Exhaust Stud Hole Issues

[mystery_kid]

So i set out saturday morning to replace the exhaust manifold gasket on saturday

long story short, someone before has tightened up all the nuts so tight it's began to shear the thread in head, so i have some along to tighen up the nuts again and shear them all more

so pretty much my only option is to tap the holes bigger to 12mm, never done any hole tapping before especially not in awkward positions like that

i've heard of mobile guys that do this etc

anyone had it done, if so who did they get to do it? exhaust shop or mobile guy

did you tap the holes yourself?

[**RB2530**]

Dude,

Save yourself a lot of pontential grief and get a mobile guy to do it. If it is in a hard spot they can be easy to get wrong then you have a bigger problem. The mobile guys have all the good tools as well...Also dont try and start it yourself because inserts like helicoils have non standard size drills and taps...

Its always good to learn so you can do it yourself but learn on something thats less critical, cheaper and has easy access..

[mystery_kid]

yeah thats how i was leaning

might do some ringing around

it really gives me the shits that proper mechanics can't even do shit properly, it's no wonder i do all my work myself

the nuts had obviously been tightened way too much last time (head was removed and repaired almost 2 years ago), to the point they had already started to come out of the head on some of them. there is heaps of evidence that it's been leaking all around like 5 of the cylinders under the non-genuine gasket they used

Edited August 9, 2009 by mystery_kid

[adis]

Have the same problem. Im getting the whole turbo set-up off and taking out the old bolts and putting new ones on. Costly but its got to be done, exhaust leak is terrible.

[jimbob2009]

I had this problem once before,tried using easy out's to remove the snapped bolts got all except one frikken bolt.Which led to me having to take the whole head off and taking it into a mechanic.

I then had to buy a new head gasket and a set of head bolts all for one stubborn bolt!!!

[mystery_kid]

adis that was my plan originally, i'd bought studs but nissan they gave me the wrong ones apparently they gave me studs for the turbo -> manifold, which i didn't realise until the day

which is mostly my fault as i asked for exhaust manifold studs meaning head studs, but at the same time the guy was like 'do you want a full set of 12?'

not that it would have mattered anyway, threads were already pretty f**ked before i even got to it

anyway got a guy coming out next week, $180 to helicoil all 12 of them and he's organising some new studs + nuts

[**RB2530**]

Just thought I would give you a couple more tips.....Last manifold I put on still going strong at 60,000km.

1. Make sure exhaust manifold is not deformed or warped. Check that all flange faces are flat by placing a steel ruler or straight edge along face that bolts to head. If it is warped it will always break the stud and end up leaking.

2. Always use Nissan genuine gasket. Worth the $120.

3. Always use new nuts. Use steel or inconel (spelling??). Never ever ever use brass. (I had a guy working at Peps once tell me brass nuts were ok to use.)

4. If a stud looks just a little bit suss, replace it. You are anyway.

5. Always use correct tightening sequence. This is in the workshop manual. Generally you tighten from centre of manifold outwards. Try and get good even tension in all nuts and do it in 2-3 passes.

6. Always use a good ring spanner. Never use a cheapy!!

7. Always use heaps of anti seize.

8. Never try and rush it...

9. Have your first beer AFTER its done....

cheers

[mystery_kid]

i want my beer now :\

yeah my issue wasn't broken studs, it was just not done properly last time to sum it all up

non-genuine gasket, tightened up too tightly so it just began to shear the threads off

when i first noticed it was making the ticking sound i found where it was coming from on cylinder 1 and the top nut there was finger loose. when i finally got around to fixing it properly 3 other nuts on that end were all finger loose.

thanks for the tips

Edited August 10, 2009 by mystery_kid

[**RB2530**]

Oh and 3 more tips...

1. Never ever use a bolt in place of a stud +nut. Studs are better because you get full thread engagement in the hole plus when you are tightening a nut on studs the sliding surfaces are steel-steel as opposed to steel-alloy.

2. When you put the new studs in but before you place the manifold over them, measure the length of the non-threaded or blank section on the stud. Make sure that this length is at least 1-2mm shorter than the thickness of the manifold flange. Some studs have a longer blank section and if the nut bottoms out or runs out of thread before it bears hard on the flange, its the same as a loose nut. Its been done before...

3. Make sure you re-tension the nuts after say 500kms then every 20,000km. Its a pain to do but worth it...The gasket compresses a small amount over time...

cheers