2002 ZR-2 4.3 Best Replacement Oil Pump

Hi All

Bad News, My Son’s “02” ZR-2 has like 136,000 miles, he hassaid for the Past few Months every once in a while, the Oil Pressure drops tolike below 10 and the “Check Gauges” light will come on.

Proper Oil Changes and Level, but his truck seems to havehad a downward issue with the Oiling System/ Pump.

Took it for a ride Monday after he said his Truck was“Dying”, I Do not need this Now !
Lifter Clacking and Rod’s a Knocking.

So I bring it to my Local Engine Swap Professional, he justdid one for another Customer last week.

I have a few Questions,

• I asked him about Changing the ReplacementEngine Oil Pump – What is the Best Pump to put in ?

I found this one on Amazon Prime Melling M155Replacement Oil Pump.
Is that the One I need ?

2. I am thinking about Taking the Old Engine anddoing a “Mild Performance” Upgrade to it and Swapping that Engine back in for aWinter Project.What type of Performance Upgradesare available for the 4.3 Engines ?
Cams, Head work?
ThanksTimmy from Trumbull, CT

 

An AC Delco, or a Melling brand oil pump are probably the only brands that I'd use. I can't say if that Melling M155 Replacement Oil Pump is the correct pump for son's Blazer. But I do know that Melling has a long history of producing good oil pumps. I installed a Melling oil pump on a high mileage '93 C*ravan about 3 years and 15k+ miles ago that's still running strong (for a Chr*sler mini van). Also ran a Melling oil pump when my dad and I rebuilt the eng. in my '65 GTO back in '74.

 

It is the correct pump.

Fuel injected Vortec 4.3s are difficult to improve much on. Biggest hurdle is the factory fuel system won't pass enough fuel to make much power, and the PCM won't allow serious modifications. IMHO it's just not a friendly engine to modify. On the up side, they do make quite good power for a V6, especially at low RPMs. The Express Vans had about 10HP more than the Blazers, due to a different camshaft and corresponding PCM calibration - but good luck finding a bonafide factory Express Van camshaft. The marine version of the 4.3 does away with the spider injectors and has the injectors mounted externally (can be replaced with ones that flow better), so that intake is an option if you want to get serious about a performance camshaft and corresponding PCM reprogramming. Most people at that point just put a V8 in it.

 

I remember reading a 4.3 L how to rebuild article in Popular Hot Rodding or Hot Rod, not sure which, many years ago. They were very familiar with Chevy 5.7L V8 rebuilding for improved performance and wanted to apply those same principles and parts to a 4.3L. They did and used the pistons and rings and so forth. But of course, they couldn't use a 5.7 cam and mentioned the hi perf. parts availability for a 4.3L were very limited. They dino'ed it and IIRC it was 210 to 230 HP range. If anyone can find that article and post the issue and date, I would be appreciative. Thanks, Jim

 

I would also recommend a Melling pump shaft. It uses a steel collar instead of plastic. It is cheap too. Around $10. However, your low oil pressure issue may not be pump related. I forget the name of the part, but there is a valve of some kind in the block under the oil cooler adapter. They go bad and kill your oil pressure. That is what happened to mine and it wound up eating a rod bearing.

 

Hi Guy's

Thanks for the Advise !
I did get the Melling Stock replacement Oil Pump.
And a New Delco CPI Spider and Gasket set, my Guy will install for the Price of Changing the Engine with a Used Engine, that is the way I need to go.

And he needs the Old Engine for a Core Charge.

It's was out as of yesterday, I'm sure there will be a few things along the way.

All good stuff so far.

Timmy

 

Hi All
As an Update, just got home with my Son's "02" ZR-2 with the Replacement Engine.
They Replaced the Oil Pump with the Melling, Installed the new AC/Delco CPI unit, new Engine Mounts, and the Used Engine w/ 1 Year, Warranty for $ 3,300.00

Had a Discussion with "the Wife" as to why we were going to spend $2,800 + on his Truck, She said we can buy him a used Hyundai for that much

With a Rust Free Body, Tires/ Wheels, Lifted work done and New Brakes/ Shocks, Blue Tooth Stereo and other stuff, I found it hard not to get the Replacement Engine.

He said it Runs great and has more Power ???
Maybe not a good thing

Timmy