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post #1 of (permalink) Old 06-19-2002, 02:54 PM Thread Starter
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Intake Manifold leak, how hard to do myself?

My 84 CJ7 (258) is running like crap (backfiring, low power, no idle at stop, etc.) due to a leak in the intake manifold I am told. The local 4x4 shop wants $250 to do the gasket job. Sounds too high for what appears like a minor job even for a backyard mechanic like me. The shop guys tells me that the real problem comes in when they start breaking the bolts off when removing the manifold. He said they are often frozen in place due to the heat. Is this accurate? Is this a tough job? Are there any good tips/tricks for doing this myself? I would hate to have all the bolts off but one and shear the head off with my huge wrench. I am somewhat mechanically capable but do not want to get in over my head.

Any advice or comments would be welcome.

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post #2 of (permalink) Old 06-19-2002, 03:08 PM
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Re: Intake Manifold leak, how hard to do myself?

$250 for an intake/exhaust manifold gasket change !?!?!?!?!? tell them to get bent. it will be easier with another set of hands, but its not hard at all. go out the night before you are going to do it and hit the bolts with a penetrating lube. get up the next morning and crank em off. i've done a few on older (70's) cj's and not had any problems with bolts sticking too bad. if you want to be safe have a drill and an easy out handy. make sure that you label anything you disconnect since you probably have emissions crap on it (save you a bit of time trying to figure out where stuff goes). but no its not that hard and that is why i dont go to mechanics (might call a few and solicit free advice, but thats about it). good luck and have fun :-)

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post #3 of (permalink) Old 06-19-2002, 03:19 PM
 
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Re: Intake Manifold leak, how hard to do myself?

I second the suggestion to tell them to go get bent!!!! Geez! 250??!! He's right, it is very easy to do. When I did my MPI install my intake came off with no problems at all. Heck, the new manifold came loose after 2 years and I had to retorque the bolts.
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post #4 of (permalink) Old 06-19-2002, 04:06 PM
 
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Re: Intake Manifold leak, how hard to do myself?

Find someone on the BBS that knows what they are doing that lives close to you, and buy the beer and steaks!

$25 worth of beer and steaks, and $25 worth of gaskets and sealer, you make a friend & wheeling buddy and you have a war story to tell when you are done!
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post #5 of (permalink) Old 06-19-2002, 04:26 PM
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Re: Intake Manifold leak, how hard to do myself?

$250 does seem high if there are no problems. The job's not hard to do, it's just time consuming and you've got to be patient... patient enough for the penetrant to do it work. I'd be soaking the manifold bolts/studs for 2 days with PB Blaster before I attempted to do the job.

There is one other little problem... and that's that exhaust manifolds warp at the drop of a hat. So, take the manifold off the engine when it's stone cold and you'll have a better chance of it not warping. It's not a bad idea to take the manifold to a machinest and have the machinest mill the face of the manifold and make sure the runners haven't warped.

I like to use Permatex Orange sealant on boths side of the Felpro gasket. This helps to seal. When you re-install the manifold use new studs, bolts, nuts and washers. There's nothing more disheartening than getting to that last bolt and having it snap. I torque the manifold down in about three steps, drive the Jeep for a hundred or so miles and retorque the manifold.
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post #6 of (permalink) Old 06-22-2002, 05:16 AM
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Re: Intake Manifold leak, how hard to do myself?

Here are comments from my learning experience --- the vacuum hoses had to be replaced - many miles of them . The removal of the approx 12 intake / exhaust manifold bolts was tricky due to the geometry of the intake / exhaust manifold combined with the myriad of other components which blocked straight easy access to the bolts . When you retorque the bolts , I concur with the previously mentioned advice of using a slow , steplike technique . There is a specific torqueing pattern to follow which starts in the middle and radiates outward. I applied antiseize compound to all the bolts. The toughest part was reassembling the EGR tube onto the exhaust manifold -- you may not have to do this step as I was replacing the exhaust manifold . I noticed that there was more than one gasket set available . The one which I used included both a metallic -style gasket and a traditional black material gasket . I was afraid to use both as it might be too thick in some places and cause excessive torqueing / warping . I opted to use just the single metalliic gasket . It seems successful. Penetrating oil the day before is a great idea.
post #7 of (permalink) Old 06-22-2002, 02:13 PM
 
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Re: Intake Manifold leak, how hard to do myself?

I am in the middle of the procedure you just described. I am reassembling the intake/exhaust now. Label all the hoses and wires, use penetrating oil liberally before attempting to remove the exhaust bolts, days before, if possible.
The bolts on the inside of the runners take an articulating adapter for a socket. Mine came right out.
I should have mine running tomorrow. Good Luck.
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post #8 of (permalink) Old 06-28-2002, 02:07 AM
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Re: Intake Manifold leak, how hard to do myself?

i'm starting the same project right now. but i'm throwing on a borla header. already snapped one bolt(the one farthest foward) on a previous attempt to fix a leak. haven't tapped the sucker out yet. any other advice on what not to do?

90yj 258w/weber
borla/pacesetter exhaust
4"+1" on 33's
post #9 of (permalink) Old 06-28-2002, 08:35 AM
 
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Re: Intake Manifold leak, how hard to do myself?

When wrenching, always do your best to apply counter torque to the head of the wrench... in other words, if at all possible, put one hand on the wrench handle and another on the socket wrench head or wrench head. Push and pull with both hands at the same time.

The idea here is that you want to do as much as you can to eliminate any force on the bolt that is not a twisting force (torque) centered on the axis of the bolt. When you pull with just one hand at the handle on the wrench, you are applying a tremendous amount of shearing force to the bolt as well as twisting force (torque - what you want).

Some bolts are all but impossible to do this with due to their location and others will shear even with proper counter torque applied due to them being brittle from heat cycling. Header bolts are some of the worst for this. Keep in mind that any time you use a universal joint or swivel to get a socket on the bolt head, you are complicating the torque path, reducing the effective torque you are applying to the bolt, and probably not going to be able to avoid applying some shear force in the process. Don't try to overcompensate for the complicated angle. Always be pushing and pulling in directly opposite directions.

Remember, you only want to pull on the wrench head enough to eliminate the shearing force. You want the torque to be centered on the axis of the bolt.

You may already be doing this, but just one more thing I thought should be mentioned when talking about shearing off header bolts. The rear-most stud on my 258 was sheared off inside the head when I bought it. If there are any that I would recommend being extra careful with, it's that one. With the firewall right there, it was a real PITFA to get a drill square to the head.

Good luck.

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post #10 of (permalink) Old 06-28-2002, 09:55 AM
 
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Re: Intake Manifold leak, how hard to do myself?

the best rusty bolt be gone spray i know of is 'pb blaster' works miracles on rusty and frozen nuts and bolts. look for it in pepboys or napa. some smaller parts stores should have it too
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