Topic: Exhaust manifold bolt size for 2.5L I-4 in '98 Wrangler

[KS98TJ]

Hey all,

An interesting thing happened yesterday afternoon. As I was driving to my aunt's house, I heard a "dink" and a knock that sounded like I'd run over a rock or some gravel. I didn't see any debris in the roadway. I remember looking in the rearview mirror.

OK. Fast forward to later in the evening after a nice dinner with my parents and relatives. I go to start 'er up and drive home. I hear what sounds like an exhaust manifold leak. Well, it goes away shortly thereafter (< 1/4 mile) and I make it home fine. It does it again this morning. At lunch, I poke around and find that the rearmost exhaust manifold bolt is missing. Aha! So that was the "mystery noise".

So, now I need to know what size exhaust manifold bolts are used on the 2.5L I-4 in a '98 Wrangler. I seem to recall the old AMC motors used a 5/16" dia. like the small block Chevy's. But, I don't know the length and want to be sure about the diameter, too. My 350 SBC in the Suburban uses three different lengths of bolts! You'd think they'd keep it simple...

Anyway, thanks for any info you could provide.

[Jeffy]

Hey all,

An interesting thing happened yesterday afternoon. As I was driving to my aunt's house, I heard a "dink" and a knock that sounded like I'd run over a rock or some gravel. I didn't see any debris in the roadway. I remember looking in the rearview mirror.

OK. Fast forward to later in the evening after a nice dinner with my parents and relatives. I go to start 'er up and drive home. I hear what sounds like an exhaust manifold leak. Well, it goes away shortly thereafter (< 1/4 mile) and I make it home fine. It does it again this morning. At lunch, I poke around and find that the rearmost exhaust manifold bolt is missing. Aha! So that was the "mystery noise".

So, now I need to know what size exhaust manifold bolts are used on the 2.5L I-4 in a '98 Wrangler. I seem to recall the old AMC motors used a 5/16" dia. like the small block Chevy's. But, I don't know the length and want to be sure about the diameter, too. My 350 SBC in the Suburban uses three different lengths of bolts! You'd think they'd keep it simple...

Anyway, thanks for any info you could provide.

Most likely it was either the front most or the rear most bolt missing.  If that's the case then it's more likely that the stud broke and the rest of the stud is still in there.  There is a part number in the FAQ.

[KS98TJ]

Thanks, Jeff.  Unfortunately, the stud broke flush with the block.  I think I'm going to end up paying someone to have this one fixed.  At least my uncle's been a certified mechanic for 30+ years and can recommend a good outift.  :?   I'd rather just suck it up than spend a couple of weekends cursing the engine-  been there, done that a couple of times...

[Bounty Hunter]

The stealership will fix it for free under the 8yr80k federal emissions warranty, got lucky and caught my '95 in time.  There is also a TSB issued for this problem.

[KS98TJ]

Yeah, I'm SOL on that account.  I had the cat replaced under the 8/80, but I now have 105K on 'er and she was built in July of '97 (early '98 model).

I may tackle it yet, but if I do, it'll be a bear.  Right-angle drilling, etc.  Ugh...

I'd rather farm it out, but not at an astronomical price.

[Jeffy]

Yeah, I'm SOL on that account.  I had the cat replaced under the 8/80, but I now have 105K on 'er and she was built in July of '97 (early '98 model).

I may tackle it yet, but if I do, it'll be a bear.  Right-angle drilling, etc.  Ugh...

I'd rather farm it out, but not at an astronomical price.

If you do it yourself start off with the simple stuff then work your way up.  It might come out with a punch and hammer.  If not then try a screw out or reverse drill, etc. (I don't recommend EZouts)

[keithert]

I've got the same issue.  If you have yours done let me know how much it cost?  The noise on mine also goes away in about 1/4 mile.  I'm tempted to leave it alone since it does go away.  Is there a danger in doing this?  I've heard you can get a burnt valve with an exhaust leak.  How serious is a burnt valve?  Can it be fixed with just a valve job or could it actually hurt the engine?

[lanulos89]

wooo wait a second u mean to tell me i could've had the stealership fix mine instead of hassling with it.  **** i recommend, either reverse drill bit, noting else if it doesn't come out don't force it.  I tried the frigging punch idea, and the punch broke off inside the stud, so then i went and smoked like 4 drill bits trying to get the hardened steel punch out, loads of fun.  I finished it in under half a day, wasn't too hard.  i recommend not using the jeep oem gasket, but going to an auto parts store, and getting theres, jeep sold me one that only too care of the intake manifold, and not the exhaust manifold.  also get some ultra copper in the tube, and spread it all round the gasket, well thats just my 2 cents.