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Username Post: Melling 10552 ST, 10553ST, 10554ST and 10555ST        (Topic#368753)
CNC BLOCKS N/E 
Senior Member
Posts: 987

Loc: NORTH EAST
Reg: 12-12-03
06-21-22 06:34 AM - Post#2843179    

The 383 I dynoed with high oil pressure using the 10552 ST oil pump was exactly what I thought was the problem. The bypass valve was to long and not exposing the complete bypass hole. I also have another engine with the same pump same problem.I don't understand why I have to there home work for them. They told me not to take the pump apart it would void the warranty. I said really.
I have used probably 35 of the10552 pumps with zero problems. Now they said the 10552 ST they did change the cover HMMMMM
Here is a link to the dyno run
https://www.facebook.com/cncblocks.northeast/posts...
PS
Good customer Jerry Brighthaupt saw my post on FB and took his 10555 ST pump apart and called me and found less the half the bypass hole was exposed. He was just getting ready to put the pump and pan on one his circle track engine. He was going to shorten the valve 3/16 of and inch which will cure his problem.
A big shop near him stopped using those pumps because of high oil pressure.

One guy that contacted me said his 10553ST pump with a 10/30 Mobil 1 runs 100 PSI


I talked to Brian at Mellings Yesterday he said he was going to look into it.

He seemed dumbfounded. I can’t believe I am the only one that has called. I told him it’s a problem with the 10552 ST , 10553 ST, And the 10555 ST pumps.

A quote from one of my customers who was just getting ready to install his 10555 pump. He shortened the valve 3/16 of an inch to fix his problem

A quote from Jerry
Jerry Brighthaupt
Carl is 100% correct....I have a new 10555st pump and with the bypass spring removed and allow the piston to go all the back less than half of the bypass hole is exposed

A link with pictures
https://www.facebook.com/cncblocks.northeast/posts...



Edited by CNC BLOCKS N/E on 06-21-22 06:35 AM. Reason for edit: No reason given.

 


grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17747
grumpyvette
Age: 74
Loc: farmersville texas USA
Reg: 03-16-01
06-21-22 08:09 AM - Post#2843180    
    In response to CNC BLOCKS N/E

http://garage.grumpysperformance.com/index.php?thr...

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
CNC BLOCKS N/E 
Senior Member
Posts: 987

Loc: NORTH EAST
Reg: 12-12-03
06-24-22 11:21 AM - Post#2843301    
    In response to grumpyvette

Unless you can spin the pump shaft 3000 RPM Or more your test is invalid, When I primed the engine I was at 58 PSI at 300 RPM

You have to compare apples to apples here !!!!





 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17747
grumpyvette
Age: 74
Loc: farmersville texas USA
Reg: 03-16-01
06-25-22 09:39 AM - Post#2843346    
    In response to CNC BLOCKS N/E

no actually you don't, simply because you can test that theory, to a large extent, yeah, you can't duplicate the total oil flow loss of an engine,

but past engine build data show the results mirror what Ive seen here. and I have tested with a milling machine, spinning the oil pump, , once the oil bye-pass fully opens , your re-routing a significant percentage of the oil flow back to the intake side of the pump, and the fact is that as pressure increases the volume of oil escaping through the various bearing clearances , lifter bores etc also increases dramatically.
yeah I though the same thing, that oil flow and as a result pressure increases lineally with rpm increases, but it really doesn't .
keep in mind the oil pump spins at 1/2 engine rpm.

OIL PRESSURE read on the oil pressure gauge is a MEASURE of RESISTANCE to oil flow, you can REDUCE the pressure the gauge reads by either increasing the engine bearing clearances or REDUCING the oil viscosity (thickness) so it flows thru the clearances faster with less resistance.(OR INSTALLING A SLIGHTLY WEAKER OIL PUMP BYE_PASS SPRING, that limits the pump pressure before it allows some oil to re-circulate back through the bye-pass valve ,from the high pressure back to the low pressure side of the pump impellers, but only the max pressure you reach is limited by the bye-pass spring, in your oil pressure bye pass circuit and its that spring resistance determines the point where the bye-pass circuit, opens and limits max oil pressure, but the bye-pass circuit has zero to do with anything else, if its functioning correctly,
there are many oil leakage points(100) in a standard Chevy engine.
16 lifter to push rod points
16 push rod to rocker arm points
32 lifter bores 16 x 2 ends
10 main bearing edges
9 cam bearing edges
16 rod bearing edges
2 distributor shaft leaks
1 distributor shaft to shim above the cam gear(some engines that have an oil pressure feed distributor shaft bearing.)
once oil exits the bearings or valve train it flows mostly by gravity back to the oil pan sump, but a properly designed windage screen and crank scraper correctly clearanced allows the spinning crank/rotating assembly to act like a directional pump that drags the vast majority of the oil flow back to the sump, by design.
high oil psi at idle serves no purpose as 15psi-25psi is all thats expected in a new engine with tight clearances using a good 10W30 oil, if your using a higher viscosity than 10w30 its reducing oil flow rates and reducing heat transfer rates, Id suggest using a good 10W30 oil. and use of a 7-8 quart, baffled oil pan and windage tray

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 06-25-22 10:03 AM. Reason for edit: No reason given.

 


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