3100 Timing Chain Stretch

[Regor]

I am replacing a bad 3100 from my '98 Malibu with a 3100 from a '95 Grand AM donor. I wanted to check out the bottom end and replace any needed gaskets while it was out. I was wondering if there is a specification for chain stretch that I could measure to determine if a replacement is needed. The (replacement) motor has over 150k on it.

I plan on replacing the following gaskets:

• Oil Pan
• Upper & lower intake
• Front cover (timing chain)
• Valve covers

There is a little bit of gunk in one of the corners of the oil pan as would be expected which will of course be cleaned out. Overall the engine looks internally clean. What "check" am I missing before I do the swap? Front/rear seals?

Thanks guys!!

[96ols60degree]

Hey.If it was me ,and I had it apart,would just put me a mild cam,and new chain in while I was there.especially since it has that many miles on it.My moddo is do it right the first time,and you will have nothing to worry about later.But it depends on you of course.

[Azrael]

I'd replace it (and the dampener) too with that mileage since you'll have the cover off with easy access. Old chains are known to make quite a bit of noise in these motors which is usually mis-diagnosed as a lifter tick.

Also, you'll have to reuse the upper intake manifold from the 98, since the 95 uses an older type of EGR valve.

[Regor]

Thanks for the quick response guys. I plan to keep as much of my old stuff that I can and just move it over. I agree, since it is out I might as well replace the chain/gears. I just a year ago replaced the LIM gasket with the new metal one. Too bad I can't reuse it as it was my third one and looked like it was finally going to keep the coolant out of the oil.

I'd replace it (and the dampener) too with that mileage since you'll have the cover off with easy access. Old chains are known to make quite a bit of noise in these motors which is usually mis-diagnosed as a lifter tick.

Also, you'll have to reuse the upper intake manifold from the 98, since the 95 uses an older type of EGR valve.

[IsaacHayes]

Azrael is right on. 150k you should do the chain and guide. And yes my engine sounded like mad lifter tick, but it was the chain/guide.

[96ols60degree]

Wow,and to think my olds was doing this for about 40-50 thousand miles!.......oops! So I guess I was riding on thin ice after all.My monte I just got is gonna need the lim changed on it,I was looking at the engine when I got back from the store.only external now,inside of this engine is silver and clean.

[IsaacHayes]

I don't know if it would have skipped a tooth or not. My chain had TONS of slack. But I'm not sure I was in any danger. I replaced it right around 200k. I'm confident this engine at 220k or whatever it is now is plenty strong. The oil pan gasket is leaking quite a bit though. Starting to see a few drips on the driveway. My trans however has seen better days and is robbing me a lot of power.

My chain was making that noise probably from 120k-200k when I replaced it.

[Regor]

Well I went ahead and got a new set just to be safe. Speaking of oil pan, do you think that the gasket will be enough to seal it back up or should I put some RTV on there as well?

[IsaacHayes]

You need RTV in the corners where the timing cover meets the pan. But not smeared everywhere.