just confirming some stuff, replacing exhaust manifold gasket

[Guest bastaad525]

Well, my exhaust manifold gasket has started to leak again. I think this is the third time. This time I want to take a shot at replacing it myself. Last time my mechanic used Copper Spray on it... I think that might be why it lasted so much longer this time Before they were going out every couple months.... always at the #6 exhaust port.

 

I THINK it's a felpro one... I searched the archives and found a post and a few people mentioned that the felpro ones are notorious for leaking, so I'll get a factory one this time. I hope to god this is the cause of the problem....

 

I have had the problem with the bolts needing to be tightened two or three times, though the last time I checked, only the very last bolt (closest to firewall) was at all loose, only needed to be torqued a little bit, otherwise they were all tight, and that's since the last time I tightened them maybe 6 mos ago?

 

So anyways... just wanted to verify some things, I guess I'm gonna do this myself, don't feel like paying what is sure to be a fortune for a shop to do it.

 

 

#1 okay so definately gonna go with a Nissan gasket this time.... or should I? I seem to remember reading about some performance gasket on here, but don't remember brand name or if anyone had used it and it worked well or not? Doing a search yielded nothing. All I remember was that I think it was an all-metal gasket. Not sure. EDIT: did some more digging and found some vague reference to a copper gasket... but I have NO idea where to get one of these, anyone know who sells these?

 

#2 if using the nissan gasket, should I use copper spray on that as well? Or just use it dry?

 

#3 what about the manifold bolts? Some stuff I read suggested that the bolts are not really meant to be reusable. Though I've reused the same ones the last few times. Anyways, would this need to be a factory part as well? Some of these things getting kinda hard to get thru the dealer... last time I had the head pulled they quoted me a 3-4 week wait for head bolts I ended up getting them from MSA.

 

Would I be able to use some 'regular' bolts from an auto parts store? Would I have to ask for anything specific?

 

#4 should I use loctite on the bolts? blue? red?

 

#5 Do I need to disconnect the oil supply lines to or from the turbo? I don't seem to remember the mechanic disconnecting any of that stuff. What other stuff am I gonna have to disconnect?

 

Well I think that's it... if you guys can think of anything else

[johnc]

#1 okay so definately gonna go with a Nissan gasket this time....

 

Use the Nissan factory turbo gasket.

 

#2 if using the nissan gasket, should I use copper spray on that as well? Or just use it dry?

 

Copper spray and I put a thin layer of Permatex Ultra Copper 700F around each exhaust port on both sides.

 

#3 what about the manifold bolts?

 

Whatever you are using, if they lose torque then they need to be replaced along with any needed washers and lockwashers. Torque them to the factory specs, don't over tighten.

 

Would I be able to use some 'regular' bolts from an auto parts store? Would I have to ask for anything specific?

 

I wouldn't buy any fasteners from an auto parts store. Find an industrial hardware store and get bolts rated at least metric 8.8. BTW... do Nissan factory turbo installations use bolts or studs? Studs are a better choice because the gasket won't slip during the install.

 

#4 should I use loctite on the bolts? blue? red?

 

Buy new lockwashers. This area gets too hot to use Loctite.

 

#5 Do I need to disconnect the oil supply lines to or from the turbo? I don't seem to remember the mechanic disconnecting any of that stuff. What other stuff am I gonna have to disconnect?

 

The diff needs to come out....

[Guest ZagatoZ]

"Before they were going out every couple months.... always at the #6 exhaust port."

 

Have you checked your manifold for warpage? that is definitely not normal.

[Z-Gad]

I would suggest taking your manifold to a cylinder head/ machine shop to true it up prior to install. That should take care of your manifold gasket problems... Oh, and yes, use the Nissan gasket!!

[Guest bastaad525]

I think last time I had the head removed, when I wasn't doing the work, they checked the manifold for trueness and it was fine. I really don't want to pull the whole thing out.

 

I've read a few times that other people have also had problems when using the felpro gasket and switched to the nissan and it never leaked again, so I'm betting that is my problem too, not a warped manifold.

 

If/when I do this (and I think it's gonna have to be me because the shop wants $300!!!!!!!!!) I'm hoping not to pull the exhaust manifold OUT, just unbolt it and move it far enough out to get the gasket off and on. I know I"ve seen the shop do it this way before, not last time when I had the head removed, but the time before that when I was JUST having the manifold gasket replaced to fix a leak. I'm just trying to remember what all they took off... I think they unbolted the upper part of the downpipe from the lower part, and that was about it... I dont remember but I was watching the guy work... I know he didn't pull it all the way out, just away from the head by a couple inches. I'm gonna call the guy and see if he remembers.

[Here comes trouble]

keep in mind manifold bolt tightening tourqe is 10-13 ft-lbs. for size 8 m and 25 to 36 ft-lbs for size 10 m

[Guest bastaad525]

yeah and knowing me, I probably way overtorqued them and that may be causing my leak as well. Since the #6 exhaust manifold bolts are the easiest to get to, I probably torqued them the most, smooshed the gasket, and caused that leak myself. Just like I did on my oil pan gasket.

 

I know I know... I need to invest in a torque wrench *hates being so broke*

 

 

Well my friend just offered me a killer deal, he'll replace the manifold gasket and swap out my '81 distributor for the '82-83 distributor and oil pump shaft for $180 total. In this case, laziness may superceed brokeness as the determining factor

[johnc]

Another very important point:

 

Make sure the head, the intake, and exhaust manifold gasket surfaces are frickin' spotless and scratch free! Use razor blades, brass wool, Scotchbrite, Acetone, MEK, etc. If it doesn't take you at least an hour to clean these surfaces you're not getting them clean enough.

[Guest bastaad525]

yeah especially since I used the copper spray last time... that stuff is a pain in the azz to remove. Learned that when I replaced my pan gasket a couple months ago

 

Sucks about that pan gasket... this time I used Permatex High Tack... I have a feeling that stuff gonna be even MORE fun to remove, then again I think it said somewhere that it's non hardening so shouldn't be too hard to remove? I hope I don't have to find out any time soon.

 

You know... I dont think there are any lock washers on the exhaust manifold bolts. So that's why they keep coming loose? I thought it was the gasket compressing. So it's okay to use the lock washers and have the bolt going that much less in to the head?

 

So no one knows anything about these all metal (copper) gaskets or where to get them?

[dapiper]

Make sure manifold surface true, not warped. Use Victor replacement which has metal flange liners. This allows for expansion without tearing gasket. Surfaces must be clean, no pits; resurface if necessary. Use metal SS flange locknuts on quality steel studs. If they are cad plated, they are probably junk. Align with studs centered in manifold holes. Use no adjunct coatings, or lockwashers which will be rendered useless at 1000 °F. Torque to spec from middle out.

 

Assure adequate ground clearance for remainder exh sys to prevent misalignment if bottom out.

[speeder]

I don't use a gasket.

 

I just make sure that the head and manifold are true and use a good high-temp copper silicone between the two surfaces. This does not burn or blow out in operation, probably due to the fact that the head is water cooled and thus helps cool the manifold flange that is directly in thermal contact with it.

 

This thermal and physical contact reduces movement of the manifold at the contact surface by limiting expansion and contraction, also by providing a more solid attachment by eliminating the soft gasket.

 

As always, any kind of upgraded stud or nut will be a good thing. However, I've always used the stock studs and nuts and found them to be adequate. Again, the head is water cooled, and I doubt that the manifold mounting hardware will see huge temperatures.

 

The "no gasket" technique is an old turbo engine builder's method for sealing cast iron manifolds, and really does work for me.

 

I would not try this on tubular headers unless they have a very substantial (thick) flange.

[Guest bastaad525]

I don't use a gasket.

 

I just make sure that the head and manifold are true and use a good high-temp copper silicone between the two surfaces. This does not burn or blow out in operation' date=' probably due to the fact that the head is water cooled and thus helps cool the manifold flange that is directly in thermal contact with it.

 

This thermal and physical contact reduces movement of the manifold at the contact surface by limiting expansion and contraction, also by providing a more solid attachment by eliminating the soft gasket.

 

As always, any kind of upgraded stud or nut will be a good thing. However, I've always used the stock studs and nuts and found them to be adequate. Again, the head is water cooled, and I doubt that the manifold mounting hardware will see huge temperatures.

 

The "no gasket" technique is an old turbo engine builder's method for sealing cast iron manifolds, and really does work for me.

 

I would not try this on tubular headers unless they have a very substantial (thick) flange.[/quote']

 

Not that I know all the factors involved here, but that my gut feeling tells me this would be asking for trouble.

 

Well I still haven't gotten this done. Luck of luck, my friend was at the JY a few days ago, and actually happened upon a 280zx that had a brand new intake/exhaust manifold gasket, nissan brand, in the box. I just haven't had the time to take care of it, and haven't touched the Z in about a week. Starting to look at upgrades for the Sentra now

[speeder]

No guts, no glory. I used to blow all kinds of manifold gaskets until I started doing it this way.

[Guest bastaad525]

well, considering I already got a Nissan brand gasket, no reason not to use it now. But if I have any problems again I'll give this a shot.

[POSTM]

I have an extra Nissan brand gasket that I could throw in as part trade on the GN I/C, (I’ll throw in a pan gasket to I don’t use them only RTV on the L6)

 

But seriously I have not used exhaust gaskets on any motor since I was 18 years old and my boss chewed on my butt for using gaskets on a SBC. I also fixed many exhaust leaks by slipping the gaskets out and bolting the manifold back up (headers are a different story). Speeder knows what he’s doing. No gasket failure if there is no gasket.

[Guest bastaad525]

I have an extra Nissan brand gasket that I could throw in as part trade on the GN I/C' date=' (I’ll throw in a pan gasket to I don’t use them only RTV on the L6)

 

But seriously I have not used exhaust gaskets on any motor since I was 18 years old and my boss chewed on my butt for using gaskets on a SBC. I also fixed many exhaust leaks by slipping the gaskets out and bolting the manifold back up (headers are a different story). Speeder knows what he’s doing. No gasket failure if there is no gasket.[/quote']

 

 

I'd have jumped on that a week ago, unfortunately i already bought myself a nissan brand gasket. I'm not too worried about using a gasket vs. not using a gasket... I mean if you look around, this gasket leaking is not that common of a problem, unless a) the manifold is warped, or some people have had bad luck with the Felpro ones but had no more problems once they went nissan. I never started having a problem until I started using the felpros, myself. It's so odd, with felpro stuff. For instance, I always use their valve cover gaskets, and NEVER have a problem with leaks, but then, with oil pan and exhaust manifold, I've had nothing but bad luck. *shrug*