When to change a timing chain.....

On a 98 Custom?



When is the appropriate mileage to change the timing chain?

There is no scheduled time/mileage for this. I would get a wrench on the crank bolt turn the cranl back and forth to see how much chain slop there is, use your judgement here. I have 220k on my 3800, it has some slop but it's still going, every car is different though.

There is no scheduled time/mileage for this. I would get a wrench on the crank bolt turn the cranl back and forth to see how much chain slop there is, use your judgement here. I have 220k on my 3800, it has some slop but it's still going, every car is different though.


Shoot....I'm mechanically declined :disappoin I think i'd have to ask my mechanic to give it a check for me.

You have 220,000 on your odometer? Wow :runaround:

Is it a Lesabre? What year is it?

98 Lumina LTZ.

An inverted link chain, steel crank sprocket, and iron cam sprocket should last almost indefinitely with lubrication. They normally don't stretch or wear after the first few thousand miles. This isn't your uncle's Toyota, where the timing set needs attention every other year.

My current project is an '89 350/4 bolt (roller block with non-roller cam) from a 1T truck with 320K on it. The steel and iron set had some slop, but would have easily gone another hundred or so without a problem.

I'd be more concerned about the cam position sensor magnet on some of the Buick V-6s failing before the timing set.

It is likely you will never have to worry about it. I have done a couple over the years and it was only because I had the timing cover off to do other repairs.

An inverted link chain, steel crank sprocket, and iron cam sprocket should last almost indefinitely with lubrication. They normally don't stretch or wear after the first few thousand miles. This isn't your uncle's Toyota, where the timing set needs attention every other year.

My current project is an '89 350/4 bolt (roller block with non-roller cam) from a 1T truck with 320K on it. The steel and iron set had some slop, but would have easily gone another hundred or so without a problem.

I'd be more concerned about the cam position sensor magnet on some of the Buick V-6s failing before the timing set.


What is a Cam Position Magnet ? :eek7:

Its also know as a cam button. It is a magnet that pops into a whole in the cam gear that the cam gear uses to generate its signal. Surprise GM made these out of plastic and the plastic fails and they fall off and you get a cam position code. The button is bigger that the hole used for the cam position sensor so you have to remove the timing cover to replace it. If there are a substantial amount of miles on the vehicle than replacing the timing chain and gears is not a bad idea and the extra charges are minimal since the timing cover is already off.

I will tell you this: from my experience rebuilding two 92 Lesabres, and tearing down a third engine at a junkyard, if your engine is old enough to need a new timing chain, there is a good chance you have some camshaft damage (pitted or worn lobes), thus making the value of a new timing chain diminished. You need to check this if at all possible before doing a timing chain. A good clue is that your idle is rough. Do a compression test (or pay someone to do one.) If your results vary significantly in one cylinder (or two non-adjacent cylinders) then you might have cam lobe trouble.

If you car is running fine, don't do anything except keep your oil changed and your fluids full.

Its also know as a cam button. It is a magnet that pops into a whole in the cam gear that the cam gear uses to generate its signal. Surprise GM made these out of plastic and the plastic fails and they fall off and you get a cam position code. The button is bigger that the hole used for the cam position sensor so you have to remove the timing cover to replace it. If there are a substantial amount of miles on the vehicle than replacing the timing chain and gears is not a bad idea and the extra charges are minimal since the timing cover is already off.

Click Here (http://www.automotiveforums.com/vbulletin/showthread.php?t=701011) for some more info on how to replace the magnet without removal of the timing cover.

Thats great fot the do it yourselfer but in my situation I pride myself on doing it right the first time. If it comes back and the JB weld repair has failed the customer will likely be very disapointed that the first repair failed, and frustrated that the vehicle is in the shop for the same problem and the bill is now much more than the original repair.

If it works than by all means I would try it on my own vehicle if I needed to replace it but like I said a customers vehicle no way!