trouble shoot problem

[chuko]

I have a 78 18' starcraft chieftain with a 140 Merc I/O. I was motoring at a pretty good clip with 4 adults and 2 kids in the boat when all of sudden the engine went clunk and we lost all forward thrust and the engine started to rev. I turned it off and open the engine compartment and it smelled like burning rubber and it was smoking. We waited for 10 min and started the engine again, and I put it into forward we started to move again and when I added a little more throttle it started to rev with no thrust again. That is when we got the spare outboard out and slowly made it back to the mainland. Can you help narrow down the problem? I am in Baja and not sure the ability to find parts and getting her going again. But I have to try, I got it all the way down here.

NB

 

[Don S]

Re: trouble shoot problem

Sound like you lost the coupler. It has a rubber hub like a prop, when it spins, inside itself the friction causes heat and smoke. Time to pull the drive, then the engine, and replace the coupler.

 

[Bondo]

Re: trouble shoot problem

Sound like you lost the coupler. It has a rubber hub like a prop, when it spins, inside itself the friction causes heat and smoke. Time to pull the drive, then the engine, and replace the coupler.

Ayuh,... No doubt about it,...

The coupler lives between the motor's flywheel, 'n the drives's input shaft...

My guess is, the motor/ drive alignment is out,...
That's what smokes the majority of 'em...

 

[chuko]

Re: trouble shoot problem

Ouch, doesnt sound good. Is there any way to verify this without removing enging and lower drive? Is there anyway this could be the prop? With engine off and in gear, I can turn prop freely. Does this provide any more info? Anyone know how to say coupler in spanish?

 

[Bondo]

Re: trouble shoot problem

Ouch, doesnt sound good. Is there any way to verify this without removing enging and lower drive? Is there anyway this could be the prop? With engine off and in gear, I can turn prop freely. Does this provide any more info? Anyone know how to say coupler in spanish?

Ayuh,... The Smoke under the motorbox pretty much rules out the prop, 'n confirms it's the coupler...

 

[dockwrecker]

Been there done that twice now. Motor has to come out, can't change it by just pulling the drive.

 

[chuko]

Re: trouble shoot problem

I have a manual so I will take off the drive, but anything beyond that will have to be done by a local mechanic, as I am renting a place (on the bay of conception-hence the boat) and I dont have much to work with.

I had a few locals take a look at it, and they thought it was a "gear" in lower unit since in gear it spins pretty freely (especially in forward) and there is little resistance that seems to suggest nothing is turning all the way through the transom. I asked him to explain the smoke in the engine compartment (with almost no ability to speak in our respective languages) and he thought water was not being pumped into the engine after the "gear" disintegrated which then the engine overheated burning something in the compartment. I didnt really buy this since I turned if off immediately. So the coupler sounds more feasible except that it just feels like there is nothing turing up that far from the prop.

No other diagnostics I can do?

 

[Don S]

Re: trouble shoot problem

We waited for 10 min and started the engine again, and I put it into forward we started to move again and when I added a little more throttle it started to rev with no thrust again.

That in itself means the drive is turning at low speed where the rubber will hold just from the friction. If gears were gone, it wouldn't move at all. Pull the top cap off the drive and look inside, if the gears are gone, you will be able to tell. You could also just drain the gear lube. If there is a lot of metal chunks in the oil, the drive failed.

 

[CheapboatKev]

Re: trouble shoot problem

Sorry but you nee to listen to what has been said.
Pull the outdrive, turn the shaft and you will see the prop turn.
Your outdrive is fine. Park under a big tree and get a chain pull and remove the motor.
The 140 hp 4 banger is about as simple a motor as there is.
What manual do you have exactly?
Please dont say Solec

 

[chuko]

Re: trouble shoot problem

Thanks Don S for other diagnostics. I will pursue those.

CheapBoatKey. I need to start listening? Sorry if I didnt jump at the first solution which was to pull my engine and outdrive and replace the coupler when I am in the middle of nowwhere with little in the way of tools or mechanics. Doubtful I will get parts here. Yes, people suggestions sounded logical but I was looking for other confirmatory diagonsitic test beyond the written description of the event- is that inapproriate for this forum? I have the mercruiser manuals, but they do not trouble shoot this problem.

 

[CheapboatKev]

Re: trouble shoot problem

Thanks Don S for other diagnostics. I will pursue those.

CheapBoatKey. I need to start listening? Sorry if I didnt jump at the first solution which was to pull my engine and outdrive and replace the coupler when I am in the middle of nowwhere with little in the way of tools or mechanics. Doubtful I will get parts here. Yes, people suggestions sounded logical but I was looking for other confirmatory diagonsitic test beyond the written description of the event- is that inapproriate for this forum? I have the mercruiser manuals, but they do not trouble shoot this problem.

I didnt mean to come across harsh, I didnt say START, I said NEED TO...
This is Don S's first reply. Print it out and show your mechanic.

Sonar a usted perdi? el acoplador. Esto tiene un cubo de goma como un puntal, cuando esto gira, dentro de s? el calor de causas de fricci?n y humo. Tiempo para tirar el paseo, entonces el motor, y sustituir el acoplador.

 

[chuko]

Re: trouble shoot problem

Sometimes things come across wrong in written form, no harm done I hope. But believe me, I hanging on to everyword written because I need to figure out how to salvage the fishing portion of this trip given the nightmare of getting this boat down here.

I removed the outdrive, and it does appear that drive shaft and prop turn together when I hold shift tab in place, so I will work with locals to have them help hoist the engine, and have my father bring me a coupler when he comes down in a week, and replace it. Looking at the manual, it doesnt look to difficult accept I dont have an alignment tool.

Thanks for the translation.

 

[CheapboatKev]

Re: trouble shoot problem

Sometimes things come across wrong in written form, no harm done I hope. But believe me, I hanging on to everyword written because I need to figure out how to salvage the fishing portion of this trip given the nightmare of getting this boat down here.

I removed the outdrive, and it does appear that drive shaft and prop turn together when I hold shift tab in place, so I will work with locals to have them help hoist the engine, and have my father bring me a coupler when he comes down in a week, and replace it. Looking at the manual, it doesnt look to difficult accept I dont have an alignment tool.

Thanks for the translation.

Up top of this forum there are specs on making an alianment tool, you could have your Father bring one if he knows a shop with a late..OR you can buy them on Ebay easily enough and get it to him to bring. BUT...any marina in Mulege or Loreto should have an alignment tool..

Best of luck, your in a nice place to be..better with a working boat I know!

 

[series60]

Re: trouble shoot problem

With the drive off use a flashlight to look inside the gimble and see how the coupler looks. You should see splines on the coupler that mate with the splines on the drive shaft. In this picture you can see how the splines might look. This one was worn out but still running. When the splines in the coupler go there is usually nothing to look at except a round hole where the splines once were. Alignment was way off on this one when I removed drive. Mind you when I say WAY off I mean a few several millimeters. This is a very critical adjustment.

​

Here is where you need to look. Down deep in the hole you can see the coupler and whats left of the splines. Good luck.

​

 

[chuko]

Re: trouble shoot problem

I just did this and I see splines that seem to be at least a deep as what is on the drive shaft. So perhaps the coupler is fine?

I ordered a coupler and alignment tool just an hour before I checked this out.

Not sure what to do next.

 

[Don S]

Re: trouble shoot problem

Did you actually check anything? Or just start ordering parts by what was said in a forum from people that can't see your engine or drive?

 

[chuko]

Re: trouble shoot problem

As I mentioned, I took off the outdrive, and with the shift tab held in place, when I turned the drive shaft the prop turned. I also took off the top of the cap of the drive as you suggested and the gear up there looks fine. I did this before I ordered parts. I have not drained the oil to look for pieces yet so perhaps I will do that next.

 

[chuko]

Re: trouble shoot problem

Based on Don S first reply " It has a rubber hub like a prop, when it spins, inside itself the friction causes heat and smoke."

Would the splines necessarily be destroyed in the coupler when it fails? Else, why would it spin inside itself buring the rubber? I havent held a coupler so I dont really know how it supposed to work? What is the rubber for?

 

[Don S]

Re: trouble shoot problem

No, the splines would not be damaged. The rubber surface between the splined inner hub and the outer housing of the coupler should be smooth. Reach in there and feel it, if spun, there would be a very rough and uneven surface.

 

[Pete104]

Re: trouble shoot problem

Don, you have to a pic of a spun coupler somewhere!

OP CHUKO, It's a flange that is bolted to the crankshaft with internal splines mounted in rubber to absorb vibration & maintain smooth operation.