20G TSi Posted May 14, 2002 Report Share Posted May 14, 2002 A friend of mine with a 1G TSi just called with a puzzleing question. "What would make a valve break?" I've heard of people burning valves, but he says this one looks like a chipmunk bit part of it off. He's bringing it to me so I can see. So, what would cause ONE valve to break? He says everything else is fine, the roller was still on the tappet and the cam. Any comments would be appreciated. Jason Quote Link to comment Share on other sites More sharing options...
slow4now Posted May 14, 2002 Report Share Posted May 14, 2002 Fatigue failure from valve flexing, excessive valve lash which causes pounding, stretching from high heat or high RPM, and sudden temperature changes are all cause of valve breakage. Quote Link to comment Share on other sites More sharing options...
20G TSi Posted May 14, 2002 Author Report Share Posted May 14, 2002 well that narrows it down!!! Thanks man. I'm wondering if his turbo will be screwed up also, considering a peice of stainless steel valve material went through it. Quote Link to comment Share on other sites More sharing options...
stealthmonkey Posted May 14, 2002 Report Share Posted May 14, 2002 If you haven't had much help here on this forum try going to. www.columbusdsm.com That forum there are tons of people know about those Tsi's. -gEoff. Quote Link to comment Share on other sites More sharing options...
rl Posted May 14, 2002 Report Share Posted May 14, 2002 If it looks like a chipmunk was eating the face of the valve, it could be detonation.. [ 14 May 2002, 07:12 PM: Message edited by: rl ] Quote Link to comment Share on other sites More sharing options...
slow4now Posted May 14, 2002 Report Share Posted May 14, 2002 Your friend is almost guaranteed to have other porblems with his engine. You can check the turbo by pulling the intak pipe off, and wiggling the compressor shaft. If it moves any more than a millimeter or two, it may need a rebuild. I doubt the turbo will be damaged, so if it doesn't wobble a lot when you move it don't worry about that just yet. He could have cylinder wall scarring, a marred piston, broken ring lans etc.etc. The important thing is to figure out why the valve broke, if it was from extreme changes in temperature (detonation as previously stated) then he need to find out why. Usually valves break at one of two places, right where the stem meets the head or where the keeper grooves are machined in the end of the valve. Let us know what you find out. Later. Quote Link to comment Share on other sites More sharing options...
20G TSi Posted May 14, 2002 Author Report Share Posted May 14, 2002 Whats odd is that its broke off 1/3 of the valve head, not the stem. His chipmunk description was right on. weird.... This is a head from a junkyard, unk. miles. The old head was a TB victom. Quote Link to comment Share on other sites More sharing options...
20G TSi Posted May 14, 2002 Author Report Share Posted May 14, 2002 Oh, to add, its been running great with this head for about 4 months..... His only mods are the aircan cut/maf silencer removal. He doesnt even have a manual boost controller, so he's running stock boost. Quote Link to comment Share on other sites More sharing options...
Mr. Jones Posted May 14, 2002 Report Share Posted May 14, 2002 Though to have just one make contact is nearly impossible..or highly unlikely rather. How is his timing belt/tensioner assembly? Quote Link to comment Share on other sites More sharing options...
rl Posted May 14, 2002 Report Share Posted May 14, 2002 Originally posted by The TSi U Fear: Though to have just one make contact is nearly impossible..or highly unlikely rather. How is his timing belt/tensioner assembly?Its a possibility that there was a damaged valve guide and it cause the valve to hang enough to hit the piston. how was everything else on the head? was the valvetrain ok? how about the shortblock? (besides obvious damage) Quote Link to comment Share on other sites More sharing options...
slow4now Posted May 15, 2002 Report Share Posted May 15, 2002 I agree with the possibility of a bad valve guide.However I don't think the valve was hitting the piston (that would be more likely to bend a valve). Check the spark plugs for signs of detonation to hopefully eliminate that as a cause. Check the valve seat and surrounding area for damage(if the one edge of the valve seat looks signficantly more worn than other sides) from a misaligned guide. What happens is when the valve seating is off square, the valve flexes everytime it seats,causing it to eventually break. This is more than likely what happened, but without pictures it is hard to say. Quote Link to comment Share on other sites More sharing options...
20G TSi Posted May 15, 2002 Author Report Share Posted May 15, 2002 Originally posted by slow4now: I agree with the possibility of a bad valve guide.However I don't think the valve was hitting the piston (that would be more likely to bend a valve). Check the spark plugs for signs of detonation to hopefully eliminate that as a cause. Check the valve seat and surrounding area for damage(if the one edge of the valve seat looks signficantly more worn than other sides) from a misaligned guide. What happens is when the valve seating is off square, the valve flexes everytime it seats,causing it to eventually break. This is more than likely what happened, but without pictures it is hard to say.That sounds like it is probably the case. I'll have to have a look at the head. Thanks all who replied! We just want to be sure of the cause before we go and put the head back on and have a repeat occurance. Thanks again, Jason Quote Link to comment Share on other sites More sharing options...
rl Posted May 15, 2002 Report Share Posted May 15, 2002 Originally posted by slow4now: I agree with the possibility of a bad valve guide.However I don't think the valve was hitting the piston (that would be more likely to bend a valve). Check the spark plugs for signs of detonation to hopefully eliminate that as a cause. Check the valve seat and surrounding area for damage(if the one edge of the valve seat looks signficantly more worn than other sides) from a misaligned guide. What happens is when the valve seating is off square, the valve flexes everytime it seats,causing it to eventually break. This is more than likely what happened, but without pictures it is hard to say.I have seen P/V contact snap valves like twigs on more than one occasion. they bend the first hit, and break on the second. wait a minute..the shortblock was fine? it didnt hurt the pistons at all? if thats the case it wasnt PV contact...where there any peices of the valve in the cylinder/ if not I would bet it was detonation 'eating' away at the valve [ 15 May 2002, 12:58 AM: Message edited by: rl ] Quote Link to comment Share on other sites More sharing options...
slow4now Posted May 15, 2002 Report Share Posted May 15, 2002 Could be a chipmunk was eating the valve! Quote Link to comment Share on other sites More sharing options...
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