20hp Chrysler water problem.

planedriver

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Oct 3, 2008
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I have a 20hp Chrysler Model 203HG which has not been in use for about 12mths and have just fitted it to a 13ft aluminium boat for my son.
Last night just on dark, we took it to the river to try it out. The motor started second pull and sounded great, but after a few minutes cut-out and was getting a bit hot. Not wanting to cook it completely we paddled back so I could check it in daylight. Naturally my first thoughts were a shot impeller. Removing the side covers on the leg, it was obvious that it was pumping heaps of water out the back, but it's not getting around the head where it's needed. I checked for blocked pipes and blew through the connections and all seemed good. I dont have a manual on the thing, but assume the thermostat is located under the cast cover where the two hoses coming from the head side cover, attach below the fuel pump.
I'm wondering whether the thermostat is stuck closed. I disconnected both hoses a gave the motor a very short run, but no water pumped through the hoses despite heaps pumping out the back of the motor. Having possibly been in there since new, I am hesitant about undoing the screws on the cover unnessesarily in case they sheer off, creating me even more work. :mad:
 

fucawi

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May 18, 2011
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Re: 20hp Chrysler water problem.

You are on the right track .the manual is here ..put another post one when you have investigated more...Its a 1975 so not the one with the dyna start or is it ?
https://rs895tl.rapidshare.com/#!do...df|910|R~0DB4B7EA4E27C260FB4361A5DCDC15B8|0|0
Click on the green download button below the blue tv screen.

What hoses are you refering to I dont recall any water hoses on this model ?

To post photos no hosting is required ..go advanced ..attachment ( the paper clip symbol) and load the photos from your computer ....

I can put you in touch with someone else with the same motor and there is another post about the 20 hp a bit lower down the listing .
 

planedriver

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Oct 3, 2008
Messages
6
Re: 20hp Chrysler water problem.

Thanks fucawi for the reply and manual download link.
I pulled the pump down and replaced the impeller, as it seemed a little bit on the limp side.
It now has tons of water pumping out the back, but does not seem to be getting around the head and its still gettng hot.

My model does not have a thermostat.
I currently have the head off and the waterways are surprisingly clean and hardly any sign of corrosion at all.
Presumeably, if i connect a hose to the copper pipe which goes into the top of the water pump, being careful not to let water get into the bores or crankcase, I assume water should start to fill the waterways in the head, if all is clear. Judgeing by the volume of water coming out the back, it's like it's all being diverted to the exhaust port out the back.
Cannot find a water-flow diagram which clearly shows where the water is split between going around the head and whats dumped to the exhaust. Any help in this regard would be so very much appreciated.
 

fucawi

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May 18, 2011
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1,039
Re: 20hp Chrysler water problem.

I would take off the exhause side cover ..this will give you access to the passages in the cover and into and arround the head. I have had bad corrosion and blockages within the cover. When its all back together feed water into the pipe that comes up from the pump and run it like that to see if it over heats or put in a barrel at least 2-4 in over the anti ventilation plate . If possible fit a pisser or tell tail to the top of the head....without a photo I cannot advise on this but its the only way to be sure its cooling ..I assume you have oil in the petrol ???/
Photo without hosting ..go advanced ..click on attachment ( paper clip symbol) and follow the instructions ....easy
 

planedriver

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Oct 3, 2008
Messages
6
Re: 20hp Chrysler water problem.

Thank you so much for your advice fucawi, it was very much apprciated.
My problem was due to some boof-head using too much silicon sealer and a bloody-great blob of it was found blocking a port of the waterway in the cylinder head.
Now it's pumping oodles of water and getting where it should be.
Many thanks for your expertise.
Kind regards
Alan
 

fucawi

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May 18, 2011
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1,039
Re: 20hp Chrysler water problem.

And thank you for letting us know the result ..so often the ignorant do not do this ....very pleased for you
 
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