replacing cross over pipe and presilencer

[Guest]

So my cross over pipe and pre silencer have finally started blowing. Going to replace with stainless steel OE design parts, but the question is as follows.

Having inspected the car, the join to the stainless heat exchangers appears to be mild steel, is this really the case? what is the point of having stainless heat exchanges with a rusty part to join with? I am now concerned that I will end up having to take the heat exchangers off, not something I am keen to attempt to be honest.

Anyone got any experience of this?

thanks

H

 

[Guest]

Hi Hugh. This is probably because some "Stainless Steel" exhaust part assemblies are actually made of a combination of stainless and mild steel. Stainless steel can suffer form cracking and so manufacturers sometimes use mild steel parts in place of the parts that are likely to suffer form cracking.

My 3.2 carrera had a stainless steel pre-silencer assembly, which was actually made of both mild and stainless steel sections welded together.

If you do have to take your heat exchangers off, invest in a MAAP gas torch. You can get them in B&Q and Halfords. It's a little Oxy-Acetelene gas torch, which comes with a couple of gas bottles (1 oxygen and one Acetelene). They can take MAAP gas as well. It's a different coloured bottle and burns much hotter than acetylene. You use this to heat up the nuts that hold the heat exchangers to the cylinder heads. They should be heated to cherry-red and cooled quickly (quenched) with a squirt of water. Do this a couple of times on each nut and they will come away easily.

You'll also need the special extended Alan-headed tool to remove the 6 barrel nuts (there are 6 normal hex-nuts and 6 barrel nuts holding the exchangers on).

HTH

Cheers
Malcolm

 

[911sse]

Get some part costs Ian/Paul from Specialist cars of Malton and
Karl from Design 911/Europorscha.......................... You wont
be dissapointed!

 

[Guest]

thanks - will give them a go. Its turning into a hellish job. Lots of chiselling and grinding

h

 

[bones]

Here's another possibility for removing the HEs without breaking any studs.
http://forums.pelicanparts.com/showthread.php?s=&threadid=148053

 

[Guest]

Thanks Bones, at the moment I am desperately trying to avoid having to touch them, If I break a stud, I am in all sorts of trouble! Still trying to get the presilencer off, done enough for one night.

The idea with the dremel is good for the nuts, I have used this before, however, you have to be super careful not to get the threads. Definately a job not to rush.

Isnt the muffler (exhaust) a tight squeeze with the valance on, really should have taken it off too, might do for reassmebly, also looking like changing the light clusters is a good idea, whilst I have access, they are pretty rusty.



H

 

[Guest]

Hi Hugh, go to my website in the footer of this message and follow the links under "3.2 Carrera", then "Upgrades" and go to the bottom of the page. Look at the difference between the before and after joints between heat exchanger/cross-over pipe and pre-silencer.

If you are scrapping the presilencer, then you can afford to hack it to pieces, to leave you lots of room to prepare the mating face of the heat exchanger and cross-over pipe joints. That is what I did.

I kept the heat exchanger in place, the first time I fixed it. Don't worry about the rusty bolts holding the pieces together. You can hack away at them with your grinder from the pre-silencer side in order to get everything separated.

I ground and hacksawed off the pre-silencer pipes just behind the flange. you get better access to the flange after that.

All the bolts can be replaced, like in the photo, for a few quid. You can use stainless steel bolts too.

Hope this helps.

Cheers
Malcolm

 

[Guest]

Malcolm,

thanks, that is exactly what mine look like! Good to see! Did you replace your heat exchangers too? The flange on heat exchange side looks better in the after shoot, is that just because you cleaned it up and painted it?

Agggghhhhh! just looked further on your site!!! Your car is written off - tradgic, how long a go was this? See you now have a C4.

Thanks for the advice, I'll post an update after tomorrow nights hacking!

hugh

 

[Guest]

Hi Hugh, I just cleaned up the heat exchanger mating face carefully with my angle grinder, but the cross-over pipe was renewed. I just painted the surface roughly with high temp' paint.

I remember just needing a lot of patience getting the exhaust back into good shape, but it was worth it and I didn't need to spend a fortune in the process. I believe it's sometimes possible to salvage serviceable exhaust parts from what first looks like a brown mass of rust. The evidence in in those photos.

The painted pre-silencer was a 2nd-hand one I was given free by a fellow owner, but it split up the seam after about a year, hence the eventual stainless one.

I later discovered that the exhaust was blowing through a crack on the top side of the one of the heat exchangers. That's the point that I resolved to removing them. A fellow enthusiast and welder soon fixed that problem easily and the exchangers continued to be serviceable.

Yes, I wrote off the car last September, after all the work I did that you see on the website. I was heartbroken. [] The car won best improved car 2003 at a local car event 2 weeks before I write it off. I owned it for about 3 1/2 years.

It all worked out OK in the end once the insurance company paid out and I made a few bob selling the wreck that I bought back from the insurance company. but that's a whole other story []

That nice shiny new pre-silencer might still be at Prestige Salvage in Leeds, if you want to give Neil a call.

Cheers
Malcolm

 

[Guest]

Thanks Malcolm thats a lot of help - I might give prestige a call.

I'll keep you all updated.

Hugh

 

[Guest]

Malcolm,

How do you get the cross over pipe out? Mine is free, but stuck between the HE and the engine? I know I could it cut it out, it is scrap, but then how do you get the new one in? Is it just brute force?

Anyone else done this?

thanks

Hugh

 

[Guest]

Hi Hugh, I wondered too, until I realised that you need to remove the nearside heat exchanger to remove and replace a one-piece cross-over pipe.

If you've not already bought the replacement, then you can get a two-piece cross-over pipe that allows you to replace without taking off the exchanger; otherwise you must remove the exchanger. The one-piece cross-over cannot be removed without cutting and you cannot replace with a one-piece cross-over with the exchanger in place.

Look at the photos again on my website and you'll see that the cross-over is the two-piece variety.

Hope this helps.

Malcolm

 

[Guest]

Thanks Malcolm,

I havent bought the parts yet, good job to. So lets see 2 peice cross over pipe or remove one heat exchange - think I'll take the 2 peice pipe please!!!

Cheers

Hugh
[]

 

[Will.birkinshaw]

Hugh
An additional problem I have come across and have not resolved is that the hex recess in 1 or 2 of the socket headed screws has gone and an Allen key of any kind doesn't work?
Have you or anybody else got any advice?

Thanks
Will

 

[bones]

Do you mean the bullet nuts in the Heat Exchanger or something else, be more specific....lol......could you take some dig' camera pics?

 

[Guest]

Will, there are a couple of possibilities that I tried with success. It depended on the access to the particular fastner I was trying to reach.

I bought a "Dremel" and cut through the side of the barrel-nut, just short of reaching through to the thread of the stud. Then with a big screwdriver, I levered open the barrel-nut until it split enough to let go its grip on the stud.

Also, I used the Dremel to cut a slot across the top of another stubborn barrel-nut, so that I could get a big screwdriver on it and turn it off like a screw with the screwdriver. I had to use the cherry-red heat method on that one too though, so the grip was already released from the stud and the screwdriver hardly needed any effort to get the barrel-nut to come off.

Hope this helps.

Malcolm

 

[Will.birkinshaw]

Thanks for your comments. However, unless I am misunderstanding the terminology, I seem to have a slightly different fixing on my G reg 1989 year model 3.2, which uses 3 high tensile socket headed screws (accessed through each heat exchanger - nuts only on other 3 studs). The problem is on cylinders 3 and 6 only where both the nuts and the cap head screws have almost disintegrated to nothing!
Sounds like an engine out job to me?

Will

 

[Guest]

Hi Will, I don't believe the '89 model used a different fastener. I think that you might just be mistaking the barrel nuts for hex bolts. As you say the ones you are having problems with are the ones which you access through the holes in the heat exchangers. These are barrel nuts on the ends of studs. Click the link below to see a photo of barrel nuts from Type-911's website:

http://www.type-911.co.uk/images/exhausts/exnut.jpg

You are also best to use the special long Alan key tool for the job, but it sounds like your barrel nuts are well past removing with any Alan key device. Here is the photo of the key, also from Type-911's website:

http://www.type-911.co.uk/images/specialisttools/extool.jpg

Hope this helps

Malcolm