Exhaust Woes, What to do now?

[Bryan]

I have replaced the gaskets on the drivers side manifold 3 times since January, and its starting to leak again. First time it wasnt leaking, it was the air injection tubes but I had already pulled the manifold off so I replaced the gaskets. Then it started leaking again about April, and I replaced the gaskets again, making sure to clean the surfaces of any old gasket material, and going back and retorqueing the bolts every couple of days. It started leaking again in November. This time I had the manifold surface planed at a machine shop and used all new grade 8 bolts. I tightened them, let it run for about 20 minutes, then retighned them with the manifolds hot. Then retightened them after 3 days, then retightened again after 2 weeks. Now its leaking again. I noticed a pattern - the rear gasket seems to keep blowing out. I also noticed that the front 2 and rear 2 bolts are smaller than the 2 center bolts, but the bolt holes drilled in the manifold are larger for the front and rear bolts than they are for the center bolts (does this make sense?). So the front/rear portion of the manifolds never center correctly, thereby leaving very little gasket material. Am I missing something here? Help!

------------------
1988 GW
30x9.50 TXR's
2.5 inch exh w/hi-flow cat & muffler

1977 Cherokee
360, T-18 4spd, D20 transfer case. Its a work in progress.

1978 Ford Bronco
351m, 4spd, NP205, 35 inch tires

[christopher]

I replaced mine once and a week later they started leaking again. I have heard of copper gaskets that are a miracle but I don't have the link. look through past leak problems and you will find many articles. they run around $35.00

[JeepFreak]

I wouldn't keep re-torquing the bolts on the manifold. If you are using the metal type gasket all you are doing by retighting is smashing the gasket more and more intill the small air baffels(???) are flattened completly and the gaskets lose their sealing ability. I just put a new motor in my 78 and resently dropped one in my 85 and neither have leaks and I never re-torqued those bolts. Just my 2¢ worth.

------------------
JeepFreak

[River Beast]

I gotta agree with JeepFreak on this one....When I got my 78, it was all original.... when I puuled the motor to go thru it, there were
NO GASKETS ON IT (Exh. manifolds) and never leaked!!! http://www.ifsja.org/ubb/eek.gif

I put the new ones in and torgued a week later and never leaked after that.

If you have a small oil leak dripping back there from the valve covers, it will deteriorate the gasket and make it leak over time as you described... you may want to check that.... but don't keep torquing the bolts.



------------------
Todd
78 Wagoneer, "River Beast"
360/TH400/QT
Dana 44's locked w/ 4.89's
39.50x15x15 Super Swamper TSL's
7" SOA in front-7" Rear Shackle Inversion Mods
4" Skyjacker Softride
3" Trailmaster Bodylift
My FSJ site: http://www.geocities.com/spazz4life (http://www.geocities.com/spazz4life)
My E-mail: monster_fsj@hotmail.com
"If you can't stop...SMILE as you go under!"

'93 3/4 ton 4x4 Suburban...a.k.a. "FSJ Hauler"

[MonsterMash]

Mr. Gasket makes the CopperSeal exhaust manifold gaskets and any parts house that carries that brand can order them for you. Summit Racing also sells them on-line. I replaced a leaky (perpetually leaky) pass. side gasket about 2 months ago and have had no further problems. They cost me about $35 but it's well worth it to not have to deal with the noise or a future repair. They are really thick (almost as thick as a penny) copper and they slip in really nicely since they are one piece and they have tabs on the ends so the outer two bolts can be started before the gasket is installed. When I pulled my manifold I noticed a bolt that was too long was used in the area of my leak so I assume that the manifold was not able to be tightened properly. Are you sure your bolts aren't too long?
The CopperSeal gaskets also came with lock washers and I only re-torqued the bolts once (there are torque specs in most manuals).

------------------
'84GW360--"Spinner"
Bigger tires and better stereo but pretty much stock
Most everything works some of the time!
1st Annual Jefferson FSJ Mud Run:

http://home.earthlink.net/~worthservices/index.html

[Bryan]

Thanks for all the reply's. I think I will try the copperseal gaskets. One of the reasons I kept retorqueing the bolts is because I could hear it start to leak a little bit (ticking noise) and retorqueing the bolts made it go away. It always seems to be coming from the same area (rear gasket) and when replacing them I can see the path on rear gasket where the blowby occurs.

MonsterMash, I hadnt thought about the bolt being too long. It is the same length as the other rear and front bolts, but shorter than the two middle bolts. I will see if I can find a grade 8 bolt that is 1/4 inches shorter and give that a try. I've done this so many times now I can have the manifold in and out in about an hour and fifteen minutes, start to finish. this is getting old!!

[Slippery]

In response to RB's surprise at a lack of gaskets...

A buddy of mine insists that since both the head and the manifold are machined surfaces, thus perfectly flat, there is no gap between them to seal. He's never, ever used exhaust gaskets, never will, and has never had a leak.

Just my $.02.

------------------
Jason K.
"No FSJ yet, but wait..."

[miked]

what is a proper replacement bolt for the exhaust manifold bolts? some i've talked to said that over time with all the heat cycles on the bolts that they tend to stretch abit and will start to loosen up.

is a grade 8 bolt the ticket or is there something special in the bolts that come in the exhaust bolt kits?

also, i'd be very wary of installing shorter bolts, you can cause much more damage to the threads by installing short bolts, torquing them down only to find that you didn't have enough thread coverage between bolt and the hole and you end up stripping the threads in the hole. i'd say that if you are not bottoming the bolt out in the hole that the problem is either in the fact that the gasket needs more compression than the torque is providing causing it to loosen after a few heat cycles, or the bolts are shot.


------------------
Mike D'Ambrogia - San Ramon, CA
69 Custom Wagoneer - The Firetruck

Built 350 w/ Buick 4 barrel manifold, 600 cfm quadra-jet, RV cam, 10:1, Pertronix ignition,8mm plug wires
MSD coil
rebuilt TH400 w/ B&M shift kit
Powr-Lok rear end
Factory A/C
Herculiner over new floorboards
Complete rewire with American Autowire Power Plus kit
LPG/Propane install coming soon!

[WINGO]

I used manifold gaskets purchased from NAPA. They were aluminum and graphite and havent leaked since I put them on about a year ago. I also placed a very thin film of permatex copper sealer on both sides of the gaskets.

Do yourself a favor and invest in new bolts and studs if you have them. I found that a few of my bolt holes were striped by the DSPO and had to heilacoil these.

Sears (Craftsman) has a real nice stud-remover that will assist you in removing you existing studs. It was about $ 25.00 and worth every penny.

Use a good quality grade 8 bolt and coat your threads with a good aluminum based antiseize. It will help you if you ever have to take the manifolds off again.

Good Luck!

------------------
WINGO
Vineland, NJ
USA
1984 GW 360
Rough Country/Heckethorn 2 1/4" AAL (actual lift)
Rough Country/Heckethorn Nitro 9000 Shocks

[MonsterMash]

Since the torque on the manifold bolts is spec'ed at 30 ft.lb. or less there really is no reason to use anything over a grade 5 bolt for this application. The stock bolts I've seen have been hollow for some reason. I've heard that this is to allow for expansion due to the extreme heat generated by the exhaust but I really don't know what benefit a hollow bolt would provide.

IMO, a thick gasket which readily deforms when the manifold is lightly torqued is the best cure for the exhaust leaks I've encountered. I certainly wouldn't advocate using really short bolts, rather I'd use lock washers on the existing bolts, but it's clear that too long of bolts will make it more difficult to properly tighten the manifold.

------------------
'84GW360--"Spinner"
Bigger tires and better stereo but pretty much stock
Most everything works some of the time!
1st Annual Jefferson FSJ Mud Run:

http://home.earthlink.net/~worthservices/index.html

[This message has been edited by MonsterMash (edited December 21, 2000).]

[Bryan]

<BLOCKQUOTE>quote:</font><HR>Originally posted by MonsterMash:
Since the torque on the manifold bolts is spec'ed at 30 ft.lb. or less there really is no reason to use anything over a grade 5 bolt for this application<HR></BLOCKQUOTE>


I would have guessed that the recommended torque would be 60 ft.lb. or more. I know I have torqued it WAY WAY WAY more than 30 ft.lbs. (not bragging or anything but I am NOT a small guy, 6 ft 275 lbs & a gym rat in my spare time).

I was told that the grade 8 bolts hold up better under the extreme heat they are subjected to vs. a regular grade 5 bolt. So I did replace all bolts w/grade 8 and used lockwashers last time. Should I try not useing a gasket since I just had the manifold machined and then just tighted it to the recommended spec (30 ft.lbs.)? Or should I just get the copperseal gaskets and be done with it?


------------------
1988 GW
30x9.50 TXR's
2.5 inch exh w/hi-flow cat & muffler

1977 Cherokee
360, T-18 4spd, D20 transfer case. Its a work in progress.

1978 Ford Bronco
351m, 4spd, NP205, 35 inch tires

[MonsterMash]

I'd say just go with the CopperSeal gaskets (Mr. Gasket p/n- 7174) and be done with it.

------------------
'84GW360--"Spinner"
Bigger tires and better stereo but pretty much stock
Most everything works some of the time!
1st Annual Jefferson FSJ Mud Run:

http://home.earthlink.net/~worthservices/index.html

[Bryan]

Thanks for the part number MonsterMash, I think thats what I'm going to do.

------------------
1988 GW
30x9.50 TXR's
2.5 inch exh w/hi-flow cat & muffler

1977 Cherokee
360, T-18 4spd, D20 transfer case. Its a work in progress.

1978 Ford Bronco
351m, 4spd, NP205, 35 inch tires

[PAJEEPER]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Slippery:
In response to RB's surprise at a lack of gaskets...

A buddy of mine insists that since both the head and the manifold are machined surfaces, thus perfectly flat, there is no gap between them to seal. He's never, ever used exhaust gaskets, never will, and has never had a leak.

Just my $.02.

<HR></BLOCKQUOTE>

My 360 didn't have any gaskets either and I don't think it leaked. I'm going to get some anyway when I put it back together. Also I used to have a '78 Bronco it didn't have gaskets either and didn't leak.


------------------
Greg

'81 J10
258,727,208
custom bumpers 4" pipe f,square tube r.
Yellow powdercoated wheels.

'77 J20
360 4BBL,400,Q-trac.
Heavy duty steel flatbed.
Currently under construction with new frame.

[nograin]

Hey guys, my 2p is to go with the factory setup. On my mopar 340, I bought gaskets but later discovered there were none originally. The last few times I have bolted up, I have used no gasket, and it works fine. But, I think it is real important to assemble it as spec'd. For the Chrylser motor, that means hanging the manifold on the two outboard studs, then screwing in the inbord bolts Then tightening the inboard on es to 30 foot pounds, then the outboard nuts to 30.

BTY, they use a heavy conical washer on two of the four. on all their v-8s I think, not just the 340. also the stud is fine threaded on the outside, making it less likely to loosen. I've gotten away with a coarse thread with no problem.

Absolutetly check for bottoming before assembling. The high strength will be more rust resistant, both 5s and 8s will be good this way.

There should be 1 diameters worth of threads into the block as a rule of thumb. Basically 2 threads is too little, over 6 is really just wasted. Most of the work is done by the first threads. The only exceptions would be an interference thread or the spiral-lok bolts.

Bottom line, gasket or no gasket, torque it to the factory specs and pattern. If there is no pattern in the book, work inside to outside, just like an intake manifold.

[Ralph]

The problem I've had with the Edelbrock headers is that I can't fit a torque wrench in there, so I've had to just bear the bolts down with a box wrench.

[nograin]

Oops,
Forgot about reality there.
Yea. I agree its not always possible to get a torque wrench in many of the places your supposed to be using one. My arm is not that well calibrated, either. I try to calibrate my arm by feeling out the ones I can get a torque wrench on to various intermediat and final torques using the box wrench....

The mopar exhaust bolts were easy to access compared to the bolts on the holly intake manifold.

One tip I forgot was to improve a flawed mating surface by lapping it if you are going for a metal to metal seal. Use a machined flat surface like a table saw, and/or heavy plate glass and a sheet of fine sandpaper, or crocus cloth. Lap moving the manifold in circular motion with even pressure - emphasize the centers. Good luck!

[Ralph]

Nograin, what Holley manifold are you using? I've got a Street Dominator #300-31Z that I love, though it's currently not installed (while figure out what to do about fuel delivery -- thinking about MPI but awfully shy of cash right now). I took it out with plans to send it to get a thermal barrier coating at Jet-Hot, then changed my mind and was going to let TPIGuy machine it for fuel injectors, etc., etc.

I had it set up with a Carter AFB 9635, and may put it back in with that. I'd really like to find the Holley carb that was intended for it, 0-9626, but like the manifold those carbs are tough to come by. What carb are you using, and do you have all your emissions stuff in place?

[nograin]

I better set the record straight. Was just applying my general mechanics experience to Bryan's problem. The holley is on my Baracuda, my Wag is stock with emissions(but messed up, see the current vacuum thread) http://www.ifsja.org/ubb/smile.gif

That said, its a holley street dominator, but I not sure I can help you. I'm running a a 750 cfm holley 4150. (list 0-3310), center hung bowls, dual feed, vacuum secondaries. The motor is 340, with Comp Cams 280 cam, and rhoads lifters. I had headers by ED, but flattened on the street, went back to 340 exhaust manifolds.

I don't know enough to say if the contender manifold would work well on a motor really set up for low rpm work. According to HP's Holley book (by Urich & Fisher) you have an improved version of my manifold, I am not sure what model the 0-9626 carb is. If its a a 4165/75, its a spreadbore and supposedly more of a replacement carb than the 4150/60 models; and if so`has a number of improvements for street and low rpm use over my carb. My feeling is the 4150 Holley carb (mine) is irritating if it used in an every day car.

------------------
360 auto select
body by beer (PO)
carries wood inside
no "wood" outside

[ClarkGriswald]

I have to agree on the copper antisieze, that stuff is GREAT on exhaust systems.. you can use it on pipe connections and assuming you didnt crank a clamp hard enough to distort the pipe's you can take em right apart again even after a year or more.. Ive done it.. Ive not had my 360's exhaust mani's off but by the looks of it there are not gaskets in it.. I have also assembled motors without Ex gaskets, but always put a little antisieze on there.. the grease burns away but the copper is there.. and allows things to come apart again someday a lot easier.. and mabye helps the seal a bit.. Not sure about that.

The gaskets I've had the best luck with were the metal one's too.. Ive never even retorqued them, just did the initial torque (mabye with my extra pound or two for good measure cause I didnt trust the wrench. but these days I have friends with the High Dollar tools so I use those now.. )