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#67269 10/17/2006 3:47 AM | Joined: Nov 2003 Posts: 8 Junior Member | | Junior Member Joined: Nov 2003 Posts: 8 | I have a 181 Mercruiser 4 cylinder (3.0 liters) in an old truck, a 1967 Landrover. It is a rebuilt engine with less than 25 miles on it. All of a sudden it has developed what I believe is a valve noise. Using an automotive stethascope (sp?) it seems that the noise is coming from the valve (3rd one back) or where the rocker arm contacts the valve stem. I pulled the side cover and the valve cover and there are no obviously bent pushrods or valves, everything looks ok. This engine is a variant of the GM 2.5, although I am confused about which engine it is exactly. I was told it is the same block as a late 70s 2.5 Chevy Monza. Is there a way to adjust the valve lash on these engines? I am not used to hydraulic lifters so it's all new to me. Anyone with any ideas on what might be causing the noise? Thanks in advance for any suggestions. | | |
#67270 10/17/2006 3:53 AM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | Shep, A plugged or partially collapsed lifter would cause a tapping or clicking sound. Have you changed the oil lately/regularly..how about the filter? Good luck with the aqua-bolt-rover.  Stuart | | |
#67271 10/17/2006 4:06 AM | Joined: Nov 2003 Posts: 8 Junior Member | | Junior Member Joined: Nov 2003 Posts: 8 | Hi Stuart and thanks for the reply. Changed the oil and filter as I though that it might be a lifter problem. Didn't help though. The noise seems to me to be up high and not down by the side plate, when I check it with the mechanics stethescope. It's a metallic clicking noise as if the rocker is "smacking" the valve. No missing, so I don't think it's a bent valve. I am out of ideas, unless the rocker arm is not adjusted properly. Shep | | |
#67272 10/17/2006 4:25 AM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | Shep,
If this is a conventional hydraulic lifter, the valve lash, or clearance should be zero. There is no room between the rocker arm and valve stem to 'smack' or click if the lifter is functional and set properly.
If you have a service manual it should give the valve lifter adjustment procedures. I think on the engines we see on this forum, the hydraulic setting is usually (by the book) something like 3/4 to 1 1/2 turn past zero lash.
If all is well, this will result in zero noise from the valve train.
I have no idea what your rocker assembly looks like, so this might be a 'uneducated guess'.
Stuart | | |
#67273 10/17/2006 4:30 AM | Joined: Mar 2004 Posts: 3,068 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 3,068 | If theres a self-locking nut in the middle of the rocker, tighten it up a quarter turn and see if you hear a difference. It should be the same as a small block that centers the lifter by adjusting the rocker. If it quiets down go another quarter turn and call it good,
Scott | | |
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