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Discussion Starter · #1 ·
I just had a new exhaust manifold installed on my 1982 280ZX for $760.00 Does that seem to be a fair price? It sure did make my car run a whole lot better. Can someone explain to me why it runs better. Thank You!

Lisa
 

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Discussion Starter · #2 ·
> I just had a new exhaust manifold installed
> on my 1982 280ZX for $760.00 Does that seem
> to be a fair price? It sure did make my car
> run a whole lot better. Can someone explain
> to me why it runs better. Thank You!

> Lisa
Lisa,
The L6 Motor has a habit of warping and pulling away from the back cylinder. Essentially, this creates a big exhaust leak. No car runs well with an exhaust leak, they all seem to like some back pressure. I think the part cost about $170.00 plus the gasket and labor so I suppose that it would be a fair price for a dealer to charge. You might consider finding a Z specialist in your area for a better deal. A Z specialist might have tried to find you a good used manifold. That might have saved you more than $100.00 Oh well, next time.
 

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> I just had a new exhaust manifold installed
> on my 1982 280ZX for $760.00 Does that seem
> to be a fair price? It sure did make my car
> run a whole lot better. Can someone explain
> to me why it runs better. Thank You!

> Lisa

Lisa, at the risk of being rude, you need to find a new mechanic, you're in here all the time telling us about what expensive repairs you've just paid for on a relatively old car. I think he's taking advantage of your lack of knowledge on cars. Yes the exhaust manifolds warp over time, but you can have the mating surface machined and reuse the old one 99% of the time, Or as an alternative you can replace the studs that hold the manifold on at the ends with higher grade material bolts, crank those tight, and it's usually sufficient.

Again, lose the mechanic he's robbing you it sounds like to me.
 

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Discussion Starter · #4 ·
Zebra

> Lisa, at the risk of being rude, you need to
> find a new mechanic, you're in here all the
> time telling us about what expensive repairs
> you've just paid for on a relatively old
> car. I think he's taking advantage of your
> lack of knowledge on cars. Yes the exhaust
> manifolds warp over time, but you can have
> the mating surface machined and reuse the
> old one 99% of the time, Or as an
> alternative you can replace the studs that
> hold the manifold on at the ends with higher
> grade material bolts, crank those tight, and
> it's usually sufficient.

> Again, lose the mechanic he's robbing you it

He showed me the crack in the old one. Can that be repaired? The new manifold was 245.00 and the remainder was labor, studs and gaskets. Should I have had him repair the old one?

Lisa
> sounds like to me.
 

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Discussion Starter · #5 ·
> Lisa,
> The L6 Motor has a habit of warping and
> pulling away from the back cylinder.
> Essentially, this creates a big exhaust
> leak. No car runs well with an exhaust leak,
> they all seem to like some back pressure. I
> think the part cost about $170.00 plus the
> gasket and labor so I suppose that it would
> be a fair price for a dealer to charge. You
> might consider finding a Z specialist in
> your area for a better deal. A Z specialist
> might have tried to find you a good used
> manifold. That might have saved you more
> than $100.00 Oh well, next time.

I agree with Rob Sime, but let me add a couple of generally unknown facts. First, the service writers at most car dealerships are on commission, which means the more they soak you for parts and labor the more they put in their pockets. You probably paid a fair dealership price for a stock header, assuming that's the kind you were sold, but I paid around $160 + $12.40 state sales tax for my Motorsport headers and $120 to have them and a set of pipes installed at the local wrench's emporium. A total of $292.40 beats the price you paid a dealer all over the place. The second ugly fact about dealerships is that in most states they can repair or replace anything they want and charge you the maximum for it once you sign your name to their estimate. That means if you come in for a fan belt they can install a whole new drive train and you've got to come up with the money pronto or they'll file a mechanic's lien and poof, like that your car is gone. That's why it's a good idea to find an independent shop, like Rob says.
 

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Re: Zebra

> He showed me the crack in the old one. Can
> that be repaired? The new manifold was
> 245.00 and the remainder was labor, studs
> and gaskets. Should I have had him repair
> the old one?

> Lisa

If it's cracked enough to see it that's a little different, (not a good thing obviously) but most of the time they just warp. Going by that I don't think the price was unreasonable, I don't believe you can weld the exhaust manifold and have it work, but I may be wrong as welding's not my strong suit. The only thing I would possibly question was paying so much for one. You should be able to find one at a junkyard for next to nothing, and usually aside from the small amounts of warpage they're pretty reliable.
 

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Re: Zebra

> If it's cracked enough to see it that's a
> little different, (not a good thing
> obviously) but most of the time they just
> warp. Going by that I don't think the price
> was unreasonable, I don't believe you can
> weld the exhaust manifold and have it work,
> but I may be wrong as welding's not my
> strong suit. The only thing I would possibly
> question was paying so much for one. You
> should be able to find one at a junkyard for
> next to nothing, and usually aside from the
> small amounts of warpage they're pretty
> reliable.

Zebra, you are right in guessing that way. Most don't know enough about the cast to know that it can be fixed. That is even the $40 an hour welder. The manifold is a cast item and can me repaired with welding. With cast welding a higher heat system is required to help with the impurities of foreign cast. Foreign cast is not just iron it is a blend of everything. Once welding at a high heat the item would have to be checked for straightness and might need machining. And depending on where the crack is it might need some internal grinding also to free the flow after the weld. Oh well nothing like money spent and money lost
 

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Re: Zebra

> If it's cracked enough to see it that's a
> little different, (not a good thing
> obviously) but most of the time they just
> warp. Going by that I don't think the price
> was unreasonable, I don't believe you can
> weld the exhaust manifold and have it work,
> but I may be wrong as welding's not my
> strong suit. The only thing I would possibly
> question was paying so much for one. You
> should be able to find one at a junkyard for
> next to nothing, and usually aside from the
> small amounts of warpage they're pretty
> reliable.
Just saw your message and response. Seems you know a little about the situation. I've got 2 zx's with the problem. ??? Trust the machine shop to see if the manifold is salvagable or just plan on replacing with new. What are the odds?
 

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Re: Zebra

> Just saw your message and response. Seems
> you know a little about the situation. I've
> got 2 zx's with the problem. ??? Trust the
> machine shop to see if the manifold is
> salvagable or just plan on replacing with
> new. What are the odds?

Well, i'd have them grind/mill the mating surface that goes to the head so it's flat. As casper stated above there may be some twist and you could have trouble lining up the downpipe and attaching it. I think the shape of the manifold makes it prone to bending away from the head on the ends and usually this is all ya need. I also would recommend replacing the studs at the very ends of the manifold with socket head grade 12.9 cap screws (and make sure they have the 12.9 on them or you could be asking for trouble) Use anti-sieze on all the manifold studs (whether it's the cap screws or the nuts if you have to take it off in the future you'll be very glad you did it) You may even wish to replace both the endmost studs with the cap screws, I just did the ends and so far they're holding up great. Keep in mind that the studs are there for a reason and you probably don't want to replace em all (makes mounting the manifold a real bitch if you don't have some studs on there) but I personally think the material is too weak on the end ones, and after so many thermal cycles, the low grade metal used in the studs just gives out and they pop off. 12.9 grade cap screws on the other hand are made for heavy duty clamping loads and will last alot longer. Also, invest in some hardened steel washers for use with the socket head screws, and if they don't have metric available, use 5/16 ID washers as it's interchangeable with 8mm bolts (plus it seems like 90% of the bolts on a Z are 8mmX1.25thread pitch anyways, so you'll find other places to use em. Finally when you do put it together, Torque it with a torque wrench, this way the load is consistent, plus you won't put yourself at the risk of snapping studs or stripping threads (both of which can make an otherwise simple operation into a big pain in the butt)
 

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Discussion Starter · #10 ·
Re: Zebra

> Well, i'd have them grind/mill the mating
> surface that goes to the head so it's flat.
> As casper stated above there may be some
> twist and you could have trouble lining up
> the downpipe and attaching it. I think the
> shape of the manifold makes it prone to
> bending away from the head on the ends and
> usually this is all ya need. I also would
> recommend replacing the studs at the very
> ends of the manifold with socket head grade
> 12.9 cap screws (and make sure they have the
> 12.9 on them or you could be asking for
> trouble) Use anti-sieze on all the manifold
> studs (whether it's the cap screws or the
> nuts if you have to take it off in the
> future you'll be very glad you did it) You
> may even wish to replace both the endmost
> studs with the cap screws, I just did the
> ends and so far they're holding up great.
> Keep in mind that the studs are there for a
> reason and you probably don't want to
> replace em all (makes mounting the manifold
> a real bitch if you don't have some studs on
> there) but I personally think the material
> is too weak on the end ones, and after so
> many thermal cycles, the low grade metal
> used in the studs just gives out and they
> pop off. 12.9 grade cap screws on the other
> hand are made for heavy duty clamping loads
> and will last alot longer. Also, invest in
> some hardened steel washers for use with the
> socket head screws, and if they don't have
> metric available, use 5/16 ID washers as
> it's interchangeable with 8mm bolts (plus it
> seems like 90% of the bolts on a Z are
> 8mmX1.25thread pitch anyways, so you'll find
> other places to use em. Finally when you do
> put it together, Torque it with a torque
> wrench, this way the load is consistent,
> plus you won't put yourself at the risk of
> snapping studs or stripping threads (both of
> which can make an otherwise simple operation
> into a big pain in the butt)

Everybody's right, if you're determined to have a stock manifold. Of course, if the stock casting is cracked and you're going to weld it, it'd be a real good idea to fluoroscope the thing before and after the work to make sure there are no more cracks in it. Personally though, since I'm not a fanatic about keeping my '82 coupe 100% stock, I just went for a set of aftermarket headers. They're much lighter and cheaper, they work more efficiently and they're no more fragile or short-lived than stock units. As a grim afterthought, I'll bet there are a lot of guys on this site who'd have sent you their old stock headers cheap just to get rid of the things.
 
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