yardage

First post, first Porsche. I'm liking her a lot so far.

'86 951 - 91K miles, all completely stock except for the radio.

A knocking sound started a couple of weeks ago - I thought the worst of course. Lifter or something.

Turns out the exhaust manifold has a pretty good leak, either in the manifold itself or a gasket. I can smell it, hear it...

So...replace to stock? Any upgrades recommended?

samluke

There aren't too many aftermarket alternatives, and the ones that are available are very expensive. There are the OBX ones on Ebay, but I am not sure of the quality or longevity.

I would recomend OEM replacement. The porsche design and quality is impresisve with the double wall and bellows etc. The challenge is that good OEM ones are becoming hard to find.

2-3 seem to be the most prone to cracking. I would resist the urge to weld up, as in my experience its a short term repair.

I have used OEM manifolds if you need any. Air pressure tested under water, which is the best methon to confirm no cracks (IMO)

yardage

Seems it's a gasket, though I guess I could replace and then find the manifold to leak too. Bleh.

Noise is louder when cold, mostly goes away when engine is warmed up, unless I put load on it, which makes me think gasket(s) as well. At least I hope. If not I may take you up on the used OEM's. Thanks for the reply samluke...

F18Rep

Even if it is just a gasket, it is a painful job to deal with. There are several seal rings in the system and they are expensive ($18 each). I would suggest you take an extra effort to know for sure where the problem is - maybe by blocking the tailpipe and looking for the leaks. You don't want to get it all back together and then fail next year's safety check. The little 90" elbow is notorious for leaking... just some thoughts...Bruce

yardage

I found the leak... a pretty easy find actually. This is on #1 - has anybody tried to change these out without completely removing the header?

Tom M'Guinn

If it's on 1, I would think you could change it without removing the headers. Remove the nuts, then double nut and remove those two studs, then slide out the old gasket and in a new one, then reinstall the studs and lock nuts. If the studs won't come out, then that's a different story....

Edit: sure that's #1? Looks like there is another to the left...? 1 might be a little easier because of the accordion, but by loosening the other nuts you should still be able to slide a gasket out/in...

zerMATT951

Use new copper lock nuts when you put it back together. An alternative would be to re-bend the locking tab (close the slit by tapping with a hammer) in the old nut so it'll lock again when reinstalled, then add some copper-based anti-seize to the threads.

yardage

To confirm - it is #1.

I got all four gaskets to replace, so based on how badly the nuts/studs are stuck, we'll see if I can replace all while I'm there. Daily driver, so...

Thanks for the tips guys! Gonna go give it a shot now.