A rattling noise from the engine may indicate that the timing chain cassette is worn. Our technicians tell us that installing an updated cassette and timing chain tensioner should correct this concern.Google+
Car Problem Reports
Mercury Mountaineer Worn Timing Chain Cassettes May Cause Rattling Noise From Engine
Mercury Mountaineer Problem
Engines Affected: 4.0L V6, 4.0L V6 SOHC, 4.6L V8, 5.0L V8
Average Mileage: 125,844 mi (66,000 mi - 190,000 mi)
Issue sounded just like a "spark knock" only under acceleration around he 2000-3000 RPM range. The easy fix of running a tank full of high octane gas made no change in the noise. I replaced the knock sensor to see if the engine timing was not being compensated correctly. This still made no change. To determine if it was a mechanical part in the engine, I dumped an entire quart of Lucas Engine Oil Treatment into the engine. As soon as I drove it for a test drive the "rattle" noise at the 2000-3000 RPM range was gone and the engine sounded very smooth. I drove the car very easy for the next few months to get past winter and progressively there began a light rattle at startup also which slightli went away a\s the engine warmed up. The startup rattle started to get louder and louder after the next few weeks to the point I decided to tear it apart (I dont recommend tearing it apart for everyone, I am a Journeyman Machinist and a master mechanic of 20 years certified with my mechanical engineering degree). After removing the upper intake plenum, the fuel rails and a few wires, I popped the passenger side valve cover and noticed the problem. The oil infused nylon that the tensioner shoe is made from was obliterated. I put some pressure on the cam to relieve the chain on the tension side and was able to pull a large portion of the broken tensioner shoe out with my fingers. The rest of it seems to of been ground into chunks and now lies in the bottom of the oil pan.
(NOW THE RATTLE NOISE)
It works like a big speaker in theory. Right under the valve cover on the passenger side, as you are standing in front of the car looking at it, to the right of the cam gear their is a machined stud that is a funny looking shoulder screw. This shoulder screw is what the upper portion of the tensioner shoe hooks to. When the tensioner shoe breaks (as they all do), it falls off the shoulder screw allowing the timing chain to now slap around and ride very tightly against the bare steel side of the shoulder screw. The effect is like a needle on a record player making a very loud noise.
After a close mechanical assessment after replacing all of the timing chains and tensioners in the vehicle, I cannot see why there has not been a recall on this design flaw. I noticed that the majority of the issues listed through different dealers seem to be about 80,000 mile range. As this design was started in 2002 the vast majority of these cars did NOT reach the mileage point by the time the design was ended in 2006. I think FORD saw the "red flag" and re-engineered after 2006 after a bunch of repairs started coming in on vehicles that were still within the engine and powertrain warranty. The list of repairs for warranty was not enough to trigger a recall on the engineering and design although this is actually one of the most well known flaws and failures of design for an engine.
Visitor, 2002 Mercury Mountaineer, 4.6L V8, 115,000 mi
timing chain issuesrattling ect.
Visitor, 2002 Mercury Mountaineer, 4.6L V8, 145,000 mi
My Mountaineer makes a very high pitched annoying sound when I start it and the noise level increases as I push on the gas pedal and accelerate. I have been so curious as to what causes this and how to fix it. I have taken it into a garage, but they have said they didn't know what it is. Sometimes the noise will subside and I won't hear it for a few days, but typically it is very loud.
rattles on startup, metallic like rattle of a heat sheild.
Visitor, 2000 Mercury Mountaineer, 4.0L V6, 136,000 mi
Broken timing chain presumably caused by broken tensioner. Ford wants $3500 to fix!
Visitor, 2002 Mercury Mountaineer, 4.6L V8, 132,154 mi
timing chain guide broken. $2500+ to fix. Ford should recall.
Visitor, 2005 Mercury Mountaineer, 4.0L V6, 109,000 mi
Timing chain noise
Visitor, 2004 Mercury Mountaineer, 4.0L V6, 112,000 mi
rattling sound at idle, as well as when accelerating, until reaching stable speed. Told it was a timing chain issue. Waiting for estimate on cost, but was told it would be expensive (like $2000 or more)
Visitor, 2002 Mercury Mountaineer, 4.0L V6
that car makes noise when it runs. has been doing this for about 5 years now. havent gotten it fix
Visitor, 1998 Mercury Mountaineer, 5.0L V8, 66,000 mi
loud tapping noise or ticking from engine. louder as I excellerate but does quite down some as the car warms.