1.8t rod knock

[Bushum]

I posted a while ago about a noise I thought was a cam tensioner. My mechanic looked at it today and said he thinks it is coming from the rod in cylinder 1. He said when the plug is pulled out while running the noise almost disappears. The Motor has about 7k on it and was rebuilt by an Audi dealership with stock pistons and IE rods. What can go wrong with rods and is there any chance of it being fixable without replacing the whole motor? The oil pan will come off next week but I'm trying to prepare myself for what to expect. Oh and since it was after market rods Audi dealer told me to pound salt, in so many words.

[murdered APR a4]

Could be an improper bearing install on the rod although idk how that would cause a knock.....and even if it is aftermarket the dealership did the work on it so they would have to take responsibility.

[Bushum]

They won't. Spent half hour on the phone between them and Audi of America.

[MmmBoost]

I found a spun bearing in my engine when I tore it down to do my build

where it was wearing


how much it had moved


where the material from the other half was piling up

[diagnosticator]

Hopfully the crank throw journal surface is not ruined. If not, a new bearing shell can be installed without removing the engine from the car. As far as Audi is concerned, leave them out of the situation.

[Bushum]

Chris,

Was yours making any noise before you took it apart? Here is what mine sounds like. It went from a light tick to this noise in about 25 miles time.

http://s665.photobucket.com/albums/v...t=MVI_4107.mp4

Diagnosticator,

If the surface is ruined would I need a new crank or just machine this one? I assume with machining it would require custom sized bearings. Also do you think something like this would cause out of round in the cylinder or ruin the rod as opposed to just bearings?

[diagnosticator]

Chris,

Was yours making any noise before you took it apart? Here is what mine sounds like. It went from a light tick to this noise in about 25 miles time.

http://s665.photobucket.com/albums/v...t=MVI_4107.mp4

Diagnosticator,

If the surface is ruined would I need a new crank or just machine this one? I assume with machining it would require custom sized bearings. Also do you think something like this would cause out of round in the cylinder or ruin the rod as opposed to just bearings?

The hardness of the crank is much harder than the bearing shell, and due to the very limited miles, there is an very good chance the crank journal is fine, and a same size bearing shell can be reinstalled. Practically all bearing failures are caused by lubrication faults, like Chris showed where the bearing shell rotated in the connecting rod, misaligning the lube delivery hole. Incorrect assembly can result in the lube oil hole being on the cap side instead of the rod side, preventing lube to the piston pin bushing. If the lube to the piston pin is blocked, due to bearing shell rotation in the rod, or from misassembly, then the noise could be coming from the piston pin bushing and not the con rod bearing. The rod bearing is lubricated from the crankshaft drillings, and even if rotated, the rod bearing will always be lubricated. The piston pin bushing is lubed by the hole in the rod bearing and a drilled oil passage in the con rod from the big end to the small end bushing. If the rod journal is damaged, then the rod journal can be re-machined undersize, and an undersize bearing shell installed that matches the new journal diameter. There is usually no connection between the bearing failure, and any other damage to the rod, or an out of round cylinder. If the rod bearing has rotated, and the piston pin lube hole in the bearing blocked, then the head must be removed to get the con rod/piston assembly out of the block so that the piston pin bushing can be replaced also.

[Bushum]

Wow! Thank you for that long detailed post. That gives me some hope that it will be a relatively cheap fix (as opposed to a new motor).

[Bushum]

Hopfully the crank throw journal surface is not ruined. If not, a new bearing shell can be installed without removing the engine from the car. As far as Audi is concerned, leave them out of the situation.

I forgot to ask this but does the head still need to come off if it only needs new rod bearings? It seems like the assembly could be moved up in the cylinder enough to fit new bearings in but I've never built a motor so I don't know.

[diagnosticator]

I forgot to ask this but does the head still need to come off if it only needs new rod bearings? It seems like the assembly could be moved up in the cylinder enough to fit new bearings in but I've never built a motor so I don't know.

Yes, all rod and main bearings can be replaced with the engine in the car, and the head installed. Only if the a piston pin bushing is loose or damaged from lack of lubrication does the head need to come off, the engine stays in the car.

[Haenszel20v]

First thing I would do is check the timing belt tensioner. If you lose the hydro tensioner, the roller will bounce up and down on the pin causing that same sort of sound. I've had 5-6 cars in the past 2 years call me thinking they spun bearings, and turned out it was just that. Might not be it, but its certainly cheaper to check that first.

[Matt Devo]

hopefully you get it figured out before your engine ends up like my buddy's B5 1.8T:

[Charles.waite]

hopefully you get it figured out before your engine ends up like my buddy's B5 1.8T:

Good god! I can't imagine that was a stock AEB was it?

[Matt Devo]

Good god! I can't imagine that was a stock AEB was it?

stock ATW (2000 MY) with 123k on it, chipped for < 8k. We picked up a used block and it honed/decked, and rebuilt it with Eagle rods. Had the head done at a shop (needed 1 new valve), but did all of the assembly ourselves. Was a lot of fun and a great learning experience, and the car absolutely hauls ass now. Fastest chipped 1.8T I've ever seen/driven/ridden in

[Bushum]

The crank is ruined. My mechanic said he is certain it was bad before the new rods were installed.

[EErie B6]

after reading this and your other thread...

Sounds like you were knowingly burned by the dealership. Like who ever did the work knew it could not come back on them simply because aftermarket parts were used... someone who did not care about it or check tolerances, they just slapped it together and sent it out the door.

That's pretty lame.

[Bushum]

I sure was. The dealer was Audi of Nashau, NH, if anyone is curious.

[Bushum]

[EErie B6]

Nice.