Zmanco Posted September 13, 2009 Share Posted September 13, 2009 The new Schneider cam is loud as if the wipe pattern is way off. Before I assembled it I measured the wipe and ordered appropriate lash pads and after installation measured them all again. All were good, although some were more to the outside. Still all had at least 2 mm gap before the edge of the rocker surface. Today I checked the wipe pattern again and several have a pattern like this one. Basically there is more gap on one side than the other, like a trapezoid. I'm thinking that these are due to a mildly bent valve as the cam bolt came loose shortly after first startup while the engine was running (don't ask how I made such a dumb move - I'm still beating myself up over it.) Luckily the gear stayed on and the chain tensioner didn't come out so I was able to put the gear back on. Engine is a stock turbo bottom end with dished pistons and head is P90 shaved .080" with Felpro gasket. The engine runs great and except for the loud valves I wouldn't think anything of it. I've checked compression and they range from 140 - 148. But I'm worried this is not a recipe for a long life for the cam. Also, in case replacing the valves is in my future, have any of you ever taken the head/intake manifold/exhaust manifold w/turbo off as a single assembly? I'm thinking of using the engine hoist to pull the whole thing off as 1 piece and setting it on a bench to make this a little easier. Quote Link to comment Share on other sites More sharing options...
woldson Posted September 14, 2009 Share Posted September 14, 2009 What head? What dose the other side look like and lash pads. Witch ones are like this, starting off on cly 1 back. Witch bolt came loose? Is the wipe patten an "optical" illusion? Meaning the wipe is not completely into the rocker arm? Or are the lines in the wipe diagonal? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 14, 2009 Author Share Posted September 14, 2009 It's a P90. Lash pads look fine, but the wipe pattern is such that the distance between the lines on one side is less than the other. Basically it's a trapezoid. About half of the wipe patterns are like that to varying degrees. It was the bolt that holds the cam gear to the cam that came loose. So the engine spun down from around 2k rpm to a stop out of sync from the cam. After posting I though about it some more and figured that the stems are slightly bent. That would cause the spring/lash pad to be offset to one side which would cause one side of the rocker to make contact with the lobe before the other. I thought I might have gotten lucky that due to the dished pistons there was no contact between valves and pistons, but looks like I just missed. Last night I pulled the head off and this weekend when I'm home I'll put a new set of valves in. Painful lesson to check everything twice before closing things up Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted September 14, 2009 Share Posted September 14, 2009 Daniel - please let us know what you find. Maybe it's the picture, but that wipe pattern looks pretty good to me. Cripes - maybe I'VE got bent valves! You must have had the cam gear bolt back waaaay out for the gear to come off the dowel on the cam to spin and crunch a valve. I would think that the tension from the chain, and the rigid nature of the chain would have kept things lined up enough to keep the cam gear from popping off the cam dowel. You got lucky that it didn't drop the tensioner! Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 15, 2009 Author Share Posted September 15, 2009 I'm sorry I didn't take a better picture as in-person there is a very noticeable difference in the length of the wipe on the left side vs. the right. Ideally I expect they should be the same. On a few rockers the difference is around 2 mm. 2eighTZ4me, that's exactly what happened, the bolt back out enough that the cam popped off the dowel but didn't come off completely. So the good news is I didn't have to take the timing cover off. But I still had to take the head off, and with the manifolds and turbo still attached, it may be difficult to replace the valves. I may land up stripping everything off the head in the end - we'll see when I get back home and can tear into it. Quote Link to comment Share on other sites More sharing options...
SHADY280 Posted September 16, 2009 Share Posted September 16, 2009 looks to me like the wipe pad is crooked on the rocker. its not a bad wipe pattern, but i understand your concern that it isnt pefectly straight. my cam was kinda loud when it was new, but went away after a short period. how is your valve lash and did you break in the cam??? both super important Quote Link to comment Share on other sites More sharing options...
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