87 Tbird noise in motor

Hi,
Son has a 97 Tbird with a 4.6 and 120k. It sounds fine when you start it but in a minute or two there is a metallic noise coming from under the RH valve cover, sounds to be
right where the cam chain runs.
Is it the chain or ?
Thanks.
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On Sat, 28 Aug 2010 20:07:17 -0700, "Dick Cheney"

What you hear is likely a lash adjuster collapsing. A lash adjuster does one of the jobs of a hydraulic lifter in pushrod engines. In the Ford 4.6L V-8, it is under one end of the cam follower sometimes called the rocker lever from pushrod engine nomenclature. The lash adjuster is in the head and supports one end of the cam follower with the valve on the opposite end. The cam is in between. On cold startupm the lash adjuster is extended to take up any clearance in the valve actualting mechanisim just like a hydraulic lifter. The proble with the 4.6L V8 is that it has relatively small oil passages which become restricted and in some cases blocked by sludge. The problem is aggraveted by cold, dirty or too heavy oil viscosity. In some cases, the problem is caused by restrictive oil filters because of its design or just plain in need of replacement. The problem can be helped in many cases by the use of the recemmended 5w30 oil for that year or by the 5w-20 oil Ford later recommended for all it's car engines. As in years past, a good quality oil is more likely to help. Almost any current 5w-20 or 5w-30 oil will meet a higher spec than that in effect when that engine was built.
Keep in mind that this may be a stubborn problem that does not respond to any combination of oil or filters. The problem can deteriorate to remain noisy even with the engine hot. If it gets bad enough or there is enough clearance when the adjuster is noisy, the cam follower can slip out of position and not operate the valve in which case the engine will have a dead cylinder and possibly other problems. If this happens, it can usually be repaired by removing the cam cover and replacing the lash adjuster and reinstalling the cam follower. You may need the special tool to put the follower back in position if you are not very creative with your tools.
Lastly, the noise may be coming from the cam chain tensioner which is located on the lower right side of the block. It functions similar to the valve lash adjuster above and can be effected the same by oil restrictions or heavy oil during warmup. If either of these are the problem, there is not much to be done in most case until you are ready to do some major work on the engine. My own CV has had this problem for the last 175K miles. Once the engine has warmed a bit, the noise goes away. I fully expect the car to die of several other causes before the noise can get it.
Lugnut
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wrote:

SOMETIMES running something like Marvel Mystery Oil or Rislone in the oil can disolve the gunk that is causing the problem and make the noise go away. It depends how badly neglected the motor has been. There is ALWAYS the possibility that you will make the problem worse by trying any chemical fix, but usually it is worth a try. Not doing anything may cause the problem to get worse too - and will definitely not make it get better.
In my experience (not on that engine ) there is something about 75-80% chance that carefull application of these products, with associated oil and filter changes, will solve the problem.
One of the risks of not changing engine oil "too often" and thereby wasting money and oil, is having these kinds of problems occur with your engine.
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