I know what everyone is thinking two scenarios, intake manifold gasket or head gasket. It's a 2007 Jeep grand Cherokee 4.8 V8 so there's no oil in antifreeze no antifreeze in oil was throwing code for bad cyl 4 replaced all plugs and coil for 4, no antifreeze in plugs either. While sat overnight entire reservoir went empty. After replacing ran great two days then check engine came back on, took it to dealership for compression test their best guess was water pump. Based on a small amount near it. My question is now it's still misfiring went to take my son to school this morning white smoke A Lot shut it off wouldn't start. Waited a few minutes and it started up. So could it pass a compression test and still have something wrong with either gasket?

 

Did the dealership also do a coolant pressure test?

If its true that you're loosing coolant and smell coolant in the exhaust, then coolant is leaking somewhere into a combustion chamber(s) where it shouldn't be.

Just looking at the spark plug may or may not tell the tale.
I'd think if coolant is leaking in one or more combustion chambers, yeah it could pass a compression test with flying colors.

If you really smell coolant in the exhaust, then forget the water pump as the root cause.

 

Well it's official now pretty sure it's the intake manifold gasket, went out earlier today after making this post and checked the fluids, milky freaking oil! And check engine light on, my dad is bringing code reader over tomorrow if the code it's throwing is still for misfire then I'm pretty sure that's where the leak is. Maybe the pressure test blew it the rest of the way. Thanks for the reply.

 

Don't overlook the head gasket!

 

Yup I know just really hoping it's not the head gasket .going to take the manifold off this weekend and check it.

 

Sounds like head gasket....