Exhaust Manifold Stud Replacement Questions

As the title states i have some questions about replacing one of the exhaust manifold studs.

A bit of history first:
1990 I6 (RENIX) 187,000
I have been experiencing a problem with low idle. It only happens after the vehicle is started. It doesnt matter if the vehicle is hot or cold. It will always happen after the vehicle is started. The RPM's go down to the first line or below on the guage for about 5 seconds then idle resumes normally. It does this for about 5 minutes then goes away. The jeep never dies (amazingly), but you can tell that its barely running.
After reading on here about how to fix idle problems (i had a high idle problem in the past) i concluded that this particular problem was caused by my manifold bolts coming loose. I was able to get some of them tight again, but i had to wait for awhile to get at a couple of them so that i could get a ratcheting box wrench (or known to some as a ring spanner). I got one the other day, and i was able to get the rest tight except for the one closest to the firewall which turns out to be a stud with a bolt. When i would tighten this one, it would feel as though it was getting tighter then get loose again. Pretty abvious the stud is broken.
So now i know that i need to remove the stud and replace all the bolts / studs and nuts with new hardware (after reading even more usefull information here).

Here are my questions:

1: ) When doing this job, should i also replace the exhaust manifold if it does not have any cracks in it? Since a part of the manifold was not tightened well, could this cause it to warp? Or should it be fine to re-use. If not then would this be a good replacement:?
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=021&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=310000335622&rd=1

2: ) If i can get to the stud and remove it (which i doubt ill be able to do) without removing the head, should i go ahead and remove the head and replace the head gasket since ive got it torn down this far anyway? The head gasket has no problems right now, but it has never been replaced (from what i can tell).

2.5: ) If you say i should go ahead and replace the head gasket at the same time would it not be a bad idea to also replace the lifters and pushrods?

(BTW Im definetely replacing the injectors at this time)

Thanks for the help!

1) You may not need to replace the manifold - especially if it's not cracked. The OEM studs have an "external torx" wrenching head - E8 or E10, as I recall. Often, those studs may be removed without removing the manifold - just pull the nut off and wrench the thing out. However, if you've been having this trouble for a while, you've probably "burned through" the gasket near there, and you'll want to replace it anyhow.

2) OEM studs don't cost much (as I recall - I used them once,) but they may also be cut from threaded rod. The strain on them is not great. You can use steel threaded rod, but I prefer brass (since it won't "heat-seize" like the steel stuff does. For the same reason, I'll use a copper-based alloy for the screws, usually silicon bronze. Call Fastenal, I've not started assembling kits yet.)

3) When replacing the manifold gasket, I find that a thin, even layer of RTV copper on both sides doesn't go amiss. It will help by holding the gasket in place, it will help in case the sealing surface is not perfect, and it will help if the screws loosen (which is more common than you think.)

4) If you can't get LocTite #272 (or equivalent,) don't bother using anything. Why? Because #272 is the only grade that holds up to exhaust heat. Even when using #272, I'll still check torque on those screws as part of my annual inspection (I usually find one or two has loosened anyhow.)

5) If you don't have one - get one. One what? One of these - http://www.sears.com/shc/s/p_10153_12605_00999516000P?keyword=socket

Actually, get two - one in 9/16" for manifold fasteners, and one in 7/16" or 11m/m for the CPS. Believe me, they do help (I know - you can put a universal joint on the backside of a socket. However, this is about an inch to an inch and a quarter shorter - and that helps! You don't need to adjust torque when using these.)

6) When you get the manifold of (both of them!) check them for warping. Use a known good straightedge or flat surface (a straightedge without any nicks in it can work, but I use a thick glass plate that's about a foot square by 1" thick. Got it years ago, built a case for it, and it hasn't broken yet...) and a feeler gage to check. With the surface you're checking on the "check surface", you should not be able to slip a .003" feeler gage in (per foot of length - that's why I got a one-foot square glass plate. Also comes in handy for checking pushrods, lifter feet, ...) If it's warped, a machinist should be able to flatten it for you in about five minutes using his belt surfacer (think belt sander on steroids) for a nominal fee. If you have to have the manifold surfaced, either have both of them done by a like amount, or get new Belleville spring washers (Fastenal again) to make up for the unevenness in the clamping surfaces - he'll have to remove .010"-.015", usually, to correct a warp (more than that, replace the manifolds.)

7) Do you need to remove the head? Not unless you suspect other problems. Are your lifters collapsing? Do you suspect a leaking/burned valve? Considering even pushrods can be serviced without removing the head (pull them and roll them on a flat - like my glass plate,) there's really no need to go to all that work.

As far as the fastener mix, you should have either two studs (one at each far end) or three studs (each far end and the top centre.) Mechanically, they're not really necessary - they're there as a convenience to service. If you didn't have studs to hang the manifolds on, you'd have to wrestle them in place while you're getting screws started - and that sucks.

Changing your fuel injectors, at this time, isn't a bad idea. I'd start keeping an eye on your radiator as well, if it's OEM.

Make sure you clean the mating surfaces thoroughly - I find that Scotch-Brite works well. Most hardware stores should have small discs that you can chuck into a drill motor that make short work of the job. If it's really nasty under there, stuff a rag dampened with solvent in the intake port before you work around it - the rag keeps crap out of the port, and dampening it with solvent will catch the dust and "wipe the port out" as you remove the rag. Stuff it in until it's just below the mating surface of the head. The intake manifold may be blown out with air or the cleaning solvent of your choice. Exhaust ports only need to be stuffed if the valve is open, and any loose dust will be blown downstream anyhow once you start the engine.

(This is the sort of thing that will go into my third book - which will, essentially, be "What the FSM Doesn't Tell You.")

5-90 said:

lots of info!

Click to expand...

Thanks 5-90. I have gotten most of this information from you before by reading this forum. I went to Ace and got 3 stainless steel threaded rods that are 3/8 x 16 x 3 which i cut to 2 1/2 inches that i will be using for the studs. Got 3/8 x 16 stainless steel nuts, and i also got 8qty of 3/8 x 16 x 1.25 stainless steel bolts for everything else. I read one of your posts where you had listed in order the preference in material that you would use here.

5-90 said:

brass or bronze (first choice,) stainless steel (second choice,) or SAE Grade 5 (third choice.)

Click to expand...

Since Ace did not have brass or bronze i went for stainless steel. Is that ok?

I have all the hardware ready to go. I know it has been like this for awhile so im going to pull the manifolds to at least replace the gaskets and clean things up.

Im pretty sure the manifold is not cracked i inspected it with a mirror fairly well. They only thing im worried about is warpage. I wouldnt mind checking it when its off, but this Jeep is my only vehicle at the moment, so im trying to find out what is more likely. If its more likely then not, warped, then ill order another one. If not, then ill re-use the OEM.
Whats more likely?
Also, you never said if that exhaust manifold i linked too would be an acceptable replacement.

Loctite isnt sold anymore here locally, only permatex stuff which they say "is" loctite. I found some thread sealer that is rated to 400 degrees, but i doubt this will do my any good.. is that correct? Loctite 272 is only to 450 degrees right?

You ARE saying it is best to leave the head alone and not replace the head gasket even though its probably never been replaced and almost already torn down that far?
I think that i may have a collapsed lifter. With the hood open slowly reving the engine, it sounds like something is going to pop out of the engine. I even made one of my friends back up cause he thought it was going to "explode". I run the shit out of this thing too, and nothing ever happens. At first i thought the timing chain was contributing, but i just replaced that with a new one (but for a 95 as an upgrade). Maybe its that noisy from the exhaust manifold being loose??
Its also possible that a pushrod is bent.. if thats even possible and stay running well. I got this Jeep from some one who thought that it was a good idea to open the valve cover and "tighten" all the rocker bolts. He tightened the front one so tight it broke, thats why he was selling it. I bought it, replaced the bolt to the right torque, and off i went. Would this bend a pushrod?

With this extra information would it now still be a bad idea to replace the pushrods and lifters (dont you have to replace them at the same time)? Its more of a "while its torn down" thing to me cause i plan on building a stroker in the future. But it could end up being a year or more before i do that... so i want this one to stay running well EXPECIALLY since its my only vehicle at the moment.

I replaced the radiator last year around this time, since i hit a deer, but thanks for that tip.


Any other suggestions after answering the questions above?

Again, thanks for your time.

The manifold listed in your ebay link is the correct one. Whether it's any good or not is another question. The ad says no returns, no warranty, so personally I'd stay away from them. Besides, if it's not cracked, you shouldn't need a new one.

Next, not to be picky, but Studs and Bolts do not go together. The end fasteners are studs that use nuts. If the stud had broken, you would likely not see anything there. More likely the nut or stud is stripped.

I just swapped out my cracked exh manifold on my 88. The old studs did not have the torx end. I double nutted them to get them out. The newer style, with the torx end were just a few bucks at the dealership and fit like "butta".

If the headgasket's OK, I'd leave it alone too. The loud "ticking" noise you hear may be an exh leak.

FWIW, On mine, the nut on the stud by the firewall was loose too. The engine is a lot quieter now considering it's got 173K.

FWIW, I have 2x 90 heads and an 89. On all three, the very last stud broke off in the head. I had them all tapped out for 20 a pop at the local machine shop (then 10 bucks for a hot tank). OEM bolts came with enough bolts to replace the studs.

LocTite is made and sold by Permatex - it's the same stuff.

Sorry I didn't comment on the header, I didn't look. Saudade beat me to it, tho. And, while I've long said that "the best warranty is one you don't need," there should be some mechanism in place for making sure you get the right parts. Even though I don't list a warranty (I've not needed to, to be honest,) I'll work to make sure what you get damn sure does work for what you need!

Stainless should be fine - it seizes a bit less (probably due to the layer of chromic oxide that makes it "stainless.")

As for the noise, it is a fair amount of work to pull the head. Get a mechanic's stethoscope, and give it a good listen. Lifters are on the passenger side of the engine (but you probably already knew that.) "Stuck" lifters are often misdiagnosed as "collapsed" - run a quart of Marvel Mystery Oil through it with the next change (sub the MMO for a quart of engine oil) and see if that improves things. If so, continue until it's clear. You can run MMO for normal oil change intervals; but if I've got a sludge problem, I'll change oil about every 1000 miles to make sure I get the crap out of the engine. Once it's clear, resume normal intervals.

Also, check the flange nuts before you take things apart - I've run across quite a few cases where someone would tell me they have a ticking lifter on warmup, but I'd start by checking the collector stud nuts and find them loose (it's happened to me a few times, so it's a quick and easy check - and usually a quick fix.) Sometimes exhaust leaks can present as lifter noises during warmup - once they get heated up, the metal expands and the leak closes...

Saudade said:

Next, not to be picky, but Studs and Bolts do not go together. The end fasteners are studs that use nuts. If the stud had broken, you would likely not see anything there. More likely the nut or stud is stripped.

Click to expand...

I concluded that the stud broke because after trying to "snug" it up and driving it i heard a "clunk" "clunk" telling me uh-oh i probably lost that stud. After i parked and check it over again, i noticed nothing was sticking out there anymore.

Thanks for all the info Saudade!

5-90 said:

LocTite is made and sold by Permatex - it's the same stuff.

Sorry I didn't comment on the header, I didn't look. Saudade beat me to it, tho. And, while I've long said that "the best warranty is one you don't need," there should be some mechanism in place for making sure you get the right parts. Even though I don't list a warranty (I've not needed to, to be honest,) I'll work to make sure what you get damn sure does work for what you need!

Stainless should be fine - it seizes a bit less (probably due to the layer of chromic oxide that makes it "stainless.")

As for the noise, it is a fair amount of work to pull the head. Get a mechanic's stethoscope, and give it a good listen. Lifters are on the passenger side of the engine (but you probably already knew that.) "Stuck" lifters are often misdiagnosed as "collapsed" - run a quart of Marvel Mystery Oil through it with the next change (sub the MMO for a quart of engine oil) and see if that improves things. If so, continue until it's clear. You can run MMO for normal oil change intervals; but if I've got a sludge problem, I'll change oil about every 1000 miles to make sure I get the crap out of the engine. Once it's clear, resume normal intervals.

Also, check the flange nuts before you take things apart - I've run across quite a few cases where someone would tell me they have a ticking lifter on warmup, but I'd start by checking the collector stud nuts and find them loose (it's happened to me a few times, so it's a quick and easy check - and usually a quick fix.) Sometimes exhaust leaks can present as lifter noises during warmup - once they get heated up, the metal expands and the leak closes...

Click to expand...

Was that permatex stuff i found ok to use? Its called "High Temperature Thread Sealant" from Permatex. Its says its good to 400 degrees.

I have used a full can of seafoam for about 500 miles, then changed my oil. And then i did the same again. Still same amount of noise. I use synthetic oil btw... maybe thats why its so loud? I am pretty sure i am going to have to pull the head to drill out that stud since its so close to the firewall. Am i going to hurt anything by replacing lifters and pushrods? They do have to be replaced at the same time correct?

Thanks again for all the help guys> Also, im sorry if some of my questions are "silly" or "newbish" i just want to make sure i have as much information as possible before i get into this, probably this weekend. Since this is my ONLY vehicle.

5-90 said:

Even though I don't list a warranty (I've not needed to, to be honest,) I'll work to make sure what you get damn sure does work for what you need!

Click to expand...

FWIW, I was referring only to online retailers especially ebay. Now, this guy does have pretty good feedback considering his score is into 6 figures!!

Speaking for myself (and I'm sure for many here) I know you're an honorable person who stands behind their work and their words.

Not to be picky again.

Muad'Dib said:

I concluded that the stud broke because after trying to "snug" it up and driving it i heard a "clunk" "clunk" telling me uh-oh i probably lost that stud. After i parked and check it over again, i noticed nothing was sticking out there anymore.

Thanks for all the info Saudade!

Click to expand...

Well now you're screwed. Hopefully there's enough left to twist it out. Otherwise, you may need to buy that headgasket afterall. :explosion

BTW: Sorry if I sounded too critical before. It wasn't intentional.

Muad'Dib said:

I concluded that the stud broke because after trying to "snug" it up and driving it i heard a "clunk" "clunk" telling me uh-oh i probably lost that stud. After i parked and check it over again, i noticed nothing was sticking out there anymore.

Thanks for all the info Saudade!



Was that permatex stuff i found ok to use? Its called "High Temperature Thread Sealant" from Permatex. Its says its good to 400 degrees.

I have used a full can of seafoam for about 500 miles, then changed my oil. And then i did the same again. Still same amount of noise. I use synthetic oil btw... maybe thats why its so loud? I am pretty sure i am going to have to pull the head to drill out that stud since its so close to the firewall. Am i going to hurt anything by replacing lifters and pushrods? They do have to be replaced at the same time correct?

Thanks again for all the help guys> Also, im sorry if some of my questions are "silly" or "newbish" i just want to make sure i have as much information as possible before i get into this, probably this weekend. Since this is my ONLY vehicle.

Click to expand...

Inspect the rods and rocker arms for excessive wear. I am in the middle of doing all of the for mentioned in this post. My engine only had 170ish and the insides (though caked with carbon and sludge) loked exceptionally good. Very light ring ridle in the cylinders, no heat marks, no excessive play on internals. IF you decide to take the head off I would take it and get it hot tanked (what I did). While it's off, you can replace the rear freeze plug.

Fel-pro perma torque series head gaskets are amazing compared to others i've used.

Saudade said:

FWIW, I was referring only to online retailers especially ebay. Now, this guy does have pretty good feedback considering his score is into 6 figures!!

Speaking for myself (and I'm sure for many here) I know you're an honorable person who stands behind their work and their words.

Not to be picky again.

Click to expand...

No worries. I'll probably write one one of these days, but the problem hasn't really come up, and I've only had stuff out "in the field" for a couple of years. There's no reason for me to expect that it won't last the life of the vehicle (barring egregious abuse,) but I've just not gotten around to it yet. I've been busier writing books...

And, I deal with my customers the way I'd want to be dealt with myself. I find it a simple model for behaviour, and it's worked well so far - so I'll keep doing so.:eeks1:

Oh - Usul, "thread sealer" is nowhere near "threadlocker" - so don't bother. Thread sealer is usually used in hydraulics, plumbing, and other fluid applications (water pump screws, thermostat screws, the driver's front cylinder head screw on the AMC150 and AMC242...) but it's not designed to hold screw threads in place, it just keeps fluid where it belongs.

Are you going to hurt anything with replacement of lifters and pushrods? No - but drop the new lifters in a bowl of oil before you get started, and pump them a couple of times before you drop them down the holes. And, be generous with assembly lube (changing the oil after about 500 miles won't go amiss, either - just to get all the MoS2 out. There's a slim chance it can clog up the filter.) Pushrods can be replaced if they're bent - but it's not strictly necessary (you do want to try to get them back on the same rocker arms, tho.)

N.B. - You can replace lifters without replacing the cam. You can NOT replace a cam without replacing lifters - the cam will be wrecked within the first hour of operation! If you remove lifters and don't plan to replace them, make damned sure they go back in the same holes!

Ok, just to be clear.
First off you guys rock, more information the better!
Let me summarize:
1.) The Exhaust manifold is probably fine as long as its not cracked. Even with 180,000 miles.
2.) Im going to need to remove the head to fix that broken stud.
3.) Replacing the lifters and pushrods is probably a good idea since its all torn down that far. Its NOT going to ruin the cam. If i decide to keep the same lifters and pushrods MAKE SURE that they are associated with the rockers the exact way they came off when putting them back on.

Does this all sound correct so far?

Just a couple more things:

Is this gasket set ok to get?
http://www.partsamerica.com/ProductDetail.aspx?MfrCode=FEL&MfrPartNumber=HS9076PT

Also if i do get that gasket set notice it comes with valve stem seals. Replace those while im at it correct?

BTW so that i could try to make my "engine sounds" more clear i took a video of my Jeep (mainly for the sound) just about an hour ago. When im revving it, i barly move the throttle body from its idle position. Id say at the most 3/4's of an inch. Probably more like 1/2 inch. Maybe this video will help to hear what it is. (btw that shiny stuff you see is "mastic" its used by HVAC companys, and has very stong glue. Seems to work great as a heat barrier. I also used it on my heat shield that i made. Does wonders. If you want to know more about the stuff or what i did to make a heat shield just ask!)

http://tinypic.com/player.php?v=73jpoqd&s=1

Thanks!!

Fel-Pro? Yeah, should be fine (I'll usually use Fel-Pro or Victor-Reinz, but Fel-Pro is easier to find.)

Replacing the valve guide seals requires being able to remove the valve springs and such - do you have a valve spring compressor?

You may not need to remove the head to remove the broken stud - depends on where it is broken, how it is broken, and what tools you have available (if the threads have been pulled to where the crests are rounded and shortened, you just need to wrench the stud out, for instance. This does not typically require removing the cylinder head.)

Replacing the lifters will not wreck the cam. If the lifters are to be removed and replaced, they must be put back on the very same lobes or the damn sure WILL wreck the cam! Pushrods should be associated with the same parts, but it's not critical (I've mixed them before without damaging anything, but it's good to pay attention to detail.)

A mechanic's steth only costs about $10-15 at Sears, and is used more to localise a sound than to properly identify it. Localisation is key here - once you have a better idea where it comes from, you have a better idea what it is (a good example of that is someone who came to me wondering what the growling at the front of his engine was - was it a water pump or a power steering pump? A: it was neither. And, I had an idler pully with a new bearing on the shelf - for five bucks and the old pully, he was good to go [the bearing cost me $5 when I replaced it as a spare.])

I do not have a valve spring compressor. Is it worth it to get one or rent one? Or should i leave it alone?

Thanks for all the info everyone!

On the exhaust manifold, I wouldn't buy from a no-return place. when I went to replace mine, I got a Dorman brand manifold from Napa. It didn't fit (flanges interfered with intake flanges) and it wasn't flat. Took it back and tried another. It fit, but someone fawked up and the port of the tube that goes to the intake was in the wrong place. Took it back for a 3rd, but figured I'd walk back to the machine shop and have it checked. Sure enough, not flat.

Ended up going OEM from the dealer $$$.

Lots of funky knockoffs out there it would seem. Really suprised in this case cause Dorman is usually pretty decent.

Muad'Dib said:

I do not have a valve spring compressor. Is it worth it to get one or rent one? Or should i leave it alone?

Thanks for all the info everyone!

Click to expand...

are you showing any signs of bad seals now? Does it give you a quick puff of blue smoke upon first start each day? If not, I'd not bother. Some engines are hard on seals, but my experience with the 242 does not lead me to believe it's one of them....... now a SBC on the other hand.......

--Shorty

Muad'Dib said:

I do not have a valve spring compressor. Is it worth it to get one or rent one? Or should i leave it alone?

Thanks for all the info everyone!

Click to expand...

You'll need one if you do the job.

Symptoms of bad valve guide seals are typically either a bit of blue smoke on cold starts (sitting >2 hours or so) or a quick bit of blue smoke when you first hit the throttle (increase vacuum pulls oil down the valve stem.) If you have neither of those, it's probably not worth bothering - especially considering it's not strictly necessary to remove the cylinder head to replace valve guide seals like ours ("umbrella" style.)

No none of that. It doesnt seem to have any real symptoms of anything wrong except for the low idle after starting, and the ticking that i got the video of.

Muad'Dib said:

No none of that. It doesnt seem to have any real symptoms of anything wrong except for the low idle after starting, and the ticking that i got the video of.

Click to expand...

Both signs of manifold trouble, taken together. You may find that, once you get the manifold fixed, the ticking goes away of its own accord. The "low idle" would be caused by the deteriorating seal of the manifold (it goes away once the aluminum intake expands far enough to close up the gap again - it's probably only a couple thousandths of an inch, but enough to break the seal.)

Service the manifold seal, and your problems are likely solved.

The ticking in the video seems a little different than a leaking manifold. That's just my two cents though; it sounds like something else.

Although now that that stud is missing......I haven't heard one with a stud missing, which would be a bigger leak than I've ever heard.