Is it even remotely possible to have exhaust fumes in a 4.0 XJ cabin caused by a cracked cylinder head or blown head gasket?

 

If your 2000 4.0 0331 cylinder head cracked where they tend to crack, no. I don't think that will cause exhaust to leak into the cabin. I wouldn't suspect a head gasket problem either.

I take it you have exhaust getting into the cabin? What will cause that is a leaking exhaust manifold gasket or a leaking exhaust pipe. I would suggest you first check the exhaust manifold. If you're certain that's not leaking, take your XJ to a good, local exhaust shop and have them inspect it. If the exhaust has a crack or a small leak, they can fix it easily and cheaply.

I do almost everything myself on my vehicles. Exhaust is one thing I refuse to mess with. Without a lift, it's at best a complete pain and at worst downright impossible.

** Don't delay. An exhaust leak is not something to mess around with. No kidding, it can make you sick or even kill you or anyone riding in your Jeep. **

 

Other than ex leaks, it could be something as simple as needing an extension on ex tip, or you may have holes in floor, etc, allowing oil vapors in.

Or, you may need a whole new exhaust.

 

Check the tailgate seal / fit.

 

Thanks for the advice guys. Smell only occurs when stationery and heater fan is blowing. As I have the dreaded cracked cylinder head with associated heating problems, was wondering if the two were linked. Head and header coming off and will have the exhaust looked at at the same time. On engine stop there is an audible hissing from behind the engine , round about where the head meets the block up against the firewall. Lasts for a few seconds, obviously is pressure of some sortand then stops. Initially thought it was a leaking injector but no evidence of fuel being spilled. New head going in along with head gaskets on Monday.

 

What cylinder head did you get? I installed a Clearwater head last month. It appears to be a very nice part and it's been running fine. I liked that it had all new valves.

I would suggest you buy a good quality gasket set and not go cheap. I like Felpro.

 

Got OEM gaskets from Jeep. Looked at importing both the Clearwater and Alabama heads into the UK but picked up a good 0331 TUPY head for less than the shipping cost for either.
BTW, is it necessary to change head bolts too?

 

If they've already been used once, they'll have a dab of paint on the tops. If that's the case, you'll want new ones. But they can be had for around $30 new so it's nice insurance to just put new ones on

 

New Gaskets? Already got those from Jeep - waiting to go in

 

or you might have meant bolts - probably bolts , yea I am a bit slow most of the time

 

Yep I meant bolts. I should have clarified!.

 

no worries, they have been ordered