A4 (B5 Platform) Discussion Discussion forum for the B5 Audi A4 produced from 1995-2001 B5 FAQ

Bent Valves?

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Old Jul 14, 2007 | 06:18 PM
  #1  
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Default Bent Valves?

I just bought a 1.8 t from a guy and it wasn't running he told me that it ran but it had very bad compression. He told me that it needed new piston rings. So i took the head off and when i did 3 of the valves were'nt flush with the head. Isn't that a sign of bent valves and if so wouldnt that be the reason it had bad compression. What i think happennend and the guy didn't know about it was that his timing bel broke because the timing belt looks brand new along with the tensioner. What do you all think. Thanks
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Old Jul 14, 2007 | 06:38 PM
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Default You sound promising.

I think you are on the right track.

Are the piston's nicked... like the same piston as those bent valves... in the right place for those valves???

Yeah the timing belt let go and he bent a few valves... I suggest that you replace them with original equipment valves... lap them in properly. Or have a machine shop do the work for you.

Search for bent valves or broken timing belt on the forum... the 1.8T has quite the history.
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Old Jul 14, 2007 | 06:43 PM
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Default Re: You sound promising.

Nope no nicks in the pistons, that what made me question if the valves were bent I haven't pulled them yet and if I don't have to i don't want to.
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Old Jul 14, 2007 | 06:53 PM
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Default who knows...

I'd get the head to a machine shop familiar with VW/Audi and have them check the head over and replace the damaged valves.
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Old Jul 14, 2007 | 08:16 PM
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Default If the valves bent because it hit the piston there would be signs of it on the top of the pistons.

Issue could be that the valve springs have failed causing those valves not to close all the way.
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Old Jul 14, 2007 | 08:34 PM
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Default My experience leads me to believe spring failure is not common on the 1.8T

It is not impossible tho... but I've yet to encounter it. Actually I've never seen a valve spring fail on a 1.8T. I think I've seen a lifter or two replaced... I've seen many failed belt drives, failed cam chain tensioners.
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Old Jul 14, 2007 | 09:11 PM
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Default The day I picked up my car from DRS after they built my 2 liter the first time

I had a valve spring fail on the way home.
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Old Jul 14, 2007 | 11:13 PM
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Default Re: The day I picked up my car from DRS after they built my 2 liter the first time

So you think its the valve springs. There is no damage to the pistons and 3 of the valves are about 1 mm from being flush with the head. I've worked on other cars before and every time this has happenend the valves were bent. I'll take a picture in the morning and post it.
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Old Jul 15, 2007 | 03:43 AM
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Default

The valves are bent.
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Old Jul 15, 2007 | 06:23 AM
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Default Is it 1mm all the way around the valve or just on 1 side?

Have you tried pushing the valves down further? My valves were slightly bent but were still able to seal, they got bent because of valve float when pushing the engine past 8k rpms. I also had marks on 3 of my cylinders because of it.
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