Chrysler engine overheating

[Uncle Punch]

Hey Picked up a 1970s boat with a 105hp chrysler engine (1059BD) but seems to have problems with overheating, the water is steaming and boiling as it comes out, the alarm goes off and it wont run smoothly. We put a new impeller in and took the thermostat out. All the water lines seem to be clear. Any ideas??

 

[jerryjerry05]

It's a 1976
You running on the hose,muffs or bucket?
The bucket needs to be real deep, 4-6 inches over the cavitation plate.
The older motors needed a special muff, need pics of the water pickup on the lower unit.
If you have the 2 piece lower? then you need a special muff.

 

[Uncle Punch]

No weve been ripping in the lake with it. But you can't get far and it starts boiling over. Its got a 19 pitch prop and I believe its supposed to be a 17. how much of a difference does that make?

 

[alldodge]

Sounds like ya need to replace the impeller in the lower leg

 

[Uncle Punch]

Sounds like ya need to replace the impeller in the lower leg

We replaced that already but it didnt seem to help at all.

 

[alldodge]

Assuming impeller was replaced and boat was put straight in the water, did not run in bucket or with muffs

Pump housing might be damaged, maybe the seal where tube connects or something is clogged.

 

[jerryjerry05]

The old impeller, did it come out complete? or were the vanes missing?
Missing vanes, they get to the bottom of the motor and clog there and that causes an overheat??
Drop the lower unit, hook a hose direct to the tube to the motor.
Turn it on and start it and see if it gets hot then.
No?? then the problems in the pump.
Pics of the pump, inside and out and the wear plate, and compare the new impeller to the old??

 

[WinnerCougar74]

My 1974 135hp had a rubber grommet where the pipe fits into the water pump housing. I changed it to the newer white plastic type that kind of funnels the the pipe into the right place. It fits nice a snug now. Also the thermostat housing is easy to remove to check it all out.

 

[Jiggz]

If you haven't done so, check the thermostat. It is easier to do so than dropping the LU unit again. I had the same problem last week and after replacing the impeller the overheating problem persists. Come to find out the thermostat has marine growth in it preventing it from opening all the way. Luckily, the overheating was not severe since the T-stat still opens a little bit. Replaced the T-stat with a new one and cleaned the old one for spare. And you can test the old T-stat for function by placing it in a hot water over a stove. If the problem still persists, then drop LU and make sure the impeller is installed properly. It is not unusual that the key was not inserted at all.

With the LU dropped and the t-sat housing removed, you can check for blockage in the cooling system with a garden hose pushed on the t-stat opening and the water should go straight out the water tube of the LU. Just make sure you throttle the pressure so as not to wet the electrical system.