I have an a4q 1.8t w/120k & 3 out of 4 cylinders compression 50% below threshold.....

I am looking into buying ring replacement kits & not sure if I should go with a kit that includes pistons???...

I welcome any advice from anyone who has experience with 1.8t comp. issues.

Im afraid that if I go with a set that includes pistons and my cylinders are so badly tapered that they need machining Ill only end up sending them back for a larger set.

Should I even buy rings until I get the engine apart & see the cylinders?

Also, if anyone has any tips to make life easier during disassembly & reassembly, or can make any recommendations who makes or offers a quality kit I would be grateful.

Thanks... Appreciate the help as always...

 

Well it looks like you've done leak downs? I would say you first need to know where the leak is coming from. First go full inline pressure, open the butterfly for the throttle body and see if air is escaping through there, that means intake valve is leaking. Then check for exhaust valve leaking, putting your hand over the muffler tip. That should let you know if your valves are leaking. If there not then yes I would go for the piston rings. And as you take the head off see if you've got cylinder wall damage. I'm sure at 130k you've got a bunch of valve guides that are bad. Does it blow smoke on cold starts?

 

Smokes like a wet boiler in January! But not just on cold starts. I haven't done a leak down test yet but I will before the head comes off. The reason we think it's the rings is b/c we did wet/dry comp. tests & it held par pressure during wet. this obviously doesn't mean it's not also valves but im 90% sure it needs rings. thanks for the good idea. ( I know audi doesn't recommend wet/dry tests.)

 

ha, ya smoke out the tailpipe can also be valve guides tho, just something to think about, would be nice to see where the leaks are coming from. Good luck man.

 

A leak down test is a must in this case. Also you can have someone check the cylinder walls with a scope. You should always know the damage before you start buying parts. If you plan on putting in new pistons you might as well go slightly bigger since you will have to have the block bored anyway.

 

sup mike... thanks for getting in on this.
ive gotten some mixed info & im pretty sure you can clear this up.
ive been told that if my cylinder walls arent tappered i can SAFELY
hone w/o boring. im still going to do the leak down & scope the block but whats your opinion on that? how likely is it that i wont have to machine the block? and if i dont, how safe is it to just get the right stones & bring the walls back to a nice cross hatch?