Anyone ever rebuild a GenIII V8 with good results?
#1
Teching In
Thread Starter
Join Date: Jul 2004
Location: Lehi, UT
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
Anyone ever rebuild a GenIII V8 with good results?
I recently acquired a 2002 Tahoe (LM7) with a fragged transfer case (there are literally chunks of the housing missing from it) and low oil pressure. My plan is to pull the engine, have my machine shop inspect the block and heads to make sure all is well, then install new bearings and rings and reassemble the engine. Once complete, I will swap the engine into... something fun. In my lifetime, I have rebuilt two engines that spun rod bearings on me (they were both turbo FWD Mopars) and everything turned out just fine--those engines both ran great for years afterward.
Lately, I've been watching tons of Sloppy Mechanics videos. On numerous occasions, Matt has said to stay away from any GenIII (or GenIV) engine with low oil pressure. He basically says if your GenIII engine develops low oil pressure, junk it and walk away. "I've never had good luck bringing one of these back from low oil pressure."
Question: is there something unique about the GenIII V8s that makes them die a permanent death if this type of disaster occurs? I've seen independent mechanics in YT videos who say low oil pressure is a common thing for GenIII engines, but they also say it's an easy fix (the oil pump pickup tube seal, I think?) and they don't sound all Chicken Little about fixing it. Is there something a newbie like me doesn't know, but I should?
Just wondering if I should cancel this project before I even start it.
Lately, I've been watching tons of Sloppy Mechanics videos. On numerous occasions, Matt has said to stay away from any GenIII (or GenIV) engine with low oil pressure. He basically says if your GenIII engine develops low oil pressure, junk it and walk away. "I've never had good luck bringing one of these back from low oil pressure."
Question: is there something unique about the GenIII V8s that makes them die a permanent death if this type of disaster occurs? I've seen independent mechanics in YT videos who say low oil pressure is a common thing for GenIII engines, but they also say it's an easy fix (the oil pump pickup tube seal, I think?) and they don't sound all Chicken Little about fixing it. Is there something a newbie like me doesn't know, but I should?
Just wondering if I should cancel this project before I even start it.
#3
TECH Senior Member
iTrader: (4)
A friend that's a SAM graduate rebuilt a battered Gen III LS1 into the 383 LS1 stroker that's in my 91 RS. No issues with the engine going on 3+ years and 10,000 miles.
Isn't part of the "sloppy mechanic" philosophy about doing max performance for the least cost, least amount of time and reusing the torque to yield head bolts over again? I wouldn't think folks that follow that idea would want to get entangled in any engine rebuild because between the parts & machine work to rebuild a Gen III LS1, it's probably less expensive to pick up a junkyard Gen IV engine in most cases these days.
Isn't part of the "sloppy mechanic" philosophy about doing max performance for the least cost, least amount of time and reusing the torque to yield head bolts over again? I wouldn't think folks that follow that idea would want to get entangled in any engine rebuild because between the parts & machine work to rebuild a Gen III LS1, it's probably less expensive to pick up a junkyard Gen IV engine in most cases these days.
#4
TECH Fanatic
iTrader: (3)
Isn't part of the "sloppy mechanic" philosophy about doing max performance for the least cost, least amount of time and reusing the torque to yield head bolts over again? I wouldn't think folks that follow that idea would want to get entangled in any engine rebuild because between the parts & machine work to rebuild a Gen III LS1, it's probably less expensive to pick up a junkyard Gen IV engine in most cases these days.
Now a 6.0 cost the same to rebuild as a 5.3, but they cost more at a junkyard so the price to rebuild a 6.0 starts to make more sense because they cost more to purchase another engine.
IMO rebuilding a 5.3 back to stock is a waste and defeats the purpose, unless your going forged and boosting the crap out of it then it starts to make more sense
But! if you have the money and want more power just start with a 6.0 especially if your going N/A
Last edited by Ls7colorado; 01-08-2019 at 12:51 PM.
#5
TECH Resident
If it's iron block then a rebuild isn't worth while price wise. A performance build is definitely the way to go. If it's an aluminum block it gets a bit tricky since the engine is worth more, but the rebuild is tricky to do (no overbore and slap it together on the thin liners) For aluminum if the liners are good then a performance build is the way to go. Basically if the bores are good build for more power and blow the doors off whatever crap youtubers think is cool.
The funny thing about the gen 3 is that they tend to have oil pressure sensor issues as they age. There's a chance some of these guys are throwing away perfect engines that just need a new sensor for the pressure gauge. Add to that the idea that the oil pump pickup o-ring may be due for a change and the number of perfectly good engines being thrown away increases more.
The funny thing about the gen 3 is that they tend to have oil pressure sensor issues as they age. There's a chance some of these guys are throwing away perfect engines that just need a new sensor for the pressure gauge. Add to that the idea that the oil pump pickup o-ring may be due for a change and the number of perfectly good engines being thrown away increases more.
Trending Topics
#8
Lately, I've been watching tons of Sloppy Mechanics videos. On numerous occasions, Matt has said to stay away from any GenIII (or GenIV) engine with low oil pressure. He basically says if your GenIII engine develops low oil pressure, junk it and walk away. "I've never had good luck bringing one of these back from low oil pressure."
.
#10
TECH Veteran
iTrader: (40)
An engine is an engine. A good rebuild is a good rebuild. A poor rebuild is a poor rebuild.
There's nothing special about an LS that makes it harder to properly build, if anything it's one of the simplest engines ever produced.
I have also had better luck with used engines than I have rebuilds, but that's because often times people opt for low cost rebuilds.
There's nothing special about an LS that makes it harder to properly build, if anything it's one of the simplest engines ever produced.
I have also had better luck with used engines than I have rebuilds, but that's because often times people opt for low cost rebuilds.
#11
TECH Resident
An engine is an engine. A good rebuild is a good rebuild. A poor rebuild is a poor rebuild.
There's nothing special about an LS that makes it harder to properly build, if anything it's one of the simplest engines ever produced.
I have also had better luck with used engines than I have rebuilds, but that's because often times people opt for low cost rebuilds.
There's nothing special about an LS that makes it harder to properly build, if anything it's one of the simplest engines ever produced.
I have also had better luck with used engines than I have rebuilds, but that's because often times people opt for low cost rebuilds.
#12
TECH Fanatic
iTrader: (5)
KCS as usual posts correct good information. I helped a friend pull and rebuild his LS1 in a C5. He had the block tanked, cylinders honed (by a very reputable machine shop), new rings, bearings, GM rod bolts, and the usual stuff you replace on a heads and cam build. 2 maybe 3 HPDEs later the motor is running great not burning oil and very little found in the catch can.
#14
Teching In
Thread Starter
Join Date: Jul 2004
Location: Lehi, UT
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
I am certain you are correct. Fortunately, my machine shop has a proven track record of high quality work. There are cheaper machine shops in my area, and many which can get your stuff in and out with less waiting time, but there are none better IMO.
#15
TECH Fanatic
If I were going to take an iron 5.3 block to the machine shop the only good reason I can see for doing so would be to have it punched out to at least fit stock 3.9 ls1 pistons. Mill the stock heads a bit while you are there and you've got an honest 11:1cr 346ci. Depending on what it's going into or back into that may be worth doing over a slimy old 5.3 or 4.8 j/y cam swapped piece.
#17
Teching In
I rebuilt one for my Tahoe, solid rust free but 180k and ticking. $500 JY engine, $700 O/H kit, $8-900 shop work, I opted for extras in sig. Now, it runs great, pulls harder and I, built an LS 5.3, 15k mi and counting. Now, what to put my old 5.3 in. If I went stock on my original it would have been around 1500. I do not trust JY motors to hop one up without rebuilding it, replace stock, probably. As for the Tahoe, sounds like it got abused. However, pull and inspect, if the mains are good and there's not a hole punched in it, build it for something. A few specialty tools and you can do it yourself, they are pretty simple.
#18
Teching In
Thread Starter
Join Date: Jul 2004
Location: Lehi, UT
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
Thanks, gang.