2.0 TFSI New Piston and Rings, leak down testing as part of quality control during assembly, FAILING
We have a 2.0 TFSI here that has the ubiquitous oil consumption issue. We replaced with new pistons with rings. Had auto machine shop replaced valve stem seals, clean valves, and head.
After building the bottom end, I verified piston/ring/cylinder interface seal by vacuum testing using a venturi style vacuum tester. The bottom end is sealed up great.
While rotating it by hand, after putting the head on and timing it, I noticed it didn't seam to have any compression. So, I decided to leak down test the system to make sure everything else is good. We get 100% leak out of intake ports. Verified we are on base circle of camshaft. I let it set for half a day and checked again, same thing.
Possible the lifters are still just pumped up, or is something else going on here?
Unfortunately I didn't think to leak down test it with the cams out. If I have to I will pull the cam bearing bridge and test.
I realize that fresh engine will not have peak leak down performance numbers but 100% is not within this threshold by any stretch of the imagination.
it's the friggin' direct injection ports, they are open. DOH! Hopefully this helps some other moron too.
Great news! I have had many of my own DOH! moments. It is really nice to hear you step up and just tell us what went sideways. Some of us could and should be better at that. Thanks for the simple truth.
So it was not leaking from the intake valves as you suspected in the beginning, correct?
I have no reason to believe so but I am going to make sure once the intake manifold and injectors are in, will post back. Thanks!
Perhaps you, or machine shop, swapped the exhaust and intake rockers? I've been there and done that, exhaust side has bigger rollers.
Charles good look! I could see that, luckily I did know they are thinner to compensate for the multi-lobe system.
If you are on base circle and the valve is still open, uh oh!. Did the head together without bleed down of the lifters or a possible verification of stem height? Some times just leaving it on valve fully open position for an hour or so will bleed them down. Hope the valves did not get bent.
I know some motors will say leave set for 30 minutes after assembly before starting or they will interfere. I think it's the 5 valve that does that? Either way, looks like stupidity was the problem on this one :)
Man, I have done a bunch of head gaskets on VW Beetles, … turbos, 5 valves. Same engine in the Audi's. They were a mother to work on. Usually it was a blown head gasket or broken timing belt, which ate all the valves. Either way, getting one to run afterwards longer than 15 minutes was a miracle at idle. The main issue is the valves contact the pistons. It doesn't take much either…
Jesse, I think the gold standard to prime these engines is a pressure lube tank. I am a believer of bleeding down the lifters (takes time) or putting in new ones before assembly of the head (s) or engine. Do you not think valves bend at idle RPM just as easily as mid ranges? The tank gives you the situation with instant lube when you start up and no chain slop or lifter clatter or other…
Valves can bent at any rpm. Even just rolling the engine over with a breaker bar. If theres interference at any RPM, it will either bend the valve or break it on these engines. It is typically very very slight touching of the valve to the piston. But, since the valves are so small, they can't take any abuse. Higher rpms put more abuse on any component. Whether its 2000 rpm or 6000 rpm. That's…
I think the 5V is the one that has the issues with interference due to lifter pump up, right? It says right in the VAG instructions. It doesn't have that warning for this CAEB 4v 2.0 TFSI. Think I will have issues? I don't remember ever having any with these?
The best part of cylinder leakage testing is that it allows you to easily pinpoint the path of leakage. While performing the test you should be able to detect/hear the escaping air: Out the tailpipe for exhaust valve issues, Out the oil filler port for piston/ring leaks, Out the open radiator cap for cracked heads/blocks/gaskets into the cooling system, Out the intake for intake valves…