'94 grand cherokee: need exh.manifold/header leak & oil smoking help !!!

[whitehorse]

I just bought and got a pretty good deal on a 94 jeep grand cherokee 4.0L 4x4 laredo. It had many issues of which a few I've already worked out. Now the ones that are still present is a exh. leak...I found a crack in the header/manifold which I sealed up w/ some exh. sealer/jb weld type of stuff. The leak is a lot quiter but still present, but I don't know where the remaining leak is ??...it sounds like it's right under the intake itself ! Also I changed the plugs and it's white smoking out the tailpipe a little bit.

The exh. leak isn't really loud, but noticeable and annoying...I just really don't wanna pull the intake/manifold ! I've heard it's a big job !?

How can I fix the smoking ? I'm thinking about jumping to some 20w50 oil and a few bottles of oil treatment may help ??

Thanks in advance for any help !

[tech_ed]

There is no real easy way to fix that exhaust leak.
1) if you have safety inspections in your state, the JBweld will not pass...and it probably is messing with the O2 sensor as well...
2) and considering that the only way to fix the remaining leak is to remove the exhause header, it's best to fix it the right way..

Here is the problem...Cherokees have a real bad problem about exhaust manifold cracks..check out http://www.nhtsa.dot.gov/ for any recalls on your jeep for exhaust cracks.
They had several voluntary recalls (meaning that the dealer can call you if they really feel like it)

Most likely, the existing leak is the exhause gasket on the last cylinder...this happens alot. In fact, it just happened to my '89 Wagoneer LTD...I had to replace the gasket...not a job for the weak or the unskilled!
To get the exhaust manifold, you have to remove the power steering pump, (put it out of the way) remove the fuel injection rail, disconnect everything connected to the intake manifold, remove the EGR tube on the exhaust manifold, disconnect the exhaust pipe, then unbolt all the bolts holding the intake and exhaust manifolds on...you see, they have to be removed as a unit! a royal pain! I found that the last bolt in the very back against the firewall almost impossible to remove...Once you get the intake an exhaust manifolds off, take the exhaust manifold to a machine shop and check that it is still true...sometimes they warp due to the heat. If it is still true, have them weld the broken seam. Then pick up a new gasket and the installation is the reverse of the removal (don't you hate it when the books say that? Installation is NEVER th reverse! It's always more difficult!)
One trick before you get everything bolted up! that EGR pipe? When you get the intake and exhaust put on the engine, and BEFORE you put on any of the bolts, connect this pipe first...you will never get it connected if you don't!

Well, I hope this gives you a little insite on what you will be needing to do!
On the flip side...my mechanic charges $500 to do what I just described...some charge more, so use my number as a reference only!
Ed
web/gadget guru

[whitehorse]

thanks!...anybody on the smoking prob., will thicker oil and some "motor honey" additive help any ??

[chrisewers]

anti smoking stuff rarely works. These motors have an almost bulletproof bottom end so whilst you are doing the exhaust manifold, change the head. You can see if it is the valve guides/stem seals:
1. is the inside of the valve cover black?
2. do a compression test (compression tester cheap) if adding oil down the plug hole does nothing to increase the compression on the lowest cylinders then valve guides/seals are the problem.