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DIY Flex pipe replacement

Help, Advice, Owners' Discussion and DIY Tutorials on S40 and V40. In this forum you'll find S40/V40-specific owners asking and answering questions on maintenance, ownership, repairs, tutorials and almost every do-it-yourself thing you can do to save money owning these Volvos.

1996 - 2004 S40
1996 - 2004 V40

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iamn8
Posts: 18
Joined: Mon Jan 11, 2010 7:57 am
Year and Model: 2003
Location: Providence, RI

DIY Flex pipe replacement

Post by iamn8 »

My Wife's 2003 V40 recently had the flex pipe fail @ 126K. I found a few threads here on the topic, but ultimately found a low cost fix that I wanted to share.

Here's the offending part:

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After taking a few measurements, I realized that the flex pipe is not round. Pipe itself is 3" x 2.5" OD, inlet/outlet is 1.5" x 2.25" OD. I was unable to find an aftermarket piece of flex that was even close to those dimensions, so I know that would also need to replace some of the oval piping.

To top it off, the bolts on the cat didn't look like they were going to come off.

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After much searching, I came across a flex "repair" available on ebay. It included the flange, stainless piping and a new section of turbo flex with interlocking liner for only $69.00. Here's how it arrived:

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Gasket WAS NOT included. $4.95 @ FCP though. I had plenty on metric stainless from the myriad of exhausts that have been on my Hondas that I could use to replace the rusty galvanized stuff.

I started soaking the cat bolts 4 day earlier with Liquid Wrench Penetrating Oil. Sprayed them nightly and tapped them with a hammer each time. I went out there yesterday morning to start this project and they came off without incident. (2) of the (4) nuts had corroded down to the point that they took a 12mm socket, but that was about the limit of obstacles faced.

With the cat nuts loose, but not removed, I used a sawzall to cut the flex section out just above the hanger. A bit of hand cutting with a hack saw was required due to limited undercar space and the giant, GC grade Dewalt saw. I had to go back and trim an additional 1" off the pipe to get the fit correct.

Cat studs were reuseable, so I left them in. I was prepared to pull them out, drill out the holes and replace the with M8 x 1.25" bolts, but it was below freezing and didn't have it in me. Nuts were replace with stainless 8mm hardware and accompanying washers.

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Fit of the replacement flex section was factory-esque.

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Ultimately, I'd like to have the joint that's currently clamped sealed up with a weld. I'd also like to add the factory hanger because of where it supports the pipe. I cut it off the old section of pipe and it's shown here just resting in place.

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Parts total with shipping was just over $100. That included the Liquid Wrech Penetrating Oil, which IMO, blows PB Blaster out of the water.

Post or PM me with any questions.

nixomose
Posts: 1
Joined: Sun Oct 02, 2016 8:19 am
Year and Model: 2003 s40
Location: ny

Post by nixomose »

I have this problem starting, there's a hole in the front of the flex pipe, and I need to do something about it before it completely breaks off.

Thanks for the info, but all your picture links are broken, which would probably help a lot. Do you still have the pictures available?

Also, what exactly is the flex pipe for? I imagine it flexes, but what's the buy? Why can't I just replace it with a piece of straight pipe?

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alschnertz
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Post by alschnertz »

nixomose wrote:what exactly is the flex pipe for? Why can't I just replace it with a piece of straight pipe?
It has to be a flexible joint to account for the movement of the engine.

Another alternate is a bolt-up replacement like this...
https://www.fcpeuro.com/products/volvo- ... 0-099-1981
'60 PV544, '68 220, '70 145S, '86 745T, '95 854T, '01 S40
'84 Prelude
'06 MPV
'13 Ford Focus SE

iamn8
Posts: 18
Joined: Mon Jan 11, 2010 7:57 am
Year and Model: 2003
Location: Providence, RI

Post by iamn8 »

Sorry everyone. It looks like Imageshack has since deleted the photos. I finally found some of them on my hard drive and put them back on imgur.

This was the pipe as it arrived.

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Here's a design element that ultimately became a problem. You're looking at the stock mounting bracket leaned up on the new pipe before install. The weld on the bracket that came with the replacement part failed, and since it was tacked in so close to the weld for the flex coupling, there is now a minor leak there. I've since reinstalled the stock bracket and secured it to the pipe with a 2.5" clamp. I'll try and slide under there today and get a new photo.

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Overall fit was good though. Here are the installed photos:

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Not sure this exact piece is still available, but a quick ebay search for "V40 flex pipe" brought up a result for an almost identical part. JUST BE SURE THE FLEX PIECE IS LINED.

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