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Chasing a leak and running low on ideas

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Hi all, The ute's developed a harsh exhaust sound when the revs come up.  Anything over about 4psi in the pipes and it sounds like I've got a screamer pipe opening on an external gate. Turbo is stock with the usual gate mod, into a 4" dump and a very free flowing system. Never had this sound until a few months ago and it doesn't seem to have any effect on power that I can tell.

 

I got in and checked all the bolts between head and dump pipe. Even left off the heat shielding so I could recheck more often and easily.  Some down near the back of the engine weren't very tight.. But most were and I'm still chasing the problem.     Concerned that the gasket had actually failed, I pulled it for a look. And I'd love some second opinions on what I'm looking at.

 

 exh_gasket1.thumb.jpg.0ab9bb9c2f43936ca5f661545c21a39f.jpg

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exh_gasket3.thumb.jpg.45f2b8c95ad8e72cf5d06fdac673e1d6.jpg

 

Normally I do my own work, but when the turbo went, I just didn't have the time nor space, so a shop fitted this gasket and installed uprated bolts (according to the invoice) 

 

So based on what I'm reading and seeing here, I think the 4 middle ports show a good seal and some sort of ceramic paste was used.  While the ports on either end would have signs of leakage and nowhere as good a seal as the middle.   Which is probably consistent with the factory manifold going banana and me not checking bolt tension often enough... 

 

Does that sound about right to you guys?

 

And with regard to putting it all back together, would you reuse that gasket?  Clean it.. as is..  With or without some of that fancy lookin permatex copper exhaust gasket goo?

Any thoughts appreciated, cheers.    

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yep, it looks like the manifold or head is warped, if it sealed in the middle but not on the edges... or the tensioning wasn't done in the right order for the bolts to get the tension correct throughout. I'd get another gasket and wouldn't re-use that one.

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Thanks, k31th.  I'd be super dissapointed if the head was warped :/  It's not a high mileage engine and whilst I enjoy it, I don't wail on it. It hasn't had a rough life lol.  

 

Ok so fresh gasket it is.. I'm assuming some but not too much additional sealer goo is good insurance.

 

The torque numbers are not all that clear, I've been trying to get accurate info and all I have is a range of numbers from 27nm to 40nm.  I'll definitely be using some copper antiseize and will be trying to locate some nordlock washers.  

 

Any thoughts on how/where to find the correct torquing order for the bolts?  

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Correct order is from outer edges to inner parts, nipping it up each time not too tight, repeating the process until it's very close to the required torque and then one final nip-up with a torque wrench. 27nm is correct for the "Exhaust Manifold to Cylinder Head" torque.

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Just looking at my lack of space problem, There must be another bolt or two somewhere that I'm not onto..    Is there a secondary mounting bracket down under the manifold where the turbo joins on these things?   I've not been able to pull the manifold away from the engine and I was thinking it was just the exhaust and general space limitations, but I've begun to suspect it's more than that??  Can't find any pics :/ 

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yep, there's a H-bracket that mounts the exhaust manifold T3 flange to the engine block, so you've got bugger all space unless you loosen that, but if you got the old gasket out, you'll get the new one in with a bit of finesse.

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Well, what an absolute pain in the backside that job is if you try to take any shortcuts.  I've got it all buttoned back up and will give the RTV time to cure... But if I ever need to get in and do something in that area again I will just buy a complete set of gaskets and seals and pull the lot out. Sure it will be a bigger job, but probably so much easier that it wouldn't take any longer.

 

While I was in there, I found a missing stud from the dump pipe to turbo housing too.  Which is probably the source of my screamer action.

 

Thanks again for the advice k31th.     

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no worries, mate. that stud/nut combo is almost always missing if you haven't checked on it haha

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