Engine decision on '97 Chevy Z71

[TeamAmerica]

Get a 2nd opinion but that sounds like a bargain for a warranty motor install.

[WItoTX]

I love that truck/bodystyle, had a '96 myself. Replace the motor, but get a 383 stroker with a nasty cam!

Seriously though, I would replace the motor. Those trucks were built well. Not to mention the cost of new trucks these days, 5k is cheap.

[Chief Big Toe]

if i did not want to buy a newer truck, and everything else worked fine, i would do the $5k, but would get a second opinion first.

[KDinTX]

Does it smoke??
It could just need a tune up.. Many things can cause your problem. I own 4 90's truck.. Get a compression gauge and check it yourself. You should be over 130 psi on each cylinder. Those engines are good for many more miles than that if routine oil changes have happened. It could also be your injectors. Those spider injectors will wear out..

I bought a brand new crate motor straight from GM for less than $3,000 including freight.

We put over 300k on 4 or 5 of those trucks. I might have someone else give you a diagnosis.

I would think replacing that 350 would be quite a bit cheaper than 5k, but I havn't looked into anything like that in a long time. I'd have that one bored and rebuilt, new cam/valves/lifters, and have the heads worked a little. I don't see the point in buying new heads and block, when the 350 chevy is the most rebuildable engine ever built, with the most aftermarket support.

Not to discredit the mechanic, but I'd check it myself. If its not making oil, putting oil in the coolant or smoking then there's something else.

The 98 3/4 I had with the same motor needed a throttle body cleaning and new plugs at about 100k, after that it ran great until I sold it, and it had a slight rough idle before all that. Several buddies owned that truck and it went well into 300k with no other issues. Might also check the mass air flow sensor and PCV valve to make sure they are clear and are working correctly. These are still simple 350's with throttle bodies instead of carbs, real easy to figure out.

But if you were going to pull it, I'd have it ran through and a few things added and touched up before a new motor.

[eastover53]

If I was going to put a new motor in it, I would do a 5.3 LS motor swap. Beats the heck out of the old vortec engines, and I bet you can do it for less than $5000.

[Zjesse22]

Get a second and third opinion and maybe get different quotes for engine and labor, I’ve seen several z71’s that have been ls swapped for around that price range that are reliable and warranty that’s just another thought, I myself am looking for a 95-98 z71 single cab to do an ls swap

[FamousAmos]

I am in no way a mechanic. I have skills but they are completely unrelated to automotive issues! The truck uses oil. I have to add a quart every thousand miles or so.

[eastover53]

You are going to find lots of shops in your area that specialize in LS swaps.

[Dale Moser]

Engine decision on '97 Chevy Z71

I am in no way a mechanic. I have skills but they are completely unrelated to automotive issues! The truck uses oil. I have to add a quart every thousand miles or so.

That could be other issues that don’t require a whole new motor. That is almost no miles for that truck, I would have someone look deeper before replacing it.


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[RifleBowPistol]

If the truck has had decent maintenance, I would think the cylinder walls would be in good condition. Breaking one or two pistons in that engine would be odd. It would help to know which two are low on compression. Possibly a head gasket. That year engine I am pretty sure has a roller cam, so flat cam lobes should not be a problem. Those engines have problems with fuel injector tubes in the intake and EGR valves getting gummed up. So is possible the EGR valve is stuck open, that would make it run rough, but not cause low compression on a cylinder. But carbon that broke loose from the EGR valve, could have gotten stuck between a valve and seat, could have happened on more than one cylinder.

If the engine really has two cylinders with only 80 psi, I would think blown head gasket or carbon between some valves and seats. Those engines were also know to have valve stem seals go bad. I would think pulling both heads and having them checked out. Then check the cylinder walls and pistons to make sure the short block is good. I really think it would be odd for the short block to have a problem that would result in two weak cylinders.
I would put money on head gasket or carbon stuck under some valves, which a valve job will fix. So most likely pulling the heads and getting a valve should fix it. But I could be wrong.

[Mike Fangman]

We put over 300k on 4 or 5 of those trucks. I might have someone else give you a diagnosis.

I would think replacing that 350 would be quite a bit cheaper than 5k, but I havn't looked into anything like that in a long time. I'd have that one bored and rebuilt, new cam/valves/lifters, and have the heads worked a little. I don't see the point in buying new heads and block, when the 350 chevy is the most rebuildable engine ever built, with the most aftermarket support.

^^ I agree with this, should be able to get, way more miles than that, on that motor. I put over 300,000 on my 350 and it still ran dang good. Get a second opinion.

[camoclad]

Predator engine from harbor freight

[easeup]

predator engine from harbor freight

lol!

[easeup]

check engine light on? what are the codes?

[WItoTX]

OP, Dale and others got me thinking. At 16x,*** something on the fuel system went bad on mine. The truck would idle real rough when warm, and got worse over time. I think it was fuel injectors? It happened after we did the head gaskets. Here is a link to the work that I had to do on mine. it was easy, but tedious.

https://www.gmfullsize.com/threads/1...h-idle.272083/