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Thread: CAS or Cam Bearing Noise?

  1. #1

    CAS or Cam Bearing Noise?

    So I just started driving my s14 more lately and it's always had this noise from under the timing cover, but I'm sick and tired of it. I've replaced the CAS and tried adjusting it but it just won't go away. It only starts when it's idling cold (around 800 rpm), but once it warms up my idle drops down to about 750 rpm and it doesn't do it. It also goes away if I keep revs around 1000. I'm sure you all have seen this before, but I've never been able to find an answer (partly cause I got fed up and stopped looking). Here's a video where its pretty obvious.
    S14, RB25DET

  2. #2
    Have you pulled your valve cover? There is a guide that sits on the top of the cam chain. Ive seen those break and cause lots of noise. BTW, the guide is not installed from nissan on the FWD KAs, so feel free to throw it away if it is the problem.

  3. #3
    It's an RB25, the video shows the motor running without the timing cover exposing the timing belt...
    S14, RB25DET

  4. #4
    Sorry the video didn't load for me.

  5. #5
    When did it start making the noise? Is the timing belt tensioner the correct one and is it clocked in the right direction? One of the guys here at work thinks it sounds like a dry bearing noise. He suspects the tensioner bearing.

  6. #6
    It's been doing it ever since ive had the will go away if I kind of put the CAS in a minor bind..does that make sense?
    S14, RB25DET

  7. #7
    Maybe you still have a bad CAS, even though its new? I'd still inspect your timing components.

  8. #8


    It's your timing belt. I have the same noise with my RB20. I was told it was from the belt been too tight as I have a Power Enterprise belt on mine.
    90 Tsi with Toys*SOLD*
    95 S14 AreB 20 lag monster
    91 NX2000 SR20VE powered daily driver.

  9. #9
    You think it's the actual timing belt itself? or the tensioners? I was talking to my dad today and he reminded me that the guy we bought the motor from had actually put in a new tensioner and belt..The previous owner gave me the old tensioner when I bought the car too. I will have to go to the rents and try and find it and inspect it. Also, does anybody know what kind of timing belt is on there (blue one)? Stockers are black right?
    S14, RB25DET

  10. #10
    A blue one is probably GReddy (or Trust). Even with the new belt the tensioner may be old/wrong, or just misadjusted. I know that the tensioner from a VG33 looks identical to one on an RB25, but they have a slightly different diameter. Things like that can cause problems. (I spun a #1 main bearing on a RB25 that way once.) Try loosening up the tension slightly on the belt and run it. SLIGHTLY!!

  11. #11


    I have a brand new tensioner on mine. The Blue belt is suppose the be stronger than the regular ones, they will last longer.
    90 Tsi with Toys*SOLD*
    95 S14 AreB 20 lag monster
    91 NX2000 SR20VE powered daily driver.

  12. #12
    Administrator Kingtal0n's Avatar
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    Jul 2004
    Check to make sure the CAS is not installed TOO FAR. Listening to the video, I doubt this is the problem (this makes more of a scrape noise) but, often on the RB engines, the little gasket behind the CAS gets flattened out, and the CAS goes into the cover too far- and makes contact. The fix is, put a thin washer under each cas bolt to keep it from going to far into the cover.
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