1999 L31 Engine with nearly 260k, Timing chain plus what else?

[redfishsc]

My 1999 C1500 Sub runs great (well, for now lol) and is approaching 260 miles. L31 Vortec 5.7. Cylinder heads, new mpfi injectors, and lifters replaced a couple years ago. No knocking, oil kept changed, and I drive it hard, maybe 5k miles per year. Trans fluid swapped annually (pan drop, I have a drain on the pan).

Got a free new timing chain from a friend recently who had the same year truck and sold it.

I'm thinking about swapping the timing chain next time I do a coolant flush.

While I'm at it, what else should I consider swapping? This old truck is my family activity/beach/fishing hauler and bass boat tow rig. So I'm entirely concerned with reliability.

Should I drop the oil pan for a new gasket, maybe swap in a higher flow oil pump? And if I'm going that far, should I consider bearings? I've never serviced the bottem end so I'm not really sure what all would be considered wise here.

 

[Komet]

Do a refresh on another L31 shortblock, and then have it ready to go when yours finally needs internal service. I'd leave what's going on in your truck alone for now until you've got a reason to crack it open.

Also no on the higher flowing oil pump. 260k is proof it has the right one already.

 

[Schurkey]

Do a refresh on another L31 shortblock, and then have it ready to go when yours finally needs internal service. I'd leave what's going on in your truck alone for now until you've got a reason to crack it open.

Sounds good to me.

Also no on the higher flowing oil pump. 260k is proof it has the right one already.

It certainly does not have the "wrong" one. Should be 3/4" pickup tube, and +10% in volume.

That said...I'm planning on an M99HV-S for any future SBC builds. Requires some modification/trimming of the windage tray.

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[Moofus02]

I pulled the pan on my 98 g30 at 416k miles. Only because the pan rusted through from the outside and started leaking. Motor had never been opened up until then. I did bearings, pump chain and gears valve seals and intake gaskets at that time out of guilt. Still had a cross hatch in cylinders, didn't burn oil, had great compression and was spotless inside. At 260k I wouldn't sweat it. The l31's I have now are all between 200 and 350k miles. Never been apart

 

[HotWheelsBurban]

If you do the timing chain, I'd also recommend you replace the cam gear as these often have nylon (plastic) teeth from the factory.

 

[99xcss4]

replace the cam gear as these often have nylon (plastic) teeth from the factory.

never new that thanks for sharing I heard of them doing that on the 2.5 iron duke/tech-4 I have heard bad things about them

 

[Erik the Awful]

Do a refresh on another L31 shortblock, and then have it ready to go when yours finally needs internal service. I'd leave what's going on in your truck alone for now until you've got a reason to crack it open.

I agree, except that I'd prepare a longblock. A Vortec head with more than 200,000 miles on it is almost guaranteed to have cracks. You can't hardly find junkyard heads any more that aren't cracked. You'll want this solved in advance so you can spend a single day doing an engine swap and have it back on the road.

 

[Schurkey]

A Vortec head with more than 200,000 miles on it is almost guaranteed to have cracks.

Cylinder heads, new mpfi injectors, and lifters replaced a couple years ago.

 

[rebelyell]

If you do the timing chain, I'd also recommend you replace the cam gear as these often have nylon (plastic) teeth from the factory.

Never say never, but I've not seen an L31 or L30 or L35 V6 with an OE nylon-clad cam sprocket (earlier motors heck yes).

 

[HotWheelsBurban]

Never say never, but I've not seen an L31 or L30 or L35 V6 with an OE nylon-clad cam sprocket (earlier motors heck yes).

I thought I remembered that the other '99 Burb L31 we had, had a plastic clad cam gear/sprocket...but I did that job in 2007 and there were several other repairs done at the same time...so I could be recalling it incorrectly. I think the '90 Burb TBI 5.7 had a plastic clad sprocket...but I did that job 21 years ago. Don't have either truck or their service records anymore so no way to check it.
Does anyone know if there's a difference between the 5.7 Vortecs built in Silao and the ones built in Flint, on this? Or a difference between the 1500 engine and the 3500 engine?