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Exhaust manifold


runar

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A month ago I noticed a little crack in the front exhaust manifold on my 94 deville

with the 4.9L. Today the crack is wider and a puff of exhaust coming out when raising the idle. The crack is easy to get at, just above the connection to the pipe.

I guess throwing money at the problem will solve it, but I am asking you guys if there is an easier fix, like an epoxy or something similar.

Regards

Runar

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A month ago I noticed a little crack in the front exhaust manifold on my 94 deville

with the 4.9L. Today the crack is wider and a puff of exhaust coming out when raising the idle. The crack is easy to get at, just above the connection to the pipe.

I guess throwing money at the problem will solve it, but I am asking you guys if there is an easier fix, like an epoxy or something similar.

Regards

Runar

You should be able to have it welded by a compentent weld shop. Cast iron (I assume the manifold is cast iron?) can be welded successfully is the proper techniques are used. Be sure to disconnect the negative battery terminal before welding so none of the electronics will be damaged. If it is a stainless header type tube, it can also be welded.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Hi Kevin

Thanks for your fast reply.I talked to a welder friend I used to work with. He wanted me to remove the manifold so he could to a good job on it.I would prefer

your way of welding it right there. How tough is it to remove the nuts without breaking the studs and what other pitfalls are there if I have to go that route?

Regards

Runar

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I would use a good penetrant - PB Blaster, Rust Buster, Break Away, etc., and an impact wrench is possible. The impact will lessen the chance of anything snapping off... There may not be enough clearance for an impact but it's worth a shot.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Hi Kevin.

Thanks for all your help. My sister is visiting me from Sweden, so I will have to put off the job til July. I will lean on you later on. Thanks again.

Regards

Runar

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Runar,

I had exactly the same problem. First I tried some stuff I got from Canadian Tire (fiber glass and cement stuff) and it turned out to be useless. Then I had a shop remove the manifold and the the welder brazed the crack (I think that's what they called it). The brazing distorted it and the mechanic had a hard time aligning the holes and ended up filing the hole so the bolt would fit. It lasted for about a year. I managed to find a manifold in the junk yard for about 150 bucks. The replacement is not that tough as long as you don't have rusted bolts or thread. You'll need some extension so you can access the bolts. I took out the fan to make more room for access. Also I put in a new manifold gasket. I did this in the middle of winter so you should have a much easier time. If you can find a manifold for cheap that would be the best route.

ShenKng

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Hi Shen

Thanks for your reply. I am looking for a used one. I think you are right. It is the way to go. A friend showed me today his old S 10 truck. A mechanic here welded his manifold right on the car. Much more room than on our cars. I will see him next week and see what he says.

Regards

Runar

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jb weld I had my doubts about the stuff. I could or would not believe an epoxy coud hold any engine part but on my harley I blew a head gasket and where the leak was got so hot that it melted a groove in the top of the cylinder head my brother in law talked me into trying JB WELD said he has used it with great results on all sorts of things and what do I have to lose by trying it. I tried it and the stuff does work. I really had my doubts an air cooled motor gets pretty hot and with 10 to 1 compression I thought it would never hold up that was 2 years ago and 12000 miles with no problems

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Have you tried to find a replacement yet? I sent one to a guy in Amsterdam as his cracked. Its a common occurance on the 4.9. If you want to try, I would get the casting/part numbers off of it and try http://car-parts.com Mike

I don't think there will be any quick fix here (epoxy, JG weld, etc...). Personally I would feel better if your friend tacked it while it was in place, if you can get at it. The seating plain MUST be perfectly in line or you will crack it again in short order.... I thought I said that above but it seems to have gotten overlooked. It must absolutely be perfect when it is bolted up or it WILL crack again, probably in a different spot, cast iron tends to be brittle... Welding tends to PULL the piece to and fro, to me the best place to tack it is on the engine.. I doubt that your friend would make a jig or have a jig to bolt it to.

Personally I think you should find a replacement at the scrap yards.. I just did a search and found a TON of them at the above link for $100 to $150...Make some calls, sounds easier to me.

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Hi Scotty

Thanks for your reply. Always good to hear from you. I will be looking here in Canada first, if I do not find one, I will get back to you.Nice of you to offer me some help.This is the first car since

1956 that I have a manifold problem with. For those of you who read my post about windshield noise, I got a new one installed last week. Took it for a long drive today, and the windnoise is the same. Maybe it has to do with the design of the car.

Regards

Runar

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Let me know if I can help. Yes I know, I had never heard of a cracked manifold until the 4.9 and from what I understand its quite common. Its probably due to some sort of stress or vibration. When I went looking for the manifold for the guy in Amsterdam I learned quickly that they can crack and they are a hot item in junk yards. Its great that car-parts.com can search Canada for you it will save you some shipping. However, make sure you get the numbers off yours so that you can match them up and not buy the wrong one.

The windshield noise bothers me. Do you have a fabric top? I assume that the windshield was installed correctly? Its definately not a design problem. Any water coming in?

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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I looked at the JB Weld and its not recommended for exhaust systems. This is directly from their site, they specifically note manifolds

Not recommended for use on manifolds, exhaust systems, and other engine components which normally operate at temperatures above 500° F.

http://jbweld.net/products/jbweld.php

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Have you tried to find a replacement yet? I sent one to a guy in Amsterdam as his cracked. Its a common occurance on the 4.9. If you want to try, I would get the casting/part numbers off of it and try http://car-parts.com Mike

I don't think there will be any quick fix here (epoxy, JG weld, etc...). Personally I would feel better if your friend tacked it while it was in place, if you can get at it. The seating plain MUST be perfectly in line or you will crack it again in short order.... I thought I said that above but it seems to have gotten overlooked. It must absolutely be perfect when it is bolted up or it WILL crack again, probably in a different spot, cast iron tends to be brittle... Welding tends to PULL the piece to and fro, to me the best place to tack it is on the engine.. I doubt that your friend would make a jig or have a jig to bolt it to.

Personally I think you should find a replacement at the scrap yards.. I just did a search and found a TON of them at the above link for $100 to $150...Make some calls, sounds easier to me.

After it was welded, I would recommend having a machine shop true up the seating surface.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Good idea, I didn't know that could be done, that would minimize the possiblity of cracking due to misalignment.

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Good idea, I didn't know that could be done, that would minimize the possiblity of cracking due to misalignment.

Any automotive machine shop can do that. Five years ago, I replaced the timing chain and gears on my '86 Park Avenue - the cam button spring weakened and made a 1/8" crater in the timing cover. I had an automotive machine shop TIG weld the aluminum pad back and they machined it to the proper dimension and took a finish pass over the sealing surface. $40 was the total - much better than $202.00 from the dealer. The junkyards would not sell me just the timing cover - they wanted me to purchase the whole engine....

70,000 miles and 5 years later, it is just fine. If I had to do it again, I would have used the TIG welder and mill at work after hours......

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Thanks to everybody for your inputs. All very interesting. I will be busy this months with my sister and her husband, it is the only time the caddy is taking a back seat.

But this is a job that I do not like to rush, I am high on DD and like to do all the prep I can make.As a retired industrial electrician I really do like fixing my own problem, and with the help of this board it makes it a lot of fun.So all of you, have a nice June and see you back in July.

Regards

Runar

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Relax and Enjoy

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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After it was welded, I would recommend having a machine shop true up the seating surface.

This adds to the expense considerably. I think that makes the used manifold all the more attractive.

Regards,

Warren

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Hi Scotty

A friend of mine had some JB Weld, so I thought I would try it. I let the car sit for a day and and a half. It really looked nice. Yesterday I went for an 80 mile trip, and right away there was a strong smell coming into the car. I opened the rear window just in case. When I got home I had a look. You were right about not recommended for exhaust system. Only some powder left, like ashes. I still think

it is good stuff but not for manifold or any heat related applications.Anyway, back to plan A looking for a manifold.

Regards

Runar

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It would be a good idea to have a machine shop true up a used manifold also. The used manifold will be "seasoned" by the fact that it has already been subjected to many heat/cool cycles. It should be fairly stable as far as heat warping goes. However, if the mating surface is not true, the act of torquing it up in a new location with out truing, may put stresses on it and cause it to crack.

I would advise replacing the manifold. Attempting to weld a manifold "in place" is not a proper way to accomplish this type of repair.

Brazing is also not a good way to repair exhaust manifolds. The heat that the manifolds run at, coupled with the different coefficient of expansion between the cast iron and bronze will cause failure in short order. Brazing is an acceptable repair for cast iron, but not in exhaust manifold applications.

The nature of cast iron in exhaust manifolds makes it a poor choice for a welding repair. I'm not saying that it can't be done. But to do it properly will probably cost more than a used manifold, and not be as satisfactory in the long run.

Britt

Britt
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Thanks for the feedback Runar. I really don't think you will have a hard time finding one, that link I gave you should do the trick (www.car-parts.com). Since these manifolds tend to crack the suggestions to true up the mating surfaces are good ones. Definately use a torque wrench. If you want me to check my local junk yards for you PM me the casting numbers (I think those are casting number but they may be part numbers also who knows). Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Hi Scotty

Thanks for your reply. I tried the the site you suggested, but no bites. Also tried a

recycler from Sacramento, waiting for a call from him. Is there any way I can find the numbers on the manifold without removing it first?As you guys suggest, machining the mating surface makes a lot of sense.

Regards

Runar

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Hi Scotty

Thanks for your reply. I tried the the site you suggested, but no bites. Also tried a

recycler from Sacramento, waiting for a call from him. Is there any way I can find the numbers on the manifold without removing it first?As you guys suggest, machining the mating surface makes a lot of sense.

Regards

Runar

The numbers are raised if I am not mistaken and they are large, you will need to get under the car with a light or put it on a lift.

I am shocked that you can not get a manifold on that site, they cover the entire country, how much time did you spend there? Not having the numbers will cause a problem for you anyway, you need the numbers, forward them to me when you get them and I will try to help... Long Island is a junkyard east of NYC... :lol:

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Hi Scotty.

I sent a request but nobody answered. I can get one from Sacramento for125.00

plus s/h. I think I will get that one. Have a nice weekend and thanks for all your help.

Regards

Runar

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