1983 Chrysler 4hp water cooled

[lljhoyer]

I bought this motor cheap knowing I had to replace a water pump impeller, as former owner said it wasn't pumping water. Bought an impeller(not cheap-paid more for it than I did for the motor), tore motor down, water pump impeller looked good but changed it anyway as long as it was apart. Started it up and I don't get any appreciable water coming out of the unit. Tore it down again, all the way, blew out pressure line to engine, blew out engine passages both ways and blew out the outlet pipe. Now in looking at it, I'm wondering where the water doew come out. The outlet stops about midway down the tower, so I guessing there is no tell-tale like other engines. Can I route this to the outside to "make" a tell-tale or what. I'm hestitant in putting this back together until I figure out how it's supposed to work. Does the water dribble out of the small holes lower on the midtower?Thanks.

 

[jerryjerry05]

Re: 1983 Chrysler 4hp water cooled

Pictures are worth a thousand words.J

 

[Can't Cast]

Re: 1983 Chrysler 4hp water cooled

I have a 6 hp Chrysler that I recently replaced the impeller on. It did not flow water very good at all, just a very slight dribble. I used a compressor to blow out the water passages like you did, but to no avail.
I took it back apart, and checked the water pump again, and all looked great. I then decided to try and run some water manually up the water tube, so I took a piece of rubber fuel line and slid it over the tube, then using my garden hose with a brass twist type sprayer I held it up to the fuel line and sealed it as best I could. I shot water full force up the line, and then let the water drain back out.
When it drained, it was loaded with mud and what looked like shell fragments. This was a strictly fresh water engine, so it seemed strange to see that. I flushed it this way until the water kept draining out clear.
Put the lower unit back on and fired it up. Water flowed good from the ports on the back of the motor now (rear of motor, halfway down, 2 holes).
Small Chryslers don't pee real hard, but you should have a good stream coming out of these ports at slower speeds. When you rev it up, the stream will get smaller, and at max throttle you may not even see any water coming out (which is normal) until you back off throttle again.
I don't know of a way to install a tell-tale setup. However you can use the old put your hand on the powerhead trick, and if it's warm and doesn't get really hot you should be OK. If it gets real hot or you smell paint burning, you have a problem.
BTW - smaller Chryslers don't have a thermostat...water should flow immediately.

 

[lljhoyer]

Re: 1983 Chrysler 4hp water cooled

I'll try flushing it with water and see what happens. Might try hot water. Thanks

 

[wickware]

Re: 1983 Chrysler 4hp water cooled

Chrysler Veterans & Pros,

I know the theory as to why the impeller puts out less water at higher RPMs (due to impeller?s vain bending. What replaces the water to cool the engine that the engine should need more at higher RPMs? With no radiator with more air flowing through it at higher speeds for cooling. This principle is hard for me to visualize what substitutes for less water flow at high RPMs (unless it needs less higher). HELP!

JOW

 

[Can't Cast]

Re: 1983 Chrysler 4hp water cooled

Wickware,

I'm guessing here, but on the smaller Chrysler's under 20 hp, the water outlet is also tied into the exhaust ports. As revs increase, exhaust gas pressures increase and water stream becomes more "vaporized" by increased exhaust pressures, turning into a mist instead of a stream. I assume the same or more water flows during this time, but it's "mistified" by the high pressure gases coming out. When you back off the throttle, the pressure drops and it turns back into a stream of water.
On 20 hp and above, you should see water stream at ALL speeds. I assume the plumbing is different for those motors.
Sorry, I ain't too good at splainin' things. I'm just a country boy who likes to catch a bass every now & then...and chug a few beers.:redface: