Help! I Cant Refit The Exhaust Manifold

[ausdrift]

As mentioned, I've removed it to fit new studs to the block as part of a turbo overhaul. The old studs came out ok, the manifold was a bitch to prise off the block, but once I broke through the stuck-on gasket, it came off.

I've installed new studs and now Im finding it impossible to get the manifold back on. There is no reason why it should be such trouble; there are 12 holes and 12 studs, it appears to line up ok, but it just wont push all the way on. Ive tried 'persuading' it with a hammer, but if I tap one end in, the other moves out, and vies-versa, and tapping the middle gets me nowhere too.

How did you get yours back on? any tips/advise?

Thanks

[Ben C34]

I've come across a similar situation. Its like the manifold is too small to fit, which is weird. I ended up using another one.

[White GTS-T]

Most likely the manifold has warped after countless heat cycles. Remove the manifold and lay the new gasket over it to see how far out it is and put a level over it. If your lucky, it might be reusable one you have the manifold faced at a machine shop. i.e. The same process as machining a flywheel.

[Ben C34]

Mine wasn't warped, it was just fair and square smaller. Was crazy.

I think i still have it, should dig it up and measure it compared to a good one.

[White GTS-T]

To clarify, this is what I meant by put a straight edge/level over the face of the manifold.

[jiffo]

First check with a straight edge that's it's not warped.

Then round file in the offending holes so there's sufficient expansion room. You'll note the centre cylinders have almost round holes and as you move to the end cylinders, the holes become more elongated.

This is for expansion and if the manifold can't slip on the multi layer gasket, you'll be replacing those studs again.

Check the spot facing areas for the thick washers too. If the washer hangs on the edge of the spot facing there's nowhere for the manifold to move with expansion.

I always run a bottom tap down all the heat shield holes too, makes for easy re-assembly.

Check the 4-turbo studs are tight into the manifold. They like to loosen up.

[White GTS-T]

Someone posted this on the Vic Drift sales site.

[jiffo]

When installing those gaskets you make a concertina section between each cylinder.

I prefer the Nissan gasket.

[White GTS-T]

^ Agreed. Alternatively, if you insisted on running a cosmetic/mls gasket, you could use the Permaseal type.

[Duncan]

I have the same issue with the race car all the time...the cast manifold bananas. I've always been able to persuade it back on and pull it in with the nuts.

[iruvyouskyrine]

I have encountered this before also. I have the studs a small massage with a hammer in the appropriate direction and it worked a treat. Obviously don't go belting the shit out of them, just a few taps to move them a few mm.

I know this sounds dodgey and that's because it is. But it was midnight the day before a drift event and it worked fine and have had no issues ever since

[ausdrift]

I have the Nissan gasket as was told to not waste money on anything else. Im going to go out soon and check how level it is. Hopefully I can get away with massaging the appropriate holes as I don't feel its horribly warped. I as able to get it half on, but no further so that's a start, and I don't have time or energy to find a place to get it faced.

[ausdrift]

Some good news, just inspected the manifold then and the surface itself is actually quite level, with only minor variations. Nissans service manual gives a tolerance of 0.3mm and at a guess Id say its pretty close.

I did the trick like in the photo above of lining up the new gasket on the manifold face and I could see that there was a slight unevenness in either the 3rd or 4th outlet. My new plan will be to file a little from both 3 and 4 and that should give enough clearance to get it back on. Easy. I hope.

[hardsteppa]

pretty sure that's what I ended up doing too from memory, just ground out a little from the elongated holes to make them a little more elongated, just enough to get it on to all studs and then it went back on just fine.

[zoomzoom]

I filed the holes too. You'll have to judge whether the mating surfaces are flat enough. Keep in mind that there is more than one direction that the metal can warp. Mine was a little warped, but the new gasket sealed fine, and its been fine for a few years now.

[boostn0199]

Your manifold warped and probably a few of the old studs have even got slightly bent, ive had it before was warped that bad i had to actually cut the manifold into peices to get it off and new manifold would not fit on until I put new studs.

[Dobz]

Are the studs tightened into the holes?

A quick thing you can try is just back the studs off from bottoming out by a thread so they can wiggle around a little. Then try to wiggle the manifold on.

When two threads bottom out on each other the stud can tweak to one side. The more clearance a thread has the worse it can tweak to one side.

[ausdrift]

I ended up filing 4 of the manifold holes out about 1mm each until the new gasket lined up. It then pretty much slid back onto the head; problem solved