Loud Bang sound

[buellton]

"I have a 1978 Chrysler 15 hp

"I have a 1978 Chrysler 15 hp engine that will not start on low speed setting. When it trys to start it seems to build up presser someware and makes a loud bang sound after 4-5 pulls comming from behind the motor. It may be comming from the cooling water return just above the water line.
Any ideas would be appreciated,Thanks, Vince"

 

[galamb]

You say will not start on low

You say will not start on low speed setting - will it start at all?

Building pressure/loud bang - maybe from the exhaust end of things?

When was this last running normal? maybe have a totally blocked exhaust tube...