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Unread 06-27-2013, 12:08 AM   #1
FortCollinsZJ
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1993 ZJ 
 
Join Date: Jul 2007
Location: Fort Collins, Colorado
Posts: 2,354
Timing problem, will not run now.

Took the water pump off today, to do some cleaning and inspecting of the coolant system, put it all back together but put the wrong bolt in the water pump and it went too deep into the timing cover, and side loaded the timing chain, which then broke when I tried to start it.

1: First things first, I want a definitive answer, is the 5.2 an interference motor, or not? I don't think I bent valve, I certainly didn't hear anything like that, IIRC.

2: Next. I replaced the gears and timing chain, aligned the two marks as the haynes manual showed, then buttoned it back up, went to start, and it cranks and cranks, and only fires if I feather the throttle, but it feels like its HORRIBLY mis timed. Like it's running on one bank. It will not stay running.

3: So, the timing gears are keyed to the crank and cam, meaning they only go on one way, and the two dots are at 6 o'clock for the cam, and 12 o'clock fore the crank. Right? Right.

4: The crank did spin a few times on its own when the timing chain broke, so do I need to re adjust the timing in the distributor now? I didn't feel like a moron when I started this project but I certainly do now.


:Update: Crank at #1 TDC, the rotor in the cap is pointing at # 6 (opposite #1 like the book says)

Also throwing code 54, 'no signal from cam sensor. problem with distributor sync'

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Unread 06-27-2013, 07:05 PM   #2
dusterdude
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Unread 06-27-2013, 09:57 PM   #3
ZeeJay1997
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are you on tdc on the compression stroke? if your on the exhaust stroke, button will be 180 out
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Unread 06-28-2013, 03:59 AM   #4
FortCollinsZJ
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I may have been 180 out, but I took the whole thing back apart, turned it 180, and turned the key. No joy. Still sounds like chit. Took my valve cover off the driver side to make 100% sure my valves were closed on the #1 at TDC. sure enough, now they are closed, but then I noticed, the two pushrods are bent to hell. The other cylinders pushrods on that bank appear, at fist glance, to be straight. I'll be checking the other (passenger) side tomorrow.

So, when I had it together yesterday, I tried revving the thing with it severely mis timed possibly, and that is when I suspect I bent some valves either by direct contact with valve to piston (I still only have about a 75% idea that this is a NON interference engine) OR the thing floated BOTH rods and bent them that way, seems unlikely, but who knows.

Can I check to see if the valves are bent WITHOUT removing heads?

I'm buying a few new pushrods tomorrow, going to see if that helps. If not, I found a 5.9 out of a dodge for 1100$ and it's going in.
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Unread 06-28-2013, 08:29 AM   #5
zjosh93
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Take all the rockers off one head and lay a mechanics straightedge across the valve stems. If any valves are bent they will be shorter than the rest. Machining tolerances and valve tip wear in an old engine will make some of them a few thousandths lower or higher anyway so you are looking for pretty significant variances. Only way to spot a valve bent just a hair is to take the head off.
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Unread 06-28-2013, 10:10 AM   #6
PolkaPower
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I am 99% sure it's a clearance engine as most early american motors.



Maybe a possibility
Quote:
When you rev too high, the springs can't rebound fast enough to keep tension on all of the valvetrain components, and you get slack between the components (cam-lifter-pushrod-rocker-valve). This is called float. When the valves float, the components (which normally all move together in one fluid motion) begin to separate and smack into each other. This in itself can bend the rods and cause other damage. Without tension on them, the pushrods actually start to bounce around in their bores (put a pencil in a paper cup and shake it around), and if the gap gets wide enough, the bottom tip can actually ride up out of its dimple to the edge of the lifter. If it catches the edge, it gets pushed up too far with a lot of force, and it bends. Even if the lifters are able to pump up and compensate quickly enough to keep the pushrod from riding the edge, once the engine slows down they can't deflate quickly enough to keep the pushrod from traveling too far - which has basically the same result.
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Unread 06-28-2013, 03:34 PM   #7
ajmorell
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Quote:
Originally Posted by PolkaPower View Post
Maybe a possibility
I doubt it, usually valve float isn't an issue until your trying to spin a motor really high into the RPM range, like 9-10k RPM and higher. I'd be surprised to find the natural frequency of the magnum v8 valve springs low enough to float like that below the stock rev limiter
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Unread 06-28-2013, 04:00 PM   #8
FortCollinsZJ
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pushrod picked a new avenue, went rogue and punched a hole in the block, in the galley. Two valves on the driver side bank are bent (used a straight edge)

5.2 is dead, and getting yanked,5.9 from a 99 Dodge is going in next. Found one "rebuilt" with 10k miles for 1000$
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