Oil pump O ring 99 T/A
Thread Starter
On The Tree
Joined: Sep 2017
Posts: 186
Likes: 27
From: Pensacola, Florida
Oil pump O ring 99 T/A 
Hows it going everyone, well I got my engine back from the machine shop and they clearly lied to me. I was told when I handed over 3000 dollars that I would have to install the oil pan and valve covers which is no problem. When I pick up my motor a month and a half later, they did not install the timing chain cover, windage tray or the pick up tube. The problem I'm having is concerning the O ring that goes on the pick up tube in to the oil pump. I've never had the oil pan off so I have no idea which O ring to replace it with because they removed the original one! It's my understanding, or lack of, there are different color O rings for this application. And since I don't know what my engine came with, I don't know which one goes back on it. I'll upload a picture of the box of mystery gaskets they sent me.
Last edited by br549; Oct 2, 2020 at 08:32 PM. Reason: pictures
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,615
From: Central Cal.
There are basically two different O-rings. A thicker cross section one, which goes on a tube with a groove rolled into it, or a thinner cross section one that goes on tubes with no groove, AKA straight sides.
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,615
From: Central Cal.
Good eye. I was guessing it was the straight one. I wasn't even aware there was a tapered one, just the straight and grooved ones. That might be the reason for some who have also put the skinny O-ring on and leaked, thinking they had the straight one. The taper isn't all that obvious!
Trending Topics
Thread Starter
On The Tree
Joined: Sep 2017
Posts: 186
Likes: 27
From: Pensacola, Florida
I just seen the post about the tapered ring. I already installed the black O ring and bolted the pan up but the motor isn't in the car yet. I'll drop the oil pan in the morning and measure the inlet. Better safe than sorry.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
TECH Addict
Joined: Dec 2017
Posts: 2,180
Likes: 969
My personal quick & dirty method (because I'm usually too lazy to walk over and get the caliper) is, attempt to put it together with the thick one; if it goes into the bore in the pump, then that must be what it wants; only use the thin one if the thick one absolutely will not go.
Another way to look at O rings... Use the one that fits, I'll explain. With o rings you need one that is thick enough to make good contact with the inner and outer sealing surfaces. Too thin it won't make good contact with either the inner or outer surface it is sealing together. Too thick it wont go together without force.
For the oil pump find the one that isn't too big or too small for the pickup tube. Both of them (o rings) are made to fit the outer sealing surface of the oil pump the same so outer diameters are the same. Find the one that fits the tube properly.
If you have a skinny tube the thin o ring will be loose on it, if you have the fat tube the fat o ring will be real tight, and wont go into the pump housing easily once installed on the tube.
For the oil pump find the one that isn't too big or too small for the pickup tube. Both of them (o rings) are made to fit the outer sealing surface of the oil pump the same so outer diameters are the same. Find the one that fits the tube properly.
If you have a skinny tube the thin o ring will be loose on it, if you have the fat tube the fat o ring will be real tight, and wont go into the pump housing easily once installed on the tube.
Thread Starter
On The Tree
Joined: Sep 2017
Posts: 186
Likes: 27
From: Pensacola, Florida
Thanks for the replies. I removed the black O ring and replaced it with the green one in the picture up top. The diameter of the green one was too big, so I went with the kinda orange one. It fit alot tighter than the black O ring. Thanks to everyone that replied this motor will die of natural causes, over revving! The way nature intended!!
Thanks for the replies. I removed the black O ring and replaced it with the green one in the picture up top. The diameter of the green one was too big, so I went with the kinda orange one. It fit alot tighter than the black O ring. Thanks to everyone that replied this motor will die of natural causes, over revving! The way nature intended!!
atta boy