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Broken cam

5K views 26 replies 7 participants last post by  03LimitedEditionRaptor 
#1 ·
What could cause this type of failure?
 
#4 ·
Over tightening of the cam sprocket bolts. Did the cam break or did the decompression weights come loose and break through the cam cover?
 
#10 · (Edited)
If he didn't reset the tensioner properly, and/or put the center bolt in the tensioner before torquing down the head cover bolts, the chain will over-tighten and a broken cam is one of the possible consequences... also check the cam journal surfaces in the head and head cover for excess scoring, the cam sprocket for bends or damage and the chain for stretching.
 
#18 ·
Willy,

One thing I found strange was putting the "form a gasket" sealer on the surfaces before installing the head cover. I don't understand how the sealer doesn't get into the cam journals. I tried to keep it away from those areas but hard to know whether it "oozes" in there when you tighten the cover.

I turned the engine over a few times by hand once it was all together, and it felt fine but how would you know if it didn't get in there?
 
#23 ·
Is there some special information on this? I went by the manual diagram of where to put the sealer...where are the oil galleries? Now I'm worried I might have plugged something.
 
#24 ·
Oil gallery is in the end of the cam. It pumps oil in to the center of the cam shaft. Then it comes out the holes in cam.
 
#25 ·
Yes I see it now. Looked at a head and cover picture. Looks like there is one in the center too but only a partial. I tried to keep the sealer slightly away from the cam when I applied it, but now concerned I may have put too much on because it oozed out pretty good on the sides...I'm going to take it apart and do it over...don't feel comfortable about the oozing...if it did that towards the cam journals it wouldn't take much to block oil flow.

I really appreciate the help because I have never done one of these engines. Have done many engines over the years but each is a little different. The manual sort of sucks because they show that whole surface covered and it doesn't say anything about a "thin" film. I intuitively tried to stay away from the cam journals, and when you think about it why do you even need any on the center ones with the exception of around the spark plug hole. That whole area is inside the oil area, only the spark plug hole and around the outside needs to be sealed...and part of the end were the cap plug with the o-ring goes.
 
#26 ·
I took the cylinder cover off and guess what? Nothing on the cam journals...but I guess I have piece of mind. Took me an hour to clean it again and install it all again. :(
 
#27 ·
Yea and the nice thing about Yamabond is it stays semi soft, and a little bit goes a long way. Regular RTV is thick and takes up to much room between the halfs. So it can cause loose tolorances. RTV can also peel off on the inside of the engine. It makes its way down in to the lower end and plugs up the oil sump / pickup.
 
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