Broken Secondary timing chain

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Rapidtransit

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I have a 2001 LS V8 with 115,000 on the clock. Has been running fine with no issues. Bought it with 89,700 and have done the ususal rear wheel bearings VCG plugs, COP's window regulators etc. The car ran fine on Friday, but when I went to start the car Saturday, there was a heavy mechanical clanking noise and then the car stalled. I managed to start the car again with accelerator floored with very heavy smoke out of the rear. I opened the passenger side valve cover and there is was, a broken secondary timing chain. The bottom piece of plastic broke off the tensioner and wedged itself between the chain and sprocket and snapped the chain. A compression test on all the cylinders on that side revealed no damage. The primary chain is still intact and the intake cam is still in time.
My question is this: rather than disasemble the whole front of the engine and front engine cover, can't I just split the new timing chain, re-install it and then re-time the exhaust cam and re-assemble?
 
I don't think you can just pop a link out of these chains like a bike chain. I'm pretty sure you'll have to remove the timing cover to align the rest of the sprockets anyway. And since one side did it, whats to say the other side wont do it soon too? Might as well pull the cover and replace all of the tensioners, and any chains/sprockets that are worn.
 
97stscaddy said:
I don't think you can just pop a link out of these chains like a bike chain. I'm pretty sure you'll have to remove the timing cover to align the rest of the sprockets anyway. And since one side did it, whats to say the other side wont do it soon too? Might as well pull the cover and replace all of the tensioners, and any chains/sprockets that are worn.
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what he said.+1
 
yep - and removing enough of the things in front of the engine so you can access this is a very long process. this is no fun - but doable.

but it is un-likely the valves/pistons are not damaged as well - One rotation of the crank with that chain broke - things hit eachother.
 
I would still want to see the tops of the pistions, valve edges....

it can make a seal - doesn't mean it is in good shape.

how could it not have hit?
 
the heavy metalic clanking sound was valves hitting pistons, weather or not its presenting itself currently or not does not change the fact that they hit, damage has been done, just a matter of time unfortunatly, could be 3 seconds after you fix it or 3 years
 
Quik LS said:
I would still want to see the tops of the pistions, valve edges....

it can make a seal - doesn't mean it is in good shape.

how could it not have hit?
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Correcto! Also say for instance the valves weren't damaged enough to not seal but still dented the tops of the pistons that would create a hot spot in the combustion stroke and probably burn a hole through the piston much sooner anyways.
 
Another View

Let me be the little voice on the other side of the controversy. If you have good compression, I think it's unlikely that valves have hit pistons. The combustion chambers are pent-roof shaped, with valves angled to match the roof 'sides'. The pistons are absolutely flat-topped, except, perhaps, for slight valve reliefs. (I've seen them both ways.) I think it quite possible that your valves touched nothing, and the fact that you have good compression is a very good sign. I'd do a leak-down test. That should make things even clearer. And I've seen 'dinged' pistons last for thousands of miles. Good Luck!!
KS
 
cammerfe said:
Let me be the little voice on the other side of the controversy. If you have good compression, I think it's unlikely that valves have hit pistons. The combustion chambers are pent-roof shaped, with valves angled to match the roof 'sides'. The pistons are absolutely flat-topped, except, perhaps, for slight valve reliefs. (I've seen them both ways.) I think it quite possible that your valves touched nothing, and the fact that you have good compression is a very good sign. I'd do a leak-down test. That should make things even clearer. And I've seen 'dinged' pistons last for thousands of miles. Good Luck!!
KS
Click to expand...

leak-down test +1
 
Correcto! Also say for instance the valves weren't damaged enough to not seal but still dented the tops of the pistons that would create a hot spot in the combustion stroke and probably burn a hole through the piston much sooner anyways.
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That's why I asked. :D At the rate I'm seeing/hearing of these First gen motors chuck timing chains, it kinda makes me wonder.
 
I believe that they are 'non'. That's from my observations and that Ive never heard of a 'crash'.
KS
 
cammerfe said:
I believe that they are 'non'. That's from my observations and that Ive never heard of a 'crash'.
KS
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I have to agree as I don't think anybody can determine that the first noise was caused by the valves hitting the pistons.
When my old car broke the timing chain and damaged the idlers I got in touch with GM and they assured me it was in fact a non interference engine.
Maybe you can do the same but the fact that the compression is still good it seems very unlikely to me that one or more valves where bent and than straighten out.:confused: :confused: :confused:
 
Here's the lastest,
Woke up early today and it's cold outside. Let me preface this by saying that all your comments sound logical. When the engine was first started last Saturday there was a clanking sound and then I new that something was seriously wrong. Compression test revealed to valve damage and a leakdown test was good. I guess I was really lucky.
I received the new Ford timing chain and tensioner yesterday. Prior to this I installed a home made cam timing tool. I used my arbor press to press out one of the link pins just past the roller. This allows the chain to be separated. You can't do this with a traditional chain breaker. This is a press fit, you need to support the other side link. I wrapped the chain around the intake cam sprocket and then installed the cam tensioner. Repressed the link pin using a c-clamp until fully inserted. Was able to round over the pin edge. Intalled the exhaust sprocket and and tightened the sprocket bolt. Pulled the tensioner compression pin and proceeded to reassemble everything else. Engine sounds just as good as new. Cost of the tensioner and chain was $194.76 delivered using one of our forum advertisers.
 
Sounds like you've got some decent tools and the ingenuity to know how to use them, more power to ya! Let us know how long it lasts.
 
I'm, first of all, very glad for you. That's a potentially bad problem quite simply repaired. I'm also intrigued by your 'home-made' tool. I've been offered the use of one when I do the reassembly of my project engine, but I've never looked at it yet. What did you do to construct one of your own?
KS
 
The home-made cam timing tool is nothing but a piece of steel. The dimensions are as follows: 1/2" thick, 1" wide and 8" long. Two 1/4" holes are drilled 6 3/4" on center. I had to get longer valve cover bolts to mount this tool. I set the intake cam with the flat on top and did the same with the exhaust cam. When mounting the tool, make sure that the flats contact the tool squarely. I used an inspection mirror and high powered light to make sure the flats were resting on the tool. Once in position, then snug the bolts. When tightening the cam sprocket bolts, you must use a spanner type tool to hold the sprocket while snugging down this bolt. It requires quite a bit of force. I had to use pipe extensions to achieve this. When the weather warms up a bit, I will change the LH secondary cam tensioner as I know this was the cause of the chain failure.
 
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