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Dec 6, 2014 | 01:49 PM

rob7.3

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Brain Teaser

2003 Explorer, 200k miles and had the timing chain guides come apart on the rear. PLEASE READ ON not the usual timing chain issue. Motor was running good when it started. Towed home started up drove in garage loud but smooth. Pulled motor replaced all guides, chains tensioners. Put motor back in and fired up sounded real good. Had a coolant leak at thermo housing. Shut off and fixed it started back up made a little noise not sure what it was and it died. Wont start again. Has gas, fire the usual checks all good. Figured it jumped time somehow. Pulled intake and right cover off. While turning to get TDC I see something I cant wrap my head around. On one stroke of the engine *only one spot when cranking the engine" there is slack on the glide side of the chain. Tensioner side stay tight all the time but after 7 revs of the motor it is sloppy. Opinions, thoughts comments???? Just cant wrap my head around this. Any opinions would be appreciated. Thanks ahead of time.

Dec 6, 2014 | 10:08 PM

shorod

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From: Cedar Rapids, IA

Did you also replace the chains, or just the guides and tensioners? I'm thinking maybe a stretched chain.

-Rod

Dec 7, 2014 | 10:50 AM

rob7.3

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nope as I said I replaced all chains, guides and even sprockets. everything is new as far as timing chains. even the $18 dollar bolts were replaced for all sprockets.

Dec 7, 2014 | 12:29 PM

shorod

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From: Cedar Rapids, IA

Actually, what you said was, "Pulled motor replaced all guides, chains tensioners." I wasn't sure if there was a missing comma between "chains" and "tensioners" or if you only replaced the chain tensioners. :P

Thanks for the clarification. With the right cover off, if you pull the spark plugs and spin the engine by hand, do you still get the spot where there is slack in the chain? Assuming there is, if you then reverse direction at that spot does the right cam pause a moment while the slack is taken up, or does it start to spin right away? Does the amount of force required to spin the engine by hand change as you approach that spot?

-Rod

Dec 15, 2014 | 08:03 PM

rob7.3

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Sorry i am just really frustrated with this freaking thing. I pulled the motor again. Started completely over. Put it back in again and the exact same thing happened. Started ran fine. Shut it down and let is set for 20 minutes or so and bam same freaking thing. To answer your questions
Yes with the plugs out and turn by hand same slack on the one side
When turning it the opposite way it is immediately turns the chain
as for how hard to turn it feels as if it is on a compression stroke doesnt seem to be any harder than usual.

It is like there should be a tensioner on both sides of the chain. This thing reminds me why I am a diesel mechanic. Give my cat and cummins back. Hell give me a detroit

Dec 15, 2014 | 09:56 PM

shorod

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Joined: Jun 2009

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From: Cedar Rapids, IA

Is there a chance the steps from the factory service manual might help you spot something that maybe you weren't aware of previously? If so, I can e-mail you a PDF of the relevant section from the service manual.

-Rod

Dec 15, 2014 | 10:06 PM

weross67

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From: South Mississippi

Sprockit

You need to set a gauge on your sprockets and check to make sure they are running in center. Make sure your cam shaft on the problem chain does not have a little bend in it. It sounds as if you have something running out of center. When the two sprockets are closest together you will have slack in the chain.
I hope this does not upset you I am sorry!