Oil pump questions

[DynaBro]

Removed and disassembled my oil pump. When installing new O rings I see the packet says:

".078 thick, large O-ring is ONLY for stock factory and Melling M63HV pumps.

Thinner .065 is ONLY for Milodon 21814 21815 pumps"

Well I disassembled the pump entirely which I am regretting. Pretty sure it's just a stock pump. I installed the thinner O-ring on the shaft and the thicker one internally between the two pump parts. This seemed correct. Am I ok?

I have also been told to "inspect" the spring. Ok, there's a spring. It's not broken. It still springs. I don't own a spring tester. Now what?

 

[jimbosride]

First .... why was the pump removed?

 

[DynaBro]

First .... why was the pump removed?

Because of a serious leak.

 

[DynaBro]

And there was no obvious cause. So far everything that’s been leaky I’ve been fixing was the result of loose bolts. No one has bothered to go over this motor in a very long time it appears and suddenly I start driving it often. Now I have lots of fail points to run down. Oil pressure while driving is always around 80.

 

[jimbosride]

OK ... I'm no expert but 80 psi on a mechanical gauge is not a stock pump. So was it leaking from the pump? there is a gasket from pump to block along with O ring seals.
If the motor has been sitting for a long time the seals will dry out then leak when re-started.

Engine size ?

 

[rickseeman]

80 psi means you have a "Hemi" spring or a HV pump which comes with a Hemi spring. These springs bypass between 70-80 psi. I've checked many springs. They are always within spec. And we know your is because it has 80 psi. The rebuild kit you have is for a Milodon or Melling. I assume you have a stock type cast iron Melling, so it sounds like you put the o-rings in the right place. Don't be afraid of tearing down an oil pump. You can do it. Just take your time. But you should have used your pinkie finger or a magnet and made sure your bypass relief piston (on the other side of the spring) moves freely. If it's stuck you will know it on fire up because it will have way too much oil pressure. I've done several oil pump "how-to" videos but I think you have done it right.

 

[DynaBro]

383. Pump sure looks stock. The gasket was so old it’s nearly impossible to remove. Like a serious chore here. Flat dried out and married to the metal. So there’s that and the o ring on the shaft. But the pump itself also splits and there are 2 o rings internally. A large diameter and a small diameter similar to the shaft diameter. These two o rings are different. I went with the slimmer on the shaft as stated above. But have not reinstalled yet so hoping to avoid any mistakes. The gasket kit doesn’t speak to this issue. Nor did it include a washer gasket for the spring plug.

Also can’t find torque values for the bolts that fasten the pump pieces together. I know the pump mounting studs are 30ft lbs.

 

[DynaBro]

80 psi means you have a "Hemi" spring or a HV pump which comes with a Hemi spring. These springs bypass between 70-80 psi. I've checked many springs. They are always within spec. And we know your is because it has 80 psi. The rebuild kit you have is for a Milodon or Melling. I assume you have a stock type cast iron Melling, so it sounds like you put the o-rings in the right place. Don't be afraid of tearing down an oil pump. You can do it. Just take your time. But you should have used your pinkie finger or a magnet and made sure your bypass relief piston (on the other side of the spring) moves freely. If it's stuck you will know it on fire up because it will have way too much oil pressure. I've done several oil pump "how-to" videos but I think you have done it right.

I will also check this piston tomorrow. Thanks.

 

[rickseeman]

It's a shame it didn't come with that gasket but let's hope it doesn't leak. The little bolts that hold it together l like to tighten last just in case the top cover needs to move to line up with the bolt holes if you didn't line it up perfect. I don't recall a torque spec on those small bolts. Hand tight or 12 ft lbs would be fine.

 

[lewtot184]

I have a hv pump that leaked between the cover plate and pump housing. Basically the cover plate wasn't flat and sealing properly. Check the cover plate for flatness.

 

[DynaBro]

Is there any harm in doing a very thin bead of RTV between the two plates just to make sure?

 

[rickseeman]

Don't even think about doing that. If there is a problem it can be corrected properly and cheaply.

 

[DeltaV]

PRESSURE-RELIEF SYSTEM

The pressure-relief valve operates against a small spring. The tension of this spring controls the pump outlet pressure. The spring supplied with most stock "B" engines is color-coded red and has a factory part number of 1737742. This spring allows a maximum oil pressure of 40-50 psi. A black spring is available from Chrysler. It was original equipment on the Hemi and 440-6 pack engines and provides a system pressure of 65-75 psi. This spring should be used in the oil pump of all high-performance engines (those that will exceed an engine speed of 5000 rpm on regular occasions).

Source:
Mopar Performance
Edited and Designed by Larry Schreib
See page 73

 

[DeltaV]

OIL PUMP PREP

All Chrysler engines use a displacement-type oil pump that consists of an inner and outer rotor encased in a cast iron pump body. The flow rate tends to be independent of outlet pressure (since oil is virtually non-compressible) and will, instead, vary directly with pump speed. The output rate can be increased or decreased by increasing or decreasing the volume of the rotor cavities. All of the Chrysler pumps utilize the same diameter rotors, however, the larger engines use a taller rotor that supplies more oil at any specific rpm level. The 6-cylinder engines use the shortest rotors, the "A" engine (340 type) uses an intermediate length,
and the "B-RB" series use the tallest design. The latter proves quite adequate for high-performance use.

The "B" pump supplies more than twice the amount of oil necessary for reliable engine operation, and a high-pressure bypass-relief valve is built into the pump body. As engine speed increases beyond a fast idle, the pump supplies more oil than can be forced through the oil passages in the cylinder block under reasonable pressure. Therefore, when this level is reached, the pressure valve bypasses some of the oil from the high- pressure side of the pump to the low-pressure inlet port. This is more efficient than allowing the overflow to return to the pan, because it puts less demand on the inlet pickup. The bypassed oil just circulates around in the pump eventually finding its way into the block oil passages.

Source:
Mopar Performance
Edited and Designed by Larry Schreib
See pages 72 & 73

 

[DeltaV]

Page 44 of the 1975 Direct Connection parts catalog lists the following for "B" engine parts:

Part Code: 10-7-2
Description: Gasket Package - Oil Pump
Part No.: 2084355
Applications: All

You can find them on eBay.

 

[DeltaV]

Oh shoot, just take the engine apart and go with full groove main bearings @DynaBro



j/k

 

[DynaBro]

Page 44 of the 1975 Direct Connection parts catalog lists the following for "B" engine parts:

Part Code: 10-7-2
Description: Gasket Package - Oil Pump
Part No.: 2084355
Applications: All

You can find them on eBay.

How is that different from this? Milodon 21591 Oil Pump Gasket Kit | eBay

 

[DeltaV]

How is that different from this? Milodon 21591 Oil Pump Gasket Kit | eBay

Buy one of each kit and compare.

The Milodon kit probably has gaskets and o-rings for both the stock and Milodon pumps most likely.

I've never had a reason to install a Milodon oil pump. I don't know the detailed differences between the two pumps.

Remove that old gasket using chemical gasket remover. Permatex used to have some gelled stuff that contained methyl chloride (I recall?). Works great.

Install new gasket dry. New o-rings should be oiled during assembly.

 

[DynaBro]

Buy one of each kit and compare.

The Milodon kit probably has gaskets and o-rings for both the stock and Milodon pumps most likely.

I've never had a reason to install a Milodon oil pump. I don't know the detailed differences between the two pumps.

Remove that old gasket using chemical gasket remover. Permatex used to have some gelled stuff that contained methyl chloride (I recall?). Works great.

Install new gasket dry. New o-rings should be oiled during assembly.

I got that Milodon one.

 

[rickseeman]

Yes, that is a good kit because it has o-rings for both Milodon and Melling.