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SBC Oil Pump Discussion

Shawn

Shawn

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I was going to run a Melling m55 HV oil pump for my 406 SBC build but after reading about quality issues I'm not so sure. Supposedly Melling did a change to the pumps which is a thinner casting and are weaker. It seems they are snapping off at the bolt and falling into the pans. A guy in Texas is recalling 50 motors he built, because he has had 3 pumps break and decided to bring the motors back and put the select pumps in on his own dime. This may be old news and Melling may have fixed the issue but I'm not sure.

Has anyone else heard about this? Also, a few are suggesting NOT to run the HV pump such as 4x4High so I'm thinking of just going with normal pressure.

More info I found:

http://www.jalopyjournal.com/forum/showthread.php?t=143630

Regardless of what brand you are buying, there is a good chance it is a re-boxed or re-labeled Melling.

A high-volume pump is not necessary or beneficial for most builds. The stock-replacement Chevy small-block standard and high-volume pumps have a casting that is prone to breakage in race situations.

The quality of the Melling Select (performance) pumps has been in question for a couple of years since they changed the billet gears to powdered metal gears. Also, the bottom casting has high spots which cause the bolt heads to seat unevenly, causing them to break. Removing these high spots and replacing the bolts is highly recommended.
Click to expand...

I have always used M-55A Melling pumps. UNTIL this past year. My supplier ran out of the first design pumps and started shipping the new design. I now have 2 of these pumps setting on the desk. Both broken from the mount bolt. Both were in a customers built/sponsored car. He is a locally known engine builder and lefthand turner.
The first one broke and the driver went three more laps before the lower end melted together. The second one was shut off at the moment of oil pressure loss. Minor damage.
Click to expand...

Additional info I found on a Nova site:

There are 5 basic cast pumps available from Melling
There are also several pumps available in the melling HP line.

Lot of people only referance the 2 basic rear sump pumps.
Melling m55 & m55hv
There are also 2 others. M155 & m155hv (Std on all GM HP SBC Engines)
The difference is the pickup tube dia.
M55 //HV series has a 5/8 pickup tube
M155 //HV has a 3/4 pickup tube.

Both m55hv & m155hv use the larger gear set

reference difference pickup tube
oilpumps008a.jpg


Also look at housing difference for the larger gears for a HV pump.
oilpumps009a.jpg


There is also a BB cased HP.HV pump specific for SBC only
this is a M99HVS, I do believe in this pump, I run it in my engine and this one in the pic came out of my old 68 Nova, it's 30 years old.
Yes, it does take more HP to run them, but "IF" something goes wrong the extra volume can save your engine. IMO I have seen it!
Smoky Yunick even suggest and has written articles on the advantages of the BBC pump, large gears and a dual check valve.
And has become a industry standard of 10PSI per every 1000RPM

With oil hot, I have 28psi at 1000RPM above 2200rpm I have a constant 60PSI to 80psi at WOT
Cold 40psi at idle.
oilpumps013a.jpg


reference,
Look at the mounting area of the old and now the light weight saving castings.
oilpumps014a.jpg


Note: The Melling M155 was removed from a GM 350/290hp engine, replaced when front sump was used on Customers 65 ChevyII

Melling You-tube



showtobuildasmallblock.jpg
Click to expand...
 
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I'm not sure which one is better thats why I posted some info to get some feedback on this.

Here's another story. Guy has a Typhoon which uses the same SBC oil pump. Granted its from Dec 2007 so hopefully Melling has addressed this issue. I guess you're not supposed to run those pumps if you have solid motor mounts.
Got a response from Melling just yesterday. heres the story.

Well way back in June my GMC Typhoon suddenly dropped oil pressure and I had my Typhoon towed home. Pulled engine and found the Melling M55-A pump was broke in 1/2 when we removed the engine and pulled the oilpan. Later on I found out that Melling made a design change to have a thinner/weaker casting to save $$$, and there was no notifications to the consumers about the change.

See this thread for more info:
http://www.syty.net/forums/showthrea...hlight=melling

After contacting Melling, they sent me several forms and requirements needed to send the pump back along with receipts of machine work/part costs to repair my engine ($2500+).

Today I received a response back where they acknowledged the broken casting but warranty was denied due to it being used in a 'performance application'. I assumed this would happen, but I had nothing to lose..

I can scan the response I received when I get home.. but here is a jist of what was mentioned:

Quote:
Condition of Received Part(s): The bolts are tight, the gears turn within specifications. The casting is broken off at the mount pad.

Analysis Comments: We did see the broken casting, this pump was used in a performance application, we send a warning sheet with this pump stating; use M Select pumps for anything that is not an original stock application.

Analysis Results: The Melling Warranty does not apply to pumps used in a performance application. We did not find a manufactures defect in the pump or in the workmanship.

*I bought the pump back in the spring/summer of '06, no sheet stating use of M-Select was included! I have checked with others including sellers of the pump and they mentioned that this Warning Sheet was not attached with the pumps until recently. Did not finish assembling engine until fall '06 and put directly into storage. Next spring got Typhoon out and put apprx 1000 miles on new engine w/o a problem til the failure occurred.

Just a warning to you guys, that Melling was very shady about this. Talking with them on the phone I felt like I was being spoke to like this oil pump failure was my fault. Melling knew I posted the original thread and questioned me about it on the phone, from which I took down the pictures of the broken pump. Ed Hess (another SyTy owner) has had the same problem, along others while searching around the net.

Here are pictures of the oil pump where it broke in half, you can easily see the casting broke:
DSC_0445.JPG


DSC_0447.JPG


DSC_0448.JPG


They still have my broken pump, I have till Jan 7th to request it back, not sure if it worth the shipping or not.. This is a known issue by Melling and they know darn well that this pump has been used for years by engine builders and they decided to make the changes w/o letting anyone know.
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Ill be keeping an eye on this thread. I just put one of these in my 327 last fall. I will be keeping a good eye on oil pressure when i'm out wheeling also.
 
You know,it SUCKS when a company that HAD a great reputation,decides to cheapen up their parts or have them made in China out of inferior quality components to increase their profits..Melling WAS a good name brand--unfortunately they are not alone,Moog has been under fire for substituting cheaper quality suspension parts in their ball joint and tie rod ends and many have failed catastrophically or way too early--yet the customer PAID the "full price" for what he thought was a good quality brand name part...

You might as well be buying the cheapest part you can find,seeing thats what you'll likely get anyway,regardless of who's name is on the box nowadays...chances are good you'll be paying double for the same part just because its in a box with a "good brand name" on it...its sickening!...you pay a bit more thinking its worth it,then end up being boned anyway...:doah:
 
After seeing this I am damn glad I decided to use a milodon oil pump on my 355.
 
anything else to add?
I have the high volume in my truck now, not sure which one though. I'm taking it out to replace the intermediate shaft and probably put a standard pressure back in. Does anyone know which pump is their "Select" series? They all look the same, but prices are all over the place. Is the difference M55 vs. H55? I don't see any H55s anywhere though.
http://www.summitracing.com/parts/MEL-M55/
http://www.summitracing.com/parts/MEL-M155/
http://www.summitracing.com/parts/MEL-10554/
http://www.summitracing.com/parts/MEL-10553/

I may have this one, but not sure. It is a Select series high volume.
http://www.summitracing.com/parts/MEL-10550/?rtype=10
But I don't remember the body being any larger, so I'm not sure about anything. If it's a high volume, the body is larger to house the larger gears.
 
K85 Octane said:
anything else to add?
I have the high volume in my truck now, not sure which one though. I'm taking it out to replace the intermediate shaft and probably put a standard pressure back in. Does anyone know which pump is their "Select" series? They all look the same, but prices are all over the place. Is the difference M55 vs. H55? I don't see any H55s anywhere though.
http://www.summitracing.com/parts/MEL-M55/
http://www.summitracing.com/parts/MEL-M155/
http://www.summitracing.com/parts/MEL-10554/
http://www.summitracing.com/parts/MEL-10553/

I may have this one, but not sure. It is a Select series high volume.
http://www.summitracing.com/parts/MEL-10550/?rtype=10
But I don't remember the body being any larger, so I'm not sure about anything. If it's a high volume, the body is larger to house the larger gears.
Click to expand...

I think you want the 10553. The 10550 is the HV pump.

http://www.speedwaymotors.com/Melli...eBase&utm_medium=feed&utm_campaign=GoogleBase
 
Small block Chevys don't need a HV pump. I turn the 350 in my Camaro to 7000 with the factory pump that came in the motor in the 1976 Scottsdale it was in. As long as the needle moves on the oil pressure gauge, you've got enough for a small block. :waytogo:

All that extra pressure has to be created by making the pump pump more. When you do that, it makes it hard to turn, putting that force on the drive rod, distributor gear, cam shaft, and timing set. There was a little blurb in the back of a Hot Rod magazine some years ago where Frysnburger (?) was pulling a 355 on the dyno. He thought the oil pressure was just a little high and swapped springs from the Z28 to the standard one. He picked up like 8hp from just that little quick swap.
 
On above statement,

We.run a standard volume race pump on our race engines. They cost about 90, have the thick casting, and a bolt on oil screen. There is a provision on the pump need where the shaft is also held better.

Now what I know about stock pumps ill be running the race pumps at std volume
 
Finally ordered the Melling Select 10553. 5/8", Standard-volume, Standard-pressure. 80 bucks! Hopefully this one does the job.

Looks like the Milodon pumps are having issues too-
http://www.stevesnovasite.com/forums/showthread.php?t=139036

Any other suggestions on good quality pumps that won't snap off or hit the crank?

Interesting results here on the different pumps:
http://www.carcraft.com/techarticles/ccrp_0911_small_block_chevy_oil_pumps/index.html

Oil Pump Test Results

Oil Pump __________________Peak HP ____Av. HP __Pressure ____GPM____Temp

Standard volume (PN 18755)____485* ___391.6* ____50.3 _____ 6 _______160
High volume (PN 18750) ________477 ____386.9 _____64.2 _____6.2 ______159
High vol., hi-press. (PN 18770) __481 ____389.7 _____65.6 _____6.1 ______160
Big-block (PN 18760) __________480 ____387.5 _____68.0* ____6.3* _____161*
* Peaks
 
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