Upgrades for header and rear main seal?

Hi folks, I just bought my first XJ two hours ago! Glad to find such a vibrant community here. I bought a '94 4-door Sport with the 4.0L and like every Jeep 4.0L I've ever seen, it's got a cracked header and a leaking rear main seal. I'm going to replace both of these in the next week. I know what I'm doing with a wrench and don't need any help with that part of it, but I would like to pick your brains about whether there are any upgraded parts I should look into that'll keep me from having to do this again for a while.

Does anyone make a rear main seal that lasts longer than the OEM part?

What's a decent, long lasting aftermarket header that won't break the bank?

Thanks!

Since you've got a 1994, you've got plenty of options. I hear good things about Banks and Borla, with Pacesetter also doing well. Mixed reviews on APN - some love it, some hate it, and it seems about even either way.

I've been installing Fel-Pro rear mains without difficulty - just be sure to soak the thing in clean oil for a while before you put it in, and make sure there isn't a groove worn into the crankshaft sealing surface. You will, however, want to get the later oil sump gasket (1996-up,) as it is one-piece moulded rubber and will save you loads of wrestling with the thing. While you're at the parts house, pick up a set of SBChevvy valve cover studs, and install about four of them in the small screw holes - near each end. DO NOT put any in the bottom of the timing cover!

Why do this? Because it allows you to line everything up, set it in place, and hold it with one hand while you start nuts (loosely!) on the studs with the other. Then, install screws (loosely!) until you get them all in place, then tighten (torque specs are on my site, but I think it's 84 pound-inches/7 pound-feet for the 1/4" screws, and 132 pound-inches/11 pound-feet for the 5/16" ones at the corners. It's easy to crush that gasket - so use a torque wrench!)

You can do the job in a day easily, even with the transmission in place (if you've not got it lifted yet, unbolting the transmission mount from the crossmember and lifting the tailend of the drivetrain with a floor jack will help you get clearance to get the oil pan off past the axle. Also, support the front end on stands, allowing the axle to droop as far as it will go. If you've got at least a 3" suspension lift, you can remove the pan with all four wheels on the ground - I've done it both ways.)

If you like, you can get a double-lip seal from Fel-Pro, but it's not really necessary (unless there's a small groove worn in the crankshaft surface. There is also a repair sleeve available - but that requires removing the crankshaft, and it's probably more work than you're planning on doing. The double-lip seal installs the same way as the OEM single-lip, but spreads the sealing load and offsets the sealing surface slightly. You'll probably have to order that one, tho.)

There's a link to my site in my sig - you'll want to start out with the Tech Archives - since that's where I've been putting tech information.

Welcome aboard!

Doug Thorley headers, ceramic coated...the poop.

Thanks for the advice, all. I think on price alone I'll go with the APN header. I'm not building a hot rod, just trying to maintain this new Jeep and keep it reliable. I'm going to find out if anyone in town has the double lip seal in stock and if not I'll just go with the standard rear main. Nashville is home to a few giant distributors of auto parts for the Southeast so I can probably find what I need locally.

Thanks again!

The stock header is actually not bad, and if you replace the engine mounts with some stronger ones you will likely have no more header cracks. I welded my stock header and installed some MORE engine mounts and have had no more problems with mine. I hadn't heard about the double lip seal, that sounds like a really good option.

jeeperjohn said:

The stock header is actually not bad, and if you replace the engine mounts with some stronger ones you will likely have no more header cracks. I welded my stock header and installed some MORE engine mounts and have had no more problems with mine. I hadn't heard about the double lip seal, that sounds like a really good option.

Click to expand...

Yeah, after doing some more reading I will probably go ahead and replace the motor mounts while I'm at it. Still think I'll buy an APN header. They're not much more expensive than stock and I might as well give it a try.

When you do the header, BE SURE TO HAVE THEM PUT A FLEX COUPLER SOMEWHERE BETWEEN THE COLLECTOR AND TRANNY MOUNT. That will get rid off all your cracked header problems. The 4.0 torque flexes too much to have a rigid exhaust, so you put a flex coupler in it and it allows the flex without cracking headers.

brandonvalentine said:

it's got a cracked header and a leaking rear main seal.

Click to expand...

LOL. My 87 was the same when I bought it.

i replaced my cracked header and worn engine mounts with an APN header and MORE engine mounts back in november. the swaps were realy easy. the apn appeared to be of good quality and a lot less $$ than banks and simlar. if your header is cracked, then almost always the motor mount on that side is crapped out. replace it or you WILL get another cracked header. the MORE mounts have a great reputation.

hth
stewie