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Loud Ticking Noise on a Honda 10hp

mattlill

New member
Hello, we have an old Honda 10hp which has ran flawlessly for years, until today. The engine suddenly developed a loud ticking noise. The engine seems to work fine, no smoke, so could it be something that is loose? Tomorrow we may take the valve cover and see if anything looks abnormal but I will only be guessing. Has anybody had this problem? Thanks
 
I assume that the ticking increases with the rpm's? If so, valve, bearing, gearbox, or drive shaft are likely causes. Drop the lower unit off and run it for a few seconds to eliminate gearbox and drive shaft. Check valve clearances, and then you may be able to do a 'dowel test' to check for bearing play (haven't tried on that engine).
 
In addition to suspecting the valve train, I would also look at the ignition system for this type of noise. A spark jumping to ground from a plug wire, boot, or cracked plug insulator can make this type of noise. Coupled with the fact that many of these outboards start and run surprisingly smoothly on one cylinder (until you add a load) a faulty plug wire can fool you.

But, don't wait to make sure all of the rocker adjustment screws are tight and the clearance is set properly.

Good luck.
 
One other thing that comes to mind is that you can't change the oil filter on these and the oil sump can get pretty "gunked" up over the years with the permanent filter getting coated with it. This might affect upper engine oiling. So, keep an eye out for that type of issue.

If it IS dry up there, you may be able to do something about it without disassembling the engine.
 
Well I looked at the plug insulater, wires and they look fine. Lots of oil underneath the valve cover. I took apart the lower case and started the engine for a few second and no noise! It purred like a kitten. Then I took apart the gearbox and water pump and could not find anything wrong with it. There is one change I did throughout this and that was to replace one spark plug as I put a little gas in the plug hole to help start the engine. Tomorrow I will go through the valve clearances and if I can't anything wrong, put it back together and see or maybe wait awhile and see if answers can be found. Maybe I was misleading in saying it was a loud ticking noise, because it could also be described as a metallic bang (?) Anyway, thanks again for you help.
 
Update! I rebuilt the gearbox and found no problems but the oil was very dirty. Then I reassembled and started it and the tick was back but not at idle. The higher the revs, the louder the tick. When I briefly started the engine before, I only let it idle for a few seconds and no tick. The valve clearances are fine. I suppose a dowel test is in order, but what is a dowel test? Any info would be appreciated before a rebuild.
 
Dowel test is to check for a bad rod bearing. If the noise is gone when the lower unit is off then your problem is most likely in the lower unit not the engine itself. If you want to do the 'dowel test' anyway here is the process.

Remove the spark plugs and rotate the engine by hand until #1 cylinder is just past TDC. Insert a wooden dowel through the plug hole and then push firmly on the top of the piston. If there is play in the bearings you will feel the piston move slightly and here a noticeable clank type noise as the piston takes up the play in the bearings. Do the same for each cylinder.
 
I just did the dowel test and yes there is a clank and play in the top piston. The reason I didn't hear the noise without the lower end was because I only let the engine run a few seconds at idle. I should of reved it but, my mistake. The question is if it is the rod bearing that needs replacing, since I am tearing the engine apart, should I replace everything else? Anyway, won't know the damage until the engine is apart. Once again thanks for your help!
 
Back again! Well the engine was taken apart and the banging noise was caused by the connecting rod bolts being loose. I live in Finland and have been unable to find information or parts because of the age of the engine and need your help in locating connecting rods and if they are oversized and undersized ones?, because the connecting rods don't have bearings in them. I can get the crank reground over but the parts and the kind of parts are the problem. The serial number of the engine is B100S-1300886. Thanks.
 
Sorry, I can't decipher your serial number. You may need the hondadude (Mike) to look it up for you.

But I did go to a parts site and it looks as though there are no undersize rods or bearings available. If the crank is scored that badly, you may be looking at the end.....judging from the price of all the parts. New crank:$261 plus 2 rods: $110 plus all the other stuff you probably SHOULD inspect and replace including oil pump, piston pin, rings, crankshaft bearings and seals.....+ shipping....it can get a bit pricey to "reglorify" an old girl like that.

Probably would be worth it though since a new replacement is still WAY more money. The only trouble is that you could do all the work and trouble and WHAM! ignition goes out! Those babies are getting old and parts are just harder to come by these days.

You might be able to find a facility near where you live that does a process called "metal spray". Wherein they add material to an existing object and then machine it back to it's original size. That may or may not be less expensive than buying a new crank. I've done that in the past with good results though. Ask around some local machine shops to see if that might be an option.

Or, you could just tighten everything up and run her till she quits since you said, in the beginning, that she ran great until you started hearing the ticking. 50 wt. oil is a 2 plus season ************ in that case.

http://www.boats.net/parts/search/Honda/Outboard Engine/0/BF100 SA/PISTON CRANKSHAFT/parts.html

I wish you good luck.
 
Thanks again jgmo. the crank doesn't look scored at all. Maybe we will just put it back together and see what happens. 50wt oil maybe the way to go!
 
Well, Mike has come up with the info...thanks Mike! So, below is the parts page for your consideration. Below that I will add the page with the crank bearings and another for the oil pump.

Item 9, the lock strap for the connecting rod bolts should have kept them from coming loose. You didn't mention WHY you thought that they came loose. Are the threads OK? If the lock strap was still bent up over the bolt head then I would fear that some sort of thread failure has occurred and should be thoroughly investigated and resolved before any reassembly. Also, if you use plasti-gauge to check the bearing clearances that will tell you just how appropriate it might be to use a heavier weight oil. If the clearance isn't excessive then there will be no need to even do that. If it is, but the crank measures out to be not too badly worn...I would opt for new rods.

http://www.boats.net/parts/search/Honda/Outboard Engine/0/BF100B SA/PISTON CRANKSHAFT/parts.html

Below is the page with the crankshaft bearings. (items 7 ...four count) If they are worn you should replace them. Also on this page the crankshaft oil seal is listed. (item 20) I would replace that regardless of any other parts selected. It would be a shame to have it leak after reassembly because you didn't.

http://www.boats.net/parts/search/H...0/BF100B SA/CYLINDER CYLINDER HEAD/parts.html

Below is the page for the oil pump. I would urge a thorough inspection of it before reassembly. In addition, this page has some gaskets listed that can fail and cause you mucho grief. I would not reuse the old ones because of this. Item 17 is a good example. That is the exhaust pipe gasket at the head. If it fails, the engine will begin having dying symptoms when the hood is on. When the hood is removed, the engine will run great. This is because exhaust gasses are starving the engine for oxygen. And, while you can make a new one from stock material, the same cannot be said for items 4, 14, and 23.
Then there is the oil pump relief (check) valve and spring. Items 9 and 10. I would not reuse the spring. Springs that are 30+ years old can be very unreliable.
http://www.boats.net/parts/search/H...A/OIL PUMP OIL FILTER EXHAUST PIPE/parts.html

So, what I'm saying is that I agree that putting her back together and running her without spending a bunch of money is a sound idea, I really think a little thought and care before "slapping it back together" will surely reap big dividends for you in the long run. This is an opportunity to do some "prophylactic" maintenance for trying to squeeze the NEXT 30 years out of her.

Good luck.
 
Thanks again jmgo! Your help and kindness has been really appreciated, and we will soon place a order and do some "prophylactic" maintenance. :) First I'm going to have a look at the connecting rods. When we took the engine apart, the lock strap was partially bent over and the bolts were only finger tight. I think new con rods will be the way to go. I'll be able to buy some plastic gauge next week, and also try and measure to see if the crank is still "round" (?) Not sure if this helps. But it will great to get some more summers out it. This is great!
 
Sounds like a plan. If you do find a bit of taper or "egging" on the crank journals, it will probably still live with new bearings if you do a little polishing and then allow for a reasonably long and gental break in period. It won't be perfect, but will likely "do ya". At least I hope so.

If only one corner of the lock strap was folded over each bolt head, that's your cue to use new straps and fold in TWO flats. If you choose to use any thread locker, remember that it effects torque specs. Typically requiring a slightly higher torque to achieve the desired "stretch".

I suggest that new bolts be used since those old ones did receive some pounding when they got loose.

Again, I wish you good luck with it.
 
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