Need an Update on Catalytic for 1998 V70!

Post by **cn90** » 01 Jun 2011, 08:04

Hi guys,

NEED an Update on Catalytic for 1998 V70 with 110K miles with stock Catalytic, exhaust and O2 sensors.

In June 2008, The union between catalytic and exhaust broke, so it was welded by a local shop. It still holds up 3 years later.

Now it leaks right after #6 (catalytic as shown). There is no more room to weld from my forum research.
I just want a New Catalytic because:
- At 110K, there is not much life left.
- At 110K, likely partially clogged.
- I plan to keep this car for another 5-8 years.

So here are the questions (I have searched up and down the forum!):

I. BRAND:
- "Davico" is out (not a good brand).
- "Bosal" seems OK, long history of quality.
- "Magnaflow": $80 for the cat alone vs $300-400 for the direct-bolt in.
- "DEC" (aka "Diversified Environmental Catalysts"): I have had good luck with this brand on my BMW in the past.

II. Catalytic ONLY vs Direct Bolt-in:
- It seems that most people here have good luck with Magnaflow:
BUT how long does this (Magnaflow stand-alone cat) last given the fact that it is welded to the existing piping which itself is 13 years old?

- The direct-bolt-in: who has used it, what brand do you recommend?

III. Lastly the O2 sensors: at 110K miles (No CEL codes).
- Leave them alone or replace them?

Thanks in advances for all advices. Here is the pic that shows you what I refer to above:

: Volvocat.JPG (86.84 KiB) Viewed 4320 times

Post by **jblackburn** » 01 Jun 2011, 13:45

- At 110K, there is not much life left.
- At 110K, likely partially clogged.

Not at all; unless you were running rich for an extended period of time or something, that catalytic converter is still perfectly fine. We had one with over 300K on it at 23 years old that still passed emissions testing.

Cats are stupid expensive; just try to get a piece of pipe welded in place by an exhaust shop.

Post by **cn90** » 01 Jun 2011, 13:50

Well,

The break is exactly as shown.
I was told that this cannot be welded because there is not much on the catalytic side for an exhaust metal sleeve to "bite on".
Any advices will be appreciated!

Related thread:
https://www.matthewsvolvosite.com/forums ... =1&t=33145

: VolvoCat2.JPG (60.2 KiB) Viewed 4302 times

Post by **billofdurham** » 01 Jun 2011, 15:34

I have shown this to a highly experienced welder who said that he thought it would be possible. He would remove part of the 'fin' under the left side blue line as, in his opinion, it doesn't need to be that long and weld on a collar.

Bill.

Post by **vjaneczko** » 01 Jun 2011, 16:38

Actually, that picture looks very familiar! (it's the thread I started last year

.) The solution was to take it to Midas for a little $76 patch job. What the mechanic did was to weld a smaller pipe inside to give support, and then welded another one on the outside to seal it up. I'm on a business trip at the moment so I can't post a pic of the finished job but if you'd like, I'll do that when I get home this weekend.

Swedish Chef · Post by **Swedish Chef** » 01 Jun 2011, 18:08

Ive welded worse but its only going to last so long and most likely fail when you dont want, and depending on how soft that pipe is you may or may not be able to use a mig in that case it would need to be braze welded and it has to be sealed or the rear 02 is gonna get a bad reading and i dont recommend removing it as the front and rear 02 sensors need to see a difference or your Check engine light will come on, my '95 850 has 300000 kms on the original exhaust and just passed a test 3 months ago!

Mmfh · Post by **Mmfh** » 01 Jun 2011, 18:54

I've welded stuff like that before, and if it were my car I would probably grab my little lincoln mig and go for it. If the metal on both sides of that break is not rusted badly and it broke because of a bad seem you should be able to make it work. Welding a small sleeve or collar would probably give it more strength, but if its clean and in good shape it should weld up good.

Make sure the battery is unhooked before doing any welding on the car!

Good Luck!

Mm

Post by **jimmy57** » 01 Jun 2011, 19:09

The pipe looks to have thinned from rust but an inner sleeve made from a piece of pipe expanded to be a snug fit and then join and weld. After the splice is complete, if it were mine, I would add three ribs of steel 1/8 thick x 1/2 wide stood on edge for strength. That break screams stress to me and the ribs would mitigate the stress. If clearance prevents them bing on edge then flat would still be a huge reinforcement in that area. THEN you assure no stress by loosening any joints and then shaking exhaust and then secure all that was loosened.

No pick-n-pull options in Omaha?

Post by **cn90** » 02 Jun 2011, 11:42

As I mentioned above, I have owned many cars before and once the rust starts in the exuahst system, it just keeps going, so it is endless trips to the muffler shop, each time $100-150 easy.

I plan to keep this baby for another 8 years or so. So I am thinking the "best bang for the bucks" as the whole exhaust system is quite rusty (rear mount on tail pipe broke off etc.).
My thought now is to do it right and forget about this exhaust system for another 8 years LOL.

I did a little more research, so here it goes, any opinions will be welcome!

MUFFLER (PN 8631006)
- Starla muffler: $220 lasts about 3 years or so.
- Bosal muffler ($250): about 6 years.
- To my sweet surprise, I checked my favorite Volvo Waltrip in TN, the Volvo OEM muffler (which easily lasts 12-13 years) is ONLY $250!

---> So If I decide to get a muffler, then definitely go OEM.

CATALYTIC (PN 8602985)
- D.E.C. brand $500
- Bosal 099-6301 $330 from Amazon
- Volvo OEM $850.

So I kind of narrow down to:
---> OEM Muffler $250
---> Bosal Catalytic $330

Not sure yet, just pondering LOL.

Post by **matthew1** » 02 Jun 2011, 12:55

I got a Contact response early this morning, sorry I'm only posting it now. It's from CC. It's as follows:

~ ~ ~

Regarding the Catalytic converter welding repair. Yes it can be welded but i would recommend removing the entire assembly from the vehicle to make the welding process easier.

tools needed:

FIRE EXTINGUISHER RATED FOR A,B,and C

A QUALITY WELDERS SHIELD WITH NO SCRATCHES IN THE SHADED GLASS!!! scratches allow the UV light through to burn your eyes.

Comfortable and substantial welding gloves

A long welding apron at the minimum a full welders coat if available.

decent quality welder that provides adjustable voltage control and ideally is set up to use inert gas shielding via CO2/ Argon mix.
If the only option is to use flux cored wire feed without shielding gas, i would leave the welder set to "reverse arc" (negative ground/ positive electrode) as opposed to the traditional straight arc (positive ground /negative electrode) used with flux cored wire. My reasoning is that in the welding process most of the heat is generated on the positive side of the arc and rusted metal exhaust pipe will blow through pretty fast if to much time is spent on one spot.

splatter jell is good to have on hand for the torch (welding gun) it keeps the nozzle cleaner throughout the process

Cooling spray. this mystery product when applied towards the rear of the weld site dissipates a tremendous amount of the work heat and reduces the blow through i talked about earlier.

Stiff wire brush.

a Coarse flat metal File
___________________

First clean the area to be rejoined thoroughly to a distance of 1 inch back from the desired butt joint; do this with a stiff wire brush.

Make sure the area is oil and grease free use soap and water for cleaning the work area.
NOTE... NEVER USE BRAKE CLEAN, ELECTRONICS CLEANER, OR CARB CLEANER on a Welding job. It rarely happens because all of these products evaporate rapidly but, if a welding arc comes into contact with any of the above chemicals the combination of the UV light and Electrical Current will catalyze the chemical into a gaseous puff of PHOSGENE which has the capability of killing you very quickly.
END NOTE

i suggest setting the voltage somewhere between 15-17 volts. Welding current between 25-30 amps

PRACTICE ON SIMILAR METAL PIPE PRIOR TO ATTEMPTING TO DO THIS WELD ON A "PRODUCTION" WORKPIECE

Begin by building up the weld metal two bead widths back from the desired joint. Lay a single height bead around the circumference of the pipe. allow time for the piece to cool between each pass. If a continuous bead is beyond the operators skill level the same result can be accomplished by laying a partial bead on one side of the work piece and then flip the work to lay an identical bead on the opposite side. this will assist in controlling deformation from thermal expansion.

clean the work piece with the wire brush between each new operation to clean off slag and splatter that can affect the quality and appearance of the finished welds

After the build up beads have been laid the operator must position the two pieces in the way the installed product will be when in the vehicle. to do this wait till both peaces have COMPLETELY cooled to the ambient temperature of the surrounding area. next the operator can install them back in the vehicle to set up the work and apply tack welds or if they are more comfortable they can position the pieces and tack weld them away from the car. it depends on the operators comfort in fabricating.

once the work piece positional alignment has been determined file the weld metal edges to a near flat mating surface to reduce the irregularities between the butt joint spacing. once spacing is uniform to within a 16th of an inch around the weld site place a .5 inch long tack weld in three spots around the pipe at approximately 120 degrees offset.
once the tack welds are complete continue a full bead around the circumference of the butt joint to complete your weld and seal the pipe.

Install in car and Drive

Helpful tip..

because you are welding such thin metal and the joint is going to be very close during welding no zig zag or swirl motion will need to be used on the bead as you lay it down.

focus your attention on bead consistency process, do this by having uniform arc distance and linear speed as you apply the weld bead.