I just learned I may have a fatal pump.A recent thread from a guy here piqued my interest.HE was suffering from low oil pressure on a new engine/w a hi-volume pump after a track run.You guys' advised he had actually ruined his main bearings from emptying the stock oil pan.My engine hasn't run yet as my restoration is extensive in scope.The L98 engine is ALL new.I reached out to a reputable Corvette guru in Flint,MI who warned me a Melling hi volume pump will EMPTY my stock pan.I am in the process of disassembling the front end AGAIN to pull the engine and rectify the pump issue.I've done a search here and also reviewed my receipts and find I installed a Melling model M55A pump which is hi pressure at a stated 70 psi. I think I may be ok with this choice.Do any of you have further insight into this issue? I've been contemplating pulling the engine again as I didn't use that white stuff on the C-beam to prevent the galvanic corrosion.But IF my m55A pump is ok then I can JUST correct the C-beam.....Advice? Current condition of my engine.

 

You're going to get a lot of different opinions on this one...


Personally, I'd say you're fine.

Here's a link to another thread that discussed the 55A standard volume, high pressure.


And I don't think it would be a real big deal with the "white stuff" on the c-beam, but if you're going to do it, better do it now.

 

My next concern WRT using a hi pressure pump may be the rear main seal.I've been advised pressure approaching 100psi may overcome it.Told the rear main seal is early in the pumping process and pressure there may be higher.I Am EXTREMELY concerned and do not want to ruin this new engine

 

I would not be concerned about the pump IMHO its a stock pump with a stiffer spring.

You could pressurize the system to get an actual pressure reading.
A mechanical gauge & drill driven priming tool will show pump operating pressure.
New motor = it needs to be primed before start up.
http://www.jegs.com/i/Mr.+Gasket/720/3795G/10002/-1

BTW the rear seal contains crankcase pressure it is not exposed to oil pressure. There is a large window in the rear main cap between the bearing insert & rear main seal. I'm referencing a gen 1 motor, memory is fuzzy on a 1 piece seal motor been decades since the last one piece motor build.

 

You can see from this pic, the rear main seal just holds back oil that has been splashed up against it. It is not holding back the 100 psi oil if that was your concern. It's not under any more pressure than any other external gasket (valve cover, oil pan, timing chain cover, etc.)

The only concerns I'm aware of in using a high volume or pressure pump is the added stress on the camshaft & distributor gears driving it. Some people put a tiny (1/16"or so) groove in the lower part of the distributor for more oiling on the gear. (a search will bring it up)

 

I've been running the Melling select #10550 with 25% higher volume for 3 years now and never had any problem . That's with a stock 5 qt pan on my 383 , so I would say you should be fine with the pump your using..I do have all my oil returns inlarged and smoothed to return oil to the pan a little faster.......WW

 

Cool responses thanks.After last weeks read I became very concerned

 

If you feel the need, you can drop the oil pan and change the pump without taking the car apart.

 

Call Melling or since you are in Flint, MI, take a ride down to see them. I believe they are still located in Jackson, MI. As an OEM and after market supplier, Melling manufacturers millions of pumps each year and they know more about oil pressure and delivery than the next million folks on these automotive forums.

I have used perhaps 25 or more Melling high-volume pumps over the years and have never experienced the pan running dry - but ask Melling to be sure since they are way smarter than I am about this. Also, I have never experienced a bearing failure from high oil pressure and have shimmed a lot of oil pressure relief springs/valves.

There are a lot of rumors that have been floating around regarding this topic forever and most are not remotely accurate. It is most interesting how over time, some rumors begin to be accepted as fact. Again, give Melling a phone call and talk with their service engineers. They will set you straight.

You are going to be fine with your set-up - there are probaly millions of Chevys running what you have and they have had no problems whatsoever. Virtually every bearing failure on a new engine can be traced to improper assembly or contamination.

Others have accurately addressed your concern regarding the rear main seal - it does not see oil pressure but rather is only exposed to splash from the rotating and reciprocating assemblies. Engine oil pressure is of no consequence here.

Some oil drain-back issues can be the result of combustion blow-by gasses flowing upward through the same holes as the oil is trying to return, since the blow-by gases are exiting the engine through the valve covers. Excessive combustion blow-by will allow the oil to be trapped under the valve covers. This is especially true with racing engine with lots of piston-to-cylinder clearance.

Again, you're going to be just fine. Call Melling for additional peace of mind.

Good luck -

Jake - -

 

Just because a guy is an expert on corvettes doesn't make him an expert on engines. As said you can change the pump in the car if you want. I'd run a m155 with the larger tube pickup if you do, it replaced the m55.

My personal experience with anyone in Flint is they are a lot of talk and poor service. In a bad economy and Flint is worse than everywhere(except Detroit) only the most cut-throat, thieving, lying, sell their own mothers survive. But maybe it's just me.

 

I am in Rhode Island.My Flint friend is family and before going out on his own he ASSEMBLED Corvette engines at the Flint engine assembly plant.He knew of differences between Corvette oil pump springs and normal SBC oil pumps.But I don't "put all my eggs in one basket" so I queried here.I have gotten excellent results thanks guys'.

 

I contacted Melling.Their tech recommends the "yellow" (stock)spring.And he states my oil pressure gage will read as max at operating speed/w the m55a as current.I am saddened I have to go back in there but i'm trying to think...."It is what it is" and better now than a fully assembled engine bay.

 

1st I mean no disrespect or personal attack, my view of Flint is my opinion and it's was intended as a view bassed on Flint auto shops. I saw your location under you user name and mine is not listed but I'm just outside Flint.

Building engines and assembling engines are two different things.

 

Hmmm... I find that a little optimistic (or pessimistic depending how you look at it), but if that's what they recommended. Of course it would mean another sale for them. Personally, I wouldn't be bothered by the extra 10 or 15lbs extra psi that h.p. pump will give you. (there's a part of me that wants to scream "Don't worry about it!!, but I respect your decision)

But Saginaw is gaining on ya.

 

You will be fine, you don't need to change the pump, it will not empty your pan. I run a HV pump on mine with no issues.

 

Same here

You would have to have some major issue to have all your oil go out the sump and not return the pressure will restrict flow, also would you not be watching your oil pressure with a new engine anyway. At the first sign of any oil pressure drop you would turn your engine off.
Anyway where is 5 litres of oil going to hide?

Do not forget there were many experiments run by oil companies, they would drain the oil and then run drive for 1,000 miles relying on the friction modifiers in oil attached to engine parts to protect the engine. They disassembled the engine afterwards and had no ill effects.

Well i would not try that with my engine but a momentary oil pressure drop will not kill an engine, only people ignoring the warning lights and racing their engine with no oil will.

I have a mellings high volume oil pump in my 383, she has survived a year so far.

Maybe bad engine builders use that excuse, clearances will determine oil pressure and volume of flow. That is the reason high performance engines have more clearance and large capacity oil pans.

 

I am cpmpletely comfortable/w my choice.The engine machine shop I stopped back at today also confirms this.I plastigaged all my crank bearings at between .001 to .0015 clearances so it's tight.

I wondered the same.

I'm not a dedicated mechanic,but I am a CNC machinist of over 30 years and am REALLY good at Desmodromics/Desmoquattros' also

 

You are a Duck' Dr!!...

 

A engine I built with all new parts including Melling oil pump would run great with high oil pressure. Having solid lifters to adjust the pumped oil would shoot up in the air and over the fenders.
Bad thing that would happen during a good street race, about the time I was into third gear a ways the oil pressure gauge would go to "Zero"
oil pressure and I would have to shift to neutral and turn the engine off.
Respecting all my money spent on my rebuild I only did this a couple of times and stopped racing.

 

I dunno, I've used big block oil pumps on my small blocks without any issue; personally, I like 'em.