Other problems with my 115hp 73 Johnson?

[teslaman]

I'm about to install a rebuilt powerhead from iboats to replace my blown-out 115hp 73 Johnson. I wanna make sure that the replacement powerhead doesn't suffer the same fate as the original.

In the original powerhead, the piston in cylinder #1 melted. Although I didn't hear any knocking, the piston definitely struck the spark plug as I noticed this problem before the fatal meltdown occured. I assumed that this was a crankshaft bearing or rod issue. However, is it possible that the carborator or power pack could have lead to this problem?

I plan to switch out the powerhead ad maintain all the ancillary fuel and electrical systems. I just wanna be be sure about the carborator and powerpack before I blow a rebuild.

Thanks

 

[mikesea]

Re: Other problems with my 115hp 73 Johnson?

i recommend rebuilding your carbs,most rebuilders do it to insure the engine wont be starved fuel,the fuel is mixed with the oil,therby getting its lubrication through the fuel oil mix,when acarb dont deliver,but others do ,you get problems,if you think you may have spark problems,do a spark check before firing the engine off.the big thing is the fuel

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

What goes into rebuilding a carb? Is it mainly cleaning?

 

[Walker]

Re: Other problems with my 115hp 73 Johnson?

Yes mainly cleaning. Clean them as good as a surgeon cleans his hands before operating.\
Do a search for carb cleaning and you will find several good threads on ways to clean them good. Then put them back together with new carb kits.

 

[reeldutch]

Re: Other problems with my 115hp 73 Johnson?

you defenatly should clean the carbs set the floats etc etc.
ask some specialist like dhadley if you want to rejet the carbs or use different carbs.
in 73 the rings were very close to the top of the piston and can not withstand any preignition detonation.
since the fuel has changed so much i would ask somebody experienced what to do before you blow a brand new ph.

from leaded to ethanol and inbetween, just make shure your doing the best thing for this ph.
gas from 73 is not around anymore.
may be retarding timing etc etc.

good luck

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

I've been told on this site that 89 grade gasoline is OK. I've already purchased the powerhead, so I need to figure out how to keep from blowing a new one.

 

[Dhadley]

Re: Other problems with my 115hp 73 Johnson?

89 is OK, 87 is better. Were you using Champion plugs? If not it may be just that simple.

If the sharp edges of the deflector on the dome was "eaten off" or rounded, suspect an ignition component to be the cause. If the skirt stuck, suspect a fuel delivery issue to be the cause.

Regardless, clean the carbs and install a new pump kit anytime a powerhead is installed.

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

I was using Champion plugs. I just bought the boat about 6 months ago, and I believe that the previous owner used either when starting the motor cold.

The motor has been hard to start when cold, but then starts up fine the rest of the day after the first time. I did notice that starting throughout the day became tougher leading up to the engine failure.

 

[hamburgerman]

Re: Other problems with my 115hp 73 Johnson?

either is a fast way to kill a 2 stroke !

 

[papasage]

Re: Other problems with my 115hp 73 Johnson?

if the engin was rebuilt and new pistons they are the new type . they don`t make the older pistons that has the ring groove close to top . the newer piston`s will work with a wrist pin kit . i use QL77JC4 .the shop manul recomends the surface gap QL16V . they will foul easley with a lot of idling and over rich carbs . better for high speed . but they do recomend the QL77JC4 if you do have a foulinf probablem

 

[F_R]

Re: Other problems with my 115hp 73 Johnson?

There were several service bulletins back in those days concerning the changes in available gasoline. Some engines were built that actually required premium leaded gas! I wish I still had the bulletins, but I don't. They involved timing changes and jet changes. Maybe iboats has info?

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

I know that the vendor who performed the rebuild will provide instructions as how to replace the powerhead as well as break-in instructions.

I've been told that any time you replace a powerhead that you should go ahead and replace the jets. I guess that I'll disassemble the carborator and replace any "replaceable" parts -- seals, jets, ect...

As far as the fuel system is concerned, what should I replace with it? I would suspect that the fuel filter and fuel pump may need to be replaced.

 

[ezeke]

Re: Other problems with my 115hp 73 Johnson?

If you are going to work on the jets, soak the carbs first.

The jets have probably been in place since the carbs were new and will be firmly stuck. If you put too much force on them and break them, you will have to replace the carburetors.

Personally, I can't see any reason to remove the jets and I would be interested in the rationale.

They are 67C for the four high speed ones and 30's for the low. I am not aware of any change from 1973 through 1975 on the 115HP series.

In addition to all of the new parts in the OMC/BRP carb kits, this would be a great opportunity to inspect the reeds and fuel pump and to replace all of the hoses and clamps.

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

So you wouldn't replace the jets?

Soaking the carbs is definitely in the plan. What all should I do to ensure that this motor won't suffer the same fate as the last.

 

[ezeke]

Re: Other problems with my 115hp 73 Johnson?

I would measure the jets [orifices] to make sure they are in fact the right sizes and try to remove them after soaking. I would definitely not consider it absolutely necessary, and if I met with resistance, I would not force them.

I believe that you said in your earlier thread that the #1 piston melted. That would usually be caused by running lean - not enough fuel and/or, too much air.

Too much air could come from air infiltration anywhere along the fuel supply, including the gasket between the carburetor and the intake manifold.

Too little fuel is my guess because the damage seems concentrated to one cylinder. That would call for a careful rebuild of the top carburetor,

This is just my opinion; there are surely plenty of other ways of looking at what information we have.

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

What exactly goes into a carborator rebuild? What parts do I need to order?

 

[ezeke]

Re: Other problems with my 115hp 73 Johnson?

You need two complete carburetor repair kits. The OMC/BRP ones are the best and most complete. If you can, get them from your local dealer.

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

Would part # 18-7046 be the carb kit that I need. iboats sells them $12.46 each.

I'm looking for some local dealers. Is there a good site where dealers are registered?

 

[ezeke]

Re: Other problems with my 115hp 73 Johnson?

Iboats' kits are aftermarket made by Sierra and I have not had any problem with them except that they did not have the floats in them.

On the BRP web site there is a dealer locator link in the upper right hand corner of the parts search page:

http://epc.brp.com/default.aspx?brands=ej&lang=E

While you are at that site, you could look up the parts manual for your motor and get the numbers for the carburetor kits and fuel hoses.

It is well worth your time to get to know the parts department personnel at your nearest dealership. They are usually very helpful people.

By the time you pay the shipping charges, you will probably not be that far apart on the cost.

Edit: I will have to retract the part about looking up the parts numbers. The Carburetor kit is 0439076. The tee to carburetor hose is 0324079 - you need two.

If you have not yet installed a full sized water separating fuel filter, you might want to look at those.

2nd Edit: The reason to replace those two hoses now is that they are virtually impossible to service without removing the carburetors. I recently took the carbs off of a 1979 115 and the hoses looked perfect. I bent the hoses against the set curve and they disintegrated in my hands.

 

[teslaman]

Re: Other problems with my 115hp 73 Johnson?

Ezeke,

I tried to use the dealer locator, but it only gives choices for Seadoos and stuff. I looked in the parts catalog and found carborator parts but no repair kits and not parts matching the 0439076 number. Am I missing something on the site?

Also, I read in the Seloc and Clymer manuas that soaking the carborator is a no no. Apparently, seal in the meter and other places will deteriorate is subjected to soaking. Directions say to use a spray solvent, brush, and an air gun.

I've never heard of that kind of a fuel pump, does it seperate water that may have built-up in the tank?