I have 170,000 miles on a 7.4 L 1999 Chevy K2500 Suburban, and wonder if the timing chain needs to be changed as in the older small blocks that I have owned in the past. The engine run nuns well, and I don't hear anything unusual.

Mal Soare
Eastern Montana

Stock 1999 Chevy K2500 Suburban

 

Ain't broke, don't fix it. I have a 5.3L with pushing 180K

 

I have the exact same vehicle. I had the plenum and intake off so figured I would put a chain on it while it was torn down that far since it's such a PITA to get all the crap out of the way. Mine has 133k on it and the chain has about 1/4" of slack. The gears are solid steel now without that nylon coating. Per All Data DIY you have to rotate the front axle assy out of the way and drop the transmission to properly replace the oil pan gasket on that engine. The timing chain cover is that cast pot steel stuff these days instead of sheet metal and the pan gasket is 1 piece rubber. So there's no more loosening the front half of the pan and wiggling the frt cvr in place with a bunch of sealant on the corners.

I went ahead and pulled the engine out so I could clean everything up and replace all the gaskets. Might get the heads done while it's all apart. A good head job always helps to be sure there's a good seal everywhere.

I had no intentions of doing any of that extraneous crud when I started though. Just wanted new injectors and to seal a water leak at the manifold. If I was you I would leave the timing chain alone.