New Exhaust Manifold?

[SuperWade2]

Any suggestions for buying a new one... I don't know exactly knew where or how bad mine is cracked/broken, but I'm 99.99% sure that it is (I had a bad one in my TJ and it's the same symptoms), and has been for a while, and likely quite severely.

 

4.0L Manifolds on Ebay are about $100-$115 (not sure of differences), RockAuto wants closer to $200...

 

How hard of a job is replacing it? Require welding (I don't have a welder)... should I pay a shop a couple hours of labor to do it?

 

Thanks

Wade

[Motion Offroad]

If you weld the factory OEM one it will just crack again in a different space. In my opinion it's not worth the hassle to have it welded just to have to yank it back off down the road again.

[dasbulliwagen]

Welding is not required to replace a factory manifold setup. Thing is the intake manifold has to be removed at the same time, and any possible stud breakages replaced too. If you pay a shop it will likely be more than a couple hours, I would think, especially if you need any studs. If you have a fair bit of technical expertise, you should be able to do it yourself no problem. If youre in a salted road area though the exhaust studs at the manifold exit will be a huge pain in the arse. Youd probably need to cut them off or break them off and hope the new manifold comes with new ones, once the old one is out, the new one will go in easy. the hard part being keeping the intake and exhaust manifolds in place while you try to tighten the bolts up. Good luck.

[Unglar]

I replaced a stock manifold that was cracked with another stock manifold. There were 2 bolts that I could not access through the gaps and had to reach up from underneath with a box end wrench, major pita. I have seen on some of the builds in this forum non-stock manifolds that have smaller pipes and thus larger gaps for easier access to the mounting bolts. I would suggest one of these manifolds if your gonna DIY.

[kastein]

pulling the air filter housing out makes it wayyyy easier, you can reach in from the front left corner then with a few extensions and a U-joint. I like to use 1/2" drive sockets and a 1/2" ratchet because I have more control of how much torque I am applying when I am not pulling as hard on the handle.

 

Use 14mm sockets, for the two studs in the collector flange I like to use a Dremel (fits quite nicely down in there once you have removed the air filter housing!) to cut 1/2 to 3/4 of the way through the studs, then use a few extensions and a 14mm socket from below to try and remove the nuts on the studs. They snap in half every time, way better than rounding the stupid rusty things off and then trying to cut them all the way in half with those tiny cutting wheels.

 

They are some metric size, I want to say 8mm but not sure of thread pitch, and if you can't find nuts that fit locally you can knock the studs out, tack weld in a couple 1.5" or 2" (I forget) 5/16 bolts, and use 5/16 hardware.

[SuperWade2]

I was quoted 4 hours of labor at one of my local shops... I don't even know what he's charging now a days, but I'm guessing $90-$100/hr.

 

Might be better off trying to get some wrenching help from guys from my club to help.

[fiatslug87]

I'm in the process of replacing the 280K+ engine in my '88 with an 110K '89 and was going to buy a new exhaust manifold. I have this same question about what manifold to purchase for replacement, all help is appreciated.

 

Good luck Wade.

[SuperWade2]

I never really got a good answer to my question about "Which new replacement manifold should I buy?"

 

The MJ hasn't moved in weeks...partially because I don't like the looks I get when people hear it "chugging" down the road and partially cause I've been driving the TJ topless since the weather has been nice.

 

Now that Winter is approaching, I'd like to get this replaced so I can put the miles on the MJ instead...

 

Thanks

Wade

[KYMJ]

I've replaced 4 manifolds on 4 JEEPS with the e-bay manifolds. All are still going. 2 Renix and 2 later models. The Renix has the PIA crossover pipe, 1 was no problem, the other didn't want to line up right. You can easily do this in 4 hrs or less. Remove the air box, so you can get your arm in there close. You'll need a good assortment of extensions and a u-joint. You'll use a different assortment of ext. for each bolt. I'm used to doing this kind of work ,however, been turning wrenches a long time. Do not take the fuel rail apart, I believe the manual calls for it. It is manageable without doing so. Good luck. I meant to reply to this weeks ago, and just forgot. You can do it. Wish I was close, I'd help. I like helping people save money on car repairs. Walked a guy through a water pump exchange today. Could have done it with my eyes closed, he just didn't have any experience, he was quite happy. :cheers:

[sinkrun]

I have bought them from advance around $200.00 and from ebay around $100.00. There the same exact thing so go for the ebay one just pick a seller with a good feedback and check several sellers the price on ebay can vary quite a bit.

[SuperWade2]

Looks like only 3 options for the RENIX

 

$102

http://cgi.ebay.com/ebaymotors/1989-89-Jeep-Cherokee-4-0-Tubular-Exhaust-Manifold-4-0L-_W0QQcmdZViewItemQQhashZitem35aca521f1QQitemZ230529769969QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_2249wt_1165

 

or

 

$115

http://cgi.ebay.com/ebaymotors/1989-89-Jeep-Cherokee-4-0-Tubular-Exhaust-Manifold-4-0L-_W0QQcmdZViewItemQQhashZitem483cd14f7bQQitemZ310257995643QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_1554wt_1165

 

or

 

$130

http://cgi.ebay.com/ebaymotors/JEEP-CHEROKEE-COMANCHE-4-0-87-90-EXHAUST-MANIFOLD-NEW-_W0QQcmdZViewItemQQhashZitem5195776554QQitemZ350399980884QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_1702wt_1165

[sinkrun]

Its been a while since I bought mine I am thinking it was the $115.00 one there may have not been a cheaper one at the time. I really would bet there all the same but if unsure I would go for the middle one. Good luck and sorry i can't help much with info on replacing it as all the ones I did were on the hoist when the engine was out the others I paid a friend to do.

[deziped]

I got two off of ebay. About $110 if I remember correctly. No matter what you get put a straight edge across the flanges from end to end to make sure their aligned. Do any straightening if needed before you start bolting it in. Basically everything said above is right on for installing it. I did shoot PB Blaster on all the nuts 2 days before I started and again the day before, everything came loose fairly easy, no broken bolts. Also i left the fuel rail attached and just lifted the intake manifold as far as I could up on the valve cover and wired it out of the way. Also check (Measure & test fit the EGR valve cross over pipe) to make sure its gonna go together alright once the manifolds are bolted up. Run it a couple weeks and then retorque the nuts/studs. Good luck.

[TrailReadyMJ]

One thing I would like to add about this is to check your motor mounts before/while you replace the manifold!

 

These manifolds like to develop cracks, but a bad motor mount is the most common cause I have personally ran into (next to submerging them in water when hot). The bad mount creates a lot more movement of the engine, thus pulling back and fourth on the manifold. Since the exhaust is more or less holding it in place, this eventually creates cracking on the manifold, usually on the back tube.

 

In general, if a non-moving part goes bad, there is usually another reason for it.

 

Just something to lookout for.

[EBasil]

I replaced my second cracked OEM exhaust manifold with a Borla, stainless steel tube header. It's got a CARB placard on it and it's been fine. Little louder, little more power, no more cracks.

[sinkrun]

Motion Off road just posted in the for sale for $400.00 hedaers new for half off now $200.00 you may want to look into this.

[SuperWade2]

Motion Off road just posted in the for sale for $400.00 hedaers new for half off now $200.00 you may want to look into this.

 

I'm kind of dumb but what does "headers" replace, the exhaust manifold and then ???

[fiatslug87]

Has anyone used the Blackjack headers? How was the install on stock RENIX exhaust system, and modifications required?

[TrailReadyMJ]

I'm kind of dumb but what does "headers" replace, the exhaust manifold and then ???

 

Header = exhaust manifold. In fact the term header is more correct in our application, the stock exhaust uses a header.

 

A "header" is a tubular exhaust manifold. A standard "manifold" is cast, and usually more of a log shape with less flow.

[SuperWade2]

Has anyone used the Blackjack headers? How was the install on stock RENIX exhaust system, and modifications required?

 

You gettin' one FS87?

 

I'm not sure I want to spend $200 ... the rest of my engine is so tired that I don't want to sink too much money into it until it blows up. I guess I could likely move new headers over if I did a rebuild or a swap with another Renix eventually.

 

I drove the MJ to work today and remember why I hadn't in a while... I just runs SOOOO poorly (and the sound...OMG it's bad)... If I wasn't loading up the TJ for a Wheeling Trip to Swamp Lake this weekend, the MJ would probably still be sitting on the street being sad.

[fiatslug87]

Yeah, I just ordered one at lunch today and it's already shipped . I was going to buy the e-Bay option #2 but thought what the heck I'll splurge. The engine I'm putting in looks immaculate (valve train and bottom end), I will rebuild the original and eventually put it back (got to keep it numbers matching :nuts: :rotf: ) and reuse this header.

 

Here are some pics of the replacement engine (thanks to a fellow CC member), just pulled the valve cover and oil pan, nothing cleaned up.

 

 

[TrailReadyMJ]

:hijack:

 

The engine I'm putting in looks immaculate (valve train and bottom end)

 

That is clean! Nice! :cheers: