deli152

I need help figuring out what’s wrong with my jeep. I have 2008 JK with 120 miles.

What is leading me to believe it’s a head gasket:
• It’s throwing a p030 code. (Misfire on cylinder 3)
• There is also a lot of white smoke coming from exhaust after startup but goes away after 5 minutes.
• There is also a noticeable misfire and slight lack of power that continues even after smoke clears up.
• A small amount of bubbles on the dipstick.

There is not a significant drop in coolant level though.
Side note: it also has a super charger on it, which makes it very difficult to pull plugs, wires, and injectors for the simple checks. It would take me about 8 hours to pull the charger, swap injectors around, and then reinstall the injectors to see if that is the issue.

Also want to confirm which side the number three cylinder in on.
I’m going to start ripping into this thing tomorrow.

Any suggestions?

thanks!

Mark Doiron

That white exhaust smoke may be coolant. Does it feel damp? Is coolant level dropping over time? #3 is center on passenger side. Suggest run a compression check on it. Hopefully it is just a bad gasket, but could be cracked head. If you pull head, probably a good idea to have a machine shop check it and mill it flat--reduces chance of replacement gasket failing sooner than it should.

deli152

I ran a pressure test on the cooling system and lost about 3lbs over two hours. I need to do some research and find out what the norm is.

Am I able to turn the motor over and test compression and/or spark without any sort of intake on it?

Mark Doiron

You want to test the engine when it is warm (ensuring oil is contributing to the compression results), so I'd so no to the intake off. Here is a general procedure for testing engine compression. It's important that you disable the engine and fuel flow before attempting to test compression. According to my 2007 owner's manual, fuse M25 is for the fuel pump. Suggest that you double-check that since you don't want to pump fuel into the cylinders during this test. Next start could cause a big bang and damage some of the exhaust system components!

How to Check an Engine's Cylinder Compression

deli152

Mark, thanks for the input.
Unfortunalty I'm unable to test the compression with the engine warm. I can't get to the plugs on that side due to the super charger covering them.

I did run a block leak test today and it didn't seem to pick up any vapor from the radiator.
The other thing to consider is the white smoke goes away after 5 minutes.