1976 35 hp Johnson

This engine starts easy, and runs out nice...except it coughs, or pauses very briefly...maybe for less than half a second, several times a minute. It makes it feel like I hit a log...then it goes on like nothing happened. I had the lower unit rebuilt, but there was no change. I've had this engine for 20 years, and it was doing this when I first got it, but only when it first started, then would run out without any hesitation.

I'm leaning towards a carburetor issue, but would like a second opinion before I rebuild it. I have the repair manual and can do whatever it needs.

Re: 1976 35 hp Johnson

Carb would be my inclination also...

Re: 1976 35 hp Johnson

Thanks Steve. I've also been reading some other postings and I a couple of comments referred to the 'hitting a log' feeling as probably related to the clutch dog. Since I have had the lower unit rebuilt, wouldn't that have been included? Unfortunately, the local boat repair place here will not stand behind their rebuild. They said they would and tore it back down. Unfortunately, they gave it back to be in pieces saying it was a broken motor mount and they couldn't find the right part. I found the part on line and replaced it...along with reassembling the motor...but still have the 'hitting a log' thing happening at full throttle. Any thoughts on the clutch dog possibility?

Re: 1976 35 hp Johnson

First, don't ever buy a thing from that dealer again. Any dealer who would take your engine apart and not put it back together again ought to lose its relationship with OMC/Bombardier.

As to the clutch dog, what did it look like before you reassembled the LU? If it had problems, the rounded edges of the "keys" on the dog should have been readily apparent. Same thing for the gears - the area where the dog engages the gears should have been visibly worn, if the LU was the problem.

Since you mentioned that this motor did something similar when it was new, I'm thinking that the problem is not LU. Also, what you are describing could be a high speed jet problem or an intermittant ignition problem.

Bring someone with you to drive your boat and run it at WOT with the hood off and the air silencer taken off. Hook a timing light up to check the coils underway, shutting the motor down each time you switch the clip from one spark plug wire to the other. If you tape the trigger on the timing light shut, it is easy to let it fire for awhile to see if any lapses in spark are apparent. Since this is a magneto motor, if there are lapses you are most likely having coil or point problems.

If the ignition doesn't seem to be the problem, take a look into the carb during WOT operation. You should be able to see the spray coming out of the high speed jet/nozzle. If not, shine the timing light into the carb as this sometimes makes the spray easier to see. If you are getting intermittant spray, you may have found your problem.

Hope this helps.

Re: 1976 35 hp Johnson

The "feels like I hit a log" statement is so classic and almost gaurantees that it is a bad clutch dog and forward gear. Combined with the fact that it happens at high speed and the diagnose is made. If it isn't the dog, then it is not going all the way into gear....and will soon be a bad dog caused by extreme wear from incomplete engagement.

An outboard that coughs or sneezes at idle is running too lean.

Bad motor mounts let the motor flop around, but don't give a hitting a log sensation.

An outboard that runs ragged at any speed probably has ignition problems. This is entirely different than the periodic "hitting a log sensation". An igniton miss is a slight random stutter, while a dog is a periodic violent thump, shaking the whole motor....exactly like you hit something.

Re: 1976 35 hp Johnson

Huh. Somehow I missed that 'hit a log' comment. Must have been reading too fast. Yep, exactly as FR says, that's the classic clutch dog issue... or mis adjusted cable/shifter which will lead to the classic clutch dog issue lickity split!

Re: 1976 35 hp Johnson

I am not positive of the particular model engine you have so I do not want to give you any wrong advice.

The same symptoms you are having I experienced also.

Turned out to be excessive play in the shift linkage from the knuckle under the engine that connects the external shift linkage to the shift rod that connects to the lu shift rod.

To inspect this pull the "window" on the side of your lu where the shift rod connects at. Disconnect the shift rods and seperate them. Reach in with your finger and push up on the upper shift rod and see if there is excessive play in the linkage.

I tore my foot apart several times thinking it was my "clutch dog". Turned out to be my linkage. The good thing is I know my foot assembly now no problems (grin) so does my 13 year old son (big grin).

How does it shift in reverse? Any slipping or hitting a log?

Re: 1976 35 hp Johnson

Wow, you folks are quick! Unfortunately, I won't be able to get the boat on the lakes until the spring thaw. I'll focus on the linkage as I can manage that in my shop.

Absolutely right about the dealer. Refused to refund anything. Was supposed to show me the lower unit parts when they rebuilt it, but said they didn't keep them...sounded like a $550 dollar mistake for me. Unfortunately, they are the only ones in NW Montana that work on vintage motors....1976 35R76 G is the model.

Thanks for working with me on this! I have tinkered with this motor off and on, but it continues to be there when I'm catching fish!

Re: 1976 35 hp Johnson

Shifts fine in reverse, although I don't think I've ever ran it wide open in reverse.

Re: 1976 35 hp Johnson

You'll do better doing your own work and just getting your parts from them as if you're mechanically inclined at all the wealth of info on this forum can get you through pretty much anything.

Re: 1976 35 hp Johnson

Your local shop sounds like a ripoff joint. If they "rebuilt" that LU, short of some abnormal problems, about all they would have done is to replace the dog, possibly cut the gears and reseal it. That shouldn't cost $550. The business about not showing you the old parts wouldn't raise a caution flag in my mind if the place had a good reputation but, given what he did to you, it makes me wonder.

If your "hitting the log" situation involves a hard "thump" then I agree that the dog is a likely candidate. What got me thinking about other things is that you mentioned having the motor for twenty years and that it had done the same thing when you first got it. You did not mention LU work to fix that so it didn't seem that the same problem now would have been a clutch dog.

The question that I would ask again is, what the did the dog and gears look like when the repair shop gave you back the disassembled LU? If there isn't a fairly pronounced rounding of the normally "crisp" edges at the contact points on the dog and gears, then I'll go back to saying that I don't think its a clutch dog problem.

PS: If you get back to looking at ignition and fuel delivery, I also agree that you may not have to run at WOT to find these things. I mentioned doing so simply because that's when you said you were experiencing the problem and one of the ways to troubleshoot a problem is to try to duplicate it.

Re: 1976 35 hp Johnson

I have never ran my WOT in reverse either. The wife has, trying to teach her how to drive the boat, needless to say she is a very content passenger, as long as she is catching fish that is.

I have turned the clutch dogs around and used thenm that way due to them being worn. Other words what was the forward side of the clutch dog now is the reververs side, reverse hardly ever gets used and some lu will allow the clutch dog to be turned around.

The more experienced guys on the boards should be able to tell you if this is possible with your engine. Good luck and interersted to see the outcome of this one.

Re: 1976 35 hp Johnson

If the gear is worn, you are only kidding yourself just replacing or turning the dog. It may fix it long enough to unload it on some poor sap though.

Re: 1976 35 hp Johnson

Yes I should have mentioned if the gear is worn that turning the clutch dog around will not "fix" the problem. Gear and clutch dog being two different components. Thanks F.R.

Re: 1976 35 hp Johnson

Okay, I went through the manual and it looks like I can replace the clutch dog by dropping the lower unit and only dismantling it to that point. Does that sound right? Or...is it possible to replace it by just going through the prop shaft opening? They show a special tool for pulling it, but can I just just a regular puller? I will buy the special tool if needed. Probably won't have the time to tackle it until next weekend but would like to order the clutch dog now. While I have it apart, is there more that I should take on?

About the dealer... Have an attorney friend (can you say that in the same sentence???) who said the court costs would be more than the loss. He recommended that I send them a letter...which I did...requesting a refund, and telling them that if they don't give a refund, that I would tell the world about them...working on doing that....

Thanks to all of you for the great ideas and help!

Re: 1976 35 hp Johnson

Brodehl, Don't go buy a clutch dog just yet. Wait until you've got it apart. What F-R is trying to tell you is that if the edges of your clutch dog are bad, then it's very likely the ears on your forward gear that engage the clutch dog are bad, too. You need to look at 'em both. There is a remote possibility that you may get away with just a clutch dog. I'd wait and see what I needed, and either buy a used lower unit or, if I wanted new, order the gear or gears at the same time as the clutch dog and save a few bucks on shipping.
Hope you get out as cheaply as possible--sounds like that dealer is not so trustworthy,
JBJ
JBJ

Re: 1976 35 hp Johnson

If he has to buy a new gear set, he may as well go looking for another LU that he can verify to be in good shape as a whole, or at least in terms of the gears in it. If it is the latter, he can canabalize the "new" LU to fix the old one. Gears are very expensive and most people find it hard to justify buying them.

He may also be able to have the gears "cut." This involves laying them down so that the "non gear side" is facing up, and then cutting a semi-circular notch where the ear on the clutch dog originally engaged the gear. I am told that this is a little tricky to do precisely, so repair facilities often send the gears out to a machine shop to get them cut.