Super Contributor

Re: 3512 engine vent problem

Your best source of information would be the Cooling Systems Application and Installation Guide found here,


Cat usually does not provide vent lines because cooling system installations vary so much.


Improper venting causes a number of problems, including yours as described.


Was a proper cooling system audit performed after original installation?  I suspect not, but if you continue to have cooling system problems a properly performed audit is your next best step.




3512 engine vent problem

Hello friends, need your urgent help..our marine engines 3512C are heating up frequently during loads. as we were studying the theory,we found that there is vent line which is (or should be) connected to the expansion tank which can be vented out so as to allow trapped air or gas to escape. however we are unable to find that line or any vent valve.Cant locate in parts manual also. Pls help in 1. finding the vent line and valve along with photo /picture/drawing showing the same. 2. at what frequency we have to do venting? 3. there are many plugs shown on top of thermostat housing and lines connecting to thermostat housing? what is the purpose of those plugs? prompt reply will be highly appreciated