lurk520

I have an 02 grand cherokee. Now either my manifold or gasket is leaking, noisy when cold. I was wondering what is the manifold made of? Aluminum? There is a spot of black carbon on top the manifold by the throttle body. Are these manifolds prone to cracking on the top? Is it most likely the gasket?

dave1123

I don't understand your question. The intake manifold is made of aluminum, but isn't connected to the exhaust manifold in any way that I'm aware of.

Older carburated cars needed heat to warm the carb and open the choke, but injected cars don't. That's what all that fancy computer stuff is for.

The carbon spot on your manifold might be from a leaking throttle body base gasket.

lurk520

I forgot to mention its a 4.0. Maybe you're not familiar with it, its a one piece manifold for both.

dave1123

I owned a 97 4.0 and I know for a fact they are two pieces. I had to replace a cracked exhaust manifold on it. I now own a 2000 4.0 and I really haven't gotten into it yet, but the exhaust is now two pieces, but aren't connected to the intake manifold. The intake and exhaust are mounted with the same bolts, but are separate units.

Now you're going to make me go out and open the hood, aren't you?

lurk520

The newer ones are two piece, I don't believe mine is two pieces.

lurk520

Lol, mine is two piece, maybe I'm not familiar with it or blind. I just know something up top is leaking when its cold, sounds like exhaust leak.

lurk520

So your 97 was a two piece and it still cracked?

lurk520

Or maybe it just sounds like up top. Who knows.

dave1123

You probably have a blown gasket or a loose manifold. If it's quiet when warm, you may be able to save it by torquing the bolts, otherwise you'll have to replace the gasket and let me tell you, that is a PITA! The lower bolts are really tough to get to. My 97 seemed to have more room than my 2000 does, probably because of the redesigned intake.

We're talking about 3 pieces, the intake and two exhaust manifolds. My 97 had a one piece exhaust manifold and it cracked where the two pipes joined the collector flange just before the exhaust pipe. The later exhaust systems used 2 manifolds to eliminate this cracking. All these parts mount to the engine with one gasket.

lurk520

Yeah I can't see much of it, being underneath the intake. Don't think I'm gonna try to tackle this one myself.

lurk520

4.2 hours labor is what the shop calls for. So roughly $400 dollars. Gasket is $20, manifolds $250 a piece. If anyone was curious.

dave1123

Everything on top is pretty easy. It's the bottom bolts that are the killer. I had to do mine from underneath the jeep. The hardest part was torquing the bolts in the proper order, getting up and down many times. They are like head bolts. If not done in the proper order, you won't get a good seal. With mine, that last bolt near the firewall was the worst. I had to use a box wrench and guess about the torque.

I you can afford it, get professional help.

lurk520

And if the Pro's don't get it right the first time....They get to take it apart again instead of me
Not thrilled about paying some one else for labor but, I've already done 2 window regulators, a radiator and a hub bearing assembly on this thing, and they were not fun tasks at all!

dave1123

Tell me about it! I'm 68 years old and have been working on cars since I was 16. I'm just not physically capable of doing a lot of things I did when I was younger. I used to be able to pick up a Chevy short block and walk away with it. Now, just lifting a tire to put it on is a hassle. Plus, I use my Jeep to make a living, so time is critical. I have a man I trust that only charges $40/hr and allows me to buy my own parts. He says he's pretty well off and only keeps the shop open so he has something to do. His yard is so full of customer's cars it's sometimes hard to get into the lot! He's got a small 2 bay operation back in the trees with no sign on the road, but he never lacks for work. AND he's honest. My kind of man!

If I didn't have him, I'd still be laying on my back on a blanket in my driveway.

BTW, I hope when you did your hub bearing, you did both. Otherwise, you'll be doing the other one soon.

lurk520

I couldn't imagine doing these PITA jobs at 68! I'm a little less than half that age. $40/Hr is a pretty awesome deal. When I saw how ratty the hub assembly was I wanted to do the other side but it cost me $100 just for one, I'm trying not to throw cheap stuff on this vehicle because I'm probably gonna be stuck with it for a while. The reason I changed it was because it was squeaking after I drove through the monsoon flooded streets, must of got some water in the bearings.