Home » Public Forums » GMCnet » Right Exhaust Manifold needed for 1974 455. (Removed manifold to replace gasket but manifold is cracked.)
| Right Exhaust Manifold needed for 1974 455. [message #255536] |
Wed, 16 July 2014 00:02  |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Hi all , this must be exhaust manifold week...I finally got the fuel lines repaired and got her to run but was pretty noisy. The PO had the copper replacement gasket for the right side manifold so thought since I was having a good day getting things fixed that I would go ahead and replace the gasket. Got the bolts out no problem but when I pulled the manifold off it was in pretty bad shape and is no point in putting it back on, must've leaked for sometime. Anyhow I'm now looking for a replacement and possibly a donut for the exhaust also due to the shape of the manifold. The copper gasket instructions didn't say anything about any sealant to use does anyone have any input on sealant or just use as is? Thanks for all the help and tomorrow I'm planning on bleeding the brakes and hopefully I'll have brakes and will be able to drive her soon. Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255543 is a reply to message #255536] |
Wed, 16 July 2014 00:35  |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Glenn,
There are a couple of sealants that won't degrade in the exhaust heat, but I have not used any of them with success. I have some out in the RV in the tool box as a roadside fix, but have not opened the package. I'll PM you tomorrow with the brand. My left header would not seal and for some reason all the parts stores around here did not have these commonplace gaskets...I don't understand. So I ordered 2 sets online and when I found some performance (the thick white ones) gaskets in a store across the river I bought those too. The thick copper gaskets were too pricey for me and I was not sure they would work on the uneven surface of the headers. I would not use any sealant on those copper gaskets you have with exhaust manifolds. I did end up having to use double gaskets on mine to get it to seal. I just used one whole set of 2 standard type gaskets on the one side. Then I had to torque them down 4 times, once on installation, and 3 times after I got them hot twice. You cannot use double gaskets on a manifold because it will compress unevenly and crack the manifold. If your manifold sealing surface is rough you can get it machined smooth, but I not sure what problem you are having with the donut seal. Brazing is always a possibility for restoring damaged cast iron.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255544 is a reply to message #255543] |
Wed, 16 July 2014 00:44 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Hey Terry, thanks for the info...do you have part numbers, brand for the white gaskets also? I might just go that route..the PO said he replaced the gasket on the left side with the copper gasket but didn't do the right side because it wasn't leaking. I can't really tell if the left side is leaking because the right was making so much noise. After cleaning all the old gasket material off of the head and manifold and sanding to smooth out I found the exhaust manifold was warped and had a crack in it. I guess due to the heat and from the leaks. Looked like it originally had the white gasket on it. When I went to inspect it a couple of days before I noticed that both end bolts were loose. The other 3 were tight. I tightened down the end ones and thought maybe that would do the trick..but when I got her running it was loud and getting louder...lol...Thanks, Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255545 is a reply to message #255544] |
Wed, 16 July 2014 01:22 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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You CAN weld cast iron if you've got a crack in it, but you'll have to gouge it out and find a welder that knows the special technique. I don't have the part number for those white gaskets as they were hanging on a peg on his wall and I just recognized them by sight. No brand name either, but they looked just like the Mr.Gasket type that are in all the part stores (except for the big block Olds!). I don't think you should use those on manifolds either as it will be real easy to crack a manifold when tightening them down. You might not even know it when you crack it. Whether you get another manifold or repair the one you've got, be real careful when using thicker gaskets. I read somewhere on here that some of these didn't even come with gaskets! I've seen that several times on the modern cars, but never on the older stuff. A long time ago Dad told me that we could machine 2 pieces of metal so close that you could press them together and not be able to pull them apart with your hands. I knew he was right, but I never thought I would see it in the automotive field until I had to take a few apart a few years ago.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255546 is a reply to message #255545] |
Wed, 16 July 2014 01:36 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Hey Terry, yeah on other motor homes I have had, they all had problems with the exhaust manifolds and gaskets..or as you say no gaskets and on most the gaskets were added due to an exhaust leak. I'm going to look at mine again tomorrow and see if it can be repaired but it will take some serious planing, might try going the sealant and double gasket route if nothing else, but as it was the exhaust leak was pretty bad. Or BadAss...sounds like one of the old stock cars without an exhaust system...lol.. Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: [GMCnet] Right Exhaust Manifold needed for 1974 455. [message #255548 is a reply to message #255546] |
Wed, 16 July 2014 02:01 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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My headers don't leak at all unless the collector to mid pipe comes loose at the three bolt junction. I would check to make sure the straight section of the exhaust has not been pinned solid to the frame somewhere during past exhaust work along the tight squeeze out all of those frame x members. If so the exhaust won't float with the motor movement and pipe expansion from heat. A flex joint between the rigid mounted portion and the motor can alleviate this.
Jwif
Todd Sullivan
Sully
77 royale
Seattle
> On Jul 15, 2014, at 11:37 PM, Glenn Whitt wrote:
>
> Hey Terry, yeah on other motor homes I have had, they all had problems with the exhaust manifolds and gaskets..or as you say no gaskets and on most
> the gaskets were added due to an exhaust leak. I'm going to look at mine again tomorrow and see if it can be repaired but it will take some serious
> planing, might try going the sealant and double gasket route if nothing else, but as it was the exhaust leak was pretty bad. Or BadAss...sounds like
> one of the old stock cars without an exhaust system...lol.. Glenn
> --
> Glenn W
> Topeka, KS
> 1974 GMC 26 ft. Color:Camel Interior:Canyon Land
> Side Bath, Rear Sitting Area
> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] Right Exhaust Manifold needed for 1974 455. [message #255549 is a reply to message #255548] |
Wed, 16 July 2014 02:19 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Senior Member |
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Hi Todd thanks, mine flexes where the donut is in the exhaust just behind the exhaust manifold, so don't think that is a problem. I think it's because PO ran it too long with an exhaust leak caused by bolts not being torqued correctly. The 2 end bolts were loose when I first checked the manifold, other 3 were tight...Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255556 is a reply to message #255536] |
Wed, 16 July 2014 06:39 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Sir: these will not leak and last a long long time. I have sealed manifolds that had the flange gone. They are fragile, do not bend. The donut gaskets are available at AZ. the smaller of the 2 offered for 76 Olds Toro. If the donut gasket leaks after installation, smack it with a hammer while it is running and it should seal.
http://www.appliedgmc.com/prod.itml/icOid/670
glenn2726 wrote on Wed, 16 July 2014 01:02Hi all , this must be exhaust manifold week...I finally got the fuel lines repaired and got her to run but was pretty noisy. The PO had the copper replacement gasket for the right side manifold so thought since I was having a good day getting things fixed that I would go ahead and replace the gasket. Got the bolts out no problem but when I pulled the manifold off it was in pretty bad shape and is no point in putting it back on, must've leaked for sometime. Anyhow I'm now looking for a replacement and possibly a donut for the exhaust also due to the shape of the manifold. The copper gasket instructions didn't say anything about any sealant to use does anyone have any input on sealant or just use as is? Thanks for all the help and tomorrow I'm planning on bleeding the brakes and hopefully I'll have brakes and will be able to drive her soon. Glenn
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Right Exhaust Manifold needed for 1974 455. [message #255557 is a reply to message #255549] |
Wed, 16 July 2014 06:36 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Glen,
All of our engines originally came without exhaust manifold gaskets. The
feasibility of continuing that probably died for everyone many years ago.
The solid copper gaskets, especially those from Dave Lenzi, may work.
More likely, those from Remflex (here's just the first Google link:
<
https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1CHFX_enUS589US589&ion=1&espv=2&ie=UTF-8#q=olds+455+remflex+exhaust+gaskets &tbm=shop&spd=9620208851399793121
>
Be sure to handle them VERY carefully because they're fragile until
installed, and follow their tightening instructions. They're especially
good with rough surfaces.
If you mill exhaust manifolds, you reduce the clearance between the
manifold and the head and may not be able to install the engine oil
dipstick.
HTH,
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc.
www.gmcwipersetc.com
On Wed, Jul 16, 2014 at 3:19 AM, Glenn Whitt wrote:
> Hi Todd thanks, mine flexes where the donut is in the exhaust just behind
> the exhaust manifold, so don't think that is a problem. I think it's
> because PO ran it too long with an exhaust leak caused by bolts not being
> torqued correctly. The 2 end bolts were loose when I first checked the
> manifold, other 3 were tight...Glenn
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255582 is a reply to message #255536] |
Wed, 16 July 2014 10:37 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Senior Member |
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Morning all, I'm going to look at the manifold again today and see if I can make a good enough repair so that it will seal better. I will try the 2 gaskets and sealant that Terry had done and see if it will quiet it down. These engines sound pretty strong without the added noises of the exhaust leak...lol..I'm sorry but I'm one of those perfectionists that likes things to be the way they were originally and try and keep things nice. It may be a challenge with these old coaches but hey that's why we get them in the first place..for the challenge.. I'm making progress and hope to soon be able to take an extended shakedown drive. Thanks again to all your input and look forward to helping others with the first hand knowledge I'm gaining while making repairs. Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255591 is a reply to message #255536] |
Wed, 16 July 2014 12:11 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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glenn2726 wrote on Tue, 15 July 2014 22:02Hi all , this must be exhaust manifold week...I finally got the fuel lines repaired and got her to run but was pretty noisy. The PO had the copper replacement gasket for the right side manifold so thought since I was having a good day getting things fixed that I would go ahead and replace the gasket. Got the bolts out no problem but when I pulled the manifold off it was in pretty bad shape and is no point in putting it back on, must've leaked for sometime. Anyhow I'm now looking for a replacement and possibly a donut for the exhaust also due to the shape of the manifold. The copper gasket instructions didn't say anything about any sealant to use does anyone have any input on sealant or just use as is? Thanks for all the help and tomorrow I'm planning on bleeding the brakes and hopefully I'll have brakes and will be able to drive her soon. Glenn
Glenn,
One of the first things I did to my coach, right after I bought it, was to replace the leaky exhaust manifold gaskets. The PO was hard of hearing and evidently didn't notice or didn't care how bad they were. I contacted Dave Lenzi and had him send me a pair of his embossed copper gaskets. When I mentioned to Dave that I was going to have my manifolds resurfaced, he cautioned against letting the machinist run them on a belt sander, saying they would ruin them. The machinist said he had no other way to surface them, so I gave the OK to belt sand them. He must have known what he was doing, because the came out OK.
Dave's gaskets came with instructions and thick lock washers. I installed them to his specs (I think he said to torque them to 22 ft lbs, I'm not sure) and to torque the top, middle bolt last. I followed his instructions, including re-torquing them two times, after running them through a couple of heat cycles, and have not had a problem with them in almost six years and over 22,000 miles. I got the donuts locally (Fel-Pro) but don't have a part number handy. If I were you, I would use the copper gasket you have and call Dave Lenzi for advice on installation,( 8 one 0) six 53 - 390 two.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Right Exhaust Manifold needed for 1974 455. [message #255624 is a reply to message #255583] |
Wed, 16 July 2014 16:07 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Senior Member |
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Hi Gary, I'm in Topeka, KS. I'm going to retry this manifold with a gasket set and some sealant as Terry suggested. Can't be any louder than it was, hopefully won't hear any other noises once that is quieted down...lol...Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255625 is a reply to message #255591] |
Wed, 16 July 2014 16:10 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Senior Member |
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Thanks Carl, hopefully can get this thing a little quieter and get some back pressure as there wasn't much on the right side...lol..Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255679 is a reply to message #255625] |
Wed, 16 July 2014 23:47 |
Mitch
Messages: 272
Registered: May 2009
Location: Tacoma, Wa
Karma: 0
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Hey Glen, I have a pair from when I changed over to the headers - yours for the cost of shipping.
If you're interested, PM me.
Mitch
Tacoma, Wa.
'80 Spitfire
'03 Windstar
'77 Jaguar XJ6-C
X(very)'76 PB 26 "The Beast"
Where it rains, always.
It's wet, No sun, Gray.
Go to Oregon.
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255681 is a reply to message #255679] |
Thu, 17 July 2014 00:19 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Senior Member |
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Hello all, got sidetracked today and didn't get to the coach. I did however order some gaskets for the manifold and will be here tomorrow. Will try putting it back on and see if I can get it quietened down any, if not I will definitely take one of you guys up on your offer. Thank you and I appreciate everyone helping each other out here keeping these old coaches going. Hopefully I can get mine resurrected...Glenn
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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| Re: Right Exhaust Manifold needed for 1974 455. [message #255773 is a reply to message #255679] |
Fri, 18 July 2014 01:57 |
glenn2726
Messages: 234
Registered: June 2014
Location: Topeka, Kansas
Karma: 2
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Senior Member |
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Ok, got to work on the coach today, looked at the manifold again and using a straight edge it is warped from center to outside edges on both sides, also there is a crack just past the last bolt on the flange side. The flange donut was also disintegrated, got a new one for that. I also found there is a hole in the exhaust at the Y so will have to repair that. So I'm definitely looking for another manifold now. I don't think this one can be planed enough to work again. I think this was caused by the bolts not being tightened on each end of the manifold. Only middle 3 were tight when removed so it warped the manifold. Thanks again all...Glenn
I sent you a pm mitch...thanks
Glenn W
Topeka, KS
1974 GMC 26 ft. Color:Camel Interior:Canyon Land
Side Bath, Rear Sitting Area
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