Exhaust manifold ??

[hooverfish]

Stopped at a muffler shop to diagnose my exhaust leak. I thought it might be the doughnut gasket since the sound was coming from that area on drivers side under the hood. This is a 72 350 automatic with stock manifolds.

They said exhaust manifolds were warped, needed to be replaced, on both sides.... 2 x $276 for manifolds, plus $400 labor.... grand total of $998.

I asked about just replacing gaskets and they said they "would only last 3 days".

Should I go somewhere else ?? just replace gaskets myself ??

[truckster]

I definitely wouldn't be paying $1k for new manifolds. Manifolds can warp over time, but I think you're being taken for a ride. Go to another muffler shop, or pull the manifolds yourself and check them.

[geezer#99]

Look here.
Find some that fit and do it yourself.
https://www.summitracing.com/int/par...-501/overview/

[Orange67]

I agree. You can easily enough pull the manifolds and take a straight edge to them to verify if they are warped.

Personally, I doubt they are. Most likely the shop didn't want the work, so they jack the price up to turn you away. I worked in autoglass for 15 years, and there were a few shops that would do that especially on the older vehicles. I actually saw a guy tell a customer with a truck like ours that the chrome grooved gasket was no longer made, all because he didn't want to deal with installing it.

[prodjay10]

Do it yourself. I believe the manifolds can be milled if they are warped and welded if they are cracked at a machine shop. It's really not that difficult. I think the hardest part will be taking the nuts and bolts off around the donut.

[GRX]

Exhaust manifolds can & do warp. As mentioned, take them off and check with a straight edge if possible.

They are usually very hard from many heat cycles, so surface grinding is most always a better option. That said ... I resurfaced many many on a large floor standing belt sander.

[garyd1961]

I'm not saying it can't happen but in 40+ years of working on these trucks and other vehicles I have never seen a warped exhaust manifold. I've even seen them run without gaskets and not leak. I have seen quite a few cracked manifolds though.

[72 Super]

Never say never, but I've never seen one warp let alone both. If it was me I would definitely try $10.00 worth of gaskets and a couple hours of time first.

Ray

[hooverfish]

Thanks for the replies and help.

Definitely going to buy gaskets and replace the noisy side (left) first and see how that does.

[jerry moss]

Originally Posted by garyd1961

I'm not saying it can't happen but in 40+ years of working on these trucks and other vehicles I have never seen a warped exhaust manifold. I've even seen them run without gaskets and not leak. I have seen quite a few cracked manifolds though.

manifolds do warp but the mistake a lot of guys make is using gaskets between the manifold and the head, they will leak sooner rather than later if you use gaskets. have the manifolds surfaced, clean the head surface and bolt them back on without gaskets. before a bunch of you guys/gals jump on me for my statement let me explain, i've been in the same muffler shop since 1985 and this is how we do them and i've never had an issue unless the head itself is damaged. start from the center out and torque the bolts to 35 ft.lbs. if you want to see serious warpage buy a dodge product with a 4.7 or 5.7, if the valve seats don't fall out first they will break the end bolts of the manifolds and warp very bad !!!!!!!

[hooverfish]

Found my problem, big cracks right down the middle. No wonder it kept getting louder.
Thanks again for all replies/input. I'm learning a lot through this.

[davepl]

I've seen them crack, I've seen ears break off them, but I've never seen them warp. And both sides?

I'd check them against a good straightedge, but I have my doubts that you'll find them both warped. It's possible, of course.

Edit: Just saw the picture. Yep, "that's yer problem right there", as they say...

[truckster]

Duct tape should take care of that...

[engineer_gregh]

Larry the same thing just happened to my neighbors 72. He ordered his replacement from Rock Auto. Just know that if you order from Rock Auto the replacement will have the ports for emissions plugged with bolts.

[hooverfish]

Originally Posted by davepl

I've seen them crack, I've seen ears break off them, but I've never seen them warp. And both sides?

I'd check them against a good straightedge, but I have my doubts that you'll find them both warped. It's possible, of course.

Edit: Just saw the picture. Yep, "that's yer problem right there", as they say...

Checked with straight edge and do not believe they are warped, just cracked. Thanks

Originally Posted by truckster

Duct tape should take care of that...

Right ....

Originally Posted by engineer_gregh

Larry the same thing just happened to my neighbors 72. He ordered his replacement from Rock Auto. Just know that if you order from Rock Auto the replacement will have the ports for emissions plugged with bolts.

Thanks for the heads-up Greg.

[LongBox]

If this was my problem, I 'd be relieved about now. It's a simple cracked manifold. Wrecking yards that have older vehicles should be the first shopping point. That same manifold may have been used on other trucks and cars, and is probably not very expensive used. Take the straight edge to the yard, and a long extension bar for your socket set. Doesn't matter if you break a bolt or stud...

[garyd1961]

I would find another muffler shop.

[jerry moss]

Originally Posted by garyd1961

I would find another muffler shop.

no shirt, if they couldn't see that i'd hate to see their exhaust work.