Chrysler 115 carb adjustment and cooling

stoney747

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Joined
Jun 7, 2007
Messages
13
I have a 115 Chrysler. When I advance the thottle, It's seems to have a rough spot or vibration between part thottle and idle. Do I need to adjust the idle mixture or is that normal for a Chrysler outboard? My second qustion is when I am at cruise, the temp is stable,(135 to145)but when I go to wide open thottle, it slowley whant to get hot. When I back down off the thottle, temp comes back down or I stop to let it Idle to cool down. I have done all of the Head gasket, New water pump, check for blockage in the channels and by-pass valve. I have a 110 thermostat. That might be to cold because the water in the river is very hot this year. N.C. As soon as I start the engine, in about 2 1/2 min the thermostat is opening and never close the whole time(2nd new 110 thermostat) which result in low water pressure on the gauge.(no resistant) Manual says it should be 140 temp Thermostat.If the Engine is to high on the transome, will this cause this problem? Any help woud be welcome.

Thank You
 

Frank Acampora

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Jan 19, 2007
Messages
12,004
Re: Chrysler 115 carb adjustment and cooling

Chrysler engines seem to always have a rough spot at partial throttle. It is the nature of the beast. Don't try to adjust the carbs.

If your river is as hot as you say, remove the thermostat completely. Height on the transom does not matter EXCEPT if the engine has one or two intake ports exposed to air and is not sucking in a full volume of water.

You do not state the year of your 115 but if it is an earlier one, before 1979, the 2 piece lower unit has water intakes above the gearcase torpedo and this can happen. After 1978, the engines had a 1 piece lower with water intakes on the side of the gearcase torpedo--very difficult to suck air unless you are set up for full race, surface running prop.
 

stoney747

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Joined
Jun 7, 2007
Messages
13
Re: Chrysler 115 carb adjustment and cooling

Forgive me. It's a 2 piece lower unit. There is a piece of wood stock, about 1/4 thick between the top boat transom and the mount. It's seems like the last owners(years ago) where trying to raise the engine a little bit to how it sits in the water.
 

jerryjerry05

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May 7, 2008
Messages
17,923
Re: Chrysler 115 carb adjustment and cooling

N.C. Salt or fresh water?
The piece of wood could be there to raise the cavitation plate,might have been too low.
Salt water,blocks the cooling passages in the exhaust.
 

stoney747

Cadet
Joined
Jun 7, 2007
Messages
13
Re: Chrysler 115 carb adjustment and cooling

Brackish water. Two piece lower unit. When i hook on the water flush muffs, at idle, the engine temp gauge red 110 deg. what gives!
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Re: Chrysler 115 carb adjustment and cooling

Brackish is salt.
The exhaust passages can hold corrosion and crud.
It will allow the motor to run cool at slow speed.
Once you raise the speed it won't cool as well.
Look up a parts diagram,powerhead section.The cover on the left side.
It has 2 gaskets and a stainless plate.
It gets clogged.
It can be removed and cleaned.
BUT!!!!! Be VERY careful when removing the screws.
They want to break off as soon as you touch them.
Use PB Blaster a small propane torch and a hammer to help remove.
Spray for a couple of days.Heat the screws first and then spray.
Do this a couple of times.Then start tapping with a hammer and then spray and heat and tap.
Then GENTLY try to undo the screws.
 
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