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Discussion Starter #1
The "mechanic" who rebuilt the engine in my '94 wagon used a high-volume oil pump. On cold startup, even running synthetic 0W20, oil pressure is just under 80 psi. (Yes, I have an F-body cluster and yes I have the resistor mod and correct sensor so it shows actual oil pressure, and yes I realize that it's probably not completely accurate.) When accelerating hard, the gauge will jump, then immediately dip to below 60 psi, like the pump is bleeding off pressure or cavitating or something.

Wear metal numbers from 5K-mile oil changes have always been higher than I'd like--not terrible, but not good. The best numbers came from 0W20, the worst from 0W40--I feel like the high-volume pump needs the thinnest oil possible to not have flow issues. Some forum members have suggested switching back to a standard-volume oil pump, and I concur that it sounds like a good idea.

My current shop of choice (not the one that rebuilt the engine), said it would change out the oil pump for $300 in labor, plus parts.

For standard-volume oil pumps, Rockauto has a Melling:
https://www.rockauto.com/en/moreinfo.php?pk=8309848&cc=1049701

And a Sealed Power:
https://www.rockauto.com/en/moreinfo.php?pk=207958&cc=1049701

There are two others but they specifically say "not for high performance or off road", so I'm gonna stay away from those.

Then, under the high-performance heading, Rockauto has literally about 20 different choices from Melling, all of which appear to be some variation of higher volume and / or higher pressure.

So, what oil pump do I want? What other parts will I need? Oil pan gasket, oil, and filter are obvious, but what else?
 

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I am running the Melling Shark Tooth 10% hv pump. Good unit and not terribly pricey. Also a good compromise between stock and higher volume. The part number is 10552 for the non Shark Tooth and 10552ST for the Shark Tooth. You can use the stock style pickup, but get the bolt-in variety. You will still have high pressure at start - I think mine is 70+. Once it warms up it drops down, but never really gets anywhere close to "low". The Melling stock volume / pressure is pressure is 10554 (I think) and that uses a press-in pickup.

The wear numbers in your UOI are interesting. If the front cam bearing was clocked incorrectly it allegedly can make for pressure issues and increased wear. Do you recall what the builder did? I have also seen where a builder used a stud that was a tick too long on the oil pump and when it was torqued down it put pressure on the backside of the bearing shell.

The dropoff on accel is due to the bypass valve in the filter. Once pressure gets too high, it opens up so bad things don't happen elsewhere
 

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While gathering my parts for my engine I researched a long time on the pump. There were many articles pro/con on the high volume pumps. Some said that you needed a deeper pan to ovoid starving the engine while accelerating. I decided on the standard Melling, with the thicker base, and used this to secure the pickup to the pump. https://www.jegs.com/i/JEGS/555/23620/10002/-1 I chose this after checking the welding route. There was much on the yeah/nays here too. My engine is not assembled yet so I can't give you an informed opinion on it's performance.

Mark: Snowman-33
 

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Flesh...do you know if your builder did slightly wider bearing clearances and chamfered the oil holes because of the HV pump?

That is why you would use one, If not than a standard volume pump would be better. You could run the high "pressure" spring in it (it is a different color spring than stock but I can't remember if it is the pink or white one)

My builder did slightly wider bearing clearances on my 383. Cold idle I am 55 PSI increasing to 70 ish with RPM but hot idle is 45 psi and 55-60 PSI at WOT rpm using the 10% HV Mellig. I have 35k mi on this motor. No "bearing hair" on drain plug when I do oil change and Blackstone test come back Steller. I even took a good look at my OP drive gear when I had intake off, perfect condition.

Many internet rumors...one being a HV pump sucks the oil pan dry. BS. You do need to run a windage tray though....or your crank will foam the oil and that's where you get oil pick up problems, especially in cornering and hard braking without a windage tray
 

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Whatever you do, get one with an bolt-on screen like the Mel-10552.
Or use a screen retainer like this one from jegs: https://www.jegs.com/i/JEGS/555/23620/10002/-1

The most common oil pump failure is simply when the pick-up falls off of the pump.

Nab
 

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I noticed that my standard volume Melling has a piece of paper stating that it is pre installed with the high pressure spring, and includes the standard pressure spring that can be swapped out. What is everyone's thoughts on high pressure vs. standard?


On that note...I always thought of pressure as a byproduct of restriction. Wouldn't you technically need higher volume in order to see higher pressures, all other things being the same? I know the springs on the oil pumps are for bleed off, but wouldn't a pump need to flow more oil in order to see increase pressures?
 

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FaSSt9602 - you have the right intuition - It depends on what the oil pressure is vs the spring setting. If the spring is set at 60 psi but the oil pump can only provide enough flow through the bearings to create 40 psi, it won't matter if you put an 80 psi spring in since there's only enough flow to generate 40 psi.
 

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Another point about oil pressure is that the reason it goes higher than the spring setting is because the bypass hole in the pump is too small for the pumps volume output.
The way to correct this is to drill the bypass hole larger.
For a stock build stay with factory pressure.
 

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Another point about oil pressure is that the reason it goes higher than the spring setting is because the bypass hole in the pump is too small for the pumps volume output.
The way to correct this is to drill the bypass hole larger.
For a stock build stay with factory pressure.
My build is far from stock, and I'm torn between leaving the factory installed "high pressure" spring in place or tearing it apart to put in the "standard pressure" spring...

396 Forged rotating assembly
Cola forged crank shaft 3.875 stroke
Oliver Billet 6.0 rods
Oliver Billet mains
JE flat top pistons
LE ported TF 23 degree 215cc heads with the big 2.08 intake valve
 

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I just checked - I have a Melling 10552 sitting on the shelf. Ran for about 3k miles. Zero problems and works perfectly. $100 shipped. I think I also have a Melling hardened steel drive-shaft for it that I'll throw in for $0.
 

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Flesh

whatever oil pump you do get, but a metal oil pump drive shaft. ARP, Mellig, etc make them for around $10

stock shaft has a plastic collar which when aged can crack on re-install which if it breaks (read it will) the motor goes boom very fast unless you catch the OP gauge pegged at zero soon enough
 

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Discussion Starter #12
So, if high volume / pressure pumps typically come with the HV / P spring installed, could I theoretically just need to swap back into the standard volume / pressure spring and be "okay"?

If yes, but I don't know what pump is currently installed, how do I know what spring to use? Is the SV / P spring for all Melling pumps for SBC motors the same, for example? (Assuming my car has a Melling pump--I have no idea what the builder installed.)
 

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I kind of have that same question. I bought the Melling Std volume, std pressure pump, and it came with the piece of paper stating that it was pre-installed with a high pressure spring, and included the std. pressure spring if I want to swap.

In theory the pressure spring just regulates the bypass within the pump itself, and really shouldn't have any effect on volume. I think (but don't quote me) the high pressure spring is pink, and the std pressure is yellow.
 

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Discussion Starter #15
I'm trying to decide between these two Melling pumps:

Melling Oil Pumps M155 - $40.46
https://www.summitracing.com/parts/mel-m155

(It recommends this: Melling Heavy-Duty Intermediate Driveshafts IS-55E - $9.37
https://www.summitracing.com/parts/mel-is-55e/overview/)

Melling Performance Oil Pumps 10554 - $96.45
https://www.summitracing.com/parts/mel-10554/overview/

I'll need this: Pioneer Oil Pump Pickup Tube Retainers 839061 - $18.99
https://www.summitracing.com/parts/pio-839061

Can I use the existing pickup? If not, what do I need?

Anything else I'll need, hardware-wise, aside from an oil pan gasket, oil, and an oil filter?
 

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I have the Melling M155 in my ERE383. The oil pressure on cold startup is around 50psi and goes down to 25 when hot. At cruising speeds(70mph) the oil pressure is ~42. WOT the pressure is ~70.

After a 20 minute lapping session on a road course(95 degree outside temperature) the oil pressure is ~20psi. I run 10W30 full synthetic oil without the external oil cooler and a larger WIX 51060 oil filter.

YMMV
 

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Discussion Starter #17
I figure I should touch base on a baffled / windage oil pan as suggested elsewhere in this thread. What I've noticed with oil pressure is this:

--when accelerating moderately, even when holding a gear manually, oil pressure seems to climb progressively with RPM and does not drop off
--the same thing happens if I accelerate moderlately / lightly all the way to redline using the transmission to hold a gear, and it usually peaks around 70 PSI with the engine warm
--when accelerating aggressively (like if I'm cruising along and then dip into the throttle pretty deep and cause the trans to downshift to second), oil pressure will seem to jump to ~70 PSI, then drop to just under ~55 PSI and hold there all the way to redline

I detailed this stuff in another thread, but of course can't find it at the moment.

Is this possibly / likely to be something that a windage oil pan would solve? It seems like now (while replacing the oil pump) would be the time to address this.
 

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Discussion Starter #19
Flesh
are you saying you don't have a windage tray now?
the stock one is fine if yours is missing and should be installed
As far as I know, my LT1 has a stock oil pan. So.. that's sufficient? Is there anything that I should have the shop check for when they have the pan off to replace the oil pump?
 

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