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Diy: 1998 Volvo V70 Exhaust Manifold Replacement

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DIY: 1998 Volvo V70 Exhaust Manifold Replacement

Alright, my exhaust leak has been chronic for a few years, as it turns out, it is a leak at the Flex Pipe, just in front of the Catalytic. It gets worse and noisy, so I decided to tackle it.

Some good references:

Use for diagram and PNs.

- Search forum for “OBX Exhaust Manifold” brand, about $200 on ebay etc., many people seem OK with it. I could not find any long-term report (such as 5 years or more) of happiness with OBX, also from my research the Honda people have some issues with OBX. Since this is a job I don’t want to do again for another 10 years, I decided to go with Volvo OEM because the OEM held up for more than 10 years!

The good news is Waltrip Volvo offers a very competitive price!

I used OEM Gaskets as well; again, this is not a job I want to do again in 10 years!

These are what I ordered from Waltrip Volvo (Franklin TN):

* OEM Volvo Exhaust Manifold: PN 9471934....$365

* Gasket Set (at Manifold, sold as set of 5): PN 271735....$24.

* Gasket @ Catalytic (qty =1) PN 9135122....$10

I regret I did not order the 4 studs at the catalytic, so had to run to local autoparts store.

Volvo PN is 978342....$2.00/each; these are M8 x 1.25 x 35 mm long. So I strongly recommend that you order these 4 studs ahead to avoid aggravation!

I re-used all the nuts, they came out fine.


- 10-mm, 12-mm, 13-mm sockets.

- Extension and swivel joint (this is a must).

- 2-foot section of 1” iron pipe (few dollars at Home Depot), this gives me a lot of torque to remove the stubborn nuts.

- Make-up mirror: a very useful tool! You can get this at Target, Walmrt, Walgreen for a few dollars.

- I broke the Heated Air Hose (Aluminum) feeding the Air Filter. Dealer wanted $50 for this piece of junk! So I got it from OReilly Autoparts for $6.00, make sure the I.D. = 2” and length is 18 inches or so.

- I could not remove the 4 studs on the Exhaust Manifold even with this out of the car and lots of heat from the torch, I called Volvo dealer and they say it will take 2-3 days to get them, so I went to Advance Autoparts and got their "Water Pump Stud Kit” (PN 25735 on the package): 3 separate sizes and 4 of each type, so 12 studs and 12 nuts total for a cheap $5.00! I only used 4 M8x1.25x35 studs from the kit). Or you can ask your local muffler shop if they have the studs.

- Propane Torch ($12 at hardware store): use only 2” of blue flame.

- WD-40 etc.

- “White-out” (liquid paper to label nuts). Make sur you label the nuts and bolts properly, it will make install a lot asier.



1. Get a box to store the nuts and bolts. Spray the nuts/bolts areas with WD-40 the night before, but don’t drive it because the WD-40 will be burned off!

2. Front of Car up on wood ramps.

3. Study the new Exhaust Manifold so you are familiar with it. Note mounting holes for Air Valve, Heated Air Cover, and the ten (10) holes for the Manifold itself.


4. Remove ground straps x2 (10-mm socket). Save the bolts.


5. Remove the 5 bolts on the Heated Air Cover. In my case, the 3 upper bolts came out fine, the lower 2 bolts near the flex pipe were so rusted in and impossible to remove w/o heat. So I got in from the bottom, heated the welded nuts with propane torch for 1 minute each. Then they came out fine. Just be careful with the propane torch; only light it when you are down there and ready to go.


6. Once 5 bolts on the Heated Air Cover, do NOT remove the Heated Air Cover yet. It won’t come out until the Air Valve is moved out of the way. I learned this the hard way, so don’t ask LOL!

7. To remove the Air Valve piping, see the pic. Remove the 2 mounting bolts (12-mm) It is a flared fitting with 22-mm nut. The reducer also has a 22-mm hex. Heat this area with Propane, taking care not to burn the car down LOL. The heater hoses are close by, just pay attention where you aim the torch. Once it is hot, you can now use the 8-inch adjustable wrenches to undo the large nut and remove the reducer from the bung. No need to disconnect the rubber hoses etc. just tie it up out of the way.


8. The Exhaust Manifold is held by 10 nuts (engine side) and 4 nuts (cat side). Guess what, the Volvo engineers decided that for the 4 nuts on the catalytic side, two (2) of them were 12-mm and two (2) of them were 13-mm, go figure! The Exhaust Manifold will be hard to get out, simply because the studs are stuck to the Exhaust Manifold, so you may have to pry with screwdriver to separate it from the Cat piping. You may need to lower the cat or push it back a bit. I barely got the Exhaust Manifold out with prying, so not much room to giggle!


Installation is the reverse of the removal but note these tricks:

1. I used anti-seize on all nuts and bolts during install to make it easier. I understand that heat will eventually burn it all but all I care is a smooth install.

2. You may need to support the catalytic with a floor jack to line up the holes.

3. Install the 5 gaskets. There is only one way they can fit. Now install the Exhaust Manifold and let it hang loose.

4. Do NOT install the four (4) studs on the Exhaust Manifold during install yet because there is simply no room! Now install the Gasket on the Cat side with the 4 studs.

5. Here is the trick when installing the 4 studs: wet the short end (the goes into the flange) with oil, gently spin it in a few turns, then use a “right-angle pliers” to spin it in until about 1mm sticks out. The “right-angle pliers” works out perfect because they also “roughen up” the stud threads a bit, so when the nut is installed, the nut helps spins the stud further.


6. I tightened the 4 nuts from below using extension and swivel joint. Look up the torque, I just tightened by hand and snug it.

7. Double-check to be sure all 10 nuts are tightened on the Exhaust Manifold.

8. Slide the Heated Air Cover but don't install the 5 bolts until you are finished with the Air Valve Piping installation.

9. Don’t forget the Heated Air Hose and clamps.

10. Lastly install the engine ground straps.

11. Start the car and you will love the smooth sound as if it just comes from the show room!

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Excellent write up! With all of the write ups you've done, I think you've earned a supporting membership. I'll let Chuck know :tup:

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I maxed out on allowed memory for upload for a member (I think it is about 8MB or so).

So I cannot write any more DIY unless you guys increase my memory limit!

Thanks again!

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Congrats on your new supporting membership. Thanks for your contributions to VS :tup: :)

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Thanks Oreo931!!!

Just curious how many MB of memory am I allowed now?

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Thanks for the detailed write up!

I'm working on replacing the exhaust manifold on a '98 S70; I've gotten four bolts out of the heat shield, but the fifth (one of the bottom two attached directly to the manifold flange) is rusted/stuck and now the head is rounded to the point where it can't be gripped by a socket...

Whats the best way to get this bolt out?

Is the manifold flange threaded or is there a nut on the bottom side holding the bolt to the flange (so rusted can't tell)?

One thought is to try to crack the nut?

any input helps, thanks!

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