How hard IS it to change the passenger side exhaust manifold? (2.8L AHA V6)

2572 Views 16 Replies 3 Participants Last post by KHedges, Oct 6, 2021

KHedges

Discussion Starter · Aug 20, 2021

Well, my mechanic confirmed there's a leak at my passenger side exhaust manifold. I don't know if it's related to the aftermarket catalytic converter hanging low on the right side and getting bonked when I go over the weird driveway hump or not. But it's leaking, and it's getting worse.

My local mechanic said one of his mechanics had done this job on this engine before and it took all day just to get to it (therefore it's going to be very expensive at $180/hr). I know a couple of Audi mechanics who'd probably be more familiar with this (and charge more per hour), but would it be at all reasonable to do it myself? I've consulted the Haynes and Bentley manuals, neither of which has a good step-by-step. Haynes says you have to get the AC system depressurized so you can remove the AC condenser--seems we just swung it over to the side when we had the front end off to do engine work when I first got it.

I have a pretty good tool collection and can use a friend's driveway, or a "rent a lift by the hour" place. Except they charge $50/night storage if I don't finish in a day...

There's over a dozen 2.8L Passat/A4/A6 at the Newark PickNPull so I should be able to get an exhaust manifold off one of them--and they're only about $40. ECS Tuning had all the gaskets, studs, etc, for the job for about $115.

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AndreasPassat

· #2 · Aug 20, 2021

It can be done. The passengers side is WAY easy than the drivers side.
Removing the air the cleaner box, MAF and the accordion type tube will net you a good amount of space for your hands to get into.
Using a 3/8 drive with flex sockets (or flex joint and a socket) is the best for getting under the exhaust manifold.
Getting the 3 nuts off exhaust down pipe will be the most difficult.

Nothing has to be done with a/c system for removing the exhaust manifold.

Make sure you check the mounting pattern of the original exhaust manifold. There are 2 different types of exhaust manifolds that were used.

AndreasPassat

· #3 · Aug 20, 2021

2

Pay special attention to the bottom row of mounting studs.
This 1st picture is missing a stud, so it has 4 studs on the bottom.

This 2nd picture has 3 studs on the bottom.

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AndreasPassat

· #4 · Aug 20, 2021

The cylinder heads used are all exactly the same. The bottom row of threaded holes has two different mounting patterns to accommodate the different exhaust manifolds.

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KHedges

Discussion Starter · #5 · Aug 20, 2021

AndreasPassat said:
The cylinder heads used are all exactly the same. The bottom row of threaded holes has two different mounting patterns to accommodate the different exhaust manifolds.

Thank you for the information!

I have the unfortunate experience of changing cats on this engine three times, so let's hope I can manage those on jacks instead of a lift. Can I get to the manifold from the side without taking the front off, or do I need to get the radiator etc. out of the way?

But I hope I didn't order the wrong gasket. I didn't realize there were two different manifolds. Is there a VIN split or is it just whatever came off the truck that day (like side mirrors)? Good thing I didn't waste time at PNP pulling a manifold...

Also, I cross posted at AudiWorld and someone was really skeptical the manifold could be the problem. He suggested a smoke test, and of course I returned my friend's tester already. My muffler guy already said it's nothing back of the flange, but I guess it could be some other thing.

AndreasPassat

· #6 · Aug 20, 2021

KHedges said:
Thank you for the information!

do I need to get the radiator etc. out of the way?

I removed the passengers side exhaust manifold without removing any of the front end on my 98 GLS V6 back in 2009.
I did remove the air box, MAF and accordion type hose like mentioned earlier so I at least had a place to get my hands into.

KHedges said:
Is there a VIN split or is it just whatever came off the truck that day (like side mirrors)? Good thing I didn't waste time at PNP pulling a manifold...

I can't answer that.
I've owned 6 V6 Passat's, 1 of them an AHA the other 5 were ATQ.
The AHA and one of the ATQ's were different than the others. Go figure.

KHedges said:
Also, I cross posted at AudiWorld and someone was really skeptical the manifold could be the problem. He suggested a smoke test, and of course I returned my friend's tester already. My muffler guy already said it's nothing back of the flange, but I guess it could be some other thing.

AudiWorld has got some good info but there are some pretty headstrong members over their with some inaccurate info.
Over the years I've found that this forum is much more reliable for info than the rest.

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KHedges

Discussion Starter · #7 · Aug 31, 2021 (Edited)

[deleted original post because I misinterpreted the photos viewing them on my phone]

According to ECS, there's a VIN split and the first one is supposed to be up to early 1998 for Passats (including a VR6?). The gasket is Rev C.

Exhaust Manifold Gasket - Priced Each "Up to VIN 4B-W-150000, split is in the 1998 model year"

078253039C - Volkswagen Exhaust Manifold Gasket | Stevens Creek Volkswagen, San Jose CA

Genuine Volkswagen Part # 078253039C (078-253-039-C) - Exhaust Manifold Gasket. Fits A4, A6, Passat, Passat Wagon. Ships from Stevens Creek Volkswagen, San Jose CA

parts.stevenscreekvw.com

But for Audi, they apparently used it throughout the production run for the 2.8L.

078253039C - Exhaust Manifold Gasket. Exhaust Manifold Gasket. To 03/1998. To 04/1998 - Genuine Audi Part (select the tab for the models)

The second SHOULD be what I have for my 1999 A6 following the VIN split, so I had already ordered the Rev G ... but I think I have four studs like the first one. The car is 45 minutes away by bicycle, and I have meetings all day Tuesday, so I guess I will check more thoroughly on Wednesday. (I removed the upper heat shield today; the lower one seems to be attached along with the lower row of nuts for the manifold itself, so all the nuts are marinating in PB Blaster for a couple of days before I try removing them.)

www.ecstuning.com

Exhaust Manifold Gasket - Priced Each

Fits the left and right side

www.ecstuning.com

And of course the Rev G is still in production and the Rev C is not. Hopefully there's some old stock still available.

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KHedges

Discussion Starter · #8 · Aug 31, 2021 (Edited)

Procedure draft Part 1: Preparing to remove the passenger side exhaust manifold

Parts to order for Part 2:
Replacement o-ring for dipstick tube connection to oil pan
Appropriate gasket for your manifold (old stud layout #078253039C or later stud layout #078253039G) THESE DO NOT NECESSARILY FOLLOW THE VIN SPLIT IN THE ECS CATALOG.
Appropriate quantity of studs & nuts for your manifold (longer studs #N90188902; nuts #N91130801) <=== ECS is confused, those nuts are the ones you see on the flange sometimes, not the copper ones you see on the exhaust manifold
Gasket for flange to catalytic converter (#8D0253115C)
Studs & nuts for flange to catalytic converter (3 each, shorter studs #N0445122; nuts #N90226404 <=== turns out those are the right ones so get a dozen
Copper anti-seize

Tools & supplies:
10mm, 13 mm, 17 mm sockets
Variety of Torx sockets, screwdrivers, or bits
Variety of ratchets, flex head ratchets, extensions
10mm & 13mm ratcheting speed wrenches
Variety of screwdrivers
Body clip removal tools
Electrical connector removal tool (#002916SCH01A)
PB Blaster or other penetrating oil

Securely lift the car by the inboard jack points with a trolley jack and support it on jackstands at the pinch weld jack points. If you only lift the front wheels, block the rear wheels.
Remove the front passenger side wheel (17mm lug nuts) and wheel liner (lots of T27 screws and maybe a few bolts). You will need as much light and space under the car as possible.
Remove the skid shield if you have one installed. (I don't, but apparently some people do?)
Remove the air duct:
1. Unscrew two Torx screws (T27?) where the front opening of the air duct passes through the radiator support.
2. Remove that piece, and pull the rest of the pieces out.
Remove the air box:
1. Loosen the clamp on flex pipe between the MAF and the intake to the throttle body.
2. Unclip the air filter cover (you don't need to remove the MAF housing or flex pipe) and remove.
3. Unscrew the Torx bolt fastening the air box to the side of the engine compartment (T40?).
4. Wiggle the air box pegs out of the rubber grommets on the frame (?) on the engine side.
Optional: I did this the first time but I didn't bother the second time.

The next steps will make space to remove the upper heat shield over the exhaust manifold. The dipstick tube is in the way, and there isn't enough clearance between the exhaust manifold and the cable guide under the aluminum heat shielding to remove the heat shield.
Remove the cable guide next to the air box grommets:
1. Gently unfold the upper edge of the flexible aluminum heat shielding where it covers the cable guide, sliding it off the tabs on the top of the cable guide. (Do not try to remove the whole piece of heat shielding--this is the top edge of the big heat shield over the transmission. I wasted quite a bit of time before I realized I didn't need to remove it.)
2. Snip any cable ties holding the bundle of wiring in the guide.
3. Using a body clip removal tool, gently unseat the clips on the underside of the cable guide on the frame.
4. Wiggle the remaining cable guide anchor point off the stud on the "mezzanine" firewall.
This definitely makes it a lot easier to reach in through the front.

Remove the passenger side headlight:
1. Remove the two large Torx screws on top of the radiator support like the one holding the air box to the side of the engine.
2. Remove the third headlight fastener inside the fender. You can see it easily with the air box out, but it's tricky to reach unless you take out the turn signal bulb holder because the handle is in the way. Alternatively, there is a hole in the fender above it that isn't wide enough to insert a standard ratchet extension but you can use a long screwdriver-type tool if you have one. I have an interchangeable screwdriver set from Home Depot that is thin enough and almost long enough. I used a bit holder as an extension and turned it using a 6mm socket.
3. Unclip the headlight wiring connector.
4. Slide the headlight free of the peg holding it on the opposite side and remove it.
Remove the oil dipstick.
1. Remove the 13mm bolt on the right side of the upper exhaust manifold heat shield that fastens both the upper heat shield and the oil dipstick tube.
2. Follow the dipstick tube down to the oil pan and wiggle it loose. It's near the rear passenger side corner of the oil pan.
3. Maneuver the dipstick tube out through the "eye socket" where you removed the headlight. Check the o-ring and see if it needs replacement.
Remove the upper exhaust manifold heat shield.
1. Remove the 13mm bolt near the upper middle of the shield.
2. Remove the 10mm bolts on the bottom of the shield. Look up from below the car; you can see the lower exhaust manifold heat shield above the engine mount. One bolt is in front of the engine mount and one is behind it. You will need the long extension and you may need to hold the ground cable off to one side to access the front one.
The lower heat shield is attached with the same nuts as the exhaust manifold, so don't try to remove the lower heat shield yet.
Apply PB Blaster to all the nuts on the exhaust manifold, finding them by touch and guiding the plastic straw to squirt them.
1. The top row is under the ledge formed by the valve cover, tucked below and behind where you unbolted the top edge of the heat shield, above the visible part of the exhaust manifold.
2. The bottom row is between the lower heat shield and the underside of the exhaust manifold.
Remove the vacuum hose from the combi valve to make a clear path to the exhaust flange. It should just slip off the tube pointing towards the side of the car.
Apply PB Blaster to the nuts on the exhaust flange to the catalytic converter.
1. You can access the top one from that space behind/beneath the combi valve.
2. You can access the bottom two from underneath the car; just follow the exhaust up past the flex tube to the flange.
You can figure out if you have the old stud layout or the new stud layout:
1. The old layout has four studs between the lower heat shield and the exhaust manifold: one at each of the lower corners, and two evenly spaced between the three ports.
2. The new layout has only three studs in the bottom row: one below each port, making a triangle with the ones in the top row.
Let the penetrating oil sit at least overnight.

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KHedges

Discussion Starter · #9 · Sep 1, 2021

Went over today and checked; it has the Rev G style with the lower studs/nuts centered under each exhaust opening. That's a relief! Package is due today.

AndreasPassat

· #10 · Sep 1, 2021

KHedges said:
Went over today and checked; it has the Rev G style with the lower studs/nuts centered under each exhaust opening. That's a relief! Package is due today.

So you've got the manifold with 3 studs on the bottom.
I still wonder why VW used two different exhaust manifolds. But I suppose they're like any other manufacturer, if they can find a way to adapt other periphery parts without changing up the more complex base parts = money saved.

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KHedges

Discussion Starter · #11 · Sep 1, 2021

8

It had two metal gaskets. It has some residue on the gaskets and mating surfaces. No cracks, however! Is there anything else I need to look for before I replace the gaskets? Do I need to replace the studs if they seem ok? (The copper nuts are single use, I presume.)

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PZ

· #12 · Sep 2, 2021

I think they had different sized outlets for some, but only because I got the wrong sized ones in a head gasket set. I know the A6 ATQ was rated at 200hp and it was "supposedly" due to more room for the exhaust.

AndreasPassat

· #13 · Sep 2, 2021

The studs you can re-use no problem.
Of the engines I did pull the exhaust off, I used all brand new copper nuts. I actually bought a whole bag of 100 of them.
The copper nuts are technically one time use because they are crimped (actually are trilobed) and have an imperfect thread. When you tighten them they grip the threads.
Yes you could re-use them but you run the risk of them loosening up over time.

KHedges

Discussion Starter · #14 · Sep 4, 2021

7

I ordered replacement parts for all of it (studs, nuts) but I know the nuts are definitely single-use. They left copper residue on the threads where they gripped.

The bad news is that it's warped. I started checking with my car friends to see if they could recommend a machine shop, but it already has a hole drilled where a stud misbehaved a couple of cat swaps ago, so I'm working on getting one from a junkyard. I found one in a donor car that already has the front stuff off and squirted the nuts with PB Blaster so it'll be ready tomorrow. (Hopefully nobody takes the engine between Friday afternoon and Saturday morning.)

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KHedges

Discussion Starter · #15 · Sep 28, 2021

Update: After getting a crummy $40 belt grinder resurfacing on a junkyard manifold, it was closer to being flat (but not perfect). I was a little too gentle with tightening the nuts because I didn't want to overtighten them and overcrush the gasket. It leaked (but less than before, just a kind of "bicycle freewheel" clicking, not "typewriter clacking) so yesterday I pulled the upper cover off and got those nuts good and tight. (The lower three would not be accessible to my torque wrench, which just plain won't fit in the gap.) Ran the engine and it sounded good, finally.

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AndreasPassat

· #16 · Oct 6, 2021

I wouldn't sweat the torque on those nuts to much. Me personally, I've never used a torque wrench for the exhaust manifold nuts.
Goot-n-tight. You can't over-crush the metal gasket.

I did however use some high temp anti-seize on them nuts on assembly. Makes tightening them nuts go smoother. The copper doesn't gall up on the threaded stud.
If I remember correctly, the Bentley procedure states to go in and retorque the nuts after a few cycles of the engine getting hot and cooling down.
But then again I might be making that up in my own head. It's an over 50 thing. For whatever it's worth though, I retorqued those nuts on all my engines after swapping the motors in and out. No issues on my end, other than a few hours of really stanky smoke rolling out from under the hood.

KHedges

Discussion Starter · #17 · Oct 6, 2021

Yes, I saw the "retighten" instructions too. I didn't drive far (5 miles to the garage, 5 miles back) but it had at least 3 heat cycles. I used the copper antiseize on those and the exhaust flange, left over from changing the O2 sensor.

Now the transmission plug is dry and the transmission gasket is leaking. Haven't gotten to the differential seals yet.

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