DIY B7 S4 engine swap into B6 S4

[Daveasus]

Where to start.
Brought a B6 S4 with engine problems. Hoping for chain problems but ended up with a scratched cylinder. Instead or rebuilding I managed to find a 2008 B7 S4 engine. Will be replacing all chains , guides, tensioners. Also cleaning pistons and valves, changing oil check valves and rebuilding cv axels.
Hoping all goes well. Here goes nothing.

Car Prior to engine work

[Lucca M]

Its plug and play. Good luck!

[Terry.Reese]

How is it plug and play? don't you have a ton of things to change over? Correct me if I am wrong though, but I was told there was a lot to change over between the two.

[jmcS4]

How is it plug and play? don't you have a ton of things to change over? Correct me if I am wrong though, but I was told there was a lot to change over between the two.

Both are BHF engines. its still plug and play. very very very minor differences between the two and its mostly updated part numbers and such

[LINDW4LL]

It's the same engine.

[pwest15]

How is it plug and play? don't you have a ton of things to change over? Correct me if I am wrong though, but I was told there was a lot to change over between the two.

There are a few minor differences in the engine itself but if OP is swapping over the whole thing, it'll be plug and play

[Daveasus]

From what I noticed so far, the valves are different, the heads in the B6 have an extra piece that the B7 don't have. Flywheels are also different. I hope the wiring is the same for the headlights. Going to use the harness from the B7. I know I have to use the ecu from my B6 because of the immobilizer.

[Daveasus]

Does anyone know why I can't post photos?

[Terry.Reese]

Awesome to know! Thanks!

[gautam]

Try using imgur and use the "Linked BBCode (message boards)" option, copy paste the link into a reply on this thread and it should post your pic.

[Terry.Reese]

Try using imgur and use the "Linked BBCode (message boards)" option, copy paste the link into a reply on this thread and it should post your pic.

or photobucket

[jmcS4]

From what I noticed so far, the valves are different, the heads in the B6 have an extra piece that the B7 don't have. Flywheels are also different. I hope the wiring is the same for the headlights. Going to use the harness from the B7. I know I have to use the ecu from my B6 because of the immobilizer.

where are you getting your info??? they're BHF engines

[Daveasus]

where are you getting your info??? they're BHF engines

I have both engines in pieces. Just noting what I can see visually. Flywheels have different part numbers. Valves are a bit different visually, maybe updated in the B7. I'll try to post some pictures.

[jmcS4]

Flywheel maybe different and or updated.

Dru or Jake from JHM can confirm.

And when you say valves you mean intake/exhaust valves??


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[Lucca M]

Yeah some parts are vin specific but nothing major. 95% is plug and play. Id transfer the valve covers from b6 engine as they are metal not plastic and intake manifold doesnt have the heater line that is useless.

[Daveasus]

exhaust valves have a small hole in the middle on the b6, B7 are completely flat.


these are the extra parts that are only on the b6, not sure what they do.

[Daveasus]

current progress

purchased B7


Took heads off, Cleaned valves and pistons. Nice and clean


New head gaskets. heads back on



test fit some intake spacers


decided to check my valley pan gasket, what happened here? does this mean my oil spray valve or oil check valves are shot?

[Daveasus]

Can you clean the oil spray valve or oil check valves? or check if they are working?

[Daveasus]

does anyone know if you can reuse the cam sprocket bolts and cam adjuster bolts?

[Bonz099]

does anyone know if you can reuse the cam sprocket bolts and cam adjuster bolts?

Both of the bolts for either cam are 100% need to replace bolts. anything with a torque spec then an additional degree to turn are torque to yeild bolts and should be replaced.

[badger.]

decided to check my valley pan gasket, what happened here? does this mean my oil spray valve or oil check valves are shot?

Pretty typical. for some reason that is a painted gasket. most everyone's is peeled like that. it is not oil or anything, just a crappy coating. I don't think it indicates anything about the condition of the spray/check valves, good or bad.

[Terry.Reese]

Pretty typical. for some reason that is a painted gasket. most everyone's is peeled like that. it is not oil or anything, just a crappy coating. I don't think it indicates anything about the condition of the spray/check valves, good or bad.

i scrubbed mine clean. only oil issue I have now is a small leak from the pan. all my issues which I thought was oil was actually power steering fluid leaking and mixing with the oil on the ground, so my driveway is a ton cleaner than it was before.

[Daveasus]

Both of the bolts for either cam are 100% need to replace bolts. anything with a torque spec then an additional degree to turn are torque to yeild bolts and should be replaced.

Thanks, I'll order them.

[pwest15]

I have both engines in pieces. Just noting what I can see visually. Flywheels have different part numbers. Valves are a bit different visually, maybe updated in the B7. I'll try to post some pictures.

Yes this is all correct. The flywheels are different. B6 has a dual mass flywheel that's more prone to failure. However, the two are still 100% interchangeable. As you later stated, the pitting on the exhaust valves are different but that shouldn't be an issue. Are you transferring the whole motor over from a B7 or just the bottom end? Also the valve covers on the B7 mount slightly differently to the B7 heads than the B6 heads. There is a bolt on each cover that is super long for the B6 heads but the B7 uses valve cover bolts that are all the same length. (Just a side note but I highly recommend buying a set of new valve cover bolts with new valve cover gaskets. The seals around the bolts get worn out and even with new gaskets, valve covers tend to leak from those areas)

[Daveasus]

Pretty typical. for some reason that is a painted gasket. most everyone's is peeled like that. it is not oil or anything, just a crappy coating. I don't think it indicates anything about the condition of the spray/check valves, good or bad.

This coating scares me. On my B6 that coating clogged one of my oil sprayers under one cylinder. Destroyed my cylinder, I'll post a pic when I get home.

[pwest15]

these are the extra parts that are only on the b6, not sure what they do.

Those are the little holes that direct some pressure flow into the valve cover exit system that goes to the PCV. you might see two rubber grommet type things that attach to your valve covers. I believe one bank has two and the other only has one. It's just how pressure gets relieved. The B7 heads don't do it in quite the same way with their valve covers.

You'll see the corresponding holes I'm talking about on this picture of B6 S4 valve covers. those little holes lead too the pathway that feeds to the hose going to the PCV

[Daveasus]

Yes this is all correct. The flywheels are different. B6 has a dual mass flywheel that's more prone to failure. However, the two are still 100% interchangeable. As you later stated, the pitting on the exhaust valves are different but that shouldn't be an issue. Are you transferring the whole motor over from a B7 or just the bottom end? Also the valve covers on the B7 mount slightly differently to the B7 heads than the B6 heads. There is a bolt on each cover that is super long for the B6 heads but the B7 uses valve cover bolts that are all the same length. (Just a side note but I highly recommend buying a set of new valve cover bolts with new valve cover gaskets. The seals around the bolts get worn out and even with new gaskets, valve covers tend to leak from those areas)

It's a full engine swap. Didn't know about the valve covers being different , was going to use the ones of my B6 since someone mentioned they were metal instead of the plastic off the B7. Great advice. I'll look into those valve cover bolts.

[Daveasus]

Those are the little holes that direct some pressure flow into the valve cover exit system that goes to the PCV. you might see two rubber grommet type things that attach to your valve covers. I believe one bank has two and the other only has one. It's just how pressure gets relieved. The B7 heads don't do it in quite the same way with their valve covers.

You'll see the corresponding holes I'm talking about on this picture of B6 S4 valve covers. those little holes lead too the pathway that feeds to the hose going to the PCV

Thanks, I wonder which system is more efficient. Could always swap it over to the B7.

[pwest15]

Thanks, I wonder which system is more efficient. Could always swap it over to the B7.

I'd recommend you keep everything on that B7 motor. They updated that system for a reason. I always want to keep the heads that came with a motor on that motor and you'd have to use B7 valve covers on the heads. Additionally, I don't disagree with Lucca on many things but I do have to say that I think B7 valve covers are superior. They may be a plastic but the magnesium material that the B6s are made out of are very prone to damage and pitting after heat cycling. My biggest issue with the B6 valve covers is that horrible coating they have on the underside. That picture I posted is a good example of how nasty it gets with mileage. I just don't trust stuff like that flaking off in my heads, granted it most likey gets combusted

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[ZimbutheMonkey]

Did you think about doing any porting to the heads while they were off?

[REVOofRustler]

If you're willing to grab some pics, I'd really like to see the difference in the B6 and B7 valve covers, and also in the heads where those PCV grommets go.

[Daveasus]

need some help, ive done the timing 5 times now and I cant get the timing perfect. using all the right tools. cant get the cam locks on both sides after rotating engine 2 times. its really close. one goes in and one as per pictures

[neilpaku]

If it's really close, so close that you can tap it in with your hand or the handle of a screwdriver, then it's good enough in my book. But looking at your picture on the left, I'd say you need to back off the weight you're putting on the wrench on this end so that the shaft is a little more rotated counter-clockwise in this picture. Use your old bolts to figure how much to load the wrench and then use the new bolts for final placement.
Did you leave those cam locks in place while torquing? I did, but I used the wrench to absorb the torque. That way I got almost perfect alignment - I had to tap the passenger side in with my hand, and the driver's side slid right in after the two rotations.

[pwest15]

If it's really close, so close that you can tap it in with your hand or the handle of a screwdriver, then it's good enough in my book. But looking at your picture on the left, I'd say you need to back off the weight you're putting on the wrench on this end so that the shaft is a little more rotated counter-clockwise in this picture. Use your old bolts to figure how much to load the wrench and then use the new bolts for final placement.
Did you leave those cam locks in place while torquing? I did, but I used the wrench to absorb the torque. That way I got almost perfect alignment - I had to tap the passenger side in with my hand, and the driver's side slid right in after the two rotations.

x2 I did it the wrench way as well.

I'd just get a crescent wrench or whatever fits and torque the cam ever so slightly so that the cam lock bar slips in the slits

[jmcS4]

need some help, ive done the timing 5 times now and I cant get the timing perfect. using all the right tools. cant get the cam locks on both sides after rotating engine 2 times. its really close. one goes in and one as per pictures

They will almost never ever ever slide in freely. tap them in. a old Audi master tech even informed me that they will never just slide right in

[Daveasus]

I appreciate all your advice I'm going to try using a wrench to hold the cam as soon as my new cam bolts come it. Thanks everyone!!

[Daveasus]

Did you think about doing any porting to the heads while they were off?

I though about it but i don't feel comfortable doing it myself, dont have any left over funds to send it to a shop.

[jmcS4]

the timing is the easy part. pulling the engine is the sucky part

[lucky1213197694]

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[badger.]

Hello yeah tear that shit up sendin support safety and Givin yards a shout out to you! Everybody hear me another man with a plan and a small situation, knowing he's pimpin his ride so that he make stronger fast ah how haulah you catch in my drift ladies all Audis are the ho hoppah filtah so we can save a dollah for that real lady who sticks around supportin real gentleman, because this is my brotha that's on a mission gonna slay down to ya ladies, I think a good nickname for the upgraded labah would be on this classy Audi female slay a would have to be the "Man hatah slay ah. " This is Jeff Givin ya a shout out from Alaska wish in you the best to be furthest from any kind of disastah!!! Hit me up with pics down the road brother keep it real!!

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