what size engines will interchange with a 2003 

need more specific info.

 

Model? Current engine? trans type?

2003 what?

What model car and what engine do you have?

 

The most common for that year was the 2.5 liter 4 cylinder - the EJ25.If that's your motor, I think 2002-2004 are direct bolt it (Someone correct me if I'm off by a year) and 2000 and 2001 are compatible but need a couple small pieces swapped from your 2003 motor.

 

If your motor simply has bad head gaskets, it's usually best to just replace them. The 2000+ 2.5 motors were much more reliable than the prior ones. The factory head gaskets were not great and eventually failed, but when replaced with the upgraded version (a search on here should yield the part #) they were good to go. I've had 2 of these motors under my watch. We sold one this summer at 351,000 miles (Still running fine) and the other is a daily driver now at 222,000