dcmock

Alright I've heard conflicting stories, I've got a new melling m295 oil pump, it comes with a black o ring and a green one. Which o ring do I use, don't want to pull apart again so please give me the right info. Thanks

neutron82

I used the fat green one... there should have been a sheet of paper with the pump that tells you which one to use according to your pickup tube type

mathia

When I installed my Melling 10296 pump I couldn't get the pickup tube to fit with the green o-ring, it seemed too big. I got a new GM one and that worked fine. No problems with oil pressure.

Paul 75 L82

Lube the baby well.

leadfoot4

I had to drop the oil pump pickup when I had mine down this past summer for a new timing chain and ATI damper. I didn't realize that the Fel-Pro timing cover gasket set would include an assortment of O-rings, so I went to the Fel-Pro catalog, plugged in "2001 Corvette oil pump o-ring", and ordered the part number their site called out. It was red. I installed it, and so far, I've had good oil pressure.

dcmock

OK so 1 person said green, one person said blue, one person said red, now just waiting to hear black and I'll be completely clear on what oring to use!

neutron82

in your original post you said you didn't want to tear it all apart again so I'm assuming you already installed the pump... which o-ring did you use?... have you started the car to check the pressure?

dcmock

I have the engine on an engine stand and want to do it right the first time

neutron82

Paul 75 L82

Over on the LS1Tech site this comes up many times. My personal take on the o ring is that all of the different o rings will seal. The problem is that when your inserting the tube in the pump with the motor in the car and the oil pan is on that guys are not getting the tube to slid up into the pump straight and they knik the o ring where it doesn't lay flat. If that happens you will not have good pressure. I made sure that the tube went up straight and that I didn't knik the o ring and if you do that you will be OK. But this little o ring can sure cause a lot of labor to be wasted if you have to go back in there to replace it after the project is complete. (I think I used the green one)

warlock007

I used the green one, had to go into the bottom end and found it was torn during install as it was to thick. replaced with black one, fits perfect and PSI is solid.

Bill Curlee

I helped WARLOCK with his install and was surprised to see that the GREEN O RING was damaged during our last install .. We were very careful installing it and it seemed to install fine.

However that said,,,,, I used the GREEN one on my 02 ZO6 during my heads cam install. 100% perfect.

The black one will work FINE as proved by our recient install. I strongly recommend using a mirror and carefully inspect the pick up tube when installing the tube/O ring into the pump. If you have a problem, you will see the O ring BULDGE out during insertion.

Just for your enjoyment, I provided this cut away so you can see how everything fits together:

leadfoot4

Looking at the picture that Bill graciously posted, gave me some food for thought....The o-ring in question is on the suction side of the pump. So, me thinks, unless you TOTALLY twist it during installation, it's really hard to have any oil pressure issues.

warlock007

That's not really true, I saw a drop in pressure but not at first, took about 2 weeks and then I noticed a couple psi than normal.

Truthfully, I wouldn't of thought it was damaged even tho it was less than what I normally saw, that's what inspired me to go into bottom end where I replaced the rod bearings and Bill and I saw it torn and squished. I'll try to find the picture of it. Bill may still have it as well.

Bill Curlee

The O ring is on the SUCTION SIDE of the pump. If it doesnt provide a 100% air tight seal,, it will allow the pump to suck air which will decrease pump pressure and volume,,, IF it pumps at all!

SO,,, its not as important to seal against PRESSURE as it is to insure that it doesnt let any air suck into the pump.

Bill

gnfan

I just installed a 10296 melling pump and used the black o ring. Works fine.
For what its worth I called Melling to ck with their tech department and he also said to use the black one. He also said the green one is used for grooved or recessed pickup tube like on some trucks.

leadfoot4

With all due respect, Bill, I worked in the precision optics industry for over 30 years, most of that time working with vacuum coating equipment. Each one of our coaters had dozens of O-rings at various sealing surfaces/junctions. If I had $5 for every o-ring I've removed/installed, I could afford a brand new C-7.

I stand by my original statement, emphasizing, as I previously said, as long as the o-ring isn't twisted/damaged during installation (and of course, the oil pickup tube is securely tightened).

dcmock

Well here's my conclusion, mine pickup tube is not grooved like the picture, but the green one is the one I used. I tried the black one too loose, blue one too loose, green one installed it and removed it a couple of times to make sure the oring didn't get damaged

neutron82

that's interesting, what year car do you have?... my 02z had a grooved pickup tube like the one on the instructions and the picture of the cutout oil pump so that's why I used the green one... it was tight but after I soaked it with oil and maneuvered the tube it slid in the pump without too much force

dcmock

My engine is a 04 which is a weird bird , cause it was a transitional year so it came factory with the ls2 timing chain and was drilled for the ls2 dampener. So maybe why mine was different but still weird that the green oring fit the best, seems like without the groove it would be even tighter