rare and hard to solve
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rare and hard to solve
it had to happen to someone else too! 1997 150XL,160'000 mls. loud knocking sound,compairable to fan hitting shroud,all gears,all speeds.no performance loss what-so-ever. Just started 2 days ago,has stopped for 20 minutes at a time then start up again. Sounds coming from pass. side.hard to locate.removed belt to see if it was anything(alt,a/c,ect.) still the knock continues.Took broomstick pressed to ear(still believe in old ways)and get same volume from starter,water pump,head.It seems to travell.Thought about bent rod,but no metallic sound from valve cover.Like I said, no performance loss or burning oil.Was told maybe pollution pump but never Knew about that.Any ideas?
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rare and hard to solve
Here is one, about a month ago we had a windstar in the shop. It had a knock that it was every hard to find. It sound like a rod knocking. End up being the flywheel was cracked and cause the knocking sound . This is just a idea, but hope it helps.
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From: Louisville,Ky.
rare and hard to solve
It's hard to diagnose on-line, let alone without truck info. It could be anything from timing chain or tensioner to a bad flywheel to a rod knocking. Does it do it all of the time? idling, accelerating ?
Jimmy
Jimmy
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rare and hard to solve
WOW! great response.first to JeremyH:yes,starter is on my troubleshoot list today.Knock occurs at startup throughout driving range;aldridgec:It's a 4.2-rear-wheel drive;next;jonmech,yes I'm keeping my fingers crossed that it ain't cracked flywheel,but also heard a story about spring falling from clucth and lodging in bottom.removed dust cover and spring fell out:lxman1;thought about timing chain slapping against cover,but wouldn't I have some performance loss? already removed belt from tensioner,still has sound.It does it all the time---idling and accelerating.
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From: Houston, Texas
rare and hard to solve
Hummm.....it would only be the starter upon startup. This is a tough one.
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From: NE TX
rare and hard to solve
Could be a bolt backed out of flywheel causing it to be out of balance. If a spring fell out of clutch, I'd look further into that. Starter isn't the problem unless it stays engaged then it would be chewed up before long. Loose timing tensioner will not hurt performance until truck jumps time.
Does the knock speed up as the engine rpm increases or does knock stay the same frequency? Clutched? In neutral clutch out? Try to isolate sound either in pan or head if its in the engine.
Does the knock speed up as the engine rpm increases or does knock stay the same frequency? Clutched? In neutral clutch out? Try to isolate sound either in pan or head if its in the engine.
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From: NE TX
rare and hard to solve
I will assume that the sound also increases at the same rate as rpm? I agree with lxman1. Some moving part is not traveling in the right path, has too much friction or something is rubbing. It could be in timing cover, head, or bottom. If it is in 1 head sound should be easier to isolate. I'm still betting on inside timing cover or flywheel. Everywhere else, you should have more symptoms. If a rocker stud broke, a valve wouldn't open and you'd have a miss. You could be right about the chain rubbing too. The friction could cause a power loss but when you speed up slack will be taken out and forced past the next gear. And eventually it'd show up with a hole in cover or broken chain or jumped time. Good luck.
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From: Lufkin
rare and hard to solve
This may help, but then again it may not. Try this web-site.
www.leakingfords.com
Talks about problems with 97-98 Ford trucks. Hope it helps!
www.leakingfords.com
Talks about problems with 97-98 Ford trucks. Hope it helps!
rare and hard to solve
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From: So. Calif.
rare and hard to solve
I has a pressure plate bolt back out of a flywheel once and it hit the bellhousing. BANG,BANG,BANG,BANG with the RPM. The bolt finally broke off after 10 minutes (I was stuck on the freeway and was driving slowly to an offramp) and the noise went away. Just an idea....
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rare and hard to solve
yes that's the tricky part. It's been a week now and still driving it 80 mls.a day. No different sound, nothings broken off. I'm starting to lean toward discribing sound as more of a spark knock,which I'm not sure but thinking about a dianogstic emmissions check.what'll ya'll think of that.can that test pinpoint it? thanks
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From: NE TX
rare and hard to solve
I'd do a compression check too. You can buy scanners at parts store or WalMart ~$25 to get comp. codes. Someone else may have a more thorough way of checking though. If the knock is because of a sensor failing the comp. will give a code. If the knock is at the flywheel or pressure plate or timing cover, it probably will not.