We got a check engine light, misfire cylinder 5. Rough Idle, white smoke out of the exhaust. Spark plug fouled by coolant, cracked head or head gasket was our initial diagnosis. Compression test to find out, but all 118 and up with the fifth cylinder testing the highest at 130. As we were doing the compression test we got to the 6th cylinder we noticed that that spark plug was also fouled but with oil. We have had a rough idle and husband noticed sweet smell coming out of the intake, we are burning coolant, jeep overheated about 20 minutes into driving when oil temp light came on , pulled over , depressurized and added water, we had not had problems with engine getting too hot previously. If the compression reading is over the 100 psi per Mopar , and at most a 10% difference between each cylinder, any ideas on what it could be? It has us beating our heads against a wall. For reference it is a Pentestar 3.6 L V6 any help would be appreciated!
Jmyrick97
You may not see any compression loss until the rings are shot. You may see some leak down or bubbles in the coolant. If there is coolant in the cylinder when you check compression, the compression will be higher. If you can look into the cylinder and see coolant, you found the culprit.
So it sounds like the typical very small head gasket leak (or small head crack, had one of those that opened up only when hot). Enough to foul plugs. When you shut off the Jeep, coolant will leak into the cylinder, then evaporates on the next startup (eventually fouls plugs). You can get lots of white smoke on startup, and even hydrolock. You should be able to detect combustion products in the coolant. When the engine is running, combustion gas is pushed into the coolant and gas is not as good a coolant as water, so it overheats.
So it sounds like the typical very small head gasket leak (or small head crack, had one of those that opened up only when hot). Enough to foul plugs. When you shut off the Jeep, coolant will leak into the cylinder, then evaporates on the next startup (eventually fouls plugs). You can get lots of white smoke on startup, and even hydrolock. You should be able to detect combustion products in the coolant. When the engine is running, combustion gas is pushed into the coolant and gas is not as good a coolant as water, so it overheats.
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