I fitted my TTE twin exhaust 3 months ago, and during this had no problems removing the 3 10mm pre-cat to main cat bolts.
A week ago, I individually removed the 5 precat manifold to engine nuts, to ensure that when I removed the precats to gut them, that all the nuts would come off easily.
When I came to remove the pre-cat on saturday to gut them, one of the 5 nuts loosened a week earlier rounded off - problem 1.
Problem 2 - Each of the 3 pre to main nuts, started to undo and then went tight, I sprayed more wd40 and worked the nuts clockwise and anticlockwise to loosen them up, but instead they just got tighter in either directon until they ALL seized solid and I had no choice but to shear them off.
I ended up drilling 3mm holes in the rounded off nut and tapping it around with a punch.
Unfortunately one of the studs sheared off flush with the flange and this had to be the one stud which was in a blind hole, the other 2 holes are through holes, and I ended up having to drill out the stud to the thread core diameter and peeling out the remains of the stud. The other 2 came out by heating with a blowtourch and by this time all the shops were shut until Monday so my car was disabled for 2 days. The 10mm threads were also cleaned out with a 10mm tap.
If I were to oirder the studs from MRT, then it would take at least 3 days, probably 4 or 5 so I phoned around and found a stockist of 10mm hi-tensile studs & nuts.
I suggest that if any of you have removed the pre-cat and foresee that you may want to remove it (or the main cat) in the future, that you replace the studs & nuts and don't re-use the old ones to prevent you from facing the same problem !
I have also replaced all nuts, bolts & washers on the main cat with stainless steel cap heads (allen key) including the ones holding the main heatshields to the pre-cat and the ones holding the shield around the main cats.
Crankshaft
crankshaft, im in the same boat as you mate! ive rounded one of the 5 manifold bolts off, and also one of the 3 manifolt to main cat 14mm bolts! you dont know how pi$$ed off i was! i dont know what to do now:
do i shear off the rounded nuts and put new ones in or just leave the sodding thing which will probably (knowing my luck) result in precat failure!
if i actually knew what i was doing in these situations and knew how to deal with a problem like this, i probably wouldnt even be too bothered.
dont suppose anyone lives near me to give me a hand?
___________
one helpless '2 owner s:( :( s:(
Hi;
The rounded manifold nut is probably easier to remove as you can get to it easily. I drilled a 3mm hold into the nut's flat which was facing up and used a hammer and punch to tap it around.
The 3 pre to main cat bolts are going to be tougher if they don't shear off as they are not very accessible. I recall that there was another thread somewhere where the removal methods were being discussed.
Did you manage to remove any of the 3 nuts sucessfully and is it just the one nut or have you not attempted to remove the other 2 ??
Crankshaft
the other 2 started to untighten but had no luck with the 3rd so it rounded off and i left it as it is.
i know the removal solutions have been discussed but im not really confident or have the experience to attempt myself s:? :? s:?
Quote from: "crankshaft"I suggest that if any of you have removed the pre-cat and foresee that you may want to remove it (or the main cat) in the future, that you replace the studs & nuts and don't re-use the old ones to prevent you from facing the same problem !
I have also replaced all nuts, bolts & washers on the main cat with stainless steel cap heads (allen key) including the ones holding the main heatshields to the pre-cat and the ones holding the shield around the main cats.
Crankshaft
Thanks for the advice Crankshaft. I would also recommend putting anti-sieze compound on any stud or bolt that you may have to remove again later. This is especially true for the exhaust system that experiences high temperatures.
I feel your pain Crankshaft. Been there and done that too.... De-cating can be a test of ones patience! s:wink: :wink: s:wink:
Ron
Oh yes, this sounds familiar, one of the 14mm downpipe nuts rounded when I tried to do mine. I've had one session with a nut splitter,but still the wretched thing won't come off. I'll try again soon when the weather is a bit cooler, otherwise I just loose patience too quickly. s:twisted: :twisted: s:twisted:
are those nut spliters any good? bin thinkin of investing in one s:? :? s:?
Well, I'm definitely going to invest in one before I try gutting the pre-CATs on mine, that and a decent tap & die set, just in case..
One note on removing things like this - I'm sure you all did this anyway and were just unlucky, but in case anyone else is ready..
Buy a can of PlusGas, and give everything a really good soak the day before you start (and don't drive the car in between times, or you just burn it all off s:) :) s:) ).. Spray again before you start, and then use good quality tools that get a good grip on the nut..
If you can't afford SnapOn tools (and lets face it, unless you're a mechanic, they're overkill for most of us) then Halfords own 'Professional' brand are an excellent second best (I've abused some of mine terribly, and they're still fine - including hammering undersized sockets onto rusted CAT nuts s;) ;) s;) )..
And here endeth my waffle.. Good luck getting those siezed nuts off if you're still stuck with 'em!
Aaron
Very close now. All five manifold nuts released, thanks to a good 24-hour soaking in bolt-loosener. When the last one came free, the sensation was akin to... well, you know.
The three pre-cat to main-cat studs and nuts: Rightmost (the one in the blind hole) was nearly sheared off and has about 3 threads visible - no locknut. (WTF?) The center released and extracted cleanly, nut seemingly welded to stud. The leftmost resisted all attempts at extraction.
Took the car to a garage owned by a friend and put the Spyder up on a lift. We heated the stud and nut with a torch until both were glowing bright translucent red. Immediately we slammed a 12mm socket onto the by-now-well-rounded nut and pounded it home with a hammer. Quickly affixing a socket wrench, the entire stud came out smoothly with virtually no effort required.
At this point, the manifold is ready to come off. MrT sold me three studs and nuds for $5 (but the gasket kit - main and precat were $50!). Will attempt to replace the rightmost stud prior to reinstallation using the torch trick again, this time heating the flange instead of the stud. Sure it's a hassle, but nothing compared with an engine replacement.
You know why the main-to-pre nuts are so hard to get off don't you. The nut some times becomes joined to the stud, because of overtightening in the first place or just corrosion. If this does happen you can still get nut and stud out but have to apply more pressure.
As long as everything is held on straight a breaker bar will still crack them off easily
QuoteYou know why the main-to-pre nuts are so hard to get off don't you.
Several reasons - corrosion, heating, possibly even galvanic action - but I've also noted that the nuts for the lower three studs are "locking nuts" which feature a gently decreasing diameter through their threadlines. That means that they can be wrenched on, but they won't back right off. If there's any big trouble in this job, these three are likely to feature prominently in the excitement.
Right before gutting the cats, I attempted to insert the three news studs I'd purchased and discovered that two of the mounting holes would need a quick re-tapping. I ran the manifold over to MrT and they did it on the spot. "How much?" I asked. "Nothing," said the shop manager, tilting his chin toward my header. "Just take good care of that." Oh I am. I am. Should finish this evening and see how the empty precat chambers affect the sound of the Team Moons. Pics 'n' impressions to follow. Thanks for all your help with this project guys - I wouldn't have had the nerve otherwise.
Sounds like people have been having a lot of problems gutting precats. s:( :( s:(
I want to do mine soon as I have no warranty to cover precat failure. Does anyone know if the all bolts that are removed while gutting precats can be replaced with new stainless steel ones?
If so, what are the sizes of each individual nuts & bolts? I want to get everything in before I start.
Thanks for your help,
Fraz.