2000 Sport 4.0 Manual

Hey guys, bought this truck a year ago but have driven it less than 100 miles as I suspected an exhaust leak due to some smoke coming from the back of the block. Planned on pulling the exhaust manifold to check for cracks. Pulled them off today and the intake manifold is disgusting inside. See photos below. Instead of a gasket there were two shims which had been welded together from the heat.. Anyone seen one of these used before? No gasket material.

Anyway, is this engine a lost cause? I have not pulled manifolds before so I'm not sure what they are supposed to look like inside. Does the dirty-ness indicate a cracked head or could it be something else? The mating surface on back end of the exhaust manifold was pretty wet with what seems like engine oil when I pulled it off. If I can conclude for sure that this head is cracked I would consider doing the Tupy replacement. The XJ has just 141k on the clock.

 

I would say your valve cover gasket is leaking and that is where all the oil is coming from. The burning you had was oil leaking out and burning on the exhaust. And that was the correct gasket for the intake and exhaust manifold. There normally two pieces of metal like that.

 

Actually, that is pretty clean compared to what mine looked like when I tore it down to rebuild it. And mine was low mileage.

 

Are your fuel injectors leaking? It looks like gas that is running from the top of the manifold down. If so you should replace them before your car catches on fire.

If it was a cracked head you would be more likely to have oil in your antifreeze / water in your oil. Other symptoms of a cracked head would include a drop in oil pressure, or a loss of coolant. The lack of grease build up on the block keeps me from thinking that it's a valve cover gasket, but it wouldn't hurt to replace it while you're in there.

 

1) the 2 shims welded together are whats known as a multi-layer steel (MLS) gasket. common practice in the automotive industry since the mid-late 90s

2) the oil you’re seeing is most likely from the positive crankcase ventilation (pcv) system on your engine. the pcv system uses vacuum created by the engine to draw vapors from the crank case into the intake manifold to be sucked down into the combustion chamber to be burnt clean, often resulting in the oil mess you see. it’s normal. clean everything up and check your pcv valve. be careful, they are brittle and break very easily.

 

I have wondered if a changeable filter of some sort could be added to the PCV system to capture some of this so it doesn't build up as fast in the intake and valve ports.

 

..known as “catch cans”.

edit: there is a lot of info on catch cans. not a filter but simply a can one empties after it fills up with oil.

 

Yes, for the oil, I have one on my bug. But I mean with a filter medium that would catch all the atomized vapors that end up cooked as carbon in there. Mine was a fairly low mileage rebuild and I had to clean out about a 1/4 inch of hardened carbon from the manifold and intake ports. I got to thinking that is a lot for so few miles and maybe some of that build up could be slowed down with an actual filter of some sort.

 

use of a catch can will, or should, greatly cut down the grime. ive used them for damn near 20 years on lsx engines and they made a huge difference. i can’t see an actual filter being useful bc it would require constant maintenance and monitoring.

edit: when i pulled the manifold off my xj at 135k miles (and 17 years of age) it wasn’t bad at all. nothing like that lsx junk haha

 

Sounds like tried and true experience with these then. I will have to look at adding one if it did make quite a bit of difference. Thank You!

 

Thanks for the info guys, very helpful. Should the MLS gasket have RTV on it when I reinstall?

 

There is no PCV valve in a 4.0. It uses a CCV (Constant Crankcase Ventilation) system rather than a PCV system. The crankcase constantly vents and has an orifice at the back of the valve cover rather than a vacuum-operated check valve like a PCV system does.

 

no rtv. clean it up and inspect closely for damage. they’re very durable, they can be reused indefinitely assuming they incur no real damage.

 

while we’re correcting each other, there is an orifice located at the front of the valve cover, as well.

 

I'm aware of that, but the metering orifice at the back of the valve cover is where a PCV valve would be located in the system if it were a PCV system. That's why I stated "...rather than..."

I was correcting the PCV statement to save the OP (and anyone else reading this in the future) from looking for a PCV valve when he doesn't have one.