melling oil pump correct spring

[Duke W.]

Re: melling oil pump correct spring

As long as that modified pickup has the screen correctly located in the pan, I see no reason not to use it and the pump if it passes inspection, or you could buy a correct OE replacement pickup and install it if you wish.

The correct OE spring for your application is 3848911 according to my '77 P&A catalog with a note that is has 21 coils with a white stripe, but no free length or wire diameter.

The 40-45 psi spring is 3814903, 21 coils, 2 7/32" free length.

I'm sure those two springs are long gone, but maybe the OE numbers can be used to find a correct aftermarket spring.

If the maximum hot oil pressure previously was in the range of 55-60 psi on the gage, then whatever spring is installed is providing the OE spec oil pressure.

Duke

[Joe C.]

Re: melling oil pump correct spring

Here are all available Melling relief springs:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.melling.com%2FPortals%2F0%2FSPRING%2520PACKS%2520SPRING%2520COLOR%2520CORRECTED.pdf&ei=CNchVLSfN8-ayASH6YBA&usg=AFQjCNEXj9kR89urg5YwdXXAVbvai_s3ew&sig2=zj-MN41FJLMMva1wUd4laQ&bvm=bv.75775273,d.aWw

You need M-29009-A

[Mike E.]

Re: melling oil pump correct spring

As long as that modified pickup has the screen correctly located in the pan, I see no reason not to use it and the pump if it passes inspection, or you could buy a correct OE replacement pickup and install it if you wish.

The correct OE spring for your application is 3848911 according to my '77 P&A catalog with a note that is has 21 coils with a white stripe, but no free length or wire diameter.

The 40-45 psi spring is 3814903, 21 coils, 2 7/32" free length.

I'm sure those two springs are long gone, but maybe the OE numbers can be used to find a correct aftermarket spring.

If the maximum hot oil pressure previously was in the range of 55-60 psi on the gage, then whatever spring is installed is providing the OE spec oil pressure.

Duke

Duke,
I Googled 3848911 and it's still available from Chevrolet Performance and sold by Summit, there is also some NOS springs available on Ebay.

http://www.summitracing.com/parts/nal-3848911

The engine hasn't been run since the mid 80's so I don't know what the oil pressure was last time it ran. I'll look over the original pump and post some pictures. I'm not apposed to saving the old pump if it can be, it seem like very simple part.


Mike

[Joe L.]

Re: melling oil pump correct spring

As long as that modified pickup has the screen correctly located in the pan, I see no reason not to use it and the pump if it passes inspection, or you could buy a correct OE replacement pickup and install it if you wish.

The correct OE spring for your application is 3848911 according to my '77 P&A catalog with a note that is has 21 coils with a white stripe, but no free length or wire diameter.

The 40-45 psi spring is 3814903, 21 coils, 2 7/32" free length.

I'm sure those two springs are long gone, but maybe the OE numbers can be used to find a correct aftermarket spring.

If the maximum hot oil pressure previously was in the range of 55-60 psi on the gage, then whatever spring is installed is providing the OE spec oil pressure.

Duke

Duke-----


Both springs are still available from GM, over 50 years since they were originally released.

[Duke W.]

Re: melling oil pump correct spring

That's amazing! No doubt the price is probably outrageous, but if Mike's pump is serviceable, I think he should install the ...911 spring, and bolt the pump back on.

And, Mike remove the spring and see if it matches the description form the parts book. Maybe it's the right one.

Same advice to anyone else who decides to buy a new pump, but for about 90 percent of rebuilds, the original pump, including the spring, should check out as ready for another 200K miles.

Duke

[Mike E.]

Re: melling oil pump correct spring

Duke,
I'm not sure if you can tell much about the pump from these pictures but here they are anyway. The first shot if the new pump next to the main body of the old. The casting seems a lot heavier on the new pump.

What concerns me about the old pump is it seems to have excessive run-out or side-play on the input shaft when I compare it to the new one. The old pump will hang while I turn by hand like the gears are binding and the new pump is nice and smooth.

Now for the original spring. Well that's another story, it seems I put in a very safe place. So safe I can't find it at the moment.














Mike

[Bruce W.]

Re: melling oil pump correct spring

Tim, Here is the answer. Gm spring works fine in melling pump. oil pressure is 45lbs at 2000 and about 35lbs at 900 rpm with 15w40 oil. Corvette central needs to get their act together they are selling this pump as a normal pressure pump. It comes with a yellow spring 58-60 lbs pressure. Bruce

[Duke W.]

Re: melling oil pump correct spring

"What concerns me about the old pump is it seems to have excessive run-out or side-play on the input shaft when I compare it to the new one. The old pump will hang while I turn by hand like the gears are binding and the new pump is nice and smooth."

Visually it doesn't look too bad, but given the above observation, put the GM spring in the new pump and you're good to go.

Duke

[Pat H.]

Re: melling oil pump correct spring

Question. I'm having the same issue in my 59, however I need to find out from the engine builder what type of pump he installed. Since I read this post, I check out the oil pump I had in a box of parts I bought from a guy. Part # 3732796 on the upper casting and 3704180 on the lower casting which houses the spring. It came out of a 350-300 69 Corvette. Are all these pumps interchangeable? The pump turn freely without any binding as mentioned in a previous thread. I think the SB ran about 40-45psi

[Timothy B.]

Re: melling oil pump correct spring

Pat, I think you will be fine with that original pump but first take it apart and check the gears for pitting and the end clearance, install a new pick up and adjust it to the correct height.

Lets see what others say about the pump.

[Joe L.]

Re: melling oil pump correct spring

Question. I'm having the same issue in my 59, however I need to find out from the engine builder what type of pump he installed. Since I read this post, I check out the oil pump I had in a box of parts I bought from a guy. Part # 3732796 on the upper casting and 3704180 on the lower casting which houses the spring. It came out of a 350-300 69 Corvette. Are all these pumps interchangeable? The pump turn freely without any binding as mentioned in a previous thread. I think the SB ran about 40-45psi

Pat-----

The pump you have is the original pump if it has those casting numbers. Does it use slotted head screws to retain the cover?

[Pat H.]

Re: melling oil pump correct spring

Joe,
It has slotted screws 1/4 x20 w/ lock washers. I order a new spring today from GM $5.00 I spoke with my engine builder and he indicated that it's a Melling pump that was installed. He also indicated that the pick up has 2 different diameters 5/8" and 3/4", which they started using in the early 90"s that probably affects the pressure as well. He doesn't remember which one is in the engine, so I guess the pan need to come off.

[Duke W.]

Re: melling oil pump correct spring

Joe,
He also indicated that the pick up has 2 different diameters 5/8" and 3/4", which they started using in the early 90"s that probably affects the pressure as well.

Uh... okay, ask him how he made this determination.

The only time either pickup will affect oil pressure is if they get uncovered and suck air in which case oil pressure will drop to zero!

Duke