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Help with Ford 4.6 |
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Silver15 
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Joined: March-24-2010 Location: Orlando Fl Status: Offline Points: 398 |
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 Topic: Help with Ford 4.6Posted: September-16-2013 at 9:45pm |
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For hunting season, we bought a very cheap 2002 Ford Expedition 4x4 with the 4.6 liter Triton engine. It has 189k and appears to be well cared for.
However, the engine is making a funny knock/tap noise. It's difficult for me to understand if it's a knock or not. I've done some research and watched videos of other 4.6 engines making a similar noise that turned out to be a chain tensioner, or head starved of oil. One guy even said it went away with a tune up (?) Point is, I think it's very possible that it has a head or timing chain issue. Are there any Ford gurus out there who might be able to help me? Looking for some tricks to diagnose a knock vs. a valve tap or any other head noise. I can post a video if need be. Thanks to anyone who can help! Jake |
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2000 Air/Sport
1978 T16 |
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P71_CrownVic
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Joined: July-07-2008 Location: SD Status: Offline Points: 534 |
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Posted: September-16-2013 at 10:05pm |
These engines suffered from numerous problems. Ones that would lead to a tick is either the timing chain guides...which would sound like a sewing machine whrn really bad...or a spark plug is ready to get launched out of the head. Genius design by Ford and a common problem on the boat anchor modular engine family. Here is a few pics of worn timing chain guides:   You'll know when the guides need replacement. Could also be just an exhaust tick...they are known for that too. |
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Silver15
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Posted: September-16-2013 at 10:27pm |
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p71, thanks. I was figuring my first reply would come from none other.
I know what you're talking about with the sewing machine situation. A friend's car has the issue and sounds just like what you described. My issue is more of a knock sound. It's as if the issue is isolated to one cylinder. It's a very consistent knocking sound. I'm just clinging to my hope that it might only be something to do with the head. I just took this video of it. It's not the best visual quality but, you can hear what i'm talking about. Knock Sound Jake |
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2000 Air/Sport
1978 T16 |
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P71_CrownVic
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Posted: September-16-2013 at 10:37pm |
You know, that doesn't sound like anything good. That sounds like rod knock to me. I just scrapped a Toyota Tercel that was making that same sound, only much louder. The only thing I would check is that all of the spark plugs are tightened to proper specs. The Triton heads have a well documented history of ejecting plugs which could make that noise, but it sounds more bottom end. That's your best hope. And I assume it's consistent with engine speed? |
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Silver15
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Posted: September-16-2013 at 10:42pm |
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Yes. It is in unison with engine speed. It sort of fades away when you give it gas. Say above 1500 RPMs or so it fades out. At least, you can't hear it over the fan noise.
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2000 Air/Sport
1978 T16 |
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Dreaming
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Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Posted: September-16-2013 at 11:13pm |
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oil pressure would increase with engine speed, put a guage on your oil pressure to see if that is within spec. I have heard bad exhaust leaks that sound similar to that, although hard to pinpoint with the phone video. check the header on the side that is worst, and see if there are cracks in the mani, or if the header is warped at all. sometimes spraying a little bit of water from a squirt bottle will give you an indication of where an exhaust leak is if that is the problem... the water will spray back at you when you find a leak.
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Silver15
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Posted: September-22-2013 at 8:21pm |
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Dreaming, if the oil pressure gauge on the dash is to be trusted at all, it has great oil pressure. (Yes, I know they aren't really very accurate or useful).
The biggest discovery we've had is that the tick only happens once every two revolutions. So that would narrow it down to a valve related issue, corect? |
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2000 Air/Sport
1978 T16 |
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67425ks
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Joined: August-11-2010 Location: kansas Status: Offline Points: 91 |
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Posted: September-26-2013 at 12:19pm |
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haven't done my google homework on the 4.6 yet, but could it be cam phasers? I have heard them on a 5.4, they sound very bad until they get enough oil pumped into them.
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Dreaming
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Posted: September-28-2013 at 4:59pm |
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Hi Silver,
I missed your post, sorry for not answering. yes, if you hear the noise every other revolution, it is valve train related. I still suspect exhaust. If you think it is all internal instead of exhaust, a screw driver handle to your ear, and the tip moved from cyl to cyl will help you to narrow down which cyl is making the noise. I suspect exhaust still, especially since the noise gets quieter with RPM |
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Silver15 wrote: