i have a 99 yukon with the L31 vortec 350.
I have always treated her good (oil changes every 3000 miles, maintanance, so on and so forth)
Well right after it turned over the 190,000 mile mark, it started making some really bad noises.
It started with a consistent ticking and then turned into a squeal and an inconsistent tick.
Any ideas on what it might be?

 

Spun bearing possibly? If you could get a vid it would help a lot. My 350 blew up this summer and the noise was terrible...

 

Are you loosing any coolant? Mabee the manifold gaskets are bad and they've been washing down your bearings with coolant.
Just about anything with Dexcool is a guarantee that the gaskets are toast.

I've heard those engines are good for 400K since theyre just a good runner.
I'd definitely check it out and not drive it. You want to minimalize any possible damage.

Oh - and welcome aboard.

 

It isn't leaking antifreeze, but i have been thinking a spun bearing sounds about right. would it take a lot of time to fix the bearing or would it be easier to just put in a new engine entirly.

 

At just shy of 200k, I would just look at trying to budget a crate engine if you think you can swing it. If you can diagnose the issue and fix it without too much of an issue, you might be able squeak by with minimal cost, but beings that you can pick up a replacement L31 Vortec style engine for around a couple grand it may be your best bet. It doesn’t take very long with the cost of gaskets, bearings, machine work and other hard parts to approach the cost of the replacement and you will still need to assemble it or pay someone to do it for you when it’s said and done.

I’m also sure at this mileage the heads need to be freshened up, which will set you back a decent amount. Two other areas to look at with this high of mileage are the spider injection assembly and the distributor itself. The bad thing about these two items, is that even with purchasing a crate engine, they don’t come with it and would have to be purchased separately. Basically you will need to decide whether the vehicle your working on is actually worth the amount your about to invest into it. Beings a running vehicle is obviously worth more than a non-runner, if you do diagnose it to be a lower bearing issue, you could do a crank kit on the cheap and use the additional money that you were going to invest into it to put towards another vehicle, unless you just have an attachment to your current ride and want to keep her.

Decisions, decisions!

 

Ok i think i might just buy a good used engine, but here is my next delemma.
I can buy an exact match engine for around $1000, but i could pick up a 5.3 for $350, and a 6.0 for around $1000, i was considering putting one of these two in but i realize it would involve work, would it be worth my time or should i just stick with the 5.7, and what parts would i need and what would i have to do. i know engine mounts might be an issue, but what else, computer? fuel system? exhaust? wiring? and anything else im missing

 

Depends on how much cash you have. Consider the body and how long you plan on keeping it.
Also count on PCM, Wiring, tuning, exhaust mods, control for the transfer case, integration to the BCM etc etc.
Fuel rail modifications for sure since yours is most likely CPI.

I would think for cost effectiveness, find a low mileage yard motor, and get a warranty with it. http://www.car-part.com (Boneyard database)

Correct me if I'm wrong gang...but I don't think a 350 4L60E will bolt up to a LS motor (Different bell housing) either.

 

GM performance parts offers a 383 that is a direct replacement for the Vortec 350, something to think about if you have the coin. Of course a GENIII swap is always great, but a little more work and more parts involvement, such as motor mounts, transmission, pcm and harness, swap headers, etc.

 

The LS motors will mount up to the old 4L60E. I have a 6.0 with my stock 60, but if you get the 6.0 you can use the stock flexplate and it will bolt right up, but I'm pretty sure if you get a 5.3 you have to get a new flexplate and spacer from S&P...

 

just throwing this out there....i rebuilt my l31 for 1900 bucks...this includes..

GM steal crank
eagle forged rods
KB hyper. pistons
reworked heads (than i ported ad polished them)
comp cams 1.6 roler tip rockers
comp cams beehive 918 springs
comp 218/224 cam 112 lsa
all gaskets
plugs, wires, new cap and rotor, water pump etc



few other odds and ends, about about 14 hours putting it all together (including p&p heads)


but i already had the updated spider injectors also (add 300)