rowekmr
Chicago
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I've been searching for an older MH and have come across many early 90's Class A's where the dealer discloses it has leaking exhaust manifolds. Was this a common problem? Is there an easy solution such as new gaskets or do they require new manifolds or headers? If so where are some good (affordable) sources of replacements.
Thanks
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mph_medic
Southaven, MS (Outside Memphis, TN)
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The problem with the 1989 Coachman I had was the bolts had broken off in the head which required a lot of extra work = $$$$ ... EZ out would not work on one and the head had to be removed. Can you say open check book and CRY .... Buyer beware...
Never do anything you wouldn't want to explain to the Paramedics...
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Daveinet
il
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Exhaust bolts can be tricky or lucky. I've heard of soaking them in brake fluid. Kroil is also a good penetrate. I found putting the air ratchet on the lowest setting, and just let it bang till the bolt comes out. I was able to get all the bolts out of the 454 that way. If you end up pulling the manifolds, count on replacing them with headers. Done right, the headers should not leak.
Dave
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Joatha
Marietta, GA
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I bought a replacement manifold for my 1990 Winnebago 454 at AutoZone fairly cheaply. I don't remember the exact amount I paid. But, it doesn't stick out as being expensive. Also, I replaced it myself. But, others have pointed out the risk with regard to exhaust manifold bolts. If they break, it will be a problem.
Last, I would not run a gasket. The manifold should be trued up and should bolt up and seal without a gasket. Make sure that you let the engine idle and cool down when you arrive and that will help mitigate the issue. I haven't had any issues with mine using that method.
To be honest, if I had it to do over, I'd probably just get a good set of headers and run it. That will help performance and also they will get the heat away from the motor better than the exhaust manifolds. So, if you get one with cracked manifolds, I'd just replace both with a set of headers.
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ets1996
tumwater,wa.
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my 1996 with a 454 had an exhaust manifold leak ended up both manifolds had cracks had new ones installed about $1,000 parts and labor. solved the problem Then about a year later an rv place was running a special on the banks power pac kit I had it installed about 2,100 parts and labor Iam happy with the banks kit. I just wish I had just got the Banks instead of the manifolds live and learn.
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Weathertodd221
FL
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Older or newer unit... get headers. Engine runs way cooler and you gain some usable power. Also a quality header will last the life of the vehicle.
Broken exhaust studs... well some pros like it and some dont. Disassembly should not be necessary in most cases.
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jolooote
Miami, FL
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Chevy older 454s are known for manifold problems. Older ones did not have a manifold gasket. They were bolted direct to the head. WHEN...you replace Urs, install the best aftermarket gaskets you can find.
If its old enough to have the 'Air Injection' system that pumps air into the exhaust to 'REBURN' the exhaust gasses, REMOVE it & the pump. U'll have to get a shorter fan belt, but not a big deal. I use to just pinch off each (8) metal tubes going to each cylinder exhaust with Vice Grip pliers. Runs cvoolerand uses less HP to run that dumb air pump. While Ur at it., reset the Timing from the normal -7 degrees to about -15 or just B4 it starts to ping. Gets great HP. Nothin helps gas mileage tho. LOL
* This post was
edited 05/15/12 09:56pm by jolooote *
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Gale Hawkins
Murray, KY
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It is a common requirement for the 454 and 460 big blocks.
It can run $1000 +/- $500 but it can knock thousands off the selling price because fewer and fewer want to pay for the fix.
After 18,000 miles and five years we are still fixed it seems.
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phillyg
Front Royal, VA
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Definitely a problem with the 460 engine. If not repaired, exhaust gasses can erode the mating surface on the block. They're either constantly repaired as stock, but can be repaired one time with headers made by Banks or other sources.
2002 Keystone Cougar 286, 8,400lbs loaded, pulled with a 2004 F150 Supercrew, 5.4, 3.73 gears. Retired and enjoying life
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mfox20
Fort Worth, TX
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I replaced the right side on my 1994 454 that I use to own. I had one broken bolt that needed to be drilled out. I just drilled it several times until I got down to very little threads left and it turn right out using an ez-out. I soaked all the bolts with PB Blaster a few days before attempting removal.
I got the 1st replacement manifold from NAPA for $116.00 and it lasted 2 years. Went back with no gasket as recommended on the 454's.
Replaced it a second time with a $59.00 one from Ebay and used a good metal gasket. Was still working great when I sold it a year later.
Not all that hard to do if you have the right tools and remove the tire on the side of the leak. I could actually sit on the rotor and work.
Hope this helps with your decision. If you have to pay someone else for the labor, it will be expensive.
Michael
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