Timing Chain Problem..PLEASE HELP!!!

[anonymous]

So out of the blue on my way home my car started making a horrable rattling noise from the top of the left bank and had a huge loss in power. After a lot of searching I found a few clips on Youtube of LS's that sounded exactly the same and they said it was a bad secondary timing chain tensioner so I pulled off the left side valve cover (breaking off a little hose connector on the front top of the valve cover which I think goes to the PCV but I could be wrong but I guess I need a whole new valve cover now but thats another issue) I noticed that both chains were tight and the secondary tensioner looked fine but the left cam (exhaust cam I think) was a little off. My question is what should I do now. I do not see anything broken and can't really afford a full $600 kit to just replace everything. If nothing is broken and the chains are all tight why would it just suddenly skip a tooth? My car is a 00 LS with around 140K....is there any way to just put it back in time or would it just happen again...I have searched but in every case there is something broken that can be fixed but that doesn't seem to be my case. Thanks in advance for any help guys

 

[anonymous]

What piece is this?

Sorry for the bad links the first time...here is the piece that I broke. Is this the connector for the PCV hose? Does anyone have a better idea of what I could do instead of just replacing the entire valve cover? I have never had anyone to teach me about cars I just learn as I go...sorry for being a noob I'm trying

 

[TooManyToys]

This is not a cheap car to repair, and when things go bad, even more so.

One tooth doesn't make a horrible rattling sound. Going around the sprocket almost 360 degrees does. The picture doe not show enough detail of the tensioner for anyone to diagnose. With what you observed the valvetrain will also need to be inspected to see if any valves are bent.

 

[oddball]

That is the "right" side head. Orientation is as sitting in the car, not leaning over the front clip. Can also refer to it as the passenger side.

Looks like the exhaust skipped a tooth. Look carefully at the tenstioner and make sure all the plastic liner is in place on the sleds for the chain. I bet it's come apart. Another possibility is the oil channel that feeds it has gotten clogged. It needs oil pressure to maintain tension on the chain.
Keep searching on here. There are threads - even one just a couple days ago - about using the master link kit from Christopher's to just do the secondary chain and tensioner without removing very much. Do lots of homework and be very certain you understand all aspects of the job before starting.

The broken nipple is the PCV feed. Definitely need to find a way to fix it. Might be able to glue, dealers can provide new, and pick'n'pull yards are an option (if you can find an engine - the v8's disappear quickly).

Also it's advisable to not drive the car until its fixed. If the cam skips again, there will likely be significant damage to valves, heads and/or pistons.

 

[anonymous]

Thanks for your help. Here is a little better pic of the tensioner. I cant see anything wrong with it at all, do you? However, I did find a TINY piece of orange plastic sitting below the chains but the tensioner looks perfect. Is anything else that same color orange as the tensioner? Thanks again

 

[1LoudLS]

, I did find a TINY piece of orange plastic sitting below the chains but the tensioner looks perfect.

dude, looks can be deceiving, if it was perfect, you wouldn't have broken pieces of plastic in you motor. chains dont just jump for no reason. this is simple, something is broke and it NEEDS to be fixed. if you cant see what is broke then you need to take it to someone than can.

IF your motor is not fukced right now, and you just line the cams back up, the next time it happens (and it will), you will probably not be so lucky. the repair bill will be astronomical compared to fixing it right the first time.

 

[reaper76]

:iconcur::iconcur::iconcur:

dude, looks can be deceiving, if it was perfect, you wouldn't have broken pieces of plastic in you motor. chains dont just jump for no reason. this is simple, something is broke and it NEEDS to be fixed. if you cant see what is broke then you need to take it to someone than can.

IF your motor is not fukced right now, and you just line the cams back up, the next time it happens (and it will), you will probably not be so lucky. the repair bill will be astronomical compared to fixing it right the first time.

This is very true!

 

[TooManyToys]

Interestingly (to me) everyone who has put up pictures of broken tensioner or guide parts has a motor where the plastic is stained deep orange and the top of the cylinder heads are stained with carbonized oil.

Dude, you have an early LS with would have come with full plastic tensioners. The broken part could have come from the body of the tensioner or from the glide on the bottom which also works just like the glide on the top which you have shown.

The picture of the valve cover shows a lot of dirt still on it's surface. Next time before you start exposing the internals of a motor to the open you really need clean the top of the motor, or anywhere else that you are going to open. Felpro did a study maybe one to two decades ago where they showed that this type of backyard work had a very high risk of bearing and oil pump damage due to dirt being dropped into the internal cavities of the motor.

 

[anonymous]

I actually thought that the tensioner just came that color because every search I have done showed pics of them looking deep orange. You are probably right and ya my engine bay is filthy and I should have cleaned it first. I know this sounds dumb but I never thought about it...I didn't pay that much for this car so to me the learning experience is worth it alone but I want to do this myself because I have nobody to teach me. Thanks for all your help. I have really been trying to avoid attempting to take off the front cover...looks like A LOT of work. Can someone explain to me how it is physically possible for the exhaust cam to skip a tooth if there is 0 slack in the chain or could it have just stretched that far? I can read everything I can find but sometimes I just need someone to explain it. Again, thanks for taking your time to help

 

[TooManyToys]

It sounds like you're in the trap many fall into. These car can be cheap as many used car dealers don't want to take them on due to the cost of these type of failures. I think you will find that the slack is at the bottom loop of the chain right now, not between the two cam sprockets. That top loop is probably tight as the two cams are tensioned against one another from the valve springs pushing on the cam lobes.

It is time consuming to remove the front cover and the biggest handicap is that the a/c compressor has to be removed, so the freon has to be recovered. The second critical issue to me is to clean the area around the dipstick where it goes into the block as this it a great potential to get sand into the motor.

It takes a fair amount of tools, can be frustrating at times, and I would give a novice about 16-20 hours to do the job. But before doing all that work the valve train needs to be checked to make sure no valves have been bent.

 

[Telco]

Can someone explain to me how it is physically possible for the exhaust cam to skip a tooth if there is 0 slack in the chain or could it have just stretched that far? I can read everything I can find but sometimes I just need someone to explain it. Again, thanks for taking your time to help

Let's see if this helps. Keep in mind that this is timing chains in general, not specific to the LS.

A timing set will normally skip a tooth when the chain is worn. Over time, when the engine accelerates and decelerates, the cams, chain and crank will speed up and slow down in relation to each other. The engine will be moving and it will all be imperceptible to us, but the following is what’s going on in relation to the parts.

The cams are driven by the crank by the chain. When this happens the crank will speed up or slow down first. The crank will pull on the chain. The chain will then start to move, which will then pull on the cam. Between the time that the crank is moving and the cam is not, the chain is stretching on the pulling side.

When the engine decelerates, the crank will slow down, then the chain, then the cams. The chain will be stretched on the following side. All this happens almost instantly, but there is a time lag between the crank’s speed change and the cam’s speed change.

Each time the crank changes speed in relation to the cams the chain gets stretched a tiny, tiny bit. Over the engine's life this will happen millions of times, all the while the chain links are spinning and turning in relation to each other along their path around the crank and cams.

Once the chain has worn enough, on one of the speed changes (usually a deceleration) the chain will have enough slack for it to jump a cog. The tensioner will help keep this from happening, but even it takes time to react. If the chain is worn, the tensioner should be to one side of its allowable range.

Now would be the time to change the chain, while everything’s still more or less in place. Wait till the chain pops, and you’ll be stranded. Per JoeGR (see post below) this is an interference engine, so if the timing chain breaks the pistons will come into violent contact with the valves. At best you'll need to replace valves, at worst the engine will scatter. The only difference will be whether you pay a core charge or not on the new/rebuild engine.

Here's a pic I found of what it should look like under there. I don't know if this is specifically a 3.9L, but the lower chain shows the stretching that TMT was talking about, on the right side.

 

[joegr]

...Near as I can tell from the internet the 3.9 isn’t an interference engine so it shouldn’t bend any valves when it goes, but you’ll still be walking...

Nope, it is an interference engine. If the exhaust jumps just one tooth, often there is no damage. More than that, and there is serious damage.

Issues with the 3.9 timing are not generally due to chain wear or stretching. They are due to tensioner failure. That's why the tensioners were changed a couple of times.

 

[Kickerbeast]

This is how I came to own my LS. Loved them for a long time but never wanted to pony up the money for one. Found one for a hell of a deal. Broken tensioner and bent exhuast valves. Cost me about a grand for a tensioner/chain kit and gaskets. Not bad to do if you know how, just tight working area.

Also, DONT take any of the chains off if you don't have the right cam and crank locking tools. Its one thing if you are putting the old ones back on, you can mark them and line them back up. New ones is another story.

 

[Telco]

They are interference. Thanks, wasn't sure as the internet wasn't clear on it. Corrected my post.