Hi guys it's me... again!
This thing can't seem to give me a break LOL.
We have been using 15w40 oil for years and never had a problem. I know it's too thick for these engines but we don't get such low temperature as people up north. Right now temps are between 70-86, it's been rainy and during winter it will get as low as 32 in the morning...
So you'll see, I decided it was time to change the oil, it was a bit over due, and decided to switch to 5w30 to see if there was any difference and to make the things the right way from now and on; well, there is actually a BIG difference, the engine isn't as loud as before, and the new fluid and filter (both motorcraft) made a tapping sound I had on cold starts go away, after many years with it!.
It idles great, runs quieter and has a 30% better fuel economy. What else coud somebody ask? This is where the ugly part comes. I don't know if I hadn't noticed before because the engine was noisier or what, but now I can hear a "weird" sound, sorry that I don't know how would you guys describe it,
at HOT idle, it seems to go away if I rev the engine (again, I don't know if the louder it's actually masking it rather than making it go away). It's running OK, hasn't taken any oil and there is no smoke coming out from the tailpipe; as I said the noise is only present after the engine has reached normal temperature.
I don't have much experience with these things, I don't know if it could be a lifter, a valve, rings, timing chain or what else!. I only get some occasional misfires and the LTFT for bank 1 goes up to +18 from time to time.
Here's a video of the noise; it seems more noticeable at the passenger side where the serpentine belt is.
http://youtu.be/Fp8FhPL3w2U
Anybody thinks this could be an exhaust leak? I've noticed that after the transmission was rebuilt, it will make a LOUD clicking sound minutes after I turn off the engine because of the exhaust pipes expanding/contracting.
Thanks in advance,
Oscar.
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UPDATE September 11 2015
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Skip all the diagnosing and go straight to the upper intake manifold. Remove it and, if you have the old 3 part version (upper and lower covers, and a baffle), take off the middle baffle, reassemble and test to see if the noise is gone. That's what solved my problem.
There's a redesigned (one piece) part from Dorman (615-277), get that.
Things I replaced to no avail:
Timing chain and tensioner
Camshaft synchronizer
Water pump
Belt tensioner
I hope this helps,
Oscar.