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

99xcss4 said:

I was just thinking dose any know why gm thought it was a good idea to use a plastic timing cover

Click to expand...

Evidently it’s a pretty good chain noise dampener, based on @Danimal08’s comments about the metal Holley cover (and I’m assuming a stamped steel cover would be similar, could be wrong about that).

At least in my case the same plastic cover has served well for 26 years and 265kmi, as it’s never been off the engine. Call me lucky.

The 350 in WCJr was originally in my Suburban, and after the rebuild it would make a loud tick every few seconds. It made me nervous, so I pulled it back out and went through it again. I ended up putting a .025" hole in the oil gallery plug behind the timing chain. The tick is gone and the engine's been running great.

1998_K1500_Sub said:

@Road Trip, are you acquainted and reasonably proficient with KVL analysis?

Click to expand...

File me under acquainted rather than reasonably proficient -- it's been a lot of years since I've
stopped and taken the time to analyze a circuit like this:




And of course his 2nd Law:





His Laws are part of my overall electrical belief system, and I have used the general principles to help me
make sense of unexpected circuit behavior while troubleshooting. But to be good enough to use KVL
to actually design a new circuit, I've have to dig out some dusty old textbooks and bust the rust off of some
ancient schooling I'm afraid.

Good question, though. It's been a long time since anyone's asked me about my take on Kirchoff, especially
in public. :0) And I remember when having a 4-channel scope was a bit of a status symbol...especially if you
had all 4 channels in use. Definite sign of a serious troubleshooting expedition going on.

Good stuff!

Road Trip said:

File me under acquainted rather than reasonably proficient -- it's been a lot of years since I've
stopped and taken the time to analyze a circuit like this:

Click to expand...

I’ll send you a PM in a day or two, I want compare a few ideas.

HotWheelsBurban said:

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?

Click to expand...

The 3500s have the L31HD instead of the L31LD in the 1500s. Not sure what the 2500s have (might be split by 6 v 8 lug).

The main differences are that the HD has 4 bolt mains, larger exhaust valves and harder exhaust valve seats. I don't actually know if there are any other differences, that's just what I dug up when I was looking for a crate engine.

...and if you use a LD engine in a vehicle that should have a HD; or the other way around...the GM warranty is greatly reduced.

SerStarfish said:

The 3500s have the L31HD instead of the L31LD in the 1500s. Not sure what the 2500s have (might be split by 6 v 8 lug).

The main differences are that the HD has 4 bolt mains, larger exhaust valves and harder exhaust valve seats. I don't actually know if there are any other differences, that's just what I dug up when I was looking for a crate engine.

Click to expand...

I think that engine was 4 bolt mains, but not 100% on that. Moot point after 17 years anyway....

SerStarfish said:

The 3500s have the L31HD instead of the L31LD in the 1500s. Not sure what the 2500s have (might be split by 6 v 8 lug).

The main differences are that the HD has 4 bolt mains, larger exhaust valves and harder exhaust valve seats. I don't actually know if there are any other differences, that's just what I dug up when I was looking for a crate engine.

Click to expand...

My 1500 had came factory with the HD engine. Perhaps because it was in a van. It had a forged crank and single roller chain as well as single angle pressed in exhaust seats to handle and dissapate more heat.

Schurkey said:

...and if you use a LD engine in a vehicle that should have a HD; or the other way around...the GM warranty is greatly reduced.

Click to expand...

I actually gave GM corporate hell about trying to downgrade my 97 Express engine warranty using the 4-bolt engine to replace the factory 4-bolt in it. They put it in writing that it had the full warranty. We were already pissed that the engine failed at 57K because of GMs ****** intake gasket design. Then they tried to downgrade the replacement engine claiming it was a 2 bolt from factory to an inferior engine in every way. They only wanted to warranty the correct HD engine for 12/12 vs 3/100. The Goodwrench engines were 3 year/100K mile warranty at the time.