high mileage AAN, likelihood of oval bores and worn skirts?

After taking these engines apart for many years, I am always still a little surprised at the shape the bores are in at this mileage and more. I have put many a head gasket on a 5-cyl motor at 250-300k and then proceeded to RS2-or Hybrid turbo swap them with no issues. We have an AAN in the shop now for a popped hg, I will try to get some pics of the inside of the block and post them.
As always, YMMV, so it's a matter of teardown and inspection..

it might be fine the way it is. it is not automatically in need of rebuild or even a freshening. You may have a hard time excepting that but it is true. or maybe rings and valve job if it needs them. The only place where mine did not spec like new was top ring grove clearance....big deal, what you going to do. no noticeable ridge or anything.

Do a leak down test before taking anything apart. I bought a 320k mile 200 20v years back that tested decent on leak down (7-10%) and threw an rs2 turbo on it and ran 26psi with no issues other than blown boost hoses and rotted PVC hoses. I also rebuilt a 200k aan last year for no reason when it was out of the car. Bearing clearances and bores measured in or very near new specs. Test the engine first.

Agree, it is amazing how long lasting these engines are. The 2226/2307cc engines are probably my favorite, ever. All that I've had apart, that were not abused, could have gone another 100k before needing anything.

cuatrokoop said:

Agree, it is amazing how long lasting these engines are. The 2226/2307cc engines are probably my favorite, ever. All that I've had apart, that were not abused, could have gone another 100k before needing anything.

Click to expand...

well, once you see one with almost no wear at 250k it kinda makes you wonder why it would not go another 250k. I think they may need a head freshening at 250-300k but the bottoms seem good for another 100k + beyond the tops, unless we are talking 10v then I think you have to add another 100k to those figures, which is just a guess since I have never known one to die at any mileage....man that is a lot of door handles though.

Just drive it the way it is and save your time and money for the rest of the car. Trust me. You will need it at some point.

Thanks for the replies, everyone! I know these are extremely stout engines but the rod:stroke ratio meant I had to ask. I'm planning a rebuild to upgrade rods and hardware. Cost is not really an object and cross country tours demand every insurance available!

This particular car has had two owners and records going back nearly 20 years so I feel tremendously reassured. Thanks again.

When I pulled the 3B from my 200 20v at 220k miles you could still see all the crosshatch in the bores. The bottom end was perfect

The AAN that I rebuilt for the URQ had ~180k miles on it and still had the crosshatch, almost no ridge, and the bearings were within the wear spec.

I just replaced the engine in my 93 s4 cause I got a good deal on a aan wit 68k on it my original had 177k+ on it and I tore it down and everything in the bottom end was perfect still has the crosshatch and the piston tops were real clean only issue I found was the cooling system was full of rusty gum so I would suggest a coolant flush just to be on the safe side. The aan engines are outstanding.

pkw said:

cuatrokoop said:

man that is a lot of door handles though.

Click to expand...

Click to expand...

:stupid: :frustrated:

Those door handles.....my god... just pre-emptively buy 12 door handles. Then you're good to go.

I would not even consider rebuilding the engine if it runs well and does not use oil. Those 20vt engines go forever with reasonable maintenance.

Reading through this has been reassuring to say the least, thanks for the info guys!

Most engines nowadays have negligible bore wear. I blame closed-loop operation keeping the cylinders from getting fuel-washed, and cheap manufacturers no longer casting blocks out of Silly Putty.

250k and no visible bore wear is the norm, not the exception.

Where you need to pay attention is the ring to piston groove clearance. That will open up over time. I have a couple sets of VW pistons that I don't really want to use because, while everything was fine in the engines they came out of, they're up close to .010" clearance.

Noisy Cricket said:

250k and no visible bore wear is the norm, not the exception.

Where you need to pay attention is the ring to piston groove clearance. That will open up over time. I have a couple sets of VW pistons that I don't really want to use because, while everything was fine in the engines they came out of, they're up close to .010" clearance.

Click to expand...

exactly. i have said it many times, it is really the only wear you see.

Hi guys, just to reopen this thread I wanted to ask about this same subject.

I am looking at a well-kept 90 20v with 260k miles. That seems like so much..but it sounds as though aside from a possible top-engine maintenance I can get away with this?

I am literally stupidly obsessed with the idea of making the 90 my only car for the next 10~? years. Right now I live in San Francisco, have a garage and don't use my car much. I am getting rid of my 2011 GTI lease and looking to make room in the garage for a 90. Do you think I should be diving after low mileage ones or find a really well maintained, driven regularly but well-kept with something like 260k miles? I really want the longevity...but the car really brings back the feels if you know what I mean.

My QSW is on roughly 380k miles (that's, what, 600k kms? 600 megameters? ) and it could really, really use a valve job and new valve stem seals but it doesn't have blowby issues and the bottom end still sounds good.

The wiring harness, on the other hand, is Done. Any wires you even bump will break (most recent: broke the wires to the washer pump by moving the bottle a little) and it develops a horrendous part-load misfire if it is raining or snowing or otherwise humid out, and this is despite having the WOT switch ziptied shut because it will not run otherwise, I believe the O2 wiring is shorted to power somewhere because it runs very, very lean if you let the computer think for itself... But the mechanicals themselves are solid!