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Old 06-16-2015, 10:28 PM   #1
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Replacing cracked exhaust manifold words of wisdom .

I found out that I have a cracked exhaust manifold. The crack is between cylinders 3 and 4 the larger of the two piece manifold.I am contemplating replacing it myself. Would like to hear words of wisdom before I start the process so far I have started putting penetrating oil on the bolts, bought both manifolds all new bolts gaskets and spacers.this is in a IS L 370 2003 Monaco Windsor. at 138 dollars per hour I may as well try it myself.For those who have done it any help would be appreciated. Thanks TRW
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Old 06-17-2015, 02:26 AM   #2
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I replaced my exhaust manifold 3 years ago. I have an ISC 350. You have started down the right path with the penetrating oil, I soaked mine for a week. I had to remove the air intake pipe, CAC hoses and pipes, turbo charger. All of the exhaust manifold bolts came out very easily. Just take your time, it took me about 6-7 hrs to complete the change out. I also replaced all the manifold bolts and gaskets and the turbo studs, nuts and gasket.
I had the new manifold HTC coated, it has not held up at all. A waist of money in my opinion.
Dennis, Debbie & Maggie our GSP
'00 36' Dynasty
'06 Toyota Tacoma toad
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Old 06-17-2015, 01:17 PM   #3
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A mixture of ATF and Acetone makes about the best penetrant available. You could try that on your bolts.

All the best.
Roy and Debbie
07 Diplomat 38 PDQ
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Old 06-17-2015, 01:29 PM   #4
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When the Danes serviced their hydraulic system,I save the ATF & mixed that with acetone -- 50/50 mix -- That is the best penetrating oil that I`ve used -- Harry Martin (happycarz) gave me a pressurized type can, & that works really well -- Bill Willard
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Old 06-17-2015, 02:05 PM   #5
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If you do get them out, replace the bolts with a stud.
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Old 06-17-2015, 03:33 PM   #6
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Just know that when you go for parts Cummins will want to know the serial number of your engine. They also suggested that I join their "club" which gives bigger discounts than someone posted here earlier when they did their replacement. Club is 19.95 a year. Cummins direct prices were about half of what a local RV shop quoted me.
2003 Beaver Patriot
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Old 06-17-2015, 06:49 PM   #7
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If you can't make up the home made brew of ATF and Acetone, the next best commercially available penetrant is Kano Kroil. It's in a orange can, available at most auto parts stores. The longer you can soak those manifold bolts, the less trouble you may encounter with broken bolts.

Another good trick is to not tighten the manifold to cylinder head bolts until you have fitted the exhaust pipe, pac brake and related mounting brackets. This will assure that everything lines up as it should.

Good luck.

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2012 Ram 2500 Laramie 4X4 Cummins 6.7L
Canada, eh?
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Old 06-17-2015, 08:36 PM   #8
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I second Jim's recommendation. I got some Kroil a few months ago and found it to be superior to any other commercially available penetrant. I especially like the spray cans of it.
Roy and Debbie
07 Diplomat 38 PDQ
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Old 06-17-2015, 11:01 PM   #9
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I always use never seize on the studs. It makes a big difference if you ever have to take
it apart again
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Old 06-18-2015, 11:07 AM   #10
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Could cracks in the exhaust manifold be welded by a really good master welder?
Joe & Annette
Sometimes I sits and thinks, sometimes I just sits.....
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Old 06-18-2015, 01:50 PM   #11
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It's possible but I've never had good luck with longevity. It will crack again.

+1 on Kroil I've used for years saved my bacon more than I care to admit. Give it time to work.
2006 Monaco 40' PDQ
25' Haulmark V-nose enclosed car trailer.
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