The 2.5 has never been a real smooth running engine. However you could do some things to make it about as good as possible. Check the compression in all the cylinders. If they are close to the same that is a good thing. Then run some good cleaner through it, I recommend Sea Foam myself. It does a great job but isn't real cheap. Use it to do a top cylinder cleaning first than dump the rest into the tank. That will remove the carbon and crud. Change the oil after you do the cleaning since it will drop carbon and crud into the oil. Now you have an engine with a clean fuel system and clean top end. If you used good plugs and cap/rotor they should still be OK. The top cylinder cleaning will also cause some carbon to clock the EGR. Remove it and clean it after you do the cleaning. Install a Kleen Screen style gasket to stop carbon from causing it to stick. Check ALL the vacuum lines for leaks. Change the PCV valve. After that your at the mercy of worn interior parts like the rings and cam lobes, lifter wear and valve seating.
The compression test and a leak down test can show you the state of the rings and valves.
Good luck.
Monday, October 27th, 2008 AT 1:19 PM
