Jump to content

IGNORED

intake exhaust gasket help


Recommended Posts

I am planning on replacing the manifold gasket on my 77. Any advice from those who have done this before? I plan on giving all of the bolts a liberal soak with PB blaster the day before. What brand of gasket is best? What snags should I expect? ect.

Link to post
Share on other sites

I did this when I changed the head a long time ago. If I recall I applied anti-seize to all mating parts of the gasket. I think Norm or someone on Zcar.com suggested this. Maybe use the higher temp copper blend. My memory is poor so I vaguely recall a metal side to the gasket and I think I put it against the head so that water/rain does not cause it to rust.

Take your time with the bolts on the studs and note where all of the thick compensating washers go. There are some related photos in this post that can help: http://www.classiczcars.com/forums/showthread.php?42420-77-280z-head-removal-step-by-step-photos

Also drain some rad fluid if you have to take off he thermostat housing.

Link to post
Share on other sites

Funny, I already saved that article you wrote to my favorites two weeks ago. I was wondering about anything that I may need to apply to the mating surfaces. I used a copper spray when putting head gaskets on my Kh400 but that was a two stroke motorcycle.

Edited by grantf
Link to post
Share on other sites

Just read a few other tips:

The copper spray is permanent and not necessary.

Some have used the Nissan Gasket with a sealer that is built in/on it. they report they could remove manifold many times w/o problems (post race inspections for porting)

Many recommend changing studs and nuts (I believe Ace hardware has studs in their metric section if you are stuck).

Link to post
Share on other sites

Changing the mounting hardware makes sense especially the exhaust. looking up the Nissan part now.... cannot find genuine Nissan gasket. Nippon Reinz?

Edited by grantf
Link to post
Share on other sites

I used a FelPro gasket with no metal inerts for a stock intake/exhaust manifold refit on my '75 280 (no headers) with a little spray-on copper gasket sealer, lightly applied around the port openings. I let it set up for a few minutes to get tacky. It worked great. I've found that 12mm Toyota exhaust manifold bolts are good replacements for the stock nuts & lock washers. They have a flared base & notching around the top. I don't why the design seems to work so well, but it's a great fastener for high temp areas like the exhaust manifold. I use a little locktite, which I'm not certain is needed because it might get baked away. Those Toyota fasteners don't seem to get "cooked" or rust as much as the stock nuts do. They could made of a different alloy or something?

Link to post
Share on other sites

I'm in the camp of replacing all hardware whenever possible. If you don't, then it will continue to rust/corrode/fossilize in place, and a stud that is merely difficult to remove now may be impossible to remove later -- at least without drilling, helicoiling, or whatever.

MSA sells a stud/bolt/nut set that worked quite well for me. I also used whatever gasket it was that they sell. I sprayed with Copper spray and rimmed the intake and exhaust holes with a tiny bit of Permatex sealant, per ZTrain's suggestion. So far everything is tight and happy. It's been about a year now.

If you do decide to extract and replace studs, you'll probably need to blow-torch the more stubborn ones, spray with PB Blaster as they cool, and then turn them out CAREFULLY with either two nuts jammed on the stud or with a SHARP/NEW pair of vice grips. It's essential that you take your time. Chase out all the threads with a tap. Use Nickel Antisieze on the new hardware. You might also pull off your thermostat housing while you're doing work there.

When chasing out threads, beware that the forward thermo housing bolt screws into the timing chain area just beneath the backside of a timing chain guide. You shouldn't chase out those threads unless you've got the valve cover removed and are watching the backside of that hole. You don't want to bend that guide! Also, when chasing out the threads, remove the tap frequently to clean it. Take your time. You don't want a jammed tap because you were too lazy to pull the tap out frequently enough!

Oh, finally, you need to know that 1 day soaking with PB Blaster isn't enough. You probably need to be soaking that stuff for a week or more. Also I've seen some test results, and Kroil is a much better penetrant. The BEST penetrant seems to be the home brew of 50% acetone and 50% ATF. I've never used it, but the test results I saw were very persuasive.

It's a heck of a job to do, but if you take your time, you can do it. :-)

Edited by FastWoman
Link to post
Share on other sites

Thanks fastwoman, I am familiar with tapping holes in steel and aluminium. We use Kroil at work, Great stuff but it seems a can stops dispensing after 1/4 use. I don't know why.

So now I am getting ready and I am F%&%&CKing stuck. the @$#%#!$% heat shield is in the way and it appears to be bolted to the underside of the intake. Any suggestions? my hands are not large but I can only just get them in far enough to touch the bolts.

Link to post
Share on other sites

I just did this yesterday on my carburated Z. There are no snags to worry about, it's just time consuming, it took about four hours including picking my kids up from school. The gasket I got was the stock gasket for a fuel injected Z so I did not use any sealer. If it was a paper gasket I would use copper spray, the old one was like that and it lasted for about 6 years.

Link to post
Share on other sites

I think this is more difficult as my Z is fuel injected and there is no way to get at the heatshield bolts. :angry::angry::angry:

I was thinking of using copper spray, still thinking....

Link to post
Share on other sites

If you can remove all of the hold down washers and the bolts on top of the manifold you should be able to remove the intake manifold with heat shield still in place.

Link to post
Share on other sites
If you can remove all of the hold down washers and the bolts on top of the manifold you should be able to remove the intake manifold with heat shield still in place.

No way.

Link to post
Share on other sites

The four top bolts are accessible. most remaining are not. The intake manifold on a 280z shares some bolts/studs with the exhaust manifold.

I have stopped being a baby and managed to remove to heat shield. There was no mention of this problem in my search on this sight or elsewhere. So if anyone else runs into this dilemma I have a few tips. first remove any component you have to first, such as the PVC tube, the AFM and boot etc. Second the heat shield is in two parts (my stupid). if you can, remove the lower heat shield first (rusty phillips machine screws). and finally take your time, use bad language, don't think about barking you're knuckles or scratching you're forearms raw for four 12 mm bolts (use a wrench, sockie no fit).

Link to post
Share on other sites

Grant, yes, you've got a lot of heat shield under there. I honestly can't remember how it all bolts up. (It's been a year.) However, I do remember all the heat shield bolts are easily accessible. The hard part is FINDING them. Your best friends will be a good drop light and a small hand mirror. You'll also need to remove the shielding around the brake master to get the EGR stuff loose, so you may as well remove that now if it's in your way.

In general, if you can't free a bolt with Kroil, heat, tapping, gentle persuasion, and the requisite swear words, your only option will be to ring it off and deal with it later. You'll probably have to "give up" on a few fasteners to get the job done. That said, my heat shielding came off just fine. The real problem points for me were the manifold studs near the front of the engine (from chronic coolant seepage) and a few bolts on the top of the manifold that held down brackets and emissions stuff. I think my corrosion was probably about as bad as it gets.

Link to post
Share on other sites

Grant, I just re-read your post. I now see you're talking about the heat shield BETWEEN THE MANIFOLDS. Right? (I thought you were talking about the exhaust shields hanging down below.)

OK, this is easy: You don't remove that one! Believe it or not, you can slip a socket with two extensions right underneath it. Just get some light under there, and peer in sideways with a mirror. You'll be able to see all the studs shared between the intake and exhaust manifold -- the ones with the big hold-down washers. As I recall, it's a bit of a squeeze to get to the forward-most one, and it's necessary to flex the heat shield just a bit, but your drive will fit in there, possibly with one long and one short extension, as I recall.

Link to post
Share on other sites

I got the manifolds removed today. The bolds and nuts seemed to easy to remove like they were not torqued down at all. the old gasket was in pretty bad shape, it looked as though someone in the past had removed the manifolds and reused the gasket damaging it in the process and there was a piece missing from cylinder one's exhaust. This makes me happy in a way as I feel I am doing this for a cause instead of a hunch.

post-17660-14150815957434_thumb.jpg

post-17660-141508159582_thumb.jpg

Edited by grantf
Link to post
Share on other sites

Wow, congratulations! Yours was a LOT easier than mine. I'd recommend you replace all the fasteners, whether they look like they need it or not.

I sprayed both sides of my gasket with this:

http://www.google.com/products/catalog?q=copper+gasket+spray&rls=com.microsoft:en-us:IE-Address&oe=&um=1&ie=UTF-8&tbm=shop&cid=7438551903716389274&sa=X&ei=3ctHToDXC6ipsAKJypDXBQ&ved=0CC4Q8wIwAA#

... and then I thinly coated all the port holes on both sides of the gasket with this:

http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers/auto_Permatex_Ultra_Copper_Maximum_Temperature_RTV_Silicone_Gasket_Maker.htm

I don't know what brand of gasket I installed. I ordered it from MSA, and it came in an un-labeled plastic sleeve. It looked reasonably substantial, to my untrained eye.

Wow, if your gasket was as bad as you indicate, this should make a HUGE difference in how your engine runs! :)

Link to post
Share on other sites

Ok, so everything is back together. I fired up the engine and it ran great. Sounded better than before. But as the engine gets hot smoke starts poring out of the engine compartment. "I don't think this is an exhaust leak as I see nothing until the engine gets hot. it will continue to smoke till the engine cools down. I am scared.

Link to post
Share on other sites

Hmmm. I am thinking this was the massive amount of PB blaster I soaked the studs with burning off. By the time I was finished removing the exhaust manifold it was coated in the stuff. Anyone else have a similar experience?

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.