Oil Pump Pressure Relief spring

[Donald H.]

I purchased a Melling 10553 oil pump for an L79 engine build. It comes with a high pressure relief spring installed and includes an additional yellow spring, which I believe is a 60#.

I have on hand some of the Melling Green 49# springs and if need be I will use one of these. But as I understand, even it is somewhat higher pressure than original which was 40#-45#

I also purchased a spring from Ebay that was advertised as an NOS 3814903, which is the GM standard pressure (40#-45#) spring. It did come in a GM parts baggie with the part number on it, but the bag had been cut open so there's no guarantee what the spring really is. The spring does not have any discernible paint daub like the Green and Yellow springs.

So my question - is there any way to tell if the spring I purchased is a correct standard pressure spring?

Thanks,

Don

[Joseph L.]

Re: Oil Pump Pressure Relief spring

Hi Don
I do not know how to tell if it is. The Melling springs are: 55049 green spring provides 49 psi, 55058 yellow spring provides 58 psi, and 55070 pink spring provides 70 psi. I have held the green and the 3814903 spring; just the color appears different.
I purchased the 3814903 from GM two years ago. That is the certain way to know if it is the spring you are looking for.
Joe

[Joe L.]

Re: Oil Pump Pressure Relief spring

I purchased a Melling 10553 oil pump for an L79 engine build. It comes with a high pressure relief spring installed and includes an additional yellow spring, which I believe is a 60#.

I have on hand some of the Melling Green 49# springs and if need be I will use one of these. But as I understand, even it is somewhat higher pressure than original which was 40#-45#

I also purchased a spring from Ebay that was advertised as an NOS 3814903, which is the GM standard pressure (40#-45#) spring. It did come in a GM parts baggie with the part number on it, but the bag had been cut open so there's no guarantee what the spring really is. The spring does not have any discernible paint daub like the Green and Yellow springs.

So my question - is there any way to tell if the spring I purchased is a correct standard pressure spring?

Thanks,

Don

Don------


As I recall, the GM #3814903 is not color-coded with a stripe. However, according to GM, it has a free length of 2-7/32" and 21 coils. It's still available from GM for $4.78, GM list.

[Dan D.]

Re: Oil Pump Pressure Relief spring

Don, FYI,

I also purchased a Melling 10553 pump for my 327 when I rebuilt it. I replaced the high pressure spring with a Melling green spring which I bought from them. The engine runs 60 Lbs. cold and 45Lbs. hot. This is too much pressure and I am worried about blowing the seals out of the FI distributor. I wish Melling did not do this to us.

I believe the correct GM green spring is still available from GM. Also been told you can cut one coil off the Melling green spring, but I cannot verify this.

-Dan-

[Donald H.]

Re: Oil Pump Pressure Relief spring

I know a couple of folks have said that this spring is still available from GM, but I now have my doubts. I place an order on one of the online GM parts dealers and got the follow response today.

Thank you for ordering parts with us.
We are writing to inform you that order VGA11305 has been voided. Your order has been voided because of the following reason(s): The ordered part(s) have been discontinued (no longer available) and/or is backordered with no ETA date by the manufacture.

I'll try a local chevy dealer next.

Don

[Joe L.]

Re: Oil Pump Pressure Relief spring

I know a couple of folks have said that this spring is still available from GM, but I now have my doubts. I place an order on one of the online GM parts dealers and got the follow response today.

Thank you for ordering parts with us.
We are writing to inform you that order VGA11305 has been voided. Your order has been voided because of the following reason(s): The ordered part(s) have been discontinued (no longer available) and/or is backordered with no ETA date by the manufacture.

I'll try a local chevy dealer next.

Don

Don------

It is possible that the spring has been very recently discontinued. In any event, the GM strike has delayed all parts orders. It could be that GM dealers are now just cancelling orders and just using a "standard excuse". Some GM dealers might have it in stock, though.

[Stanley S.]

Re: Oil Pump Pressure Relief spring

Don

I ordered a 3814903 4 days ago from GMPartsGiant.com. They notified me within 3 hours that the part had been shipped. I haven't received it yet so I suppose I can't say for certain that I will receive what I ordered but at least they didn't say it wasn't available.

Stan

[John H.]

Re: Oil Pump Pressure Relief spring

Don,
I just went thru this with my 67 300 hp coupe getting it ready for the PV at Frisco last week. My rebuilder used the "low volume" Melling pump. We were getting about 42# on the low end up to 55# on the high end. We pulled it out and ordered the #49 spring. The pressure was still too high. We went to a light weight oil with no decrease. I bought an NOS 327 oil pump and installed it. A small drop in pressure but still too high. I called my local Chevrolet dealer and ordered the 3814903 spring. It shipped from MI and came within 2 days. It wasn't color coded at all, just black. The others were either green or yellow. The correct spring did the trick. It probably would have worked in the Melling pump but I stayed with the NOS GM pump. Low end pressure is right on 30# with high end (1700 rpm) at about 45#. I just bought the spring in early Oct so it should be available. My parts guys said the warehouse in MI showed to have several. I passed the PV with it.
Good luck.
John

[Joe L.]

Re: Oil Pump Pressure Relief spring

Don,
I just went thru this with my 67 300 hp coupe getting it ready for the PV at Frisco last week. My rebuilder used the "low volume" Melling pump. We were getting about 42# on the low end up to 55# on the high end. We pulled it out and ordered the #49 spring. The pressure was still too high. We went to a light weight oil with no decrease. I bought an NOS 327 oil pump and installed it. A small drop in pressure but still too high. I called my local Chevrolet dealer and ordered the 3814903 spring. It shipped from MI and came within 2 days. It wasn't color coded at all, just black. The others were either green or yellow. The correct spring did the trick. It probably would have worked in the Melling pump but I stayed with the NOS GM pump. Low end pressure is right on 30# with high end (1700 rpm) at about 45#. I just bought the spring in early Oct so it should be available. My parts guys said the warehouse in MI showed to have several. I passed the PV with it.
Good luck.
John

John------


What was the part number of the NOS GM pump that you bought?

[John H.]

Re: Oil Pump Pressure Relief spring

Joe,
The box had part number 3764547 listed as a 1st design 283, 305 ,327, 350 exc hi perf. It was almost identical to the Melling pump and may have been produced by them as they manufactured for GM. It had raised lettering/numbers that said GM 12 2796. I bought it on Ebay for $125.
John

[Joe L.]

Re: Oil Pump Pressure Relief spring

Joe,
The box had part number 3764547 listed as a 1st design 283, 305 ,327, 350 exc hi perf. It was almost identical to the Melling pump and may have been produced by them as they manufactured for GM. It had raised lettering/numbers that said GM 12 2796. I bought it on Ebay for $125.
John

John------


The GM #3764547 is a standard pressure pump. So, I do not understand why it produces too high of oil pressure or produces higher oil pressure than when the GM #3814903 spring is installed. The latter should be the exact same spring installed in the 3764547 pump. This spring has no "color code" or paint stripe.

By the way, the pump you have is of GM internal manufacture. Melling didn't start making pumps for GM until after that part number was replaced.

[John H.]

Re: Oil Pump Pressure Relief spring

Joe,
That's the reasoning why I went with the NOS GM pump. I "assumed" that it was the right pump with the low volume spring per OEM specs. It still gave me too high of a reading. My gage was right on as we tested the pressure externally as well. Changing out the oil pump 3 times wasn't fun so hopefully others can learn from my "mistakes". The Chevy parts guy did say the spring was discontinued but was still in stock. If anyone needs one, you'd better grab it.

[Joe L.]

Re: Oil Pump Pressure Relief spring

Joe,
That's the reasoning why I went with the NOS GM pump. I "assumed" that it was the right pump with the low volume spring per OEM specs. It still gave me too high of a reading. My gage was right on as we tested the pressure externally as well. Changing out the oil pump 3 times wasn't fun so hopefully others can learn from my "mistakes". The Chevy parts guy did say the spring was discontinued but was still in stock. If anyone needs one, you'd better grab it.

John------


All I can figure is that someone changed the spring before you got the pump. Check the removed spring and note if it has a stripe of white paint OR otherwise appears different than the 3814903 you bought.

By the way, the spring does not control volume; it only controls oil pressure. High volume pumps have different pump bodies and different internals. No such pump was ever used in a PRODUCTION small block. Ever.

[Duke W.]

Re: Oil Pump Pressure Relief spring

This spring issue comes up all the time. First, there's usually no reason why the old pump can't be reused. It's simple to disassemble and inspect. Unless the gears are galled due to debris ingestion, it should be okay to use. Or, if for whatever reason you replace the pump, simply install the spring from the old pump assuming it's original and registered the correct pressure on the gage.

Duke

[Donald H.]

Re: Oil Pump Pressure Relief spring

Don,
I just went thru this with my 67 300 hp coupe getting it ready for the PV at Frisco last week. My rebuilder used the "low volume" Melling pump. We were getting about 42# on the low end up to 55# on the high end. We pulled it out and ordered the #49 spring. The pressure was still too high. We went to a light weight oil with no decrease. I bought an NOS 327 oil pump and installed it. A small drop in pressure but still too high. I called my local Chevrolet dealer and ordered the 3814903 spring. It shipped from MI and came within 2 days. It wasn't color coded at all, just black. The others were either green or yellow. The correct spring did the trick. It probably would have worked in the Melling pump but I stayed with the NOS GM pump. Low end pressure is right on 30# with high end (1700 rpm) at about 45#. I just bought the spring in early Oct so it should be available. My parts guys said the warehouse in MI showed to have several. I passed the PV with it.
Good luck.
John

Thanks John, I'll visit my local Chevy dealer Monday and see if I can get a parts guy to help me.

Don