Hi All,
Went to check the gear oil level in my 40hp Tohatsu outboard the other day.3years since done by a mechenic.The screw was super tight and I had to use a spanner on the screwdriver to get it undone.Some metal filings came out with the oil.Panic.Was thinking gear problem to start with.When I put the screw back in it would not tighten up, only get firm.The threads on the leg appear to be stripped.I believe that it was overtightened by the mechenic and damaged the threads.How to fix this? Go to bigger diameter screw and re tap threads or get helicoil set and do that way.Any advice be helpful thanks.
Scott >:(
Wow that's a bummer. I've never had that problem. You have to be careful not to get aluminum shavings inside too, so that's going to take someone with more experience than me. Is the depth of the thread enough for a heli-coil?
I don't know how 'firm' you mean, but what about Loctite blue-ing it in place? Change the fluid, put it back in. Make sure you use a new crush washer too.
Good luck.
Hey Scott, not that a helicoil isn't a strong system, but for that problem I think I'd go for a re-tap.
Look it over carefully as some of those holes have a counterbore to keep the screw flush. If it is feasible and your lucky enough to find a larger size screw you'll notice they're almost always a fine thread. They have to be tight but not to the extreme you mentioned.
The tight fitting nylon washer does a great job of sealing and keeping it tight.
Good luck with your project.
.................. Lou
PS maybe a good outboard mechanic may be able to offer the best advice. Its possible a self tapping screw might be available just like those for car oil pans.
I think tapping it to the next available size would probably be your best option. One other option would be a Time-Sert threaded insert. I prefer them over the Heli-Coil inserts because once installed there's no chance of it falling inside the gear case.
Not sure if there is enough room or depth for helicoil yet.Thought about loctite but did not know if it would set with oil over everything.Will have to look at their www to see if they have a product that will suit.Do the ring around today to boat shops and get their idea's on what to do.
Maybe use Alan's aluminum can trick here?
Wrap a thin strip of aluminum, and maybe some Teflon tape, or liquid gasket around the screw, to get it to hold snug, and seal properly.
If there is very little pressure use one of those champagne stoppers. The ones that expand when you twist the top. If it will hold the pressure of a champagne bottle it will hold oil in and water out. I'm being serious here. Dominick
I had a Bass, Ski Boat for many years. 150 Horse Evinrude outboard.
Never had that issue, but if I did. I would actually replace that part of the skeg or have it professionally tapped.
Mine was tapered. I wouldn't trust anything but the original screw. A lot goes on under there. My boat would push 70 mph. l did the maintenance myself. After 20 plus years. I had to let her go.
Thanks guys, rang one mechenic yesterday, what a waste of time.No help at all.Did not want to give advise on how to fix, just said it would be hard.Reminded me why I don't go there anymore.Ring another today.Not sure of the time-sert system will have to Google.Think a small piece of aluminium can would give enough purchase but would be very worried that some may get in to gearbox.Could under fill gear box by 1/4 inch and lactate.Don't think that much would make a difference.Could jack up side of trailer that filler is on to give false reading of under fill then do job and let it down and hopefully it is very close to full.
If you are going to retap a thread use grease on your tap for the alloy to stick and the scrap will come out with the tap.
Quote from: Superhook on September 26, 2016, 08:35:16 PM
If you are going to retap a thread use grease on your tap for the alloy to stick and the scrap will come out with the tap.
Good advice.
I was thinking about how to deal with this concern too. I think certain tap types will retain the shavings better as well.
Agreed on taping it out. I have heli coiled a few on my race units but that's all we had there. Use grease as mentioned on the tap. Also use a washer on the screw as well. They don't need to be tight just snug. Fill with oil and flush. You can always tell if water is in your unit to if the oil turns white or milky color fyi.
Going to tap and put next size screw in.Have to find a screw with low profile head.Do you think it would matter if used a standard hex head.Would create a bit more drag but I am not concerned about that.Only worried if it would create a turbulence problem.
McMaster Carr sells them. Look up low profile stainless steel socket head screws.They may even carry the slotted style if you want them. The grease on the tap will work as suggested. I would only tap a thread or two at a time, remove and clean the tap and regrease, and tap again until its completed.
If the motor is on the transom of the boat, maybe you can turn the engine on its side (to a point) to be xtra cautious not to get any chips in there. Save the old oil and pump it thru with a squeeze bottle from the top port. This should help flush everything out in case you miss something.
Don't forget the tight fitting nylon washer. It makes the seal and helps keep it tight.
And yes, you don't want a screw that sticks out!
GL, .. Lou
Do you have any reputable machine shops in your area? You could have the turn an aluminum insert that could be countersunk and tig welded in the case. I recently had this done on a set of atv engine cases.
I'd check a larger outboard lower unit so you can use the proper screw, they have a magnet on the end to attract and hold metal filings from inside the gearcase. Then look for matching tap and drill size.
This is a touchy project. Any leaks will grow under drive pressure. Good luck.
Man, Oh Man,
This is why I don't have a boat anymore.
They are fun, but when stuff goes wrong, it really goes wrong.
I am very Happy now just going to Florida once or twice a year. Use my Kayak to get my bait out and come back and wait for a monster to eat my bait.
To me, It is way more fun than being in a boat. Challenging, Exciting, and no need to worry if it breaks down.
I hope you get the problem fixed Scott. We are rooting for you. ;)
I like that idea of the larger screw from a bigger outboard.Will investigate.
Just had look at the leg and there is a flush screw beside the oil fill hole.The flush screw is about 2mm in diameter bigger.Maybe a bit too big though I think.