above and you can bet your life something will go wrong!
Option two - and this really pains me - and you will see why when I publish my part two video next week - I could take off the lower section again and lift off the pump housing and pull out the gear selector rod and pour in the oil down that hole. 😨
Option three, and here my thanks goes to Stu and Tanzer for this - I could drain out the engine oil and tip the outboard on its end and then take out the lower gear oil drain screw and with a syringe, put in 6ozs of gear lube over a period of time, allowing it to settle and for air bubbles to rise to top and escape. By taking the engine oil out, it won't go everywhere in the engine or leak out and I won't need to replace the spark plug.
Well that's the theory!!
Of course, I have no idea which of the three options is best and there is no escaping the fact that it doesn't resolve the problem of the blocked upper oil drain hole!
If anyone else has any more suggestions to add to those of the guys above, on the causes of that blocked hole and my next steps - I would really, really welcome them about now! 😟
"Of course son, you could just pay for it to be serviced annually and avoid the hassle. But where would the fun in that be?"
In the meantime, if you didn't catch part one of me learning to service my own outboard, and having fun, 😵 here it is.
Postscript
As I often do, I went to the FaceBook forums as well. Thank you to all those who got back to me. the main ideas are
1. it is a sheared bolt so I need to drill a small hole and get a bolt extractor into it, flush loads of WD40 down the hole and then slowly extract the sheared bolt
2. drill a tiny hole to see how thick the blocking material is. Keep a hoover on it to suck up the drill swarf and then if it the drill goes through - I have an air hole and so I should be able to squeeze oil into the lower chamber via the lower oil drain hole.
3. there are some old cruising forums which talk about similar problems with 3.5hp Mariner, Mercury and Nissan engines - in almost all cases a bearing or a seal had melted, slipped, whatever and so blocked the hole. None of the forums suggested any more answers to the ones above other than disassemble the gear unit and replace the bearings or seals!
Ho Hum - fun times ahead. Some would say - "just learn to sail better and not take an outboard with you".
5 comments:
Hi Steve. Sorry to hear about your outboard engine woes. My recommendation would be to fill the lower unit with gear oil using option #3 (ie drain engine oil, lay engine on its side so as to elevate the lower unit drain hole as high as possible). Fill the lower unit with gear lube. Then, simply never bother to change the lower gear lube again. Considering the age of the engine, and the very few hours we use them, and assuming no saltwater leaks into the lower unit, you can get away without changing the gear oil ever again. Another option would be to look for a used lower unit. Here in the states we sometimes see them used for about $100-$150 US on eBay. Or you can remove the lower unit, soak the broken off bolt with WD40 for a couple days, apply some heat, and use a screw extractor to [maybe] remove the bolt, but you risk causing more damage if unsuccessful. Saltwater corrosion is deadly deadly to outboard engines. That's the source of the problem. Your mechanic should have notified you and given you a cost estimate to fix the broken bolt instead of hiding it. My mechanic did the same thing to me when they broke a screw on the carb of my Suzuki. Now I do all my own engine work. Good luck, stay safe and healthy. -Joel
Just as a matter of interest.. have you 'poked it' to get an idea of the material?? No need to be aggressive but a poke with a nail or needle would give you an idea of the material??
'Have I poked it yet?' Hahaha - Steve, I couldn't resist it. I can't leave anything alone. Dad tells a great story of how he found me aged three with a screwdriver taking apart a live electrical socket in the living room whilst he was in the kitchen. (I was also three when I discovered how to untie the latch and string on the front gate. I'd often take myself off along the road to the park apparently :) ) To answer your question - yes and it feels solid and metallic.
Joel - how are you? Hope you are well. Your part of the USA looks to be getting things under control after some tough times. I like the first 6 sentences of your response. The remaining few sentences after scary me on several fronts - a) asking the boss for money to look for a second hand lower unit (that just ain't going to happen buddy hahahaha - and b) me with a heat gun and a bolt extractor - err - have you been reading my blog over the years? When have I ever managed to be that coordinated on anything?
But you are right - from now on - I service my own outboard and yes - I'm liking option 3 a lot.
Steve, Joel - thanks for all your help - again - both of you and your families stay safe and well and thanks guys - much appreciated.
Steve:
What is the gearbox housing made of? Is it ferrous or non-ferrous (does a magnet stick to it)? If the housing is non-ferrous, see if the blockage is ferrous or non-ferrous.
Generally speaking, shafts are made of steel (magnetic). Gears are usually made of steel (magnetic), brass/bronze (non-magnetic, but more of a yellow color), or plastic.
If the housing is aluminum and the blockage is made of steel or brass, I would be a bit concerned and want to open things up. Also, if a bolt sheared, the end of the bolt should show evidence of breaking.
If the housing is aluminum and the blockage looks like aluminum, I would be less concerned.
Best of luck!
Wayne
That's really useful wayne - thanks for the tips - will go investigate later after i have done the gardening duties ordered by SWMBO. I'm leaning towards Joel's idea of basically draining the engine oil and taking out any fuel from the tank and then tipping the outboard up somewhat and syringing the gear oil through the bottom drain hole and then leaving it for several years. My outboard does no more than 15 - 20 hours per year, so I should be able to go a few years before it needs changing again. I am suspecting that that is what the people who have serviced my engine for the last ten years thought as well - given the colour of the oil that drained out :)
Thanks for the tips - the scientist in me wants to go off and investigate some new learning and thinking. Take care, stay safe now and thanks for the help - much appreciated.
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