DIY rear engine RWD car?

In reply to Leviathan888 :

while it is true that there are V6 Audis with manual transaxles, i believe they are all Quattro AWD.  Only the 4cyl 2.0T was available in FWD.  I know this is true for USA vehicles, at least in the B7 generation in which the 01X transaxle was used.  Maybe Canada got configurations that weren't available in the USA?

it is possible to convert a Quattro transaxle to FWD but the result is arguably not as strong as an actual FWD box due to distance between bearings and some other internal design details which enabled the rear output.

Canada definitely gets drive configurations that aren't available in the US and has a higher percentage of manuals. We used to own a 1991 Passat wagon with a stick, which you couldn't get south of the border.

Went back to the wrecker today, narrowed the donor car options down to 2. 

2008 Audi A4 quattro with 205,xxx kilometers, 2.0T inline 4 engine. FWD 5 speed manual. 

200x Subaru legacy, j25 twin turbo. AWD 5 speed manual

Starting with the Audi, while a bit stripped it seems to be all there. Engine turns and compresses, took of the valve cover to see the cleanest top end I've ever seen. Bit of water, but would rebuild. Main issue is that it looks too good. No major body damage, undercarriage looks good, leather interior. Cars that are good/unknown have it written on the windshield, anything without writing has some issue. Since the audi has no writing there is something wrong with it, but I couldn't figure out what. It all seemed good though. When you turn the engine while in gear the wheels spin, but I only checked with the one gear (4th I think). Owner of the yard said he'd sell me the motor and trans as a package for $400, and couldn't remember the story behind the car.

The Legacy I didn't spend much time on. Listed as motor and trans unknown, it might or might not work. Visually all checked out, minor front end and all around body damage, but nothing interfering with the engine. Manual transmission, and if I remember correctly the engine turned over fine. 

Could take a stab at the Audi or spend some more time with the subaru. Other option is to wait and watch local marketplaces for an audi/subaru with rear end damage, and hopefully get a working drivetrain for cheap. Any suggestions?

If the Audi is a Quattro, it's not a FWD. FYI :)

But it sounds like a better bet to me. That's assuming you can get engine management and convince it to run without the rest of the car. I know that's well documented for the Subaru thanks to the VW swap community, can any Audi experts comment?

I agree that the audi would be better, and am sure theres some way to figure out the electrical as most of it is unnecessary for my purposes. The only thing is I don't know where else to look for the extent of the damage. I guess taking the head off and looking for block damage is the next step, I just can't exactly rebuild the engine in the junkyard to see if it runs. 

Leviathan888 said:

 The only thing is I don't know where else to look for the extent of the damage. 

Pull the spark plugs. Look for signs of

• too much fuel
• not enough fuel
• steam-cleaned by blown head gasket
• crusty from oil consumption

stick your finger in the tailpipe (!) and give it a wipe, see if it comes out overly sooty or oily

i assume you've already pulled the dipstick and had a look at the engine oil?

The oil looked and smelled quite good, have yet to check the plugs as they are recessed very far into the block and I didn't bring any socket extensions. Exhaust looked good, I wiped the turbo and manifold. Just from my brief check up, I think it's the transmission that would be bad. Although it shifted into each gear without abnormal resistance and turning the engine turns the rotors. Another person in the yard agreed with me, imports seem to have weaker transmissions that engines and maybe the owner used it as a track car? I can source a new transmission though, so I'll go back there tomorrow and try some more things. 

Given it's an Audi, I reckon it could just be a mess of electronic issues that caused the owner to give up on it

In reply to amg_rx7 (Forum Supporter) :

Yeah, at 205,000 kilometers it might not have been worth while for the owner to fix. I hope you're right about this as it could be a really good find for my project. Gonna go back there tomorrow with a battery, a jack to check everything underneath, pull the plugs, and maybe even take the head off. 

I believe the Audi has one of the last years of the FSI engine. Hopefully it has some of the fixes in place, and I'm by no means an expert at those engines. I think they had high pressure fuel pump and cam follower issues. I'd do a little research and see if there are warning signs you can look for on the engine before you buy it.

It may bolt to the B5 Passat transmission, so if you go that route - I'd see if you can do a test fit at the salvage yard before buying it.

Also, snag the full uncut wiring harness and ECU. There are companies out there that can convert the harness to something that's more accommodating to a new build if you're not inclined to stare at wiring diagrams until the end of the time.

In reply to AngryCorvair (Forum Supporter) :OB3 trans is v6 and 2wd and takes all of the torque

 

Audi OB3 trans, amazingly short bellhousing, driveshafts at the flywheel, allows huge engines in small spaces

In reply to Brotus7 :

It would be awesome if it bolts to the passat tranny, there are multiple B5 passats in the yard with me I could take. 

As for the wiring I'll try, but a fair bit of it has been stripped or cut. Looked like some relatively thick harness going to everything in the front bumper had been chopped through. Also the wiring to the starter and the battery cables are gone, so I'll have to re-wire those. 

Here are some pictures of the car. Gonna jack it up and remove the oil pan to check for metal, then take out the plugs.

Update! Found the only reason the car is in here (so far) 

Jacked up the car and checked undercarriage for damage, to which there was none, except for a small hole in the support beam for the transmission that was from when someone took the exhaust. Doesn't affect anything though. Pulled the coil packs and plugs, they all looked good. Pictures of each below. I couldn't drop the oil pan as it is covered by the sub frame, but after opening the drain plug I strained some oil and it looks beautiful, nothing metal and not creamy.  Theres a picture of the valves below. 

Decided to check the transmission more thoroughly, it's a 6 speed plus reverse. I went into each gear and turned over the motor, the wheels spun the right way and there was no abnormal noise. Wait... If this is an AWD car, I have the front up on blocks, and the back wheels are on the ground, shouldn't the car be moving when I wrench it? Finally realized the only problem so far is that the back wheels don't turn. To determine the cause of this disconnect, I need a second person to crank it while I watch the driveline to figure out whether the issue is in the tranny or rear. Intending to head back there tomorrow with a friend for a final conclusion.

I hooked the starter up to a battery and it sprang to life, so I'll also connect that back up along with the ignition. 

Also I dug around in the car a bit more, and promptly realized everything stripped from the engine bay is sitting in the trunk of the Audi. No clue what is going on with that, but the airbox, rad, alternator, wipers, ac pump, and a bunch of plastics are all there.  Maybe this is some sort of impound car? 

Plugs look a bit dark to me.   Maybe an Audi expert will chime in.   I didn't sleep in a Holiday Inn last night.

In reply to Purple Frog (Forum Supporter) :

The car has 200,000km on it though, so maybe thats a normal amount? Not an expert either

Not to discourage, but I always scratch my head when a car shows no sign of being in a wreck and its in a yard.   Just saying.

In reply to Purple Frog (Forum Supporter) :

I totally agree... Still trying to puzzle through it but so far the engine and tranny (what I need) seem completely functional. I know theres something wrong with it as the scrapyard basically marked it as unsalvageable, but then again the car is only worth about 10k in used condition so the driveline issue I mentioned could make it not profitable to fix? Seems too good to be true, but no issues with the parts I need yet.

After inspection with a second hand today, I came to some conclusions. The main reason the audi is in the yard is because the transmission is broken. When you put a wrench on the crank pulley, the front axles spin but the back ones don't. I had a look underneath while a friend turned it over, the driveshaft going the length of the car quivers back and forth about 1/10 of a rotation with every crank. It never makes a full rotation, all the way into the transmission. Not sure what that indicates, but I'm hopeful it is on the rear end of the diff and tranny so I can still use the front outputs like intended for my project. 

Onto getting the engine running. The starter sitting in the engine bay works but doesn't engage the flywheel, the bendix isn't the issue its just the wrong starter. Beside the audi is a 3.0 inline 4 VW passat, which looks to have the same starter and bolt pattern. I took it out of the passat but ran out of time to actually test it on the audi, though I believe it should be compatible. 

Theres my update, I'm also piecing the wiring back together as most sensors, cables, lights, and harnesses are cut. The major harness going from the battery into the fuse box looks good, and where it leads into the interior nothing is taken apart so I think thats all good. I'm more familiar with older systems, but I think the ignition and engine vitals are all there. Although after hooking up a battery the car shows no signs of life, except a pump in the front right of the engine bay spins. I think its an oil or fuel pump?

Any thoughts?

In reply to Rigante :

You made me spend half a day learning how to connect one of these to an LS engine. Its weird, but doable.

I plan on using one soon but the UK keep coming up with new regulations that limit where you can use home built stuff.  A guy here got an Audi V8 into a series 1 MR2 with that trans...

That car will have a center differential. That's why the rear wheels on the ground aren't trying to turn. Normal. Desired, even - without a center diff, you wouldn't be able to drive on dry pavement. 

In reply to Keith Tanner :

Oh... That makes sense. So something on the driveline isn't broken, it should be like that. In that case I'm even more confused as to why the car is in the wrecker. I'm gonna head back there on Monday to test the passat starter, then try and figure out the electrical. All the fluids have been drained from the engine, but I assume cranking it over quickly with the starter wouldn't ruin anything? 

As for wiring, most of it is cut in the middle so I can find both ends. If I split apart the individual wires, can I just put a crimp/coupler thing on and reconnect them?

If they're normal wires, you can splice them. If they're shielded, you'll probably also want to connect the shield.

I think some insurance companies will total a theft recovery vehicle.

You can certainly crank the engine over a few times to make sure the starter works, but I wouldn't do more than a second or two. That's about all it would take anyhow.