Audi engine internals....failed connecting rod bearing in a 4.2

[Cloudsurfer]

I realize this is not the Audi forum, but since my father's A6 4.2 is having a major problem, I thought I'd ask some of the other great minds on here some advice.

The other day he started hearing a metallic knocking/ tapping sound. Independent dug into it a bit, first thinking it was something in a head, it turns out one of the connecting rods spun a bearing.

Now, where it gets interesting, is that after a phone call with the dealer, they claim that that Audi does not sell engine internals. So, the option is to either replace the engine with a crate motor from Audi ($7500) or find a salvaged one for roughly $3k-$4k. I can only imagine what labor will be to swap that monster motor in and out of an AWD chassis.

Based on my logical thinking, there has to be a way to repair this that doesn't involve a new motor or pulling the block out of the car. I'm going to talk some guys at the engine shops in town I know, but I don't see why a) a conn rod can't be sourced SOMEWHERE and b) that the crank couldn't be inspected, magnafluxed and re machined if necessary.

I'd really appreciate any input from those who could help on this.

Patrick

[Pat]

You should have no problem finding just the parts you need. Try calling Carson at Riverside Audi, or Pete at Autoworks Colorado. If anyone can get the part, they can. They'll wonder why you're calling them from so far away. Just let 'em know Pat from AudiWorld sent you.
Good luck.

[Moostang]

Though i can't be of much help, my fiance's a4 suffered the same fate. They didnt pull the motor out. An independant did the rebuild as well. Good luck

[racer_d]

Dealers don't like doing engine rebuils. It's not where they make money. They need to tie up a couple of techs for quite a bit of time. For the dealer, the plug and play method of a new crate motor works best, especially if it is "refunded (by Audi) warranty work". Not sure how much an independent would charge for a remove, rebuild and re-install. My guess is the crate motor might come with a new warranty as well.

[Cloudsurfer]

Pat, thanks for the advice. I will call them tomorrow.

Car is out of warranty, and is currently at the independent that services it. I completely understand how motors work with dealers, esp under warranty. This is not the case here.

Patrick

Not ragging on your mechanic, but a pointy stethoscope would have isolated the problem top or bottom fairly quickly. Maybe noisy lifters were throwing him off??Hope he didn't burn up too much time diagnosing.


Without knowing the exact particulars, the motor will probably have to come out. Here's why:


Most motors do not have enough clearance to remove the piston/rod through the crank side because the crank registers for the crank bearings/journals are in the way. Typically, motors are assembled with the pistons slipped in from the head side. That means the head will have to come off, which means the intake manifold and the exhaust will have to come off too, which means coolant hoses, draining coolant etc... Then there are issues of how the cams are driven (chains and or balance shafts?). Pulleys/damper on one end and flex plate/clutch at the other will be hanging up the crank so that must be addressed. The mechanic will have to monkey also with front cover, tranny, and driveline. Basically it will require doing everything just short of pulling the motor, only it will be a pain in the arse working around sub systems instead of having them right out in the open.


Another drawback is cleanliness and thoroughness will be marginal at best doing internal motor work with motor in car. So much easier with motor out of car.



If it is JUST a spun rod bearing that is not badly chewed up, a competent machine shop can fix it, install oversized bearings and turn the crank for a few hundred dollars. But you don't really know how much metal shavings circulated in the oil waiting to eat up other parts. Thus the slippery slope, a complete tear down/assembly $$$ might as well get a salvage motor, and since labor is $$$ super sizing up to crate motor with warranty sounds pretty good.



Tough call. Cost wise I think it would be ~3k min for a pro to do it. Depends on how much your dad likes the car and how much longer he wants to keep it I suppose.

[Cloudsurfer]

Mechanic didn't burn up much time diagnosing, just sounded like something in the head at first and then quickly become obvious it was lower end. I saw the rod the other day, here's where its REALLY weird. As anyone who has experience with engine internals can attest, typically a spun bearing makes the component attached to it overheat rapidly and resemble burned toast. The rod and the crank are super clean, shiny, non discolored metal. I don't know about you, but I've never seen something like this before.

Anyway, found an engine shop that will look at the motor once its out of the car, and yes, its been confirmed theres no way to do anything with these with the block still in the car.

So, we shall see what they say once they tear it down....

Patrick