5 weeks in and first issue

[SteveS]

Right advice please from those more knowledgeable. 

 

I have a 2007 Cayman S and on start up this morning there was a horrible noise from the exhaust, sounds like it's blowing, it ran ok but I did notice that fuel consumption was a little higher than I expect.

 

just a dodgy exhaust? Or something else I need to investigate.

 

thanks guys for anything forthcoming.

 

[Beanoir™]

It's most likely the flange joints where headers meet back section, you can see it through the rear wheels.  If you can get down there normally push your hand through and feel it blowing.  The nuts (3 each side) rust and the joint loosens. A very common issue, but easily fixed if the bolts aren't too seized.  

 

I had mine go both sides on my Gen1 - cost is 6 bolts and 2 gaskets (cheap).  Labour depends on whether you do it yourself or take it in somewhere.  

 

Quite often you'll notice a metallic rattling noise too if the bolts have worked that loose.  

Edited March 26, 2017 by Beanoir

[SteveS]

Hey thanks for that. I did listen at the rear wheel and it does seem to be coming from that area.

 

puts my mind at rest and didn't want the expense of a new exhaust yet, although a noisier one does sound appealing but not yet.

 

 

[SteveS]

An update. The issue was as suggested here, kit purchased, garage sourced but the nuts/bolts are so rusted in that he was wary of breaking them in the manifold. So now off to the local engine specialist this weekend for his assessment. 

 

Typical now the weather is good I have a Cayman that sounds like a tractor and is spending its time sitting in the garage.

 

 

 

 

[Rob63]

Hi Steve, sorry to hear that. Just to clarify, Beanoir suggested (and rightly so as this is the most likely fail point) that it was the flange joints where the headers meet the back section, but from your post it sounds as though it's the header section?

 

If it is indeed the flange joints then there's nothing a grinder and slitting disc won't defeat.

[Beanoir™]

Grinder is most often the solution, or a pneumatic chisel is the other weapon of choice for many specialists that take on the job. 

[Woodhouse]

Don't underestimate the utter PITA involved in getting the rusted bolts (studs) out of the flanges.  It took me about 10 hours.  Cutting the studs off flush with the flange face is easy; however the stud heads are tack welded to the rear face of the flange and so they need to be ground off too (access is very poor) and then you either need a hot torch (oxy acetylene) and try to punch the stud remains out (the shanks are splined and an interference fit in the flanges!) or drill them out (and again access is poor). 

 

Had a quote from our local specialist to do this on our other Cayman - 4 hours labour.  I'd take that option next time!

[Rob63]

Actually I'd say 4 hours would be pretty good going, and if you're not too handy on the tools is the best option by far!

These bolts, commonly known as Demonbolts, are in use on most cars. The ones on the 350/370Z are particularly difficult as access is worse than on the Cayman, I've had pretty good sucess with an air drill, a selection of good quality cobalt bits and cutting compound .

[Beanoir™]

I'll dig the invoice out for when I had my Carnewal exhaust fitted at Paragon.  My car was 4 years old with less than 20k miles and the studs were rusted to buggery.  If I recall it was c.£350 in labour 

 

I think I was waiting there for about 4 hours actually...

[Bushman]

Nut splitters might work if you can get one in, or grinding one side of the nut away till it either splits or the heat has expanded it enough to break it loose. Studs, especially splined studs tend to be hard, nuts are usually soft. if you can get the nut off without shearing the stud, once the pipe has been removed, you can rescue the thread with a die nut in a socket. reassemble all threads with Copperslip type assembly paste, ( other makes are available). better than Loctite (other makes available) too as it allows a tighter torque due to lower friction. and should never seize again . either through corrosion or heat.

hope this helps.

[Rob63]

7 hours ago, Bushman said:

Nut splitters might work if you can get one in, or grinding one side of the nut away till it either splits or the heat has expanded it enough to break it loose. Studs, especially splined studs tend to be hard, nuts are usually soft. if you can get the nut off without shearing the stud, once the pipe has been removed, you can rescue the thread with a die nut in a socket. reassemble all threads with Copperslip type assembly paste, ( other makes are available). better than Loctite (other makes available) too as it allows a tighter torque due to lower friction. and should never seize again . either through corrosion or heat.

hope this helps.

Granted, all pretty good advice on what really should be a pretty straight forward task for the average DIY job. However, there's no such statement as a tighter torque, there's only the correct torque when assembling fasteners. The difference in applied torque between a dry assembled fasterner and one with an applied lubricant is vast, and at the end of the day having gone to the effort of removing a corroded nut you'd be best advised to change out the bolt as well; a level of corrosion will be evident on the bolt/stud .

[twopointnine]

Last year I paid £258 at Brookspeed for the replacement of the flange gaskets, bolts, and nuts on both sides. I don't know whether they took the manifolds off to do this, if they did there was no mention of any difficulty with the manifold to head bolts.

[SteveS]

Thanks guys, all good advice. Popped in to the garage at the weekend and all booked in to be done later this month, they are busy. Nice guy that owns the garage who took me under the ramp to show what needs to be done and generally have a look around. Did find a bit of scoring on the brake disk that needs to be looked at sometime and one tyre is wearing on the inside, other than that it looked pretty good. 

 

I was recommended to the garage and always reassuring when you turn up and the owner spends time with you showing you around. The engine building room was amazing. Bentley, Rolls Royce, Ice Cream van engines all there along with several race engines they are building. Out the back was parked a nice Aston, Ferrari and a lovely Austin Healey. 

 

 

[Rob63]

Hi Steve, pleased to hear that you're booked in. Sounds like a pretty impressive garage, ask for the Ice Cream van labour rates and not the Bentley rate .

 

Is the garage local to you, just curious as to where it is? I was in Suffolk the other day, used to live there and had forgotton just how nice the countryside is.

[SteveS]

Hi Rob, yes it's in Holesley called Coltec, they bought out Holbay the race engine company so have lots of knowledge. 

 

My only other option was Norwich where the car had been serviced or into Essex, so will try this and see how it goes. The first guy I went to did manage to tighten a bit and put some sealer on to stop it making as much noise and keep the fuel comsumption manageable, So am still driving art weekend,

 

 

[Rob63]

Good luck, I hope it all goes well for you and keep us posted