70hp chrysler overheating

[EM1]

Pulled the head and cleaned water ports. Replaced head gasket. New waterpump housing/impeller. Motor runs good. Get excelent water flow in trash can high and low rpms. Run the motor at full throttle on water. Water flow is not steady. It serges out about once a second. Motor got hot. Pulled the thermostat and tried it again. Still water serges from leg but doesn't seem to get hot. Temperature gage is all or none. Block seems cool to the touch. Is this serging normal at higher speeds? Is this enough water? Does some water exit out the exhust port below surface of water? Is this border line for overheating? Any suggestions?<br /><br />Thanks

 

[The Marine Doctor]

Re: 70hp chrysler overheating

It is possible that when you installed the new impeller that 1 blade got turned the wrong way.<br /><br />Or the head gasket or some other gasket is pressurizing the water jacket.<br /><br />And...you could use a new T-Stat.<br /><br />TMD

 

[scotiany]

Re: 70hp chrysler overheating

First, replace or reinstall the thermostat. Thermostat should be a 143-145 temp.You should get a visible pulsating flow( not necessarily a steady flow) at cruise speed. Most of the water goes out with the exhaust gases through the motor leg and then the lower unit(at cruising speed).

 

[The Marine Doctor]

Re: 70hp chrysler overheating

The spray that comes out the discharge holes should be heavy at all times.<br /><br />It should look like you are holding your thumb over the end of a garden hose and spraying.<br /><br />You might knowtice rythemic pulsing...but if it stops and starts...there is a problem.<br /><br />TMD

 

[fishlips]

Re: 70hp chrysler overheating

I have the same motor and was having overheating problems and after many, many hours of replacing and troubleshooting I came to find out it was the wrong head gasket so water ports were blocked in the head. Dont know if this is the problem but be sure you line that gasket up and check the holes. Good Luck!

 

[rbruce63]

Re: 70hp chrysler overheating

Make sure the grommet of the water pump is snuggly fit in the water pump hosing otherwise, you could loose pressure at WOT.