1991 120 hp Force/Chrysler No Spark at amy cylinder, please help.

[dan2744]

Actually on muffs it does not overheat, when it is ran in a tub of water, that is when it overheats. I noticed that I have not tightened down the water inlet hose, will that make a difference? Is my impeller not doing it's job?

 

[Jiggz]

From the last video, with the engine running with heavy smoke I see water running out but since this is an L-drive I am not sure if that is coming out of the exhaust. On non-L-drive units the only definitive way to test an impeller while on earmuffs is to watch the water flow from the exhaust snout. Rev the engine a bit (lit racing it) up to about 2000 RPM and you will see an increase in volume on the water coming out. That in itself tells you the impeller is working. I'm not sure with L-drive though. But I'm quite sure there is a way to monitor the volume of cooling water coming out of the exhaust to see if the impeller is actually working.

As for the wetting on the plugs, double check it is not water by squeezing it between your fingers. Gas does have different feeling than water in that is has petroleum base on it while water doesn't. If you really want to make sure then use water paste or water finding paste. A tube costs about $5. Ace hardware might have it.

What is the status of checking the timing? An improperly timed engine can certainly overheat.

 

[dan2744]

With the muffs on when I rev it, the volume of water increases dramatically, when I take the muffs off and run it straight from the tank it will overheat and the volume of water never changes. I did a test (not sure if it's a great test) by loosening the thermostat cover and seeing how much water seeped out by revving it up. On muffs it pours out of the thermostat, without muffs it never even leaks. I am guessing the impeller is bad and that is probably how the previous owner destroyed it. My hose has pretty good water pressure, maybe that is why it runs fine on muffs. I think the plugs are covered with fuel, it feels more like premix than water.

 

[dan2744]

I'm getting a timing light tonight so I can take care of the timing once and for all. Should I time it and then see if it still overheats then?

 

[Jiggz]

With no change in cooling water volume when submerged when rev'ed up, there is an issue in here. Either the lower unit is not fully submerged as it is really short compare to non-L Drive units or there is a problem with the impeller. On ear muffs it does not overheat which means the impeller is working or it is being helped only by the water pressure.

You mentioned previous owner with regards to the impeller . . . if the current impeller is still the same impeller when you got the motor, you definitely need to replace it. There is nothing like having a known new working impeller rather than second guessing it when you know it is a very critical item.

Lastly, check the timing, set the idle and you should be ready to do sea trials. When you do sea trials for the first time make sure you have some tools with you. Until you can verify it is perfectly working you might just want to stay by the shore. Goodluck.

 

[dan2744]

Will do Jiggz, do you know if west marine carries that impeller or do I have to order it? Can I go to service maina and pick it up/ Do I put the boat in full forward like on an inboard when changing?

 

[Jiggz]

The impeller (or substitute) is actually carried here at iboat not really sure about West Marine. You can check and the part # is F694065.

Here's utube on how to dismount the lower unit and get access to the water pump or impeller. Very informative.

https://www.youtube.com/watch?v=sugP5tPK9YQ

 

[dan2744]

Took lower unit off to check impeller and it was badly damaged and broke into pieces.

 

[Jiggz]

Wow! I guess that's a very good thing you noticed the overheating before a catastrophic damage occur. I still have to hear you time the motor. You're almost there. Hopefully this next weekend you will be enjoying your hard work. The impeller is a preventive maintenance item. Depending on the length of the boating season in your locale it is recommended to be replaced annually or no more than every two years. I do the latter and our local boating season is only 3 months.

 

[dan2744]

I also noticed that there was no gasket installed on the impeller housing. It was just the plastic housing, followed by the metal plate or gasket, and then that was directly bolted to the bottom of the housing. Is that correct, it doesn't look like it leaks, was this a mistake, or is it supposed to be that way? I will try to post a picture of it.

 

[Jiggz]

The water pump gasket is at the bottom of the water pump back plate (this is the thin stainless metal). Above the back plate is the impeller and then the pump body that is made of nylon. Just to be sure I'll start from the top like when you are disassembling it, pump body, impeller, back plate and then the gasket. Don't forget there is a woodruff key holding the impeller to the drive shaft. This is very important as without this the impeller will not rotate with the drive shaft.

 

[dan2744]

No Title

This is all that came off.

 

[Jiggz]

Well, this is the diagram showing there are actually two gaskets for the L-drive.

 

[dan2744]

No more overheating but I wished it would idle better. I hope I timed it right. https://www.youtube.com/edit?o=U&video_id=deXtiaZuBYk

 

[Jiggz]

You provided the wrong link.

 

[Jiggz]

Anyways, for idle rpm make sure it runs about 1000~1100 rpm in neutral and about 750 rpm idle in gear. These numbers are not written in stone but your settings should be very close to these. Use the idle set screw located at the bottom of the tower shaft to set the idle speed. Make sure the air fuel mixture screws are set 1 1/8~ 1 1/4 out from lightly seated. Make sure none of the plugs is fouled and none of the spark plug boots is arcing over. Meaning you should be able to touch any boot while the engine is running without getting shock. If you do, try applying a thin film of dielectric grease on each plugs tip where the boot inserts. And lastly, these 2 cycle motors do not like prolong idling. With prolonged idling they tend to idle rough since unburned fuel mixture accumulates at the bottom cylinders #2 and #4. Although there is this so called fuel recovery system, it only works at higher rpm.

 

[dan2744]

No Title

This fell out of the water inlet, I think, I was taking the lower unit off again so that I could put on gasket for impeller housing. It looks like a rubber seal, 3 bearings and a housing for the rubber seal, what is this, and how does it go back on?

 

[Jiggz]

No Title

That is the shaft spline seal. It comes with a rubber boot. It goes on the very top of the LU drive shaft (spline section). Here's a pic on how it goes.

 

[dan2744]

Why do I see ball bearings? I am not sure why ball bearings fell out. I found three of em on the ground. Is there a bearing in there? I'll try to take a video of it.

 

[dan2744]

https://www.youtube.com/edit?o=U&video_id=yHjCYAmaOEY Can you see anything wrong in the video? Should there be that much movement?