I have a 2002 4.7L V8 HO Grand Cherokee. While my wife was driving the vehicle, it suddenly started to run very rough and would stall while driving. She noticed smoke from the exhaust (I think it was white). I took a look and the engine light was on with P0203 and P0303 codes. According to my wife, the coolant had been low for a few days and was dry when I looked at it.
I tested the resistance in the fuel injectors and they appear to be working. There appears to be power and spark to the #3 cylinder. The dipstick was not milky and just looked like oil. When I opened the radiator cap, it looked a little like milky oil. I suspect it is a blown head gasket. I do not have a compression or leak down tester. I may go get one or both in the morning. What are your thoughts? I am really tight on funds. If I could only buy one of the testers, which would you recommend?
White smoke is a tell-tale sign of a coolant leak.
code P0203 is a fuel injector code. It can be tested by swapping injectors with adjacent cylinder (#1). You may be able to smell unburned fuel if the injector is stuck open.
Ok. I got a compression tester and the #3 cylinder had 0 psi (needle did not move at all). The adjacent #5 cylinder only had about 65 psi. All the other were above 160 psi. I put some oil in the #3 and #5 cylinders. Nothing changed in the #3, but the #5 went way up (over 250 psi). I am a little confused. I know a low reading on two adjacent cylinders is an indication of a bad head gasket and would also explain the other symptoms, I think. But the increase in the compression after adding oil indicates worn piston rings. Any thoughts?
0 PSI could be an indication one of the calves is not closing. Could be a valve seat has let loose and is holding it open. If this is the case the rocker arm would be lose enough to get tossed off (good thing). It's pretty easy to pull the driver side valve cover and see if a #3 rocker arm is loose.
I decided I would try to pull the heads and see if it is a blown gasket. After I remove the vibration dampner (harmonic balancer) to get to the timing cover, do I need the Special Tool required to install it? It looks like it is hard to find and very expensive. I have found a lot of discussion about getting the thing off, but I want to also make sure I can get it back on. Any help would be much appreciated.