69GMC/99LS1

Have been researching this, haven't found any clear answers other than early year ls1 pumps blow and should be replaced with a LS6 unit, preferably a ported one.

Does anyone know what was so bad about the original pumps and what was done to correct the problem on the LS6? For instance, too small internal passages, Too loose/too tight on the clearances??? If it was a design issue why do the LS1/LS6 pumps show the same #??

TIA
Brandon

69GMC/99LS1

oops, never mind - answered my own question

https://ls1tech.com/forums/generation-iii-internal-engine/234236-what-makes-1-sponsor-s-ls6-ported-oil-pump-different-another.html

ROCNDAV

iTrader: (100)

I took apart three different year pumps. I think a 97/98, a 99 and an 01/2. I measured every dimension that I could, and everything measured the same between the pumps (relief valve length, diameter, inlet/outlet diameters, gear/rotor thickness). The only thing that I did't measure was the spring pressure and metal harness of the pumps rotor.

One thing that I did see in a magazine article, that I had never heard of before was a problem with the 97-00 blocks themselves. If you compare two blocks, a 97-00 and an 01-02 block, look at the back side with the rear cover removed. The earlier blocks are solid betweent he two oil feed lines, so oil must cross over through this small channel in the rear cover itself. THe newer blocks have this area completely milled open.

For my LS1 project, not only did I port, polish & shim my pump, but I also ported and polished the rear cover. I simply placed the old gasket over the rear cover and traced the ID of the gasket with a Sharpie marker.

I'm thinking of putting a mirrored groove into the block as well.


.

JordonMusser

iTrader: (1)

any pictures of this?

ROCNDAV

iTrader: (100)

Of the block differences or of what I did? THe magazine showed the two blocks side by side, but I dont have that issue anymore, I loaned it to someone and never got it back.

I can take a picture of my 97 block if someone wants to take a rear picture of an 01 or newer block.

I can take a picture of my rear cover work (I would like to wait until I also finish the block) tonight or tomorrow. I only opened it up about a millimeter on each side, but any little bit helps.

As for the differences, it is possible that the rotor or castings themselves were made of different material or the spring pressure rating could have changed. Someone on here once told me that there were some pumps that had shattered their pump gear.

Camaro99SS

iTrader: (4)

It's hit and miss with the earlier pumps. My 99 has 89k, and gets 40+ psi at hot idle, 55-60 cruise, and close to 70 at WOT. When cold, it almost pegs the guage if it sees 4000+ (I rarely do this). This is with German Syntec and K@N 2006 filter.

Jason

CBX

I have a 97 with 56,000 miles, about the same pressures though. I have a lingenfelter pump that I just bought. I will install it when I do my H/C. I use Royal Purple.

Viper

iTrader: (6)

Hit or miss, my 99 pump died at 35K and the dealer said screw off.

Oh well, went to court, GM is too big.

Camaro99SS

iTrader: (4)

While you're in there installing the heads/cam, throw that pump on. It's not really any extra work, just cheap insurance. I'd do the same with a ported LS6 pump if I were doing this.

Jason

gwj

Interesting. When I bought my car, there was a lot of buzz on LS1.COM about failing oil pumps. The buzz then was it could be any year LS1. For about 3 years I never failed to look at oil pressure on startup.
Funny thing is, I don't recall ever seeing one single cause of failure. Folks would just start the engine one day, no oil pressure. I don't -remember- ever hearing of a case where someone was driving and the pressure went to 0.

CBX

That's why I bought it, I'm doing it at the same time I do the H/C swap, also going to do a new timing chain and underdrive pulley. Also while everything is out, I'm adding a transmission cooler.