Sounds like you are running with an engine smaller than 250 rating. You must have 10 heat sinks on your mech to be able to launch it. When you upgraded to double heat sinks it strips all of your old heat sinks off the mech. So if you have an engine smaller than 250 you now have less than 10 heat sinks. You have to put 1 heat sink outside the engine every 25 engine ratings under 250 and you can add 1 heat sink inside the engine for every 25 ratings over 250.
Examples:
245 rating engine has 9 internal heat sinks and requires you to mount 1 more somewhere in your mech.
225 rating engine has 9 internal heat sinks and you must mount 1 more heat sinks somewhere in your mech.
220 rating engine has 8 internal heat sinks and you must mount 2 more heat sinks somewhere in your mech.
275 rating engine has 10 internal heat sinks and also has 1 slot where you can add 1 more heat sink in it without taking up critical space in the mech but it will still weigh 1 ton to add.
These rules apply to both single and double heat sinks.
Edited by Boogie Man, 01 January 2013 - 07:05 AM.