Exhaust work sucks...and which way do the manifold gaskets go?

HondaDustR · 10-08-2008, 08:52 AM

Ok, I've found my new "do not want to have to do this ever again" job! Since my car is still down waiting for a transmission, I've decided to do a couple other jobs that have been waiting, including replacing the exhaust manifold gaskets...and it's a good thing the car's not going anywhere, 'cause it's turned into a miserable job.
It could've been worse...the manifold studs actually came out pretty easily. The real monster was the header to y-pipe bolts that were about as stuck as a bolt could possibly get, not to mention they are next to impossible to get a good angle with any kind of tool. Some bolts I had twisted off both the bolt head and the nut, leaving a little stub inside the hole fused to the flanges with solid rust and still could not get it out without dremeling it to practically nothing before it would finally punch out! So I finally got the 1-4 header loose, and could not get it past the heater coolant pipe, so after removing that, still could not get it out! (either they dont come out from the top on a 924S, or my engine mounts are flat as a pancake...) It was already like 11pm and I still had 3 more bolts to grind away at that are not reachable by any normal means, and I'm covered with metal shavings from cutting the others (and the shavings my cutting bit makes are horrible...they stick into your skin and are very hard to get out). I dismounted the 2-3 header from the head and thank God for a missing catalytic converter rubber mount! The whole thing just dropped down about 6 inches...and gave me the idea that dropping the entire exhaust would be alot easier at this point..and it was (Words do not describe the realisation of not having to cut those bolts from under the car)! So now I have an entire assembled exhaust system sitting in the driveway! At least now I can finally get a good angle on the remaining bolts.

So for anyone that says pulling the manifolds are easy, I beg to differ...
I do have some nice (expensive!) stainless steel hardware to put it back together with, but the question is, which way do the new exhast manifold to cyl head gaskets go back on? It all fell apart and I didn't notice. I'm thinking the smooth side faces the head, but I just want to double check.

...and the cyl 4 gasket was leaking pretty good, so I feel alot better that I'm not wasting my time. I have been suspecting a leak for awhile, but not able to definitely prove it.

Schumi · 10-08-2008, 09:11 AM

I'm planning to have some of these welded in specific locations to make dropping the exhaust easier:

http://store.summitracing.com/egnsearch.asp?N=400090+315764+115&autoview=sku

We have used them on formula cars for years. You weld the flanges in place of any bolt connections.

Unfortunately they cannot be welded to the header downpipes as they are made of cast iron. And as you found out the bolts on those triangle cast pieces always seem to be the ones that are hardest to get at/round off easily. I swear I think one of those bolts cannot be accessed with a socket wrench of any type.

flashgordon13 · 10-08-2008, 10:16 AM

I wouldn't use stainless hardware on the exhaust. After it heat cycles a few times it becomes impossible to remove the nuts.

flash968 · 10-08-2008, 10:23 AM

agreed - it also becomes brittle

phoenix_iii · 10-08-2008, 12:01 PM

So what's best on an exhaust? Don't forget anti-seize!

krystar · 10-08-2008, 02:44 PM

i had to use ez outs for my exhaust flanges. and then the entire pipe ripped off from the cat.....yea i still gotta weld that back on.

HondaDustR · 10-08-2008, 05:28 PM

Quote:

Originally Posted by Schumi

And as you found out the bolts on those triangle cast pieces always seem to be the ones that are hardest to get at/round off easily. I swear I think one of those bolts cannot be accessed with a socket wrench of any type.

I think that would be the only bolt left in this picture! Notice the broken off bolt that is in fact broken off at BOTH ENDS! There's just a little stub that is holding the two parts together quite nicely with super solid rust. I had to beat the crap out of it with a hammer to punch it out of the 2-3 header once I got all the others out and cranked the parts apart.

I just remember several times just laying there complete in awe as to why they made this thing this way so that half the bolts, for all practical purposes, are not accessible by any normal means, let alone be able to work them loose if (more like when) they are totally rusted shut. Or just drop the entire system, but only once you've at least got the 1-4 header off!

It looks so cool all in one piece.

Pure art! I need one just for the front yard.

And please can anyone confirm which side of the cyl head exhaust gaskets faces the head?

And just how brittle does stainless hardware get when used on exhaust parts? Just brittle, or brittle enough to possibly break during use? I really don't care if they break if I try to take it back apart someday, I just don't want something that will weld itself to the holes with rust again.

Ritzblitz · 10-09-2008, 02:42 PM

IIRC I put the metal side towards the head.

nynor · 10-09-2008, 02:56 PM

yeah, metal side towards the head.

HondaDustR · 10-09-2008, 08:01 PM

Well, I got it all back together, and did not end up putting the metal side towards the head.

I looked at how the old cyl 4 gasket was squished, seeing that the slot shape for the far back bolt hole had pressed against the metal side, so I just put them in the way the old ones came out...I hope it doesn't turn out to be that big a deal. I went through some trouble filing the header flanges smooth, of which a couple were not perfectly flat, so I hope that should help. And btw, I see now why they make cylinder liners out of cast iron, since those headers were really hard to file. And I also possibly see why the steel headers are much more prone to cracking, since when bolting everything up, the y-pipe didn't match up exactly perfect to the headers, so it was nice that the cast iron ones were rock solid enough to make the y-pipe flex into position. The steel parts probably wouldn't stand up to that quite as well.

It did seem a bit quieter under the hood and I couldn't feel any leaks, so it seems good for the moment. I'll just have to see what happens once it gets really hot from some real driving.

nynor · 10-10-2008, 07:17 AM

be sure to re-torque the nuts at the top of the headers after they have heat cycled a few times. i doubt it REALLY matters which way you put the gaskets on.

bleu951 · bleu951's Garage

Sorry, but I disagree with the metal side of the gasket towards the head. I put the metal on the manifold since it gets hotter than the head. The head is water cooled after all.

Techno Duck · Techno Duck's Garage

The best option is to use liberal amounts of antiseize on the fasteners, use cadmium (or zinc) plated bolts and copper clad nuts.

Dont worry about the gaskets, i have seen people recommend both ways and dont think anyone has ever had problems. I put the gaskets metal side to the head, mainly because i dont want to clean off fiber material from the cylinder head if i dont have to (in the event they ever fused to the sealing surface). Taking a wire wheel to the exhaust manifold is no big deal, but not a great idea on a aluminum head.

Exhaust work really sucks in general, especially when working on jack-stands or ramps. Ive had my fair share of nightmares on these cars. A few memorable experiences..

1) Replacing the catback on my '87 n/a from SFR. The exhaust came at about 6pm and i couldnt help myself, so i started installing it around 7pm in the dead of winter. I was under the car a good 2 hours trying to get the 3 bolts off that hold the catback to the cat section of the exhaust. What a freaken nightmare. Those bolts had seen exposure to tri-state area winters all of its life. Needless to say all 3 of them broke on removal. I was literally bench pressing the wrench trying to get them out. Horrible experience...

2) Replacing the head gasket on my 951, getting the headers unbolted from the crossover is a real pain due to how the crossover wraps around the flanges. It makes it very difficult to get a socket in there or a boxed end of a wrench for that matter. Getting those 6 fasteners out took me the better part of 3 hours.

The stuff nightmares are made of..

3) Removing the stock wastegate on my 951. 110k miles of heat cycles and being in the tri-state area snow belt. The wastegate has studs, luckily even when broken the wastegate will still come out. I broke 7 of the 8 studs trying to get this thing out. PITA..

HondaDustR · 10-10-2008, 09:13 PM

I'd show you what my nightmares are made of, but they're in many, many more pieces than those bolts...and spread all over the place outside. let's see, there's only one whole bolt, a few twisted off nuts and bolt heads in the driveway, a couple broken off nubs, and lots of metal filings everywhere (including some still stuck in my hands...). Thank God the studs didn't break off or anything! Actually, my nightmares have just been updated with CV joints, too. I do not want to see another bit of grease for a long time, or have to put together another CV joint (talk about a test of patience)!

I finally got my new transmission installed, test drove it, and didn't smell exhaust anymore, so it must have went together properly.