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Open Roads Forum  >  Tech Issues

 > Workhorse 8.1 GM exhaust gasket replacement

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Vacationer04

Arnold,MO

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Posted: 09/29/19 11:22pm Link  |  Quote  |  Print  |  Notify Moderator

My 2004 HR 36' MH (Workhorse - 8.1L GM) has a bad gasket between the exhaust manifold and the cylinder head only on the passenger. It does not at present have any broken studs or manifold but they are rusty enough that I do not have any confidence that I can get them off intact myself.
I have called about every place that I can locate that does truck service but I get told that it's too big, too old, or it's a Workhorse with the reputation of broken studs and manifolds. Has anybody used a place near St. Louis for this kind of problem? I had planned to acquire an Ultra Tuning ECM but after talking with them and giving them the scanner data I discovered an exhaust leak that was not audible until checking fuel pressure with the doghouse open. I was advised that the ECM would not be an improvement to my low performance until the repair causing it to run lean was corrected.
Help! I'm at my wit's end with frustration, unable to get anybody to consider my dilemma. I believe an acetylene torch would break the rust but I have no access to one.


Jim & Linda E.
'04 Holiday Rambler Vacationer 36WDD, 2 slides
'03 Honda CR-V EX Awd
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bucky

Raleigh metro

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Posted: 09/30/19 05:06am Link  |  Quote  |  Print  |  Notify Moderator

A local welding shop may be your best bet and there are some that will come to you. They cut, fabricate, and weld and will have the proper cutting tips for their equipment to remove your manifold.


2005 Cummins 2500 2WD LB quad cab pulling a 2007 Jayco 345bhs.


sayoung

Tx

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Posted: 09/30/19 12:00pm Link  |  Quote  |  Print  |  Notify Moderator

Any good muffler shop should be able to remove the manifold. I would go ahead and have both sides done while they have it. If you were comeing near me here in Tx my BiL shop would do it .

Bipeflier

Centralia, MO

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Posted: 09/30/19 12:36pm Link  |  Quote  |  Print  |  Notify Moderator

Have you tried one of the larger GM dealerships?


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77rollalong

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Posted: 09/30/19 03:56pm Link  |  Quote  |  Print  |  Notify Moderator

I find the easiest thing is to use the torch and blow the nut off flush with the manifold, then remove the manifold, then you can remove the studs from the head,, most of the studs now are 8mm, trying to undo them you are more than likely to break them off, then get new studs and nuts.. as they are cheep insurance...

wa8yxm

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Posted: 09/30/19 04:49pm Link  |  Quote  |  Print  |  Notify Moderator

You can torch 'em but I'll give you a different warnign in a bit

I went to a place out east and paid over 400 cause they said one of the bolts was stripped and would not come out so it took 'em hours to remove that stud. at worst a 30 minute job for me and I'm not a certified mechanic (But I've done that kind of thing) OH well.

They put in a fiberious gasket (They come in two types Fiber and Slintered Metal) that lasted 3 days.

The next shop (American RV, Burton MI) put in the proper metal ring gasket and that was 1.5 years ago now.


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Ava

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Posted: 09/30/19 07:10pm Link  |  Quote  |  Print  |  Notify Moderator

The exhaust bolts on my old Cummins have a good portion of the bolts exposed. I heated the engine good then melted an ice cube on the exposed part of the bolt. They all came off without any problem.

JerryBQ500

Anoka MN

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Posted: 10/01/19 07:01am Link  |  Quote  |  Print  |  Notify Moderator

I did my 8.1 two years ago. Heat each nut on the exhaust manifold
red hot and they will come right off. I had an engine machine shop
plane off the manifold for $40. Only the right side manifold was bad on mine. Retired after 40 years as a auto and truck mech.


JerryB

Vacationer04

Arnold,MO

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Posted: 10/10/19 02:46pm Link  |  Quote  |  Print  |  Notify Moderator

I finally found a place that would take me in. It didn't turn out as planned. After dropping it off 40+ miles away, they called to let me know that a brake line had ruptured and was leaking brake fluid on their shop floor.
Ok. Maybe I dodged a bullet there but? They had it a week before calling to tell me I could pick it up.
When I arrived, I got told they had to replace my newer lifetime warranty spark plug wires because they were rotten upon removal from the plugs. I had just replaced the plugs a few weeks ago and they were fine then. When I raised an objection to that issue they credited back the cost of the new wires. But they also destroyed my woven boot heat shields that I will have to eat the cost of. My opinion is that they tried to torch the RH manifold nuts without removing the wires first.
When starting to leave the engine had a miss and upon my own inspection, I found 2 wires on the other bank not on the plugs but just shoved in beside them. After I got home, I went to replace the heat shield that I took off while diagnosing the exhaust leak. When I tried to unplug the "new" wires with spark plug boot pliers the right way, on 2 wires the boots just shredded which now will require me again buy a new set of wires. I was taught years ago to use die-electric grease inside the boots on both ends before installing them on the plugs, which was not done by them. At least no broken studs needed to be replaced.
The replacement brake line looks like a blind guy did it the way it was routed. It will function right but looks like hell. My total cost was $947. I wasn't told they automatically add a 2% credit card fee. I found that out after getting in my coach to leave. No Posted Notice to warn you in advance.
My point here is to warn RVers in the area to avoid COMPLETE AUTO & RV REPAIR in St. Charles,MO. Their website looks impressive and the shop looks good, lots of Class As on their lot, but workmanship is less than acceptable.
If I could have gotten access to a torch I could have done this repair myself, so I learned to look farther for assistance in the future.

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