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8.3L Exhaust Manifold Leak Repair Cost

May 20, 2023, 01:22:57 pm

Hey Guys,

I'm trying to help a potential new owner do a pre-purchase inspection on a '93 GV in Oregon.  Talking to him long distance by phone and text.  The most serious thing he has found so far is a fairly substantial exhaust leak at the base of the manifold.  Sounds like a warped manifold or blown out gasket.  He is wondering about the cost to repair or replace the manifold.  I've not had the pleasure so I can't advise.  Looking for wisdom from the collective:  what might be a ballpark dollar and/or time estimate for this repair?

Also he is asking if he can drive the coach from Oregon to Las Vegas before he gets exhaust leak fixed.  I said I don't know.  Any advice?

Thanks for any help!

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #1 – May 20, 2023, 02:02:41 pm

If he was near me we could do the job here but,probably depends how bad the leak is,I would keep it at minimal RPM,can he do
the job himself,it's just taking rusted blts apart and putting new manifold back on.

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #2 – May 20, 2023, 02:23:38 pm

Problem is he and his partner flew from Nevada up to Oregon to look at coach, so no tools and no place to work.

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #3 – May 20, 2023, 02:26:31 pm

The problem being with trying to estimate a cost is how many broken bolts? Cummins manifold bolts gaskets 12-1500.00 in parts plus labor. I'd did mine aftermarket parts 400.00 parts no broken bolts 5 hours labor. I will almost guarantee broken bolts!

Depends on how bad the exhaust leak is, a bad leak will cause a loss in boost/power. If I were buying the coach and going to outsource the repairs I'd get it done locally, before leaving if possible.

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #4 – May 20, 2023, 02:43:15 pm

So it has been operating in this condition for awhile already. Would have to be able to evaluate in person, but I would probably drive it home as long as it is not causing any damage. It's anyone's guess how the repair will go. May have been apart before and reassembled without anti seize resulting in every bolt breaking off. May come apart uneventfully? I personally would replace all hardware with factory OEM even if I was using a aftermarket manifold. Use rated anti seize. Use an accurate torque wrench. Does he have a real reference on just how bad it is leaking or is he looking at 50K miles of staining? So many variables. I always prefer to be at home waiting on parts that are back ordered than on the road, not to mention tooling support being home.
How many miles?
Scott

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #5 – May 20, 2023, 02:49:33 pm

Quote from: dsd – May 20, 2023, 02:43:15 pm

How many miles?

He reports eighty something thousand miles on the odometer.  Seems kinda low miles to be having exhaust manifold problem.  My identical model year engine has 190,000 on the original manifold.  Defective part from the factory build?  Who knows...

The coach is advertised on the Grand Villa Facebook page by Captain Scott Hays Whittaker in case anyone is curious.  Scroll down the opening page to below the photos of a coach on fire.

Redirecting...

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #6 – May 20, 2023, 04:30:32 pm

Mine was 1300 bucks. 10 years ago.

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #7 – May 20, 2023, 07:08:50 pm

I had a manifold leak on our M-11.  I am guessing it is similar.

I sprayed the bolts with CRC Freeze Off and warmed the engine - several cycles over a week.  Every bolt came loose.  The fix was new head-to-manifold gaskets.  I was able to do this without removing the manifold, the turbo, etc.

Total cost was maybe $100-ish.  I will see if I can find my write-up.

Edit:  Found it!  Hope this helps.

My M-11 exhaust manifold gasket replacement

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #8 – May 21, 2023, 01:40:32 pm

Assuming its an 8.3 cummins, a common problem is the shrinking manifold syndrome.  Newer rigs have a 3 piece manifold that allows for shrinking and expansion, unfortunately not retrofittable.  When the manifold shrinks it tends to fracture studs.  I did mine....a tough, out of position job and several studs broken despite heat penetrant impact etc.  In retrospect I should have pulled the manifold. refaced ports drilled oversize holes and reinstalled with new gasket.  A new, green cast manifold will shrink just like the old one.

This is a good job to farm out to an experienced truck shop.  Insist they use genuine Cummins studs with Nickle/moly 2500 degree neverseize.  Buy your own can if necessary, Amazon sells it.

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Re: 8.3L Exhaust Manifold Leak Repair Cost

Reply #9 – May 21, 2023, 03:54:30 pm

I replaced the exhaust manifold also at 100,000 miles last winter because of one broken bolt.  Purchased aftermarket manifold reinforce between exhaust ports, maybe that will help with the shrinkage factor and snapping bolts. Replaced all hardware including turbocharger studs and gaskets with genuine Cummins parts @ $400. I farmed it out to a local truck shop they SAID they broke seven bolts, should have asked to see them. I soaked them with all the recommended juices with heat cycles for weeks before removal.
3929779 | Cummins C8.3 Engine Exhaust Manifold for Sale

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