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RVing message boards => Tech Talk => Topic started by: farmer dan on August 17, 2012, 06:04:59 PM

Title: exhaust manifold gasket hard to replace?
Post by: farmer dan on August 17, 2012, 06:04:59 PM
Hi all, made our trip to Luray, VA and back. Got a leak in the passengers side exhaust manifold. I wad wondering if anyone could give me advice on doing it. I have been told by some its easy, and by others I should leave it to the pro's. What's anyone's thoughts? 34rq winnebago adventure.  1996 ford f53 chassis 460 v8.
Title: Re: exhaust manifold gasket hard to replace?
Post by: donn on August 17, 2012, 06:20:33 PM
Not easy but doable by an average compentent mechanic.
Title: Re: exhaust manifold gasket hard to replace?
Post by: mnmnutswer on August 17, 2012, 06:34:16 PM
Because of the heat and age be ready for some broken and striped bolts. When that happens you will need a torch and drill bit and easy outs (not easy) just there name. I would hire this job out jut because of the headache's and maybe special tool you might wish you had.
Title: Re: exhaust manifold gasket hard to replace?
Post by: farmer dan on August 17, 2012, 07:42:24 PM
I was quoted at a big rig service center 500 a side as a low price and they said no more that 1700 for both sides. (worst case). That sound right?
Title: Re: exhaust manifold gasket hard to replace?
Post by: mnmnutswer on August 17, 2012, 08:28:52 PM
I would make sure they mill the heads and see how long they will stand behind there work.
Title: Re: exhaust manifold gasket hard to replace?
Post by: Jim Dick on August 17, 2012, 11:29:47 PM
It may be easy to remove but I just had to have mine done on a Cummins diesel. The bolts were so frozen that they broke several. They had to remove the head, requiring an engine hoist, so they could try to remove the broken bolts. Fortunately, they did get the bolts out. If not, it would have been another $2000!!!!

Title: Re: exhaust manifold gasket hard to replace?
Post by: SeilerBird on August 17, 2012, 11:58:19 PM
Changing the spark plugs on my RV was horrid enough. I can't imagine changing an exhaust manifold. Try a mobile mechanic from Craigslist and see what they would charge.
Title: Re: exhaust manifold gasket hard to replace?
Post by: SLJKansas on August 20, 2012, 10:16:15 AM
Before you really tear into it, you may want to look at the manifold bolts. The 460 had a problem with shearing the bolts, which maybe you problem. If you are going to do the work, order a can of Kriol from http://www.kanolabs.com/  (http://www.kanolabs.com/). (it's the best you can get, and forget PB blaster. ) and use a directed. It will save you time and money. If the bolt is sheared flush with the head, it's your call, a drill and an easy out, of pay to have it done.

You may want to take a drill and use the next size drill bit on the maifold holes, this will give room for the bolts to expand and keep from beaking.  I would also use new bolts.
Title: Re: exhaust manifold gasket hard to replace?
Post by: captsteve on August 20, 2012, 06:09:45 PM
Dan,

Getting mine done wednesday. The biggest concern is the rear bolt breaking off a chunk of the head. Make sure the shop can fix that without pulling the head. Mine is gonna run about $300.00 total (short of breaking a head) And I have been soaking the bolts with Kroil for a week.

Steve
Title: Re: exhaust manifold gasket hard to replace?
Post by: catblaster on August 20, 2012, 06:21:11 PM
Steve...I have to know how that works out for ya.....I've got to pull the manifold on our 300 cummins when the time gets right. We already broke off the only two bolts we tried to remove so had to drill out and retap to larger size...I have to agree that Kroil is probably the best, especially if you can apply a little heat and let it suck in......later....Will
Title: Re: exhaust manifold gasket hard to replace?
Post by: gwcowgill on August 20, 2012, 06:29:50 PM
With a plasma cutter you can remove the broken bolts fairly easy... BUT, most smaller shops do not have a plasma cutter.               
Title: Re: exhaust manifold gasket hard to replace?
Post by: catblaster on August 20, 2012, 06:36:08 PM
I have a plasma cutter...how would I go about that ?  blow a hole down the broken bolt instead of drilling....then..?
Title: Re: exhaust manifold gasket hard to replace?
Post by: gwcowgill on August 20, 2012, 07:24:27 PM
You can carefully cut the center of the bolt or you can split the bolt and never damage the threads if you are careful. It's a trick that a lot of machinists use. I learned it hanging around a machine shop.
Title: Re: exhaust manifold gasket hard to replace?
Post by: catblaster on August 20, 2012, 07:28:41 PM
I never thought of trying that, my work even better since the bolts are not threaded into a blind hole. It's open on the backside. Even if I mess up a little it wouldn't be any worse than a drill bit walking off center.....Good thought THANKS....Will  :) :)
Title: Re: exhaust manifold gasket hard to replace?
Post by: captsteve on August 22, 2012, 05:03:30 PM
Well, It's done! One broken stud, kinda. it was a long one that was double nutted for the heatsheild, the top part snanned off. No biggie!

Total cost    $240.00 including parts.  Mechanic thanked me for soaking with KROILfor a few days.


Steve
Title: Re: exhaust manifold gasket hard to replace?
Post by: catblaster on August 22, 2012, 05:18:36 PM
Thanks Steve, glad it worked so well. The only thing lost would be the cost f the Kroil and I could always go to the plasma torch like gwcowgill suggested. At any rate it looks like it will be a while before I can tackle that job.....Will
Title: Re: exhaust manifold gasket hard to replace?
Post by: farmer dan on August 22, 2012, 05:41:48 PM
ok steve, i want your mechanic. I dont know many small shops around that can get a rig this big in. let alone in their lot. It seems we are takleing the same jobs about the same time. The parking brake, The speedo pulsing over 60.. now the manifold gaskets. I did call a Winne dealer in the next state over. He quoted me 6 hours of work and a price of 450 with two broken bolts. He told me to assume that if they are leaking there is a broken bolt. 2 leaks two bolts. I am gonna get some kroil. start spraying and make an appointment. maybe i can find one cheaper before then.
Title: Re: exhaust manifold gasket hard to replace?
Post by: captsteve on August 22, 2012, 05:52:57 PM
The shop I use is a local tire shop that does mechanic work. His bay is just big enough to get the front inside to do engine/ trans work.

I have known the owner for years and get treated extremely well there.

Hope you can find someone like him. He fits me in anytime I need him!

Steve

PS. no broken bolts, the gaskets were just worn to the point they were gone on the rear cylinders.
Title: Re: exhaust manifold gasket hard to replace?
Post by: farmer dan on September 11, 2012, 11:24:54 AM
I got my MH in the shop picking it up tomorrow. Shop was under the quote so i am super happy. Only 340 instead of 450. So shouldn't be anymore exhaust leaks. Now to get it home and pack it for the in-laws to take Saturday to the races. Thanks for all your comments. I ordered some kroil but it came the day after I dropped it off. I coated it twice with pb blast cause that's all I had. I don't think I had any broken bolts as they expected I did. I will llet you all know tomorrow
Title: Re: exhaust manifold gasket hard to replace?
Post by: HueyPilotVN on September 15, 2012, 10:19:01 PM
I had a 96 Dutch Star with the F53 460 ford engine.  They were known for either exhaust leaks or cracked exhaust manifolds.  I think one of the explanations was that after pulling a long grade the maniford would heat up and then cool down too fast as you went down the hill.  I replaced the stock manifold with headers, solved the problem except It needed a special gasket and bolts.  I also had to retorgue the manifold bolts after so many miles.  Just mentioning it because you might also need to check the bolts after awhile to prevent another leak from loose bolts.

I am glad you found a good price.  The first time I replaced the manifold the head did break in the rear section and I had to get two new heads, be careful with that back bolt.
Title: Re: exhaust manifold gasket hard to replace?
Post by: farmer dan on September 16, 2012, 10:57:39 AM
Well I got it back. Sorry it took so long to respond. Wife start an overnight job so life had been crazy. RV is much quieter. Feels like more power. It certainly runs cooler. makes sense what you said about hard climbs then quick cool downs. We did that on our trip to Luray V.A.  just off  I-81. we did a 20 minute climb and the poor engine heated up. When we crested the top the gauges quickly dropped. Is there anything one can do different to keep it from heating up then cooling too fast?
Title: Re: exhaust manifold gasket hard to replace?
Post by: captsteve on September 17, 2012, 12:57:23 AM
Well I got it back. Sorry it took so long to respond. Wife start an overnight job so life had been crazy. RV is much quieter. Feels like more power. It certainly runs cooler. makes sense what you said about hard climbs then quick cool downs. We did that on our trip to Luray V.A.  just off  I-81. we did a 20 minute climb and the poor engine heated up. When we crested the top the gauges quickly dropped. Is there anything one can do different to keep it from heating up then cooling too fast?

I would try downshifting a gear on the downhill side. Keep the RPM's up for a bit.
Title: Re: exhaust manifold gasket hard to replace?
Post by: gwcowgill on September 17, 2012, 08:00:44 PM
downshifting just puts more cold air through the exhaust as you close the throttle plates, no fuel entering the engine therefore no fuel to burn thus no heat. I don't know any way to slow the cool down. This is an inherent problem with gas engines. Diesel engines do not run as high exhaust temp so normally they don't seem to have the problem as often.
Title: Re: exhaust manifold gasket hard to replace?
Post by: 85Itasca22RC on September 20, 2017, 04:03:04 PM
I know this is a very old post but I just joined the forum. I thought I would reply in case anyone arrived here on a google search, as I did. I have browsed the RV forum community and everyone here is very helpful and informative.

On the topic of exhaust manifolds: I have an 85 Itasca Sunflyer 22RC (Class A) built on the Chevy p30 chassis with a 454 engine. I bought this RV very inexpensively because it needed some work, which included the exhaust manifolds. Both were cracked and only held on to the block by the bolts.

I paid a mechanic I trust to do the work, and it was $25.41 for one gasket set and $309.40 for the cost of each manifold. I am not sure what brand manifold he installed and I can't tell you the exact labor costs because he did it along with a bunch of other work. Hope those part price references help a little.